Preparation method for sintering-resistant cu-beta zeolite catalyst, and use of sintering-resistant cu-beta zeolite catalyst

Abstract

The present invention relates to the technical field of petrochemical catalysis and to a preparation method for a sintering-resistant Cu-Beta zeolite catalyst and a use of the sintering-resistant Cu-Beta zeolite catalyst. The present invention uses hierarchically-porous dealuminated Beta zeolite modified by nest expansion as a carrier, and uses an improved ammonia evaporation method to load copper into the pores of the zeolite carrier. The core of the improved ammonia evaporation method is that isovolumetric impregnation is performed on the zeolite carrier by using a copper-ammonia complex solution, copper hydroxide is mainly deposited in the pores of the zeolite carrier, and once copper hydroxide is subjected roasting and hydrogen reduction treatment, highly dispersed nanometer and sub-nanometer copper particles can be directly formed at hydroxyl nest lattice defect sites in the pores of zeolite. The hierarchically porous dealuminated Beta zeolite carrier modified by nest expansion has strong hydroxyl nest accommodation capacity, and the copper particles obtain sintering-resistance by means of tight interaction with hydroxyl nests. A Cu-Beta catalyst prepared by the method provided by the present invention has high activity and good stability when applied to a reaction of preparing caprolactam by means of gas-solid phase hydrogen amination of caprolactone.

Description

Preparation method and application of anti-sintering Cu-Beta zeolite catalyst TECHNICAL FIELD

[0001] The present application belongs to the field of petrochemical catalysis technology, and relates to a preparation method and application of an anti-sintering Cu-Beta zeolite catalyst. BACKGROUND

[0002] Copper-based catalysts are widely used in alcohol dehydrogenation, carbonyl hydrogenation, ester hydrogenolysis, amination, hydrocarbon hydrogenation, isomerization, and C-C bond and C-Si bond hydrogenolysis reactions, etc. The outstanding advantages of copper-based catalysts are high selectivity, low price, and no pollution to the environment. However, easy deactivation is a problem that must be faced in the industrial application of copper-based catalysts. Poisoning deactivation (sulfur, chlorine) and coking deactivation are common phenomena in the industrial application of copper-based catalysts. However, these deactivation problems can generally be addressed through control of raw material purity, optimization of reaction conditions, and regeneration treatment. High-dispersed copper particles are prone to sintering and growing (Ostwald ripening), which is a difficult problem causing the deactivation of copper-based catalysts. This deactivation is usually irreversible and non-regeneratable, and thus has the greatest impact on industrial applications. The main reason for the easy sintering and growth of high-dispersed copper particles is that the ionic radius of copper metal is large, the melting point is low (1083℃), the Tammann temperature and Hüttig temperature are low. Supported copper catalysts can sinter at a temperature of 170℃. Some people have summarized the thermal stability of common metal catalysts, and given the following order: Ag < Cu < Pd < Fe < Ni < Co < Pt < Rh < Ru < Ir < Os < Re. As can be seen from the order, the thermal stability of copper is lower than that of most common metal catalysts.

[0003] In 1966, KANEGAFUCHI, BOSEKI KABUSHIKI KAISHA first disclosed a catalytic method for preparing caprolactam from caprolactone in a gaseous phase in British Patent GB1109540. The method is to first vaporize caprolactone and a certain amount of water, and then mix with ammonia and hydrogen gas, and the mixed gas is subjected to catalytic reaction at 120-350℃ under normal pressure through a copper chromite catalyst. The conversion rate of caprolactone can reach 100%, and the selectivity of caprolactam can reach 97%.

[0004] In 1972, KANEGAFUCHI, BOSEKI KABUSHIKI KAISHA disclosed a caprolactam production process using copper chromite as catalyst in U.S. Patent 3652549. The copper chromite catalyst was prepared by coprecipitation method using copper nitrate and ammonium dichromate as raw materials and ammonia as precipitant. The technical features of the catalyst preparation process include that the precipitate formed in the coprecipitation reaction is further soaked in dilute acetic acid solution after filtration, dehydration, low temperature drying (75-80°C, 20h) and high temperature decomposition. The catalyst precursor after soaking is treated by filtration, water washing and drying (125°C, 12h) to become catalyst. The catalyst is pressed into tablets before use in fixed bed reactor. The catalyst is also reduced by hydrogen at 200°C before use. The atomic ratio of chromium to copper in the copper chromite catalyst is 0.1-5, preferably 0.1-3. The catalyst can also contain a third metal component (Ba, Ca, Mg, Sr, Al, Ga, Ti, V, Mn, Fe, Co, Ni, Zn, Mo, Ru, Rh, Pd, Ag, Cd, Sn, Pd, As, Bi, Sb). The atomic ratio of the third metal component to copper is 0.001-1, preferably 0.01-0.2. The raw material for caprolactam production conforms to the general formula X-(CH2)4-COY. Wherein, X = CHO, -CH(OR)(OR1), -COOH, -COONH4, -CONH2, or COR2; Y = OH, ONH4, NH2, or OR3. The reaction is carried out in a fixed bed reactor in gas-solid phase, the reaction temperature is in the range of 170-300°C, and the hydrogen partial pressure is in the range of 0.1-1.5 atm. The feed also contains ammonia and water vapor, and their preferred amount (molar ratio to raw material) is in the range of 2-50 and 10-100, respectively. When dimethyl adipate is used as raw material, the reaction results of copper chromite catalyst containing a small amount of zinc are: raw material conversion rate is 99%, and caprolactam selectivity is 95%; the reaction results of copper chromite catalyst containing a small amount of Mo are: raw material conversion rate is 100%, and caprolactam selectivity is 96%.

[0005] In 1975, Japan's Teijin Corporation disclosed a catalytic process for the production of caprolactam from caprolactone or C1-C4 alkyl ester of 6-hydroxycaproic acid in US Patent 3888845. Specifically, the patent disclosed a process for the production of caprolactam from caprolactone or C1-C4 alkyl ester of 6-hydroxycaproic acid, hydrogen and ammonia as raw materials, through gas-solid phase catalytic reaction. The process is characterized by low reaction temperature and low reaction pressure, high conversion rate of caprolactone or C1-C4 alkyl ester of 6-hydroxycaproic acid, and high selectivity of caprolactam. The solid catalyst used in the process is composed of three parts: A, a kind of oxide carrier, selected from titanium oxide, aluminum oxide, silicon oxide and a composite of aluminum oxide and silicon oxide; B, the main metal component of the catalyst, copper; and C, the trace metal component of the catalyst, which can be nickel or chromium. The catalyst can be prepared by deposition precipitation method. Among them, the carrier is preferably anatase titanium oxide, the weight ratio of copper to the carrier can be selected in the range of 0.5-200, preferably 5-100, and more preferably 10-70; the atomic ratio of Ni(Cr) to Cu can be selected in the range of 0.001-1, preferably 0.005-0.25. The gas-solid phase catalytic reaction for the production of caprolactam from caprolactone or C1-C4 alkyl ester of 6-hydroxycaproic acid can be carried out at 200-320℃ and 0.01-2atm, preferably at 220-310℃ and 0.1-1.2atm. The optional range of hydrogen and ammonia dosage is 5-70(H2 / ester molar ratio) and 1-50(NH3 / ester molar ratio) respectively, and the preferred range is 10-50(H2 / ester molar ratio) and 2-25(NH3 / ester molar ratio) respectively. In addition, the process also emphasizes the importance of the molar ratio of hydrogen to ammonia and the addition of water in the reactor feed. In general, the use of appropriate molar ratio of hydrogen to ammonia is beneficial to improve the selectivity of the reaction. The addition of water in the feed of the reactor not only can reduce the side reaction and improve the selectivity of caprolactam, but also can delay the deactivation rate of the catalyst. The optional range of the molar ratio of hydrogen to ammonia is 0.2-30, and the preferred range is 0.5-15; the optional range of the molar ratio of water to ester is 0-50, and the preferred range is 5-30. Under the preferred conditions, the conversion rate of caprolactone can reach up to 99% when caprolactam is produced from caprolactone, and the selectivity of caprolactam can reach up to 90%. The problem is that the catalyst deactivates quickly due to carbon deposition. However, the patent provides two catalyst regeneration methods. One method is redox treatment, and the other method is steam treatment. The redox treatment actually regenerates the catalyst by burning carbon with molecular oxygen first, and then reducing the catalyst with hydrogen. The carbon burning with molecular oxygen can be carried out at a temperature range of 100-800℃, preferably at a temperature range of 150-500℃. The carbon burning time is 20 minutes to 20 hours; the hydrogen reduction after carbon burning can be carried out at a temperature range of 170-350℃, preferably at a temperature range of 170-270℃.The water vapor treatment can be carried out at a temperature of 100 to 500°C, preferably at a temperature of 200 to 400°C. The water vapor treatment is carried out for a period of 20 minutes to 20 hours. The water vapor treatment can also be carried out in the presence of hydrogen, and after the water vapor treatment the catalyst is preferably subjected to a reduction treatment with hydrogen. The hydrogen reduction can be carried out at a temperature of 170 to 350°C, preferably at a temperature of 170 to 270°C.

[0006] The above patent not only discloses an important use of copper-based catalyst in the reaction of caprolactone to caprolactam, but also provides a method for improving the anti-sintering performance of copper-based catalyst by adding chromium, nickel and other additives to the copper-based catalyst.

[0007] As is known, ε-caprolactam (CPL) is a white solid organic compound, most of which is used to produce polycaprolactam chips, and a small part of which is used to produce lysine and pharmaceutical intermediates. In the downstream products of polycaprolactam chips, nylon-6 fibers and engineering plastics consume about 70% and 20% of polycaprolactam chips, respectively. The remaining polycaprolactam chips are processed into packaging films and food preservation films.

[0008] Nylon-6 is the first synthetic fiber product developed in the world. The most prominent advantage of nylon-6 fiber is that its wear resistance is higher than that of all other fibers. It is 10 times higher than that of cotton and 20 times higher than that of wool. At the same time, the strength of nylon-6 fiber is 1-2 times higher than that of cotton and 4-5 times higher than that of wool, and is 3 times that of viscose fiber. Adding a small amount of polyamide fiber to blended fabrics can greatly improve their wear resistance, elastic recovery rate and folding breaking resistance. In addition, nylon-6 fiber also has good moisture absorption and dyeing properties. Nylon-6 fiber can be used as civilian silk and industrial silk. Nylon civilian silk is used to make shirts, sweaters, pajamas, carpets, blankets, curtain lines and luggage, etc.; industrial silk is used to make tents, automobile tires, transmission belts, hoses, cables, fishing nets, ropes, insulating materials, etc.

[0009] At present, the benzene process caprolactam process is the mainstream process for producing caprolactam. This process mainly includes three basic processes of benzene to cyclohexanone, cyclohexanone to cyclohexanone oxime, and rearrangement of cyclohexanone oxime to caprolactam.

[0010] As is well known to those skilled in the art, the traditional benzene process for caprolactam has many serious problems. However, in recent years, some successful improvements have been made to the traditional benzene process for caprolactam in accordance with the requirements of green chemistry and atom economy, including the replacement of the process of non-selective hydrogenation of benzene to cyclohexane and the process of air oxidation of cyclohexane to cyclohexanone with the process of selective hydrogenation of benzene to cyclohexene and the process of hydration and dehydrogenation of cyclohexene to cyclohexanone in the step of preparing cyclohexanone from benzene; and the replacement of the hydroxylamine sulfate (HSO) process, which has the problems of by-product ammonium sulfate and equipment corrosion, with the process of catalytic ammonoximation of cyclohexanone using titanium silicalite (TS-1) in the step of preparing cyclohexanone oxime from cyclohexanone.

[0011] However, the improved benzene process for caprolactam still has many shortcomings, including: (1) low efficiency of the process of selective hydrogenation of benzene to cyclohexene and the process of hydration of cyclohexene to cyclohexanol; (2) large solvent consumption, fast deactivation of the TS-1 catalyst and large consumption of the TS-1 catalyst in the process of ammonoximation of cyclohexanone (TS-1 is expensive. The production of cyclohexanone oxime from cyclohexanone by the liquid phase reaction has the problem of invalid loss of the TS-1 catalyst due to the dissolution of the skeleton silicon in the strong alkaline environment); and (3) the liquid phase Beckmann rearrangement process (the current mainstream process) still uses fuming sulfuric acid as the catalyst, which not only causes corrosion of the equipment but also produces 1.5-1.8 tons of ammonium sulfate per ton of caprolactam. The gas phase Beckmann rearrangement technology, which is highly expected by people, has the problem of fast deactivation of the catalyst, and people have encountered setbacks in their efforts to replace the liquid phase Beckmann rearrangement process with the gas phase Beckmann rearrangement process.

[0012] In view of the current technical situation of the benzene process for caprolactam and the problems faced by the development of new processes, people in the field are seeking a new process for the efficient preparation of caprolactam that has no low-value by-products (such as ammonium sulfate), no problems of equipment corrosion and environmental pollution, high atom utilization rate and low energy consumption (low carbon emissions).

[0013] It can be seen from the early efforts of Japan Kaneka Spinning Co., Ltd. and Japan Teijin Corporation that the preparation of caprolactam from caprolactone can save the Beckmann rearrangement step of cyclohexanone oxime in the existing benzene method caprolactam process and can avoid the problems existing in the cyclohexanone ammoximation step, which is a new route for caprolactam production with great application potential. However, at present, the technical route for preparing caprolactam from caprolactone raw materials has not been paid attention to. The existing process methods and catalysts for preparing caprolactam from caprolactone are mainly disclosed in patents and papers before the 1970s. In general, the reaction process methods proposed in the early stage are mainly divided into non-catalytic method (US3000879, US3000880, US3317516, US3317517, GB1121109, US3320241, CA770148, US3401161, US3497500, published Japanese literature Kobunshi Ronbunshu, 58(12), 679-684 (2001)) and catalytic method (US2817646, GB1109540, US3652549, US3888845, DE102012006946A1, CN108774172A, published literature Bulletin of the Chemical Society of Japan, 1977, (7), p. 1013-1017, published literature ChemSusChem, 2022, 15(16)). Among them, the non-catalytic method needs high temperature and high pressure reaction conditions. Due to the problems of thermodynamic limitation and generation of by-products, the caprolactam yield of the non-catalytic method is low. In contrast, the reaction conditions of the catalytic method are mild, which is not only beneficial to the reaction thermodynamics, but also beneficial to avoid side reactions, reduce equipment investment, reduce energy consumption and reduce production cost. Thus, it is beneficial to industrial application. However, the catalytic method needs catalysts with high activity, high selectivity and strong anti-deactivation ability, and the existing catalysts cannot meet the needs of industrial application. SUMMARY

[0014] The purpose of the present application is to provide a preparation method and application of an anti-sintering Cu-Beta zeolite catalyst.

[0015] Specifically, the anti-sintering Cu-Beta zeolite catalyst provided by the application is a catalyst prepared by loading copper in the pores by using an improved ammonia evaporation method, with the multi-level pore dealuminized Beta zeolite modified by cavitation as the carrier. The multi-level pore dealuminized Beta zeolite carrier is obtained by subjecting the Beta zeolite matrix containing multi-level pores to acid dealuminization treatment. The cavitation modification refers to a Beta zeolite carrier modification technology for further using weak organic alkali control desilication technology to make the hydroxyl cavities generated by dealuminization larger, so as to better accommodate and stabilize the nano and sub-nano copper particles. The catalyst provided by the application is used for the gas-solid phase catalytic reaction of caprolactam prepared by hydrogenation of caprolactone.

[0016] It is found through research that, for the gas-solid phase catalytic reaction of caprolactam prepared by hydrogenation of caprolactone, from the perspective of catalytic activity and selectivity, the supported copper-based catalyst has the most industrial application prospects. However, from the perspective of catalyst stability, the deactivation problem is the biggest challenge for the industrial application of the supported copper-based catalyst. The deactivation reason of the copper-based catalyst in the gas-solid phase catalytic reaction of caprolactam prepared by hydrogenation of caprolactone is not only carbon deposition. The sintering problem of the highly dispersed copper particles is also an important reason for the deactivation of the catalyst. As known by those skilled in the art, carbon deposition deactivation belongs to temporary deactivation of the catalyst, and the catalytic activity can generally be restored by various regeneration methods, thereby prolonging the service life of the catalyst. In contrast, sintering deactivation generally belongs to permanent deactivation of the catalyst, and has the greatest impact on the service life of the catalyst.

[0017] The Cu-Beta zeolite catalyst and the preparation method thereof provided by the application have the following main benefits. Firstly, the dispersion and stability of the loaded copper particles by the hydroxyl cavities of the dealuminized Beta zeolite are utilized, and the weak organic alkali control desilication technology is used to make the hydroxyl cavities generated by dealuminization larger, increase the contact surface of the hydroxyl cavities and the copper particles, and further strengthen the stability of the loaded copper particles by the hydroxyl cavities of the dealuminized Beta zeolite. In addition, the Cu-Beta zeolite catalyst and the preparation method thereof provided by the application also introduce the multi-level pore structure into the zeolite carrier, increase the flexibility (structural variability) of the zeolite carrier, and thus add the ability of the hydroxyl cavities of the zeolite carrier to further stabilize the copper particles by swelling deformation. These measures enable the Cu-Beta zeolite catalyst to be used without adding anti-sintering additives such as chromium and nickel.

[0018] In summary, the anti-sintering Cu-Beta zeolite catalyst and the preparation method thereof provided by the application have the following main technical features.

[0019] Firstly, the anti-sintering Cu-Beta zeolite catalyst and the preparation method thereof provided by the application use the multi-level pore dealuminized Beta zeolite modified by cavitation as the carrier.

[0020] The catalysts for the catalytic conversion of caprolactone to caprolactam described in the prior art patents and academic papers are mainly non-supported bulk copper chromite catalysts and copper catalysts supported on amorphous single oxide carriers (such as titanium oxide, aluminum oxide, silicon oxide) and binary composite oxide carriers (such as silicon oxide and aluminum oxide) with the addition of a second metal component of nickel or chromium. As is known to those skilled in the art, the specific surface area of non-supported copper chromite catalysts is small, and the exposed metal active sites are few, so the amount of metal used is large and the catalytic efficiency is low; the use of amorphous oxide carriers (single oxide carriers and binary composite oxide carriers) to support copper, copper-nickel and copper-chromium can overcome the problems of non-supported catalysts, but the supported copper catalysts have the problem of easy sintering and deactivation, which is a great challenge for industrial application. The addition of chromium to the supported copper catalyst to form a copper chromite phase can improve the sintering resistance of the supported copper catalyst. However, chromium is a metal that is subject to restricted use. In clinical practice, chromium and its compounds mainly affect the skin, respiratory and digestive systems of humans, and even a very low chromium content can have a strong toxic effect on the human body. Therefore, catalysts containing chromium will encounter great difficulties in the processes of preparation, use and harmless treatment of waste catalysts. The addition of nickel to the supported copper catalyst can also improve the sintering resistance of copper. However, our research results show that for the reaction of caprolactone to caprolactam, the introduction of a large amount of nickel into the supported copper catalyst can significantly reduce the ability of the catalyst to catalyze the gas-solid phase hydrogenation of caprolactone to caprolactam. For example, under the same conditions, the copper-amorphous silica catalyst (10 wt. % Cu) prepared using fumed silica (fumed silica) as the carrier, when a small amount of nickel (Ni:Cu = 0.3) is added, the ability of the catalyst to catalyze the hydrogenation of caprolactone to caprolactam decreases by 15-20%. In the relevant patent (US3888845), nickel is used as an additive for the preferred supported copper catalyst, but its addition amount is strictly limited to the range of Ni:Cu = 0.001-1 (atomic ratio), preferably 0.005-0.25. It is needless to say that the addition of a small amount of nickel can improve the sintering resistance of the supported copper catalyst, but the effect of a small amount of nickel alone is not enough to properly solve the problem of sintering and deactivation of the supported copper catalyst.

[0021] The present application uses a multi-level pore dealuminated Beta zeolite modified by channelling to prepare a supported copper catalyst, aiming to take advantage of the structural flexibility characteristics of the multi-level pore structure and the expansion effect of the channelling modification to strengthen the dispersion and stabilization of the copper particles by the hydroxyl pits of the dealuminated Beta zeolite carrier, so as to prepare a supported copper-based catalyst with strong sintering resistance without the addition of metal additives such as chromium and nickel, which can be used for the gas-solid phase catalytic reaction of caprolactone hydrogenation to caprolactam.

[0022] The main idea of the present invention comes from the inventors' own previous work. In the previous work, the inventors have conducted in-depth research on the physicochemical properties and catalytic functions of the hydroxyl nest lattice defect sites in the MFI zeolite family (ZSM-5, B-ZSM-5, Silicalite-1 (S-1) and TS-1). Some representative research works are described in the following publications: Silicalite-1 zeolite acidification by zinc modification and its catalytic properties for isobutane conversion, RSC Advances, 2018, 33(8), p. 18663-1867; Pt supported on Zn modified silicalite-1 zeolite as a catalyst for n-hexane aromatization, JOURNAL OF ENERGY CHEMISTRY, 2018, (36), p. 96-103; Operando Dual Beam FTIR Study of Hydroxyl Groups and Zn Species over Defective HZSM-5 Zeolite Supported Zinc Catalysts, Catalysts, 2019, 1(9), p. 100; Effect of Zeolitic Hydroxyl Nests on the Acidity and Propane Aromatization Performance of Zinc Nitrate Impregnation-Modified HZSM-5 Zeolite, Industrial&Engineering Chemistry Research, 2020, 37(59), p. 16146-16160. Liu Guodong. Research on the Surface Acidity and Catalytic Performance of ZnO Modified Nano Silicalite-1 Zeolite[D]. Dalian University of Technology, 2020.; Lin Long. Characterization, Modification and Catalytic Performance of Defective ZSM-5 Zeolite[D]. Dalian University of Technology, 2022.). In short, the above research results show that the silicon hydroxyl groups in the hydroxyl nest lattice defect sites are prone to form hydrogen bonds, and their chemical reactivity is much higher than that of the isolated silicon hydroxyl groups on the outer surface of the zeolite crystal.In addition, it is particularly worth mentioning that the inventors have found that zinc oxide preferentially locates in the hydroxyl pocket defect sites of the defective all-silica zeolite S-1 and the defective ZSM-5 zeolite in the research of zinc nitrate impregnation and preparation of zinc oxide modified catalysts. Moreover, the zinc oxide located in the hydroxyl pocket defect sites of the zeolite is highly dispersed sub-nanometer zinc oxide species. These research experiences provide important scientific guidance for the present application.

[0023] However, the present application does not use the defective MFI zeolite (for example, the defective all-silica zeolite S-1 and the boron-depleted B-ZSM-5 zeolite) as the carrier for the preparation of the copper supported catalyst, but uses the dealuminated Beta zeolite as the carrier for the preparation of the copper supported catalyst. This is not because the hydroxyl pocket defect sites in the defective MFI zeolite (for example, the defective all-silica zeolite S-1 and the boron-depleted B-ZSM-5 zeolite) cannot disperse and stabilize copper particles, nor because the copper supported catalyst prepared by using the defective MFI zeolite (for example, the defective all-silica zeolite S-1 and the boron-depleted B-ZSM-5 zeolite) as the carrier is ineffective for the catalysis of the gas-solid phase reaction of caprolactam from caprolactone. Rather, it is because the cylindrical pores of the MFI family zeolite are ten-membered rings, and when the loading amount of copper is slightly large, the effective size of the pores will be significantly reduced, which is not conducive to the intraparticle diffusion of the reactant caprolactone (seven-membered ring), nor to the formation and intraparticle diffusion of the caprolactam product which is also a seven-membered ring, thus not conducive to the preparation of a catalyst with high activity, high selectivity and strong anti-deactivation ability.

[0024] As a crystalline porous catalytic material, Beta zeolite has similar advantages to MFI zeolite, such as (1) both are high-silica zeolites, thus having high thermal stability and hydrothermal stability, good regeneration performance, and allowing repeated regeneration and reuse after being made into a catalyst; (2) both have cylindrical pores and a three-dimensional intersecting pore system, thus having good pore diffusivity and strong anti-clogging ability, which is conducive to maintaining the activity stability of the catalyst in a long period of continuous reaction. In addition, Beta zeolite has unique features compared to MFI zeolite. On the one hand, the three-dimensional cylindrical pores of Beta zeolite are all large pores with a twelve-membered ring. In the three-dimensional pore system of Beta zeolite, there is a group of "Z" type curved pores parallel to the

[0001] direction with an elliptical cross-section and a pore size of 0.56 nm x 0.65 nm; there are also two groups of straight pores parallel to the

[0100] and

[0010] directions, which also have an elliptical cross-section and a pore size of 0.66 nm x 0.77 nm. In comparison, the three-dimensional cylindrical pores of MFI zeolite are all mesopores with a ten-membered ring. In the pore system of MFI zeolite, there is a group of straight pores parallel to the (100) crystal face with a nearly circular cross-section and a pore size of 0.53 nm x 0.56 nm, and two groups of "Z" type curved pores parallel to the (010) crystal face with an elliptical cross-section and a pore size of 0.51 nm x 0.55 nm. It can be imagined that the pore system of Beta zeolite is more suitable for the intraparticle diffusion of the reactant caprolactone (seven-membered ring) and the formation and intraparticle diffusion of the product caprolactam (also a seven-membered ring), and thus is more conducive to preparing a catalyst with high activity, high selectivity, and strong anti-inactivation ability. In fact, Beta zeolite is the only zeolite in industrialized zeolite catalytic materials that has the advantages of high molar ratio of silicon to aluminum oxide, a three-dimensional intersecting pore system, and all pores being large pores with a twelve-membered ring.

[0025] On the other hand, the framework aluminum of Beta zeolite can be easily removed by acid treatment to produce a high density of hydroxyl pit defect sites on the crystal framework. This feature is not common in industrialized zeolite catalytic materials and is unmatched by MFI zeolite. When Beta zeolite is subjected to acid dealumination treatment, four Si-O-Al bonds are required to be acid-cleaved for each framework aluminum removed ([Al-(OSi)4] - + 4H2O = [Al(OH)4] - + 4≡Si-OH, [Al(OH)4] - + 4H + = Al 3+ + 4H2O, and the overall reaction equation is [Al-(OSi)4] - + 4H + = Al 3++4≡Si-OH), resulting in a hydroxyl pocket lattice defect site surrounded by four silicon hydroxyl groups (≡Si-OH). In MFI zeolite, the hydroxyl pocket lattice defect site of the defective all-silica zeolite S-1 is randomly formed during hydrothermal synthesis of S-1 zeolite in an alkaline medium, and the number and distribution are poorly controllable; the framework aluminum content of ZSM-5 zeolite can be adjusted in a wide range, and the lower limit of the molar ratio of silicon to aluminum (Si / Al) can reach about 10, and the upper limit can be an all-silica zeolite, i.e., Silicalite-1 (S-1). However, it is difficult to completely remove the framework aluminum of ZSM-5 zeolite. Therefore, in the research on the preparation of titanium atom hybrid ZSM-5 zeolite by post-synthesis method, the general method is to first synthesize ZSM-5 zeolite containing boron (B-ZSM-5), and then remove boron from the B-ZSM-5 zeolite to obtain a ZSM-5 zeolite carrier with a high density of hydroxyl pocket defect sites on the framework.

[0026] In summary, the main reason why the MFI zeolite (for example, defective all-silica zeolite S-1 and boron-removed B-ZSM-5 zeolite) with a hydroxyl pocket lattice defect site is not used as a carrier for preparing a copper-based catalyst in the present application is that, for the purpose of the present application, the Beta zeolite, which has three advantages of a high molar ratio of silicon to alumina oxide framework, a three-dimensional twelve-membered ring cross-channel system, and easy complete removal of framework aluminum, is a material advantage that is difficult to match. In addition, the Beta zeolite is a catalytic material that has been industrialized for a long time, that is, it can be obtained in large quantities from the market, and it can also be easily prepared by a hydrothermal synthesis method.

[0027] The multi-level channel structure can increase the flexibility (structural variability) of the framework of the zeolite carrier. During the loading of copper (especially during the high-temperature calcination link), the structural variability of the framework of the zeolite carrier can be utilized by the hydroxyl pockets of the zeolite carrier. The hydroxyl pockets of the zeolite carrier utilize the structural variability of the framework of the zeolite carrier to expand and deform, resulting in an increased ability to stabilize copper particles. This is an unexpected finding of the present application.

[0028] As is known to those skilled in the art, the crystalline aluminosilicate catalytic materials (i.e. zeolite catalytic materials) that have been industrialized and applied are basically microporous zeolite materials (main pore diameter < 1 nm). In general, implanting mesopores (2-50 nm pore diameter range belongs to the category of mesopores) in microporous zeolites to make micropores and mesopores interconnect and form a more open multi-level pore system can reduce the internal diffusion resistance of reactants and products with larger molecular kinetic diameters (Mesoporous beta zeolite obtained by desilication, Microporous and Mesoporous Materials 114 (2008) 93-102; Hierarchically porous BEA stannosilicates as unique catalysts for bulky ketone conversion and continuous operation, J. Mater. Chem. A, 2016, 4, 1373; Hierarchical Ti-beta with a three-dimensional ordered mesoporosity for catalytic epoxidation of bulky cyclic olefins, New J. Chem., 2021, 45, 10303), which is beneficial to the preparation of zeolite catalysts with high reaction activity and strong resistance to carbon deposition deactivation.

[0029] For the gas-solid phase hydrogenation reaction of caprolactam from caprolactone, the Beta zeolite with multi-level pores (multi-level pore Beta zeolite) is also beneficial to the reaction activity and carbon deposition resistance of the catalyst. This is because the gas-solid phase hydrogenation reaction of caprolactam from caprolactone involves caprolactone reactants and caprolactam products, both of which have seven-membered ring molecular structures, and they are very active polymer monomers. Using multi-level pore Beta zeolite as a carrier can help reduce the micropore diffusion resistance of caprolactone and caprolactam and improve the accessibility of active centers in micropores. On the one hand, reducing the micropore diffusion resistance of caprolactone and caprolactam helps to reduce the opportunity for caprolactone and caprolactam to polymerize and coking in the pores of the catalyst. On the other hand, reducing the micropore diffusion resistance of caprolactone and caprolactam and improving the accessibility of active centers in micropores will also help to improve the reaction activity of the catalyst.

[0030] However, the inventors have unexpectedly found that the use of the anisotropic aluminated Beta zeolite with hierarchical pores as the support for the preparation of Cu-Beta zeolite catalysts also helps to disperse and stabilize the nano and sub-nano copper particles and to improve the sintering resistance of the catalyst. This will be demonstrated by the experimental results in the examples of the present invention. Although the anisotropic aluminated Beta zeolite support can be obtained by dealumination of a hydrothermally synthesized hierarchical pore Beta zeolite (Chem. Mater., 2011, 23, 4301-4310; J. Am. Chem. Soc., 2014, 136, 2503-2510), the hydrothermal synthesis of hierarchical pore Beta zeolite requires the use of a mesopore template, which is costly. Therefore, the present invention chooses to prepare the hierarchical pore anisotropic aluminated Beta zeolite support by a post-synthetic method. In brief, the post-synthetic strategy chosen by the present invention is to first treat the Beta zeolite precursor with a solution of inorganic or organic base to obtain a mesoporous Beta zeolite precursor, and then to treat the mesoporous Beta zeolite precursor with acid to obtain the hierarchical pore anisotropic aluminated Beta zeolite support. Hydroxides of alkali metals and carbonates of alkali metals are both usable inorganic bases for the desilication of zeolites. Quaternary ammonium bases (such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, etc.) are usable organic bases for the desilication of zeolites. But the usable inorganic bases and organic bases are not limited to these few, and the inorganic bases and organic bases disclosed in related invention patents and other public literature can all be suitable for the purpose of preparing the hierarchical pore Beta zeolite precursor described in the present invention. But the hydroxides of alkali metals and carbonates of alkali metals, especially sodium hydroxide, are a relatively inexpensive inorganic strong base, and thus are more suitable for use in the present invention. The desilication of the Beta zeolite precursor with an aqueous solution of sodium hydroxide to prepare the hierarchical pore Beta zeolite precursor is a low-cost and simple post-synthetic strategy.

[0031] The hierarchical pore anisotropic aluminated Beta zeolite support also needs to be anisotropically modified before use to enlarge the hydroxyl pockets produced by dealumination so as to better accommodate and stabilize the nano and sub-nano copper particles. The anisotropic modification refers to the supplementary modification of the hierarchical pore anisotropic aluminated Beta zeolite support with an aqueous solution of a small molecule weak organic base to controllably remove 1-2 silicon atoms from the walls of the hydroxyl pockets, thereby expanding the small hydroxyl pockets originally with only one framework atom deficiency (acid dealumination) to larger hydroxyl pockets with 2-3 framework atom deficiencies.

[0032] This is the enlightenment obtained after a large number of preliminary exploratory studies. Since the atomic radius of copper is much larger than the ionic radius of aluminum Therefore, the small hydroxyl pocket generated by dealumination of the Beta zeolite can only accommodate at most one copper atom. Obviously, the active silanol in the hydroxyl pocket of the Beta zeolite only interacts with one copper atom, which inevitably limits the dispersion and stabilization ability of the copper particles.

[0033] If 1-2 silicon atoms can be controllably removed from the hydroxyl pocket edge of the hierarchical pore dealuminated Beta zeolite, thereby expanding the small hydroxyl pocket with only one framework atom deficiency (acid dealumination) to a larger hydroxyl pocket with 2-3 framework atom deficiencies, the dispersion and stabilization ability of the hydroxyl pocket for the copper particles can be enhanced. According to this idea, the inventors carried out a large amount of exploratory research work using a weakly basic organic base aqueous solution. Compared with alkali metal hydroxide (inorganic strong base) solution and quaternary ammonium base solution (organic strong base), the weakly basic organic base has weak dealuminating ability and can only remove a small amount of silicon, so it is easy to achieve controllable dealumination. At the same time, the weakly basic organic base has weak dealuminating ability, so it is also easy to achieve selective dealumination, i.e., mainly removing silicon from the weakest part of the Beta zeolite framework, i.e., the hydroxyl pocket deficiency site. It is found that the aqueous solution of small molecule aliphatic amine (methylamine, ethylamine, propylamine, t-butylamine, isopropylamine, n-butylamine, diethylamine, ethylenediamine, isobutylamine, triethylamine) and small molecule alcohol amine (ethanolamine, diethanolamine, triethanolamine, isopropyl alcohol amine, diisopropyl alcohol amine) has a controllable dealumination effect when it is contacted with the hierarchical pore dealuminated Beta zeolite, i.e., it exhibits a "pocketing" effect on the hydroxyl pocket of the Beta zeolite. Compared with general organic bases, the small molecule aliphatic amine and alcohol amine have the advantages of good water solubility and small dosage. In order not to make the specification of the present application too complex, the present application only takes ethanolamine as an example to modify the dealuminated Beta zeolite by pocketing. The pocketing modification is essentially an alkali-catalyzed hydrolysis dealumination modification ([(OSi)3-O-SiOH]+3H2O=Si(OH)4+3≡Si-OH), and for each silicon atom removed (in the form of orthosilicic acid (Si(OH)4)), i.e., for each silicon atom "chiseled" from the wall of the hydroxyl pocket (in the form of Si(OH)4), three silicon hydroxyl groups (≡Si-OH) will be generated on the new wall of the hydroxyl pocket.

[0034] Secondly, the anti-sintering Cu-Beta zeolite catalyst and the preparation method thereof provided by the present application are mainly characterized in that the copper is loaded on the dealuminated Beta zeolite support modified by pocketing by using an improved ammonia evaporation method.

[0035] The improved ammonia evaporation method copper loading technology, its core is to use copper ammonia complex solution impregnation zeolite carrier with equal volume, in this process, rely on the capillary condensation of zeolite carrier channel into the zeolite channel most of the copper ammonia complex solution, so that in the process of ammonia evaporation generated copper hydroxide directly deposited in the channel of Beta zeolite. Therefore, in the subsequent drying, calcination and hydrogen reduction treatment process, copper hydroxide can be converted into copper oxide in the zeolite channel, and further converted into sub-nanometer and nanometer particles of metal copper. The sub-nanometer and nanometer particles of metal copper can be directly captured by the hydroxyl hole lattice defect site mainly existing in the zeolite channel after the hole treatment, thereby being dispersed and stabilized in time and more effectively.

[0036] As known to those skilled in the art, ammonia evaporation method is one of the most commonly used methods for preparing copper-based catalysts. Ube Industries Ltd. (US4 440 873 (1984), EP0 064 241 B1 (1985)) first proposed using ammonia evaporation method to prepare Cu / SiO2 catalyst for the purpose of dimethyl oxalate gas-solid phase hydrogenation to glycol and glycolate. The specific method of the earliest ammonia evaporation method is as follows: first, prepare a copper ammonia complex solution. First, dissolve a soluble copper-containing compound in water to obtain an aqueous solution containing copper ions, then add an appropriate amount of concentrated ammonia to the aqueous solution containing copper ions to make the pH value greater than 10, for example, to make the pH value reach 10-12. Thus, a deep blue transparent solution containing copper ammonia complex can be obtained; second, mix the silica sol as the precursor of SiO2 carrier with the copper ammonia complex. That is, add the silica sol to the deep blue transparent solution containing the copper ammonia complex, and mix it uniformly by stirring. This stirring and mixing process can be carried out at normal pressure and under pressure, at room temperature to 150°C; third, ammonia evaporation treatment. That is, the mixture containing the copper ammonia complex is subjected to ammonia evaporation treatment to obtain a solid catalyst precursor. The ammonia evaporation treatment can be carried out under pressure and under reduced pressure, and the preferred temperature range is 60-90°C; fourth, pretreatment of the solid catalyst precursor. This step refers to the pretreatment of the solid catalyst precursor before hydrogen reduction, including drying, water washing. In addition, pre-calcination treatment can also be selected. The temperature range of pre-calcination treatment is 400-800°C, preferably 500-750°C; fifth, hydrogen reduction treatment. The pretreated solid catalyst precursor is subjected to hydrogen reduction treatment. The hydrogen reduction time is 1-15h, and the reduction temperature range is 150-500°C, preferably 200-400°C.

[0037] Examples of soluble copper-containing compounds that can be used to formulate copper ammonia complex solutions are given in US Patent 4 440 873, including copper nitrate, copper sulphate, copper oxalate, copper chloride and copper acetate, with copper nitrate being the preferred option. In Example 1 of that patent there is the following description of the preparation of a Cu / SiO2catalyst by the ammonia evaporation method: (1) 19.0 g of copper nitrate (Cu(NO3)2.3H2O) was dissolved in 200 ml of water to give an aqueous solution containing copper ions, to which was then added 60 ml of a concentrated aqueous ammonia solution to give a deep blue solution containing a copper ammonia complex, the pH of which was adjusted to 11-12; (2) 66.6 g of a silica sol (30 wt.% SiO2) was added to the copper ammonia complex solution and stirred at room temperature for several hours; (3) the reaction mixture of step (2) was subjected to ammonia evaporation at elevated temperature. Ammonia evaporation was continued until most of the water was also evaporated, to give a solid product; (4) the solid product was dried at 120°C for 12 h. The dried product was then subjected to water washing and then to drying again. The drying conditions were 140°C x 14 h; (5) the dried product was subjected to hydrogen reduction. The reduction conditions were 350°C x 2-3 h. The Cu / SiO2catalyst so prepared contained about 20 wt.% of copper.

[0038] It can be seen from the above that the earliest proposed ammonia evaporation method for preparing Cu / SiO2 catalyst has the following characteristics: on the one hand, the amorphous silica support is not pre-prepared, but is generated in situ during the ammonia evaporation process using a silica sol as a precursor. Specifically, during the ammonia evaporation process, the silica sol is converted into silica gel. At the same time, the copper ammonia complex loses ammonia to form copper hydroxide precipitate, which is deposited on the surface of the silica gel. This process has dynamic characteristics. That is, the silica gel particles continue to grow after being generated, and at the same time, the copper hydroxide precipitate is continuously generated. The silica gel particles grow on one side, and the copper hydroxide precipitate is deposited and reacts on the surface thereof, resulting in a layer-by-layer mixed loading state of the silica gel and the copper hydroxide. Later, researchers in the field pointed out (J. Catal. 257 (2008) 172-180) that this ammonia evaporation method essentially belongs to a homogeneous deposition-precipitation method, and the prepared Cu / SiO2 catalyst is a layered copper silicate. On the other hand, a diluted copper ammonia complex solution is prepared and used. The volume of this copper ammonia complex solution is greatly excessive relative to the liquid holding capacity (pore volume) of the finally generated silica gel, and the water solvent therein needs to be removed by post-processing operations such as filtration or evaporation, and the loading and dispersion mechanism of copper on the silica support is deposition-precipitation, that is, the silica gel particles grow on one side, and the copper hydroxide precipitate is deposited and reacts on the surface thereof, and the layer-by-layer mixing of the silica gel and the copper hydroxide achieves a uniform loading state. It can be imagined that if the silica support is not generated during the ammonia evaporation process, but is pre-prepared, then using this diluted and volumetrically excessive (the volume of the solution is greatly excessive relative to the total pore volume of the silica support) copper ammonia complex solution for ammonia evaporation operation will inevitably result in a large amount of copper hydroxide being deposited on the external surface of the support particles, leading to the non-uniform consequence of less copper loaded in the pores of the support and more copper loaded outside the pores of the support.

[0039] Thereafter, some scholars in the study according to the earliest proposed ammonia evaporation method for the preparation of amorphous oxide carrier supported copper-based catalysts for the purpose of oxalic acid dimethyl ester gas solid phase hydrogenation to ethylene glycol. For example, in the published literature J. Catal. 257 (2008) 172-180 and Appl. Catal. A: Gen. 458 (2013) 82-89, there are relevant research reports, the amorphous oxide carrier involved is silicon dioxide and binary compound of silicon dioxide and titanium dioxide. In the case of silicon dioxide as the carrier, silica sol (Ludox AS-40) is used as the precursor of the carrier. In the case of binary compound of silicon dioxide and titanium dioxide as the carrier, silica sol (JN30, Qingdao Haiyang Chem. Co., Ltd.) and titanium dioxide sol are used as the precursors of the carrier. After ammonia evaporation (the pH value of the slurry is reduced to 6-7), the amorphous oxide supported copper hydroxide solid product is obtained by filtration.

[0040] Some researchers improved the ammonia evaporation method in the preparation of Cu / SiO2 catalysts for the gas-solid phase hydrogenation of dimethyl oxalate. In the published literature J. Am. Chem. Soc. 2012, 134, 13922 - 13925 and J. Catal. 297 (2013) 142-150, researchers reported the ammonia evaporation hydrothermal (AEH) method. In fact, the AEH method is a water thermal treatment of the ammonia evaporation product (slurry containing copper hydroxide / silica gel precipitate, pH = 6-7) of the traditional ammonia evaporation method (the earliest ammonia evaporation method) in a high-pressure synthesis kettle at 190-210℃ for 12h, and then the solid product is subjected to conventional filtration, washing, drying, calcination and hydrogen reduction treatment. In other words, the AEH method is not an improvement of the ammonia evaporation method itself, but a water thermal post-treatment before the conventional post-treatment of the ammonia evaporation method. It is important to note that the operation before the water thermal post-treatment of the AEH method is the same as that of the traditional ammonia evaporation method, the silica support is generated in situ using silica sol as the precursor, and the water solvent of the diluted and volume-excess copper ammonia complex solution is finally removed by filtration; in the published literature J. Phys. Chem. C 2015, 119, 13758-13766, researchers added urea as a deposition precipitate aid in the solution when preparing the copper ammonia complex solution. Other methods are the same as the traditional ammonia evaporation method. The silica support is generated in situ using silica sol (Ludox AS-40, 40wt.%SiO2) as the precursor, and the water solvent of the diluted and volume-excess copper ammonia complex solution is finally removed by filtration; in the published literature Natural Gas Chemical Industry (C1 Chemistry and Chemical Industry), 2013, 38(3): 43-47, Natural Gas Chemical Industry (C1 Chemistry and Chemical Industry), 2014, 39(5): 31-34 and Journal of Shenyang University of Chemical Technology, 2016, 30(3): 212-216, researchers used pre-made JN-25 type basic silica gel (primary particle size 10nm, Qingdao Marine Chemical Co., Ltd.) as the carrier of the Cu / SiO2 catalyst prepared by the ammonia evaporation method, and added a certain amount of silica sol as the precursor for in-situ generation of silica gel carrier to achieve uniform deposition of the precipitate. In order to overcome the problems caused by the reduction of the amount of silica sol when using pre-made JN-25 type basic silica gel as the carrier of the Cu / SiO2 catalyst, researchers also tried to add cetyltrimethylammonium bromide (CTAB) surfactant to the configured copper ammonia complex aqueous solution to disperse the silica sol and generate mesoporous in the in-situ generated silica gel.Other methods are no different from the traditional ammonia evaporation method; in the public literature RSC Adv., 2015, 5, 29040-29047 and Applied Catalysis A: General 509 (2016) 66-74, researchers use pre-prepared titanium dioxide (P25, Degussa Co., Ltd) as the carrier of the Cu / TiO2 catalyst prepared by the ammonia evaporation method, and other methods are no different from the traditional ammonia evaporation method. It should be noted that the P25 type TiO2 carrier belongs to a low specific surface carrier, and its capillary pores are not developed, so in the prepared Cu / TiO2 catalyst, it does not have a uniform deposition precipitation effect, that is, the copper hydroxide loaded mainly exists on the outer surface of the titanium dioxide carrier, and the sample after calcination is analyzed by X-ray diffraction, and there are obvious diffraction characteristic peaks of CuO phase at 2θ = 35.5°, 38.7° and 48.7°, indicating that the hydrogen reduction product-metallic copper has poor dispersity.

[0041] In addition, it is worth special mentioning that in the published literature Applied Catalysis A, General 539 (2017) 59-69, researchers used pre-prepared ordered mesoporous silica (OMS) as the support of their Cu / OMS catalyst prepared by the ammonia evaporation method. In order to reduce the damage of the basicity of the copper ammonia complex solution to the ordered mesoporous structure of the pre-prepared silica support, the researchers also appropriately reduced the concentration of ammonia in the prepared copper ammonia complex solution (which the researchers considered as an improvement of the ammonia evaporation method). In addition to the above two points, the improved ammonia evaporation method described in the study is no different from the traditional ammonia evaporation method. After the ammonia evaporation is completed (the pH value of the slurry is reduced to 6-7), the water solvent of the diluted and volume-excessive copper ammonia complex solution is finally removed by filtration to obtain a solid product loaded with copper hydroxide. The research results show that the ordered mesoporous structure of the pre-prepared silica support used in the study has been mostly destroyed after being loaded with metal copper by the ammonia evaporation method, and there is a large amount of layered copper silicate in the catalyst, indicating that the pre-prepared silica support used is largely dissolved into silica sol during the contact with the copper ammonia complex solution, which produces a uniform deposition and precipitation effect with copper hydroxide during the ammonia evaporation process; In the published literature Journal of Catalysis 280 (2011) 77-88, researchers also used pre-prepared mesoporous silica (HMS) as the support of their Cu / HMS catalyst prepared by the ammonia evaporation method. In addition to this, the researchers also added a water-soluble nickel salt (nickel nitrate) to the prepared aqueous copper ammonia complex solution, so that the prepared copper-based catalyst contains metal nickel (CuxNi / HMS). The ammonia evaporation method used in this study is no different from the traditional ammonia evaporation method, except that it uses a pre-prepared mesoporous silica support and adds a water-soluble nickel salt (nickel nitrate) to the prepared aqueous copper ammonia complex solution, so that the prepared copper-based catalyst contains a metal nickel additive. Its ammonia evaporation operation is carried out at 90°C, and after the ammonia evaporation is completed (the pH value of the slurry is reduced to 7-8), the water solvent of the diluted and volume-excessive copper ammonia complex solution is finally removed by filtration to obtain a solid product loaded with copper hydroxide and nickel hydroxide. Similarly, in this study, the ordered mesoporous structure of the HMS silica has been mostly destroyed (the specific surface area has decreased by more than 50%) after being loaded with metal copper and nickel by the ammonia evaporation method. Moreover, the XRD characterization results show that the prepared supported catalyst sample has characteristic diffraction peaks of metal oxide phase before hydrogen reduction (450°C calcination for 4h), and has characteristic diffraction peaks of metal phase after hydrogen reduction, indicating that the metal copper and nickel are not uniformly loaded on the HMS support and have poor dispersion.

[0042] According to the literature research results, in addition to a recent open literature (Science 10.1126 / science. adj1962 (2023).) reported in the Science journal that a copper catalyst supported on a dealuminated Beta zeolite carrier was prepared by the ammonia evaporation method for the purpose of the gas-solid phase hydrogenation of dimethyl oxalate, so far, no other research work on the preparation of metal catalysts supported on zeolite carriers by the ammonia evaporation method has been found at home and abroad. It should be noted that the related research work recently published in the Science journal used the traditional ammonia evaporation method to prepare a copper catalyst supported on a dealuminated Beta zeolite carrier. The specific approach is as follows: First, 0.23 g of Cu(NO3)2·3H2O was dissolved in 100 ml of an ammonia water solution (containing 0.75 g of NH3·H2O) and stirred at room temperature for 10 min to prepare a copper-ammonia complex aqueous solution; Second, 1.94 g of a dealuminated Beta zeolite carrier (Beta-deAl) was added to the copper-ammonia complex solution, and ammonia evaporation treatment was carried out under vigorous stirring. The ammonia evaporation temperature was 80℃, and the ammonia evaporation time was 6h; Third, after the ammonia evaporation was completed, the water solvent of the diluted and excessive volume of the copper-ammonia complex solution was finally removed by filtration; Fourth, the obtained solid product was dried at 100℃ overnight and calcined at 400℃ for 3h to obtain the catalyst; Fifth, in order to use the catalyst to catalyze the hydrogenation of dimethyl oxalate, it was reduced by hydrogen at 400℃ for 3h. It is not difficult to see that in this study, in addition to the catalyst carrier being a pre-prepared dealuminated Beta zeolite (obtained by subjecting an Al-Beta zeolite mother body with Si / Al = 13 to acid dealumination treatment with a 13M HNO3 solution at 80℃ for 12h), the other approaches are no different from the traditional ammonia evaporation method. In the prepared copper-ammonia complex solution, the concentration of copper ions is very dilute (only about 9.5mmol / L); In the preparation of the catalyst by the ammonia evaporation method, the initial liquid-solid ratio is as high as about 51.5(ml / g), that is, the volume of the copper-ammonia complex solution is greatly excessive to the zeolite carrier. The results show that the prepared dealuminated Beta zeolite supported copper catalyst Cu / Beta-deAl, although the copper content is very low (about 3wt.%Cu), the specific surface area loss is as high as 15% (excessive copper-ammonia complex solution (NH3 / Cu molar ratio 22.5) causes a large amount of dealuminated Beta zeolite to be dissolved and the framework structure to be destroyed), and there are still obvious characteristic diffraction peaks of metallic copper (2θ = 43.3°) in its XRD pattern. Transmission electron microscopy studies show that the copper in the fresh catalyst is mainly supported on the outer surface of the dealuminated Beta zeolite, and the particle size is relatively large (the use of diluted and excessive copper-ammonia complex solution leads to excessive deposition of copper hydroxide outside the zeolite pores during the ammonia evaporation process), which needs to be post-treated by methanol vapor to transfer it to the zeolite pores through the reverse Ostwald ripening process.The research work clearly shows that when copper catalysts are prepared by using copper-ammonia complex solution and zeolite as support, the traditional ammonia evaporation method reported in the literature for silica support cannot be used, otherwise the following problems will occur: (1) excessive copper-ammonia complex solution will deposit a large amount of copper outside the zeolite pores during ammonia evaporation; (2) the dealuminated Beta zeolite will undergo desilication reaction (ammonia evaporation temperature 80°C) in the presence of excessive copper-ammonia complex solution (pH = 10-12), resulting in the destruction of the crystal structure.

[0043] Therefore, the present application proposes an improved ammonia evaporation method different from the known method to meet the need for loading copper in the pores of zeolite support, especially in high-silica zeolite support such as dealuminated Beta zeolite which is prone to desilication.

[0044] In addition, the main feature of the present application is also that the Cu-Beta zeolite catalyst provided is for the purpose of preparing caprolactam from caprolactone in a gas-solid phase reaction state. So far, neither the published patent nor the other published literature has involved this application purpose of Cu-Beta zeolite catalyst. This reaction system is different. This is mainly because the reaction of preparing caprolactam from caprolactone in a gas-solid phase reaction state involves the use of water vapor, hydrogen and ammonia. This is a demanding application scenario for copper-based catalysts.

[0045] As mentioned above, so far, in the catalytic methods for preparing caprolactam from caprolactone described in the existing related patents and academic papers, the catalysts used are mainly two kinds, one is a non-supported bulk copper chromite catalyst, and the other is a copper catalyst supported on a single oxide carrier (such as titanium oxide, aluminum oxide, silicon oxide) or a binary composite oxide carrier (such as silicon oxide and aluminum oxide) (with the addition of a second metal component nickel or chromium). The single oxide and binary composite oxide used as the carrier in the supported copper catalyst (with the addition of a second metal component nickel or chromium) are amorphous.

[0046] The gas-solid phase reaction state is a suitable way to convert caprolactone into caprolactam by hydrogenation in a catalytic way. As mentioned above, the catalytic methods for preparing caprolactam from caprolactone disclosed in British Patent GB1109540 (1966) and US Patent 3652549 (1972) of KANEGAFUCHI, BOSEKI KABUSHIKI KAISHA, and US Patent US3888845 (1975) of TEIJIN CORPORATION all adopt a gas-solid phase reaction state.

[0047] It is well known that the gas-solid phase reaction state is a common form of heterogeneous catalysis, specifically, the reactants in the form of gas contact with solid catalyst for catalytic reaction. In the field of heterogeneous catalysis, sometimes the gas-solid phase reaction is simply referred to as gas phase reaction. The gas-solid phase reaction state is a reaction form with mild reaction conditions, high mass and heat transfer efficiency, and very simple operation. For the gas-solid phase reaction, the process of conversion of reactants on the catalyst to products consists of seven elementary steps: (1) external diffusion of reactants. In this step, the reactants pass through the adsorption film on the surface of the solid catalyst and contact the outer surface of the catalyst; (2) internal diffusion of reactants. In this step, the reactants diffuse through the pores on the surface of the solid catalyst into the inside of the pore to approach the catalytically active center in the pore; (3) chemical adsorption of reactants on the catalytically active center. In this step, the reactant molecules are activated to become activated molecules; (4) surface reaction. In this step, the reactants are converted into adsorbed product form on the catalytically active center; (5) desorption of products. In this step, the adsorbed product is desorbed from the catalytically active center; (6) internal diffusion of products. This step is the movement process of product molecules from the inside of the pore to the outside surface of the catalyst after leaving the catalytically active center; (7) external diffusion of products. In this step, the product molecules leave the pores on the outer surface of the solid catalyst, pass through the adsorption film on the surface of the solid catalyst, and leave the solid catalyst particles to become reaction products.

[0048] The Cu-Beta catalyst provided by the present application is suitable for the gas-solid phase catalytic reaction conditions of the hydrogenation amination of caprolactone to caprolactam described in the related patents and academic papers. As described above, in 1966, KANEGAFUCHI, BOSEKI KABUSHIKI KAISHA first disclosed a gas-solid phase catalytic method for preparing caprolactam in British Patent GB1109540, specifically, the caprolactone and a certain amount of water were first vaporized, and then mixed with ammonia and hydrogen, and the mixed gas was catalytically reacted at 120-350°C and normal pressure through a copper chromite catalyst; in 1972, KANEGAFUCHI, BOSEKI KABUSHIKI KAISHA again disclosed a method for preparing caprolactam in U.S. Patent 3652549, which is also a gas-solid phase catalytic method. Specifically, the method uses a fixed bed reactor, and the reaction temperature is in the range of 170-300°C, and the hydrogen partial pressure is in the range of 0.1-1.5 atm. There are also ammonia and water vapor in the feed, and the preferred amount range (molar ratio with the raw material) is 2-50 and 10-100, respectively; in 1975, TEIJIN CORPORATION disclosed a method for preparing caprolactam in U.S. Patent US3888845, which is also a gas-solid phase catalytic method. Specifically, the gas-solid phase catalytic reaction can be carried out at 200-320°C and 0.01-2 atm, and preferably at 220-310°C and 0.1-1.2 atm. The optional ranges of the amounts of hydrogen and ammonia are 5-70 (H2 / ester molar ratio) and 1-50 (NH3 / ester molar ratio), respectively, and the preferred ranges are 10-50 (H2 / ester molar ratio) and 2-25 (NH3 / ester molar ratio), respectively. In addition, the process also emphasizes the importance of the molar ratio of hydrogen to ammonia and the addition of water in the reactor feed. In general, the use of appropriate molar ratio of hydrogen to ammonia is beneficial to improve the selectivity of the reaction. In addition, the addition of water in the feed of the reactor not only can reduce the side reactions and improve the selectivity of caprolactam, but also can delay the deactivation rate of the catalyst. The optional range of the molar ratio of hydrogen to ammonia is 0.2-30, and the preferred range is 0.5-15; the optional range of the molar ratio of water to ester is 0-50, and the preferred range is 5-30.

[0049] In summary, according to the gas-solid phase catalytic reaction of hydrogenation amination of caprolactone to caprolactam described in the related patents and academic papers, in addition to the caprolactone raw material, the reactor feed also includes water, ammonia and hydrogen. From the molecular formula (C6H 10 O2) of the caprolactone raw material and the molecular formula (C6H 11It can be seen from the above reaction formula (I) that ammonia and hydrogen are also reaction raw materials, and water vaporized into water vapor is a dilution gas. The optional range of the reaction temperature is 120-350℃, the optional range of the reaction pressure is 0.01-2atm, and the optional range of the ammonia-ester, hydrogen-ester and water-ester molar ratio is 1-50, 5-70 and 0-100, respectively; the preferred range of the reaction temperature is 220-300℃, the preferred range of the reaction pressure is 0.1-1.2atm, and the preferred range of the ammonia-ester, hydrogen-ester and water-ester molar ratio is 2-25, 10-50 and 5-30, respectively. In order to facilitate people in the art to better understand the implementation effect of the present application, in the present application, the catalytic performance of the provided Cu-Beta zeolite catalyst in the gas-solid phase hydrogenation reaction of caprolactone to caprolactam is evaluated, and the reaction conditions used are within the above ranges.

[0050] The technical scheme of the present application:

[0051] A preparation method of an anti-sintering Cu-Beta zeolite catalyst, comprising the following steps:

[0052] First step, preparation of a hierarchical pore dealuminated Beta zeolite carrier

[0053] As described above, the hierarchical pore dealuminated Beta zeolite carrier is prepared by using a post-synthesis strategy in the present application. Specifically, the Beta zeolite mother body is first subjected to desilication treatment with a sodium hydroxide solution to obtain a Beta zeolite mother body containing mesopores, and then the Beta zeolite mother body containing mesopores is subjected to acid dealuminization treatment to obtain the hierarchical pore dealuminated Beta zeolite carrier. Engineers familiar with the art can prepare the hierarchical pore dealuminated Beta zeolite carrier from the Beta zeolite mother body according to the requirements of the present application, combined with their own work experience and reference to the methods reported in the relevant literature. The requirements of the present application are as follows:

[0054] (1) Selection of the Beta zeolite mother body

[0055] The Beta zeolite mother body refers to Al-Beta zeolite. The present application does not limit the grain size of the Beta zeolite mother body, nor does it limit the production process of the Beta zeolite mother body. However, in order to facilitate the implementation effect of the present application, the Beta zeolite mother body has the following limitations: 1) the Beta zeolite mother body does not contain impurity crystals; 2) the Beta zeolite mother body has good crystallization; and 3) the Beta zeolite mother body has a suitable molar ratio of silicon and aluminum oxides (molar ratio of SiO2 to Al2O3).

[0056] The presence of impurities in the Beta zeolite matrix can be confirmed by X-ray polycrystalline powder diffraction (XRD). Those skilled in the art know that the molar ratio of silicon to aluminum oxide (SiO2 to Al2O3) in Beta zeolite produced by hydrothermal synthesis is typically between 10 and 200 (US3 308 069 (1967)). Beta zeolite products with lower SiO2 to Al2O3 molar ratios generally may contain mordenite (MOR) impurities, while Beta zeolite with higher SiO2 to Al2O3 molar ratios generally may contain ZSM-5 zeolite impurities. By sampling and performing XRD analysis on the Beta zeolite matrix, and comparing the XRD patterns of the samples with standard diffraction cards for Beta zeolite, MOR zeolite, and ZSM-5 zeolite, it can be determined whether the sample's XRD pattern contains characteristic peaks of MOR zeolite and ZSM-5 zeolite impurities, thus determining whether the Beta zeolite matrix is ​​a pure Beta zeolite phase.

[0057] Theoretically, the crystallinity of the Beta zeolite matrix can also be analyzed using XRD, with the relative crystallinity index used as a measure. However, the XRD relative crystallinity index requires comparing the sum of the intensities of the medium-intensity characteristic diffraction peaks (2θ = 7.6-8°) and the highest-intensity characteristic diffraction peaks (2θ = 22-23°) of the Beta zeolite matrix with the sum of the intensities of the corresponding diffraction peaks of a reference sample (standard Beta zeolite with 100% crystallinity). Furthermore, there is no universally defined reference sample. Additionally, the intensities of the medium-intensity and highest-intensity characteristic diffraction peaks (2θ = 7.6-8° and 2θ = 22-23°) of Beta zeolite are significantly affected by post-processing conditions such as calcination. Therefore, using the XRD relative crystallinity index to determine the crystallinity of the purchased or synthesized Beta zeolite matrix has poor universality. Therefore, this invention recommends using the specific surface area index of the Beta zeolite matrix to measure whether the crystallinity of the purchased or synthesized Beta zeolite matrix meets the requirements. Based on our statistical results of the literature reports on the specific surface area of ​​Beta zeolite, the BET specific surface area of ​​well-crystallized Beta zeolite produced by hydrothermal synthesis is generally not less than 450 m². 2 / g. Engineers skilled in the art can use conventional nitrogen physical adsorption methods to first measure the nitrogen adsorption isotherm data of the Beta zeolite matrix, and then calculate its BET specific surface area value according to the BET model. In summary, this invention requires that the BET specific surface area value of the Beta zeolite matrix used be ≥450m². 2 / g indicates that its crystallization is good.

[0058] The silicon-aluminum oxide molar ratio (molar ratio of SiO2 to Al2O3) is a key index of the Beta zeolite mother substance. On the one hand, the lower the silicon-aluminum oxide molar ratio (molar ratio of SiO2 to Al2O3) of the Beta zeolite mother substance, i.e. the higher the content of framework aluminum, the more the number of hydroxyl pocket lattice defect sites of the de-aluminized Beta zeolite carrier for dispersing and stabilizing nano and sub-nano copper particles; on the other hand, it is difficult to synthesize pure-phase Beta zeolite with a very low silicon-aluminum oxide molar ratio (molar ratio of SiO2 to Al2O3) by a hydrothermal method. Moreover, after the Beta zeolite mother substance with a very low silicon-aluminum oxide molar ratio (molar ratio of SiO2 to Al2O3) is made into a multi-level pore de-aluminized Beta zeolite carrier, the number of mesopores is small, the framework thermal stability is poor, and the crystallinity will be lost in the subsequent calcination step of preparing a Cu-Beta zeolite catalyst, resulting in poor performance of the catalyst. Therefore, the suitable range of the silicon-aluminum oxide molar ratio (molar ratio of SiO2 to Al2O3) of the Beta zeolite mother substance required by the present application is between 15 and 100, preferably between 20 and 80, and more preferably between 25 and 60. The analysis of the silicon-aluminum oxide molar ratio (molar ratio of SiO2 to Al2O3) of the Beta zeolite mother substance can be performed by a traditional chemical analysis method (titration method), or by an X-ray fluorescence spectroscopy (XRF) method or an inductively coupled plasma emission spectroscopy (ICP) method. The simple and fast XRF method is recommended by the present application.

[0059] Beta zeolite precursors meeting the requirements of the present invention can be obtained commercially or synthesized in-house. Engineers skilled in the art can also synthesize Beta zeolite precursors meeting the requirements of the present invention based on their own experience and other literature reports.If the Beta zeolite precursor is synthesized by oneself, the following methods reported in the invention patents and open literature can be selected: US3 308 069 (1967), EP187 522 A2 (1986), US4 847 055 (1989), CN1 086 792 A (application date 1993.9.20), CN1 108 213 A (application date 1994.3.11), CN1 108 214 A (application date 1994.3.11), CN1 154 341 A (application date 1996.1.11), CN1 154 242A (application date 1996.1.9), CN1 154 342 A (application date 1996.1.11), CN1 268 545 A (application date 1999.3.30), CN1 133 497 C (application date 1999.3.30), CN1 108 275 C (application date 1999.9.10), CN1 100 004 C (application date 2000.5.19), CN1 335 258 A (application date 2001.2.28), CN1 116 227 C (application date 2001.3.12), CN101 205 072 B (application date 2006.12.18), Chem. Comm., 1996, 625; J. Mater. Chem., 1998, 8(9), 2137-2145; Microporous and Mesoporous Materials 21 (1998) 305-313; Applied Catalysis A-GENERAL, 166 (1998), 97-103; Microporous and Mesoporous Materials 48 (2001) 23-29; Microporous and Mesoporous Materials 56 (2002) 1-10.; Journal of Molecular Catalysis A: Chemical 252 (2006) 76-84; Microporous and Mesoporous Materials 94 (2006) 1-8; J. Mater. Sci. 41 (2006) 1861-1864; Cryst. Res. Technol. 44, No. 4, 379-385 (2009) DOI 10.1002 / crat.200800474; Microporous and Mesoporous Materials 143 (2011) 97-103; RSC Adv. 2019, 9, 3653-3660.

[0060] (2) Preparation of hierarchical pore Beta zeolite mother substance

[0061] In the preparation of the hierarchical pore Beta zeolite mother substance by alkali treatment desilication of the Beta zeolite mother substance with sodium hydroxide solution, mild desilication conditions should be used. Because only the Beta zeolite mother substance with moderate mesopore porosity prepared by mild desilication can further be dealuminated to obtain the hierarchical pore dealuminated Beta zeolite carrier with better crystal structure, and the catalyst with the effect of the present application is prepared. On the contrary, if the desilication is excessive, although the mesopore porosity of the Beta zeolite mother substance can be increased, the structure of the zeolite mother substance is unstable after dealuminated, and the crystal structure is severely damaged, which is not suitable for the purpose of the present application. It is found that the concentration of the sodium hydroxide solution, the ratio of the volume of the sodium hydroxide solution to the amount of the Beta zeolite mother substance (liquid-solid ratio), the desilication temperature and time are the main factors affecting the desilication degree of the Beta zeolite mother substance, and can be used as a means to control the desilication degree and mesopore porosity in the preparation of the hierarchical pore Beta zeolite mother substance. The present application has the following requirements for the value range of the above four parameters:

[0062] The suitable range of the concentration of the sodium hydroxide aqueous solution is 0.01-0.5M, the preferred range is 0.05-0.4M, and the more preferred range is 0.1-0.3M;

[0063] The ratio of the volume (milliliter) of the sodium hydroxide aqueous solution to the amount (gram) of the Beta zeolite mother substance (liquid-solid ratio) is preferably in the range of 2:1-30:1 (milliliter / gram), more preferably in the range of 3:1-20:1 (milliliter / gram), and even more preferably in the range of 5:1-15:1 (milliliter / gram);

[0064] The suitable temperature range of the desilication reaction temperature is 15-60℃, the preferred range is 20-55℃, and the more preferred range is 25-45℃;

[0065] The suitable range of the desilication reaction time is 10-180min, the preferred range is 15-120min, and the more preferred range is 20-60min.

[0066] Engineers skilled in the art can complete the preparation of the hierarchical-pore Beta zeolite precursor according to their own work experience or by referring to the methods reported in the relevant literature (e.g., the published literature Appl. Catal. A 325 (2007) 121.; Microporous and Mesoporous Materials 114 (2008) 93-102; J. Mater. Chem. A, 2016, 4, 1373) in combination with the requirements of the present application. As an example, the preparation of the hierarchical-pore Beta zeolite precursor by desilication of the Beta zeolite precursor with a sodium hydroxide solution can be carried out according to the following basic steps: first, the Beta zeolite precursor is pretreated by drying and calcination. The drying can be carried out under conditions ranging from 80-200 °C for 3-24 h to fully remove the adsorbed water and volatile organic compounds. The calcination can be carried out under conditions ranging from 500 °C to 600 °C for 3-8 h to remove the organic template and other organic compounds that can be left in the pores of the Beta zeolite. Second, the pretreated Beta zeolite precursor is desilicated. Specifically, a sodium hydroxide solution of a certain concentration is prepared and heated to the desilication reaction temperature, and then the pretreated Beta zeolite precursor is added to the sodium hydroxide solution according to a certain liquid-to-solid ratio, and the reaction is carried out under stirring for a certain time. Finally, after the reaction is completed, the reaction mixture is immediately cooled, and the solid product is recovered by conventional solid-liquid separation, and then the solid product is washed with water to neutralize the pH value, and then dried at a temperature of 80-200 °C for 3-24 h and calcined at a temperature of 500 °C-600 °C for 1-6 h to obtain the hierarchical-pore Beta zeolite precursor.

[0067] It is emphasized that, in the case of preparing the mesoporous Beta zeolite precursor by desilication of the Beta zeolite precursor with a sodium hydroxide solution, for the Beta zeolite precursor with a higher molar ratio of silicon to aluminum oxide (molar ratio of SiO2to Al2O3), the desilication condition should be relatively weak within the range of conditions provided by the present application. For the Beta zeolite precursor with a lower molar ratio of silicon to aluminum oxide (molar ratio of SiO2to Al2O3), the desilication condition can be relatively strong within the range of conditions provided by the present application. It is understood that the desilication condition resulting from the combination of the upper limit values of the four parameters, i.e. the concentration of the aqueous sodium hydroxide solution, the liquid-to-solid ratio, the desilication reaction temperature and the desilication reaction time, is the strongest desilication condition within the range of conditions provided by the present application. The desilication condition resulting from the combination of the lower limit values of the four parameters is the weakest desilication condition within the range of conditions provided by the present application. The desilication conditions resulting from other different combinations of the values of the four parameters within the range of conditions provided by the present application will produce different desilication strengths between the strongest and the weakest. It is needless to say that the above explanation of the present application is intended to provide the engineers in the field with the principle guidance. For different Beta zeolite precursors, the desilication conditions for achieving moderate desilication and producing moderate mesopore porosity are preferably determined by experiments.

[0068] It is further noted that, in terms of desilication ability, solutions of other inorganic bases or organic bases are also applicable. Hydroxides of alkali metals and carbonates of alkali metals are common inorganic bases that can be used for desilication of zeolites. Quaternary ammonium bases (e.g. tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, etc.) are common organic bases that can be used for desilication of zeolites. In fact, the applicable inorganic bases and organic bases are not limited to these. The inorganic bases and organic bases disclosed in the relevant patent applications and other publications are actually applicable to the preparation of the hierarchical pore Beta zeolite precursor according to the present application. However, hydroxides of alkali metals and carbonates of alkali metals, especially sodium hydroxide, are a relatively inexpensive inorganic strong base. The present application recommends the use of aqueous sodium hydroxide mainly considering the cost factor.

[0069] (3) Preparation of the hierarchical pore dealuminated Beta zeolite support

[0070] As mentioned above, the multi-level pore dealuminated Beta zeolite support can be prepared from the multi-level pore Beta zeolite precursor by using conventional acid dealumination method. The present invention requires that the molar ratio of silica to alumina (Si02 to Al203) of the prepared multi-level pore dealuminated Beta zeolite support is as high as possible, i.e. as much as possible of the framework aluminum of the multi-level pore Beta zeolite precursor is removed. The suitable range of the molar ratio of silica to alumina (Si02 to Al203) of the multi-level pore dealuminated Beta zeolite support according to the present invention is ≧ 700, preferably ≧ 800, and more preferably ≧ 900. Because the molar ratio of silica to alumina (Si02 to Al203) of the multi-level pore dealuminated Beta zeolite is very high and the aluminum content is very low, the molar ratio of silica to alumina (Si02 to Al203) of the multi-level pore dealuminated Beta zeolite support is determined by inductively coupled plasma emission spectroscopy (ICP) or atomic absorption (AA) method. The present invention recommends the use of ICP method.

[0071] When the multi-level pore Beta zeolite precursor is subjected to acid dealumination treatment, it is desirable to remove as much as possible of the framework aluminum. The harm of excessive residual framework aluminum on the multi-level pore dealuminated Beta zeolite support is that the strong acidity of the framework aluminum will accelerate the coking deactivation of the Cu-Beta zeolite catalyst and reduce the selectivity of the catalyst to the caprolactam main product.

[0072] Although the framework aluminum of the Beta zeolite is easy to remove, so that the high-temperature steam dealumination method, the EDTA complexing agent dealumination method, the organic acid solution dealumination method, the inorganic acid (concentrated hydrochloric acid, concentrated nitric acid) solution dealumination method, or the dealumination method formed by any combination of the above different methods can be used to prepare the multi-level pore dealuminated Beta zeolite support according to the present invention from the multi-level pore Beta zeolite precursor, but considering the production cost, process complexity and difficulty in treatment of waste liquid generated by dealumination of the multi-level pore dealuminated Beta zeolite support, the present invention recommends the use of concentrated nitric acid aqueous solution dealumination method to prepare the multi-level pore dealuminated Beta zeolite support according to the present invention.

[0073] Engineers skilled in the art can prepare the hierarchical pore dealuminated Beta zeolite carrier according to their experience or the specific methods disclosed in the following documents by using concentrated nitric acid aqueous solution to dealuminate the hierarchical pore Beta zeolite precursor: Chemical Communications, 1998, 1: 87-88; Micropor. Mesopor. Mater., 1999, 31: 163-173; Micropor. Mesopor. Mater., 2001, 49: 103-109; Micropor. Mesopor. Mater., 2008, 110: 480-487; Micropor. Mesopor. Mater., 2012, 163: 122-130; ACS Catalysis, 2014, 4(8): 2801-2810.

[0074] When the hierarchical pore dealuminated Beta zeolite carrier is prepared by using concentrated nitric acid aqueous solution to dealuminate the hierarchical pore Beta zeolite precursor, the concentration of the nitric acid aqueous solution, the ratio of the acid solution to the zeolite (liquid-solid ratio), and the temperature and time of the acid treatment are important factors affecting the degree of dealumination of the hierarchical pore Beta zeolite precursor. The effects of the above factors on the dealumination of the hierarchical pore Beta zeolite precursor are ultimately reflected in the residual aluminum content of the hierarchical pore dealuminated Beta zeolite carrier. However, if the hierarchical pore dealuminated Beta zeolite carrier with a required molar ratio of silicon-aluminum oxide (molar ratio of SiO2 to Al2O3) cannot be obtained after one dealumination, the molar ratio of silicon-aluminum oxide (molar ratio of SiO2 to Al2O3) of the hierarchical pore dealuminated Beta zeolite can be adjusted to meet the requirements of the present application by secondary or even multiple supplemental dealumination. The present application recommends using 13M concentrated nitric acid as the dealumination acid solution, and using the acid solution in a liquid-solid ratio (ml / g) of 20:1. Under this premise, the dealumination reaction is carried out at 95°C for 20h; after the dealumination reaction is completed, the solid product is recovered by solid-liquid separation, then the solid product is washed with water to neutral pH, and then dried at a temperature of 80-200°C for 3-24h and calcined at a temperature of 500°C-600°C for 3-8h to obtain the hierarchical pore dealuminated Beta zeolite carrier. After dealumination of the hierarchical pore Beta zeolite precursor, a large number of hydroxyl pit lattice defect sites are generated, and the water absorption and moisture absorption capacity is stronger, so it should be sealed and stored for use.

[0075] Second step, using an aqueous solution of ethanolamine to modify the hydroxyl pits of the hierarchical pore dealuminated Beta zeolite carrier

[0076] The hydroxyl pocket drilling modification is carried out by a conventional aqueous solution impregnation method. The drilling modification is essentially an alkali-catalyzed hydrolysis reaction modification ([(OSi)3-O-SiOH]+3H2O=Si(OH)4+3≡Si-OH), and for each silicon atom (in the form of orthosilicic acid (Si(OH)4)) removed from the edge wall of the hydroxyl pocket, three silicon hydroxyl groups (≡SiOH) are generated on the new edge wall of the hydroxyl pocket.

[0077] When the multi-level pore dealuminated Beta zeolite support is impregnated with the ethanolamine solution for drilling modification, the concentration of the ethanolamine aqueous solution, the ratio of the ethanolamine solution to the multi-level pore dealuminated Beta zeolite support, i.e. the liquid-solid ratio (ml / g), and the impregnation temperature and time are the main factors affecting the drilling modification of the hydroxyl pocket of the multi-level pore dealuminated Beta zeolite by the ethanolamine solution. The present application provides the value range of the four parameters as follows:

[0078] The suitable range of the concentration of the ethanolamine solution is 0.01M-0.4M, the preferred range is 0.02M-0.3M, and the more preferred range is 0.03M-0.16M;

[0079] The suitable range of the ratio of the ethanolamine solution to the multi-level pore dealuminated Beta zeolite support, i.e. the liquid-solid ratio (ml / g), is 1:1-100:1, the preferred range is 2:1-50:1, and the more preferred range is 3:1-20:1;

[0080] The suitable range of the impregnation temperature is 20℃-100℃, the preferred range is 30℃-90℃, and the more preferred range is 40℃-80℃;

[0081] The suitable range of the impregnation time is 0.5h-24h, the preferred range is 1h-10h, and the more preferred range is 2-5h.

[0082] Engineers familiar with the art can refer to the impregnation process commonly used in the preparation of heterogeneous catalysts to impregnate the multi-level pore dealuminated Beta zeolite support with the ethanolamine solution, so as to achieve the purpose of drilling modification of the hydroxyl pocket of the multi-level pore dealuminated Beta zeolite support. Details are not repeated. Similarly, after drilling modification, the liquid-solid mixture should be processed according to common sense, mainly including conventional liquid-solid separation, water washing (to neutral pH), drying and calcination treatment. Among them, the conditions of drying and calcination treatment can refer to the drying and calcination treatment conditions of the multi-level pore dealuminated Beta zeolite support in the first step (preparation of multi-level pore dealuminated Beta zeolite support) of the embodiment of the present application. Details are not repeated.

[0083] However, it is particularly pointed out that for the multi-level pore dealuminated Beta zeolite carriers with different numbers of hydroxyl pits prepared from different molar ratios of Beta zeolite mother bodies (molar ratio of SiO2 to Al2O3), the key to the controllable pit modification of the hydroxyl pits by using the aqueous solution of ethanolamine lies in the correct selection of the modification conditions composed of four parameters (concentration of the ethanolamine solution, liquid-solid ratio (ml / g), impregnation temperature and time). It is not difficult to understand that the modification conditions composed of the lower limit values of the above four parameters have the weakest desilication effect and are suitable for the pit modification of the multi-level pore dealuminated Beta zeolite carriers with a small number of hydroxyl pits; the modification conditions composed of the upper limit values of the above four parameters have the strongest desilication effect and can be used for the pit modification of the multi-level pore dealuminated Beta zeolite carriers with a large number of hydroxyl pits; and the modification conditions composed of other different values of the above four parameters within the specified range will produce different desilication effects between the weakest and the strongest. Similarly, the above explanation of the present application is intended to provide the engineers in the field with the principle guidance. For different multi-level pore dealuminated Beta zeolite carriers, the ethanolamine solution impregnation treatment conditions for achieving a moderate pit modification degree are preferably determined through experiments.

[0084] Third step, loading copper in the pore channels of the pit-modified multi-level pore dealuminated Beta zeolite carrier by using the improved ammonia evaporation method to prepare a Cu-Beta zeolite catalyst

[0085] As mentioned before, the core of the improved ammonia evaporation method according to the present application is to use the copper ammonia complex solution to impregnate the zeolite carrier in equal volume, and in this process, most of the complex solution is absorbed into the pore channels by the capillary condensation of the zeolite channels, so as to achieve the purpose of depositing copper hydroxide and loading metal copper in the pore channels. The specific method is as follows:

[0086] (1) Preparation of dilute ammonia water base solution and saturated solution of copper ammonia complex: according to the proportion of 4.4 g of industrial ammonia water (containing NH3 25-28 wt.%) to 100 ml of deionized water, a dilute ammonia water base solution with pH value = 11-12 is prepared and sealed for storage; then according to the molar ratio of 1:4 of copper ion (Cu 2+ ) to ammonia molecule, copper nitrate trihydrate (Cu(NO3)2·3H2O) is used as a soluble copper-containing compound to react with industrial ammonia water to synthesize copper ammonia complex; finally, the copper ammonia complex is dissolved in the dilute ammonia water base solution at room temperature to prepare a saturated solution of copper ammonia complex, which is stored in a sealed container. The concentration of copper ammonia complex ions in the saturated solution of copper ammonia complex is about 0.4 mol / L (0.4M), with a deep blue color and clear transparency.

[0087] It is to be noted that although the soluble copper-containing compounds that can be used to prepare the copper-ammine complex solution include copper nitrate, copper sulfate, copper oxalate, copper chloride and copper acetate as described in US Patent No. 4 440 873 (1984), considering that sulfate and chloride ions increase the burden of subsequent water washing, and that oxalate and acetate ions have corrosion problems, the use of copper nitrate (Cu(NO3)2-3H2O) is recommended in the present application.

[0088] (2) Impregnation of the zeolite support with the copper-ammine complex solution in equal volume: The saturated water absorption of the zeolite support is first determined, and the amount of copper-ammine complex solution required for the equal volume impregnation of the zeolite support is calculated therefrom. Then, the concentration of the copper-ammine complex solution required is calculated according to the copper loading of the Cu-Beta zeolite catalyst to be prepared. When the calculated concentration is equal to 0.4 M, the zeolite support is directly impregnated in equal volume with the saturated solution of the copper-ammine complex; when the calculated concentration is lower than 0.4 M, the saturated solution of the copper-ammine complex is diluted with the dilute aqueous ammonia base solution as appropriate, and the zeolite support is then impregnated in equal volume; when the calculated value is higher than 0.4 M, the zeolite support should be impregnated in equal volume for several times, the concentration of the copper-ammine complex solution for each equal volume impregnation is recalculated, and the copper-ammine complex solution of the required concentration is prepared from the dilute aqueous ammonia base solution and the saturated solution of the copper-ammine complex for each equal volume impregnation. After each impregnation, the zeolite support is subjected to ammonia evaporation treatment.

[0089] The equal volume impregnation is carried out in a closed container at room temperature. In this process, the zeolite support absorbs the copper-ammine complex solution into the zeolite pores by capillary condensation, so that the copper-ammine complex ions contact and interact with the hydroxyl lattice defect sites in the pores. The suitable range of the equal volume impregnation time is 0.5-24 h, the preferred range of the equal volume impregnation time is 1-12 h, and the more preferred range of the equal volume impregnation time is 2-6 h.

[0090] (3) Ammonia evaporation treatment: The ammonia evaporation process can be carried out at normal pressure or under reduced pressure. The suitable range of the ammonia evaporation temperature and time is 50-100 °C and 0.5-48 h, the preferred range of the ammonia evaporation temperature and time is 60-90 °C and 1-24 h, and the more preferred range of the ammonia evaporation temperature and time is 65-85 °C and 3-12 h. In the ammonia evaporation process, the copper-ammine complex decomposes to generate ammonia gas and copper hydroxide, the former is absorbed with water, and the latter is deposited in the zeolite pores and the hydroxyl lattice defect sites.

[0091] (4) Dehydration and drying treatment after ammonia evaporation: The suitable range of the drying temperature and time is 100-200 °C and 0.5-48 h, respectively, the preferred range of the drying temperature and time is 110-170 °C and 1-24 h, respectively, and the more preferred range of the drying temperature and time is 120-150 °C and 3-12 h, respectively.

[0092] (5) Calcination treatment after ammonia evaporation: This step is used to convert the copper hydroxide precipitate deposited in the pores of the zeolite and in the lattice defect sites of the hydroxyls into nano and sub-nano copper oxide particles, thereby obtaining a catalyst precursor. The calcination is performed in an air atmosphere, and the suitable ranges of the calcination temperature and time are 350-650°C and 0.5-24h, respectively, the preferred ranges of the calcination temperature and time are 400-600°C and 1-12h, respectively, and the more preferred ranges of the calcination temperature and time are 450-550°C and 2-6h, respectively;

[0093] (6) Hydrogen reduction treatment of the catalyst precursor: A Cu-Beta zeolite finished catalyst is prepared. The suitable ranges of the reduction temperature, time and hydrogen flow rate (expressed by the volume space velocity of hydrogen, defined as the volume of hydrogen passing through the catalyst per unit time per unit volume, calculated as an ideal gas) are 280-600°C, 0.5-20h and 1-2000h -1 , respectively, the preferred ranges are 300-550°C, 1-15h and 10-1500h -1 , respectively, and the more preferred ranges are 350-500°C, 2-8h and 20-1000h -1 .

[0094] The Cu-Beta zeolite prepared by the above preparation method is used to catalyze the gas-solid phase reductive amination of caprolactone to prepare caprolactam.

[0095] As mentioned above, one main feature of the present application is that the provided Cu-Beta zeolite catalyst is used to catalyze the gas-solid phase reductive amination of caprolactone to prepare caprolactam.

[0096] However, the present application does not limit the specific method of preparing caprolactam by the gas-solid phase reductive amination of caprolactone. Engineers familiar with the field can refer to the methods disclosed in related patents and other literature to implement the gas-solid phase reductive amination of caprolactone. According to the related patents and other literature, the present application collates the referenceable reaction condition ranges of the gas-solid phase reductive amination of caprolactone as follows: the suitable range of the reaction temperature is 120-350°C, the suitable range of the reaction pressure is 0.01-2atm, the suitable range of the feedstock space velocity (WHSV) of caprolactone is 0.1-5h -1 , and the suitable ranges of the molar ratios of ammonia-ester, hydrogen-ester and water-ester are 1-50, 5-70 and 0-100, respectively; the preferred range of the reaction temperature is 220-300°C, the preferred range of the reaction pressure is 0.1-1.2atm, the preferred range of the feedstock space velocity (WHSV) of caprolactone is 0.2-2h -1 , and the preferred ranges of the molar ratios of ammonia-ester, hydrogen-ester and water-ester are 2-25, 10-50 and 5-30, respectively.

[0097] In order to facilitate the illustration of the implementation effect of the catalyst and the preparation method thereof and avoid unnecessary complexity, a typical method of carrying out the gas-solid phase hydrogenation of caprolactone on the Cu-Beta zeolite catalyst to prepare caprolactam is introduced as follows by taking a small fixed bed reactor in a laboratory as an example: the small fixed bed reactor adopts the operation mode of feeding from the top and discharging from the bottom, and the Cu-Beta zeolite catalyst is loaded in the constant temperature zone of the reactor. The upper and lower spaces of the catalyst bed are filled with inert porcelain balls. Among them, the upper porcelain ball area of the reactor serves as the vaporization and preheating zone of the raw materials. For the sake of convenience, the caprolactone, water and ammonia gas can be mixed into a mixed feed, which is delivered by a micro-metering pump, and the hydrogen gas is controlled by a mass flow meter. The reaction is carried out under fixed conditions: the reaction temperature is 260℃, the reaction pressure is 1atm, the feed space velocity (WHSV) of caprolactone is 0.6h -1 -1, the molar ratios of ammonia-ester, hydrogen-ester and water-ester are 6, 50 and 30 respectively.

[0098] The beneficial effects of the present application are as follows:

[0099] Firstly, the Cu-Beta zeolite catalyst is prepared by the improved ammonia evaporation method on the multi-stage hole modified dealuminated Beta zeolite carrier, so that the copper ammonia complex mainly occurs in the zeolite pore in the process of ammonia evaporation to deposit copper hydroxide. The copper hydroxide deposited in the zeolite pore can form high-dispersed nano and sub-nano copper particles at the hydroxyl hole lattice defect site in the pore after calcination and hydrogen reduction treatment, and the latter can obtain the anti-sintering ability by interacting with the hydroxyl hole. Secondly, the application utilizes the dispersion and stabilization of the dealuminated Beta zeolite hydroxyl hole on the loaded copper particles, and at the same time, the weak organic base control desilication technology is used to make the hydroxyl hole generated by dealuminization larger, increase the contact area of the hydroxyl hole and the copper particles, and further strengthen the stabilization of the dealuminated Beta zeolite hydroxyl hole on the loaded copper particles. In addition, the Cu-Beta zeolite catalyst and the preparation method thereof provided by the application also introduce the multi-stage hole structure into the zeolite carrier, increase the flexibility (structure variability) of the zeolite carrier, and thus add the ability of the hydroxyl hole of the zeolite carrier to further stabilize the copper particles by expansion deformation. These measures enable the Cu-Beta zeolite catalyst to be used without adding anti-sintering additives such as chromium and nickel. Secondly, the core of the improved ammonia evaporation method used in the application is to impregnate the dealuminated Beta zeolite carrier with the copper ammonia complex solution in equal volume. Since the amount of the copper ammonia complex solution is small, it is conducive to inhibiting the damage of the silicon dissolution of the copper ammonia complex alkaline solution (pH = 10-12) to the framework of the dealuminated Beta zeolite, thereby facilitating the dispersion and stabilization of the dealuminated Beta zeolite hydroxyl hole on the high-dispersed nano and sub-nano copper particles, and facilitating the preparation of the Cu-Beta zeolite catalyst with high activity, high selectivity and high stability. Finally, the Cu-Beta zeolite catalyst is used for the purpose of gas-solid phase hydrogenation of caprolactone, which can greatly reduce the industrialization difficulty of the technical route of preparing caprolactam from caprolactone. BRIEF DESCRIPTION OF DRAWINGS

[0100] Figure 1 is the infrared spectrum of the hydroxyl region of the Beta zeolite mother body with a silicon-aluminum oxide molar ratio (molar ratio of SiO2 to Al2O3) of 24, which is first desilicated by a sodium hydroxide solution to generate a multi-stage hole Beta zeolite mother body, and then dealuminated by acid to become a multi-stage hole dealuminated Beta zeolite carrier (Beta24c), and the infrared spectrum of the hydroxyl region of the hole modification multi-stage hole dealuminated Beta zeolite carrier (Beta24C) prepared by controlling the desilication of Beta24c with a weak organic base ethanolamine aqueous solution.

[0101] Figure 2 is the XRD pattern of the hole modification multi-stage hole dealuminated Beta zeolite carrier (Beta24C), and the XRD pattern of the Cu-Beta zeolite catalyst (Cu3-Beta24C-1) with a copper loading of 3.0wt.% prepared by the improved ammonia evaporation method using Beta24C as the carrier.

[0102] Figure 3 is the hydroxyl region infrared light spectrum of the channeled modified hierarchical pore dealuminated Beta zeolite support Beta24C, and the hydroxyl region infrared light spectrum of the Cu-Beta zeolite catalyst (Cu3-Beta24C-1) with copper loading of 3.0 wt.% prepared using the improved ammonium desorption method and using Beta24C as the support.

[0103] Figure 4 is the high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) image of the Cu3-Beta24C-1 catalyst.

[0104] Figure 5 is the high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) image of the high temperature calcination (550°C x 3h) sample of the Cu3-Beta24C-1 catalyst.

[0105] Figure 6 is the XRD pattern of the channeled modified hierarchical pore dealuminated Beta zeolite support Beta24C, and the XRD pattern of the Cu-Beta zeolite catalyst (Cu3-Beta24C-CE1) with copper content of 3 wt.% prepared using the traditional ammonium desorption method and using Beta24C as the support. DETAILED DESCRIPTION

[0106] The implementation effects of the present application can be evaluated by two aspects of characterizing the physicochemical properties of the prepared Cu-Beta zeolite catalyst and detecting its catalytic performance in the gas-solid phase hydrogenation of caprolactam from caprolactone reaction.

[0107] In the characterization of the physicochemical properties of the Cu-Beta zeolite catalyst, the damage of the crystal structure, the occupation of the hydroxyl pockets, the high dispersion of the loaded copper metal, and the anti-sintering of the copper particles can be characterized.

[0108] Among them, the damage of the Beta zeolite crystal structure can be characterized by the X-ray polycrystalline powder diffraction (XRD) method. If the ammonium desorption treatment causes significant damage to the crystal structure of the Beta zeolite, the intensity of the characteristic diffraction peak at 2θ = 22-23° of the XRD pattern of the catalyst will be significantly reduced. If the channeled modified hierarchical pore dealuminated Beta zeolite support is used as a reference sample, the relative crystallinity reduction degree of the zeolite support in the Cu-Beta zeolite catalyst can also be estimated.

[0109] The occupation of the hydroxyl pockets in the Cu-Beta zeolite catalyst can be characterized by obtaining the hydroxyl vibration infrared spectrum of the catalyst using the Fourier transform infrared spectroscopy (FT-IR) method, and comparing it with the hydroxyl vibration infrared spectrum of the channeled modified hierarchical pore dealuminated Beta zeolite support to make a qualitative judgment. The more the nano and sub-nano copper particles fall into the hydroxyl pockets, the more the characteristic infrared bands of the hydroxyl pockets (located at 3300-3600 cm-1) of the catalyst will be reduced.-1 The weaker the intensity of the broadened absorption band between 4000 and 400 cm"1, the weaker the intensity of the absorption band between 4000 and 400 cm"1.

[0110] In addition, the high dispersion of the supported copper metal in the Cu-Beta zeolite catalyst can be observed by transmission electron microscopy (TEM), and the anti-sintering of the copper particles can be concluded by calcination treatment combined with TEM observation. The attenuation of the catalytic activity (caprolactam yield) of the catalyst in the gas-solid phase hydrogenative amination of caprolactam to caprolactam reaction can also be used for judgment.

[0111] As for the catalytic performance of the Cu-Beta zeolite catalyst in the gas-solid phase hydrogenative amination of caprolactam to caprolactam reaction, a laboratory small fixed bed reactor can be used for evaluation. The operation method and reaction conditions are as described above. The composition of the reaction product is analyzed by gas chromatography (GC) with a FID detector, equipped with an OV-1701 column, and the conversion of caprolactam and the selectivity of caprolactam are calculated by the internal standard method (internal standard is 1, 4-dioxane). The yield data of caprolactam is obtained by the product of the conversion of caprolactam and the selectivity of caprolactam, which is used as the evaluation index of the catalytic activity of the catalyst.

[0112] The present application will be further described by examples, but the present application is not limited by these examples.

[0113] Example 1: This example is used to illustrate that the Cu-Beta zeolite catalyst prepared by loading copper in the pores of the modified multi-level pore dealuminated Beta zeolite carrier with the improved ammonia evaporation method not only can better maintain the crystal structure of the dealuminated Beta zeolite carrier, but also can make the supported copper mainly in the form of highly dispersed nano and sub-nano copper particles located in the hydroxyl pit lattice defect site in the zeolite pores, and the active silicon hydroxyl in the hydroxyl pit and the highly dispersed nano and sub-nano copper particles are combined more tightly, which better improves the anti-sintering ability of the catalyst. The prepared Cu-Beta zeolite catalyst is suitable as a catalyst for the gas-solid phase hydrogenative amination of caprolactam to caprolactam.

[0114] First, the Cu-Beta zeolite catalyst is prepared according to the embodiments provided by the present application:

[0115] First step, preparation of multi-level pore dealuminated Beta zeolite carrier

[0116] (1) Synthesized a Beta zeolite mother substance with a molar ratio of silica to alumina (SiO2 / Al2O3) of 25 as a raw material for preparing a hierarchical-pore dealuminated Beta zeolite carrier according to the hydrothermal crystallization method provided in U.S. Patent No. 3 308 069 (1967). After the synthesized Beta zeolite mother substance was subjected to a conventional filtration, washing, drying (110°C, 12h) and calcination for removing a template (540°C, 6h), it was observed by TEM to have a crystal size of less than 100 nm, and was thus a nano-Beta zeolite. No any impurity crystal was found in the nano-Beta zeolite by XRD, and the BET specific surface area thereof was calculated from the nitrogen physical adsorption data to be about 550 m 2 / g. The molar ratio of silica to alumina (SiO2 / Al2O3) thereof was measured by XRF to be about 24, which met the technical requirements of the Beta zeolite mother substance according to the present application, and was stored in a sealed state for use.

[0117] (2) Alkaline treatment of the Beta zeolite mother substance with a sodium hydroxide solution to prepare a hierarchical-pore Beta zeolite mother substance

[0118] First, a sodium hydroxide solution with a molar concentration of 0.1M was prepared. Then, 40g of the Beta zeolite mother substance subjected to the drying and calcination treatment described above was added to 400ml of the sodium hydroxide solution (0.1M) in a three-neck flask under stirring at a liquid-to-solid ratio of 10:1 (ml / g) to perform an alkaline treatment for desilication. The desilication temperature was 35°C, and the desilication time was 30min. During the desilication reaction, the three-neck flask was kept in a condensation reflux state. After the desilication reaction, the liquid was immediately cooled to room temperature, and the solid product was recovered by filtration. Then, the hierarchical-pore Beta zeolite mother substance was prepared by a conventional water washing, drying (110°C x 12h) and calcination (550°C x 3h) treatment. The weight loss by desilication was 7.27%, and the total specific surface area of the hierarchical-pore Beta zeolite mother substance was 650 m 2 / g, and the micropore specific surface area thereof was about 491 m 2 / g.

[0119] (3) Dealuminization treatment of the hierarchical-pore Beta zeolite mother substance with concentrated nitric acid to prepare a hierarchical-pore dealuminated Beta zeolite carrier.

[0120] First, a concentrated nitric acid solution with a molar concentration of 13 M was prepared. Then, 30 g of the hierarchically porous Beta zeolite precursor subjected to the drying and calcination treatment described above was added into a three-necked flask containing 600 ml of the 13 M concentrated nitric acid solution under stirring at a liquid-to-solid ratio of 20:1 (ml / g) to perform the dealumination treatment. The dealumination temperature was 95°C, and the dealumination time was 20 h. During the dealumination reaction, the three-necked flask was kept in a reflux state. After the dealumination reaction was completed, the liquid was cooled to room temperature, and the solid product was recovered by filtration. Then, the hierarchically porous dealuminated Beta zeolite support was prepared by using a conventional water washing, drying (overnight at 110°C), and calcination treatment (550°C for 3 h). The molar ratio of silicon to alumina oxide (molar ratio of SiO2 to Al2O3) of the dealuminated Beta zeolite support was 960 (> 900) as measured by ICP. The support was suitable for use as a catalyst of the present application (coded as Beta24c, where the lower-case "c" represents the hydroxyl pockets produced in the Beta zeolite by dealumination). The support was stored in a sealed state to avoid moisture absorption and was ready for use.

[0121] Second, the hierarchically porous dealuminated Beta zeolite support was subjected to a pocket modification treatment by using an aqueous solution of ethanolamine to modify the hydroxyl pockets of the hierarchically porous dealuminated Beta zeolite support

[0122] The said cavity modification is carried out by atmospheric pressure impregnation. First, prepare an aqueous solution of 44 mmol / L (44 mM) ethanolamine as the cavity modification liquid. Then, add 20 g of the hierarchical pore dealuminated Beta zeolite support into 120 ml of the ethanolamine modification liquid according to a liquid-solid ratio of 6:1 (ml / g). Heat the reactant to 40°C under stirring, and allow the reactant to react at the temperature for 2 h under continuous stirring. During this period, the weak base catalytic hydrolysis desilication reaction of the hydroxyl cavity on the Beta zeolite support in the weakly basic solution of ethanolamine occurs: [(OSi)3-O-SiOH] + 3H2O = Si(OH)4 + 3≡Si-OH, and for each silicon atom (in the form of orthosilicic acid (Si(OH)4) removed, three silicon hydroxyl groups (≡Si-OH) are generated on the new side wall of the hydroxyl cavity. After 1 h of reaction, filter the reactant to recover the solid product, then repeatedly wash the solid product with deionized water until neutral, and then dry (overnight at 110°C) and calcine (at 550°C for 3 h) to obtain the cavity-modified hierarchical pore dealuminated Beta zeolite support. Seal and store for later use. According to the weight loss estimation, the average number of framework silicon atoms (in the form of SiO2) removed from the lattice defect site of the hydroxyl cavity of the dealuminated Beta zeolite support is 1.0 silicon atom, indicating that the cavity modification is a moderate desilication under controllable conditions, which meets the requirements of the cavity modification of the dealuminated Beta zeolite support, and the code of the cavity-modified support is Beta24C (the capital "C" indicates that the cavity modification of the dealuminated Beta zeolite makes the volume of the hydroxyl cavity larger). The hydroxyl vibration infrared spectra of the hierarchical pore dealuminated Beta zeolite support (Beta24c) and its cavity-modified sample (Beta24C) are obtained by Fourier transform infrared spectroscopy (FT-IR), as shown in Figure 1. As can be seen from Figure 1, the hydroxyl vibration infrared spectrum of the hierarchical pore dealuminated Beta zeolite support has changed significantly after cavity modification, indicating that the cavity modification indeed occurs at the lattice defect site of the hydroxyl cavity of the hierarchical pore dealuminated Beta zeolite.

[0123] Third step, load copper in the pore of the cavity-modified hierarchical pore dealuminated Beta zeolite by improved ammonia evaporation method to prepare Cu-Beta zeolite catalyst

[0124] (1) Prepare a dilute ammonia water base solution, and synthesize a copper ammonia complex with copper nitrate trihydrate (Cu(NO3)2·3H2O), and then prepare a saturated solution of the copper ammonia complex at room temperature. Among them, the pH value of the dilute ammonia water base solution is 11-12, which is prepared according to the proportion of 100 ml deionized water plus 4.4 g industrial ammonia water (containing NH3 25-28 wt.%); the copper ammonia complex is obtained by reaction of Cu(NO3)2·3H2O and industrial ammonia water according to a molar ratio of copper ions to ammonia molecules of 1:4; the saturated solution of the copper ammonia complex is obtained by dissolving the copper ammonia complex with the dilute ammonia water base solution, which contains about 0.4 M copper ammonia complex.

[0125] (2) Impregnate the zeolite support with an equal volume of copper ammonia complex solution to prepare a Cu-Beta zeolite catalyst with a copper loading of 3 wt.%. First, take 5 g of the post-calcination and seal-kept channeled modified hierarchical-pore dealuminated Beta zeolite support (Beta24C), titrate with deionized water until all samples are uniformly wet but there is no free liquid water, and a total of 6.25 ml of deionized water is consumed, and the water absorption rate of the channeled modified hierarchical-pore dealuminated Beta zeolite (Beta24C) is calculated to be 1.25 ml / g. According to the 10 g of support feed amount, a total of 12.5 ml of copper ammonia complex solution is required. According to the copper loading of 3 wt.%, the concentration of the required copper ammonia complex solution is about 0.38 M. That is, the calculated value of the concentration of the required copper ammonia complex solution is very close to the concentration of the saturated copper ammonia complex solution (0.4 M). Therefore, directly impregnate 10 g of the channeled modified hierarchical-pore dealuminated Beta zeolite support (Beta24C) with an equal volume of 12.5 ml of the saturated copper ammonia complex solution. The equal-volume impregnation is carried out at room temperature, and the impregnation time is 4 h.

[0126] (3) Perform ammonia evaporation treatment on the equal-volume impregnated material at normal pressure. The ammonia evaporation temperature is 80°C, and the ammonia evaporation time is 10 h. In this process, the copper ammonia complex that enters the zeolite pores due to capillary condensation gradually deposits in the zeolite pores in the form of copper hydroxide due to the loss of ammonia gas.

[0127] (4) Perform dehydration and drying treatment on the ammonia-evaporated material. The drying temperature is 110°C, and the drying time is 12 h.

[0128] (5) Perform calcination treatment on the dried material. The calcination temperature is 500°C, and the calcination time is 3 h. After calcination, the copper hydroxide deposited in the zeolite pores is converted into nano and sub-nano copper oxide particles, thus preparing a catalyst precursor.

[0129] (6) Perform hydrogen reduction treatment on the catalyst precursor. The reduction temperature is 400°C, the reduction time is 4 h, and the hydrogen flow rate (expressed by the hydrogen volume space velocity, defined as the hydrogen volume passing through the unit volume of catalyst per unit time, calculated as an ideal gas) is 300 h -1 After hydrogen reduction treatment, the finished Cu-Beta zeolite catalyst is prepared, and the code is Cu3-Beta24C-1.

[0130] Secondly, in order to understand the implementation effect of the catalyst preparation method provided by the present application from the aspect of the physical and chemical properties of the catalyst, the XRD pattern and the hydroxyl vibration infrared spectrum pattern of Cu3-Beta24C-1 and the multi-level hole dealuminated Beta zeolite support (Beta24C) modified by drilling holes were measured in parallel by XRD method and FT-IR method respectively, as shown in Figs. 2 and 3. In addition, the TEM photos of Cu3-Beta24C-1 catalyst and its high-temperature calcined sample (550℃×3h) were taken by transmission electron microscope, as shown in Figs. 4 and 5.

[0131] As can be seen from Fig. 2, the Cu3-Beta24C-1 catalyst prepared by the improved ammonia evaporation method provided by the present application retains the crystal structure of the Beta zeolite support well, and the relative crystallinity of the zeolite in the catalyst calculated based on the multi-level hole dealuminated Beta zeolite support (Beta24C) modified by drilling holes is 78%. As can be seen from Fig. 3, the Cu3-Beta24C-1 catalyst prepared according to the method of the present application has a greater decrease in the intensity of the infrared characteristic band of the zeolite hydroxyl hole compared with the multi-level hole dealuminated Beta zeolite support modified by drilling holes, indicating that a large number of hydroxyl hole lattice defect sites are occupied by copper. In addition, as can be seen from Figs. 4 and 5, the copper in the Cu3-Beta24C-1 catalyst exists in the state of highly dispersed nanometer and sub-nanometer particles, and the average particle size is about 3-4nm. After being calcined at a high temperature of 550℃ for 3h, the dispersion state of the copper particles changes little, and the average particle size is about 4-5nm. These data show that the hydroxyl hole lattice defect sites of the multi-level hole dealuminated Beta zeolite support modified by drilling holes have a very good effect of dispersing and stabilizing nanometer and sub-nanometer copper particles.

[0132] On this basis, the catalytic performance of Cu3-Beta24C-1 catalyst and its 550℃ high-temperature calcined sample was evaluated by caprolactam reaction prepared by gas-solid phase hydrogenation of caprolactone. The reaction was carried out in a small fixed-bed reactor. The inner diameter of the stainless steel reaction tube was 9mm, and the operation mode was top feeding and bottom discharging. 2g of the catalyst tabletted and formed (the sample after sieving was 20-40 mesh) was loaded in the constant temperature zone of the reactor. Inert porcelain balls were filled in the upper and lower spaces of the catalyst bed. Among them, the upper porcelain ball area of the reactor served as the vaporization and preheating zone of the raw material. The reaction temperature was 260℃, the reaction pressure was 1atm, the space velocity (WHSV) of caprolactone feed was 0.6h -1For convenience, caprolactone, ammonia raw material (analytical pure, ammonia concentration of 25-28 wt.%) and deionized water are mixed into raw material liquid according to the ammonia-ester molar ratio of 6 and the water-ester molar ratio of 30, and fed into the reactor by using a micro-metering pump, and hydrogen is fed by using a mass flow meter according to the hydrogen-ester molar ratio of 50. The reaction product is continuously collected in a stainless steel collection tank connected to the outlet of the reactor with a cooling water jacket, and the product liquid is collected at fixed time intervals for analysis on a Shimadzu gas chromatograph GC-2014 (FID detector, OV-1701 chromatographic column). The caprolactone conversion rate and caprolactam selectivity are calculated by using an internal standard method (internal standard substance is 1,4-dioxane). Under the above conditions, when the caprolactone hydrogenation reaction is continuously carried out for 6 h, the caprolactam yield of the Cu3-Beta24C-1 catalyst is about 88%; and the caprolactam yield of the sample of the Cu3-Beta24C-1 catalyst calcined at 550 ℃ is also about 88%. The above reaction results show that the Cu-Beta zeolite catalyst provided by the present application has excellent performance in the caprolactone hydrogenation reaction for preparing caprolactam.

[0133] Comparative Example 1: This example is used to illustrate that when a multi-level pore dealuminated Beta zeolite modified by channelling is used as a carrier and copper is loaded on the carrier by using a traditional ammonia evaporation method to prepare a Cu-Beta zeolite catalyst, the crystal structure of the Beta zeolite carrier is damaged to a large extent, the loaded copper mainly locates outside the zeolite pores, the dispersion degree is low, the copper particle size is large, and since the active silicon hydroxyl groups in the hydroxyl channelling of the dealuminated Beta zeolite are not protected, the sintering resistance is poor, so that the prepared Cu-Beta zeolite catalyst has poor performance in the caprolactone gas-solid phase hydrogenation reaction for preparing caprolactam.

[0134] Example 1 is repeated, but after the second step of preparing the multi-level pore dealuminated Beta zeolite carrier modified by channelling (Beta24C), copper hydroxide is deposited on the zeolite carrier by using the traditional ammonia evaporation method in the same way as the published document Science 10.1126 / science.adj1962 (2023), and the specific steps are as follows:

[0135] (1) 1.18 g of Cu(NO3)2·3H2O is dissolved in 515 ml of an ammonia water solution (containing 3.86 g of NH3·H2O, which is equivalent to 8.1 ml of 26 wt.% industrial ammonia water, and the molar ratio of copper ions to ammonia molecules is about 1:23) to prepare a copper ammonia complex aqueous solution (the complex ion concentration is about 9.5 mmol / L, i.e. 9.5 mM) which is stirred at room temperature for 10 min;

[0136] (2) 10 g of the multi-level pore dealuminated Beta zeolite carrier modified by channelling (Beta24C) is added to the 515 ml of the copper ammonia complex solution, and ammonia evaporation treatment is carried out under vigorous stirring. The ammonia evaporation temperature is 80 ℃, and the ammonia evaporation time is 6 h;

[0137] (3) After the ammonia evaporation was completed, the water solvent of the diluted and excess volume of copper-ammonia complex solution was finally removed by filtration, and the obtained filter cake was dried, calcined and hydrogen-reduced according to the same post-treatment method of Example 1 to obtain a Cu-Beta zeolite catalyst, which was coded as Cu3-Beta24C-CE1 (CE = Comparative Example).

[0138] In order to understand the characteristics of the Cu-Beta zeolite catalyst prepared by the traditional ammonia evaporation method from the aspect of the physicochemical properties of the catalyst, the Beta zeolite crystal structure of the Cu3-Beta24C-CE1 catalyst was characterized by XRD, and was compared with that of its support (Beta24C), as shown in FIG. 6. In addition, the Cu metal dispersion of the Cu3-Beta24C-CE1 catalyst and its high-temperature calcined sample (550°C x 3h) was characterized by transmission electron microscopy, and the catalytic performance of the Cu3-Beta24C-CE1 catalyst and its high-temperature calcined sample was evaluated by the caprolactam production reaction of caprolactone gas-solid phase hydrogenation.

[0139] The XRD characterization results showed that the damage degree of the zeolite crystal structure of the Cu3-Beta24C-CE1 catalyst prepared by the traditional ammonia evaporation method was relatively large, and the relative crystallinity of the zeolite calculated based on the support (Beta24C) was 60%. According to the characterization results of transmission electron microscopy, the average particle size of Cu metal of the Cu3-Beta24C-CE1 catalyst and its high-temperature calcined sample was 11 nm and 19 nm, respectively, that is, the Cu metal dispersion on the catalyst was low and easy to sinter. The reaction evaluation results showed that under the same reaction conditions, the caprolactam yield of the Cu3-Beta24C-CE1 catalyst was about 75%, and the caprolactam yield of its high-temperature calcined sample was 70%. The reaction results showed that the Cu-Beta zeolite catalyst prepared by the traditional ammonia evaporation method on the delaminated Beta zeolite support modified by the channelling method had low catalytic activity for the caprolactam production reaction of caprolactone gas-solid phase hydrogenation and poor anti-sintering deactivation ability.

[0140] Comparative Example 2: This example was used to illustrate that when the Cu-Beta zeolite catalyst was prepared by the improved ammonia evaporation method on the channelling-modified delaminated Beta zeolite support, the introduction of mesopores into the zeolite support to form a hierarchical pore system was not only beneficial to improving the anti-sintering ability of the Cu-Beta zeolite catalyst, but also beneficial to improving its catalytic activity.

[0141] Example 2: This example is to illustrate that the mesopore modification of the dealuminated Beta zeolite support is beneficial to the sintering resistance of the Cu-Beta zeolite catalyst prepared by the improved ammonia evaporation method. The procedure of Example 1 was repeated, but in the first step, the Beta zeolite mother phase without desilication treatment by sodium hydroxide solution was directly used for dealumination treatment by concentrated nitric acid to prepare a dealuminated Beta zeolite support (Beta24c). On this basis, by a second step of the chisel modification and a third step of the copper loading in the zeolite channels (by the improved ammonia evaporation method), a Cu-Beta zeolite catalyst was prepared. In this case, when the dealuminated Beta zeolite support was impregnated with an equal volume of the copper ammonia complex solution, the water absorption of the dealuminated Beta zeolite (Beta24c) was measured by the titration method to be 1.25 ml / g. According to the calculation of the 10 g support feed amount, a total of 12.5 ml of the copper ammonia complex solution was required. According to the calculation of the copper loading of 3 wt.%, the concentration of the required copper ammonia complex solution was about 0.38 M. That is, the calculated value of the required copper ammonia complex solution concentration was very close to the concentration of the saturated solution of the copper ammonia complex (0.4 M). Therefore, 10 g of the chisel-modified dealuminated Beta zeolite support was directly impregnated with an equal volume of the saturated solution of the copper ammonia complex of 12.5 ml. The other procedures were unchanged. The obtained Cu-Beta zeolite catalyst was named as Cu3-Beta24C-CE2.

[0142] To avoid the complexity, in this case, only the caprolactam production reaction by the gas-solid phase aminolysis of caprolactone was used to evaluate the catalytic performance of the Cu3-Beta24C-CE2 catalyst and the high-temperature calcined sample (550°C x 3 h) thereof. The reaction evaluation results showed that under the same reaction conditions, the caprolactam yield of the Cu3-Beta24C-CE2 catalyst was about 85%, and the caprolactam yield of the high-temperature calcined sample thereof was also close to 85%. By comparing the results with the reaction results in Example 1, it can be seen that the introduction of mesopores in the chisel-modified dealuminated Beta zeolite support is not only beneficial to the sintering resistance of the Cu-Beta zeolite catalyst, but also beneficial to the catalytic activity thereof.

[0143] Comparative Example 3: This example is to illustrate that when the dealuminated Beta zeolite is used as the support and the copper is loaded in the channels of the zeolite by the improved ammonia evaporation method to prepare the Cu-Beta zeolite catalyst, the chisel modification of the zeolite support is beneficial to the sintering resistance of the catalyst.

[0144] Example 3: This example is to illustrate that the Cu-Beta zeolite catalyst prepared by the improved copper-ammonia complex impregnation method has better anti-sintering ability than the Cu-Beta zeolite catalyst prepared by the traditional copper-ammonia complex impregnation method. The procedure of Example 1 was repeated, but in the first step, the Beta zeolite mother substance without desilication treatment by sodium hydroxide solution was directly used for dealumination treatment by concentrated nitric acid to prepare a dealuminated Beta zeolite support (Beta24c). Then, the dealuminated Beta zeolite support (Beta24c) was directly used in the third step to load copper in the pores by the improved ammonia evaporation method to prepare a Cu-Beta zeolite catalyst. In this case, when the dealuminated Beta zeolite support was impregnated with an equal volume of copper-ammonia complex solution, the water absorption of the dealuminated Beta zeolite (Beta24c) was measured by titration with deionized water to be 1.2 ml / g. According to the calculation of 10 g of support feed amount, a total of 12 ml of copper-ammonia complex solution was required. According to the calculation of the copper loading amount of 3 wt.%, the concentration of the required copper-ammonia complex solution was about 0.39 M. That is, the calculated value of the required concentration of the copper-ammonia complex solution was very close to the concentration of the saturated solution of the copper-ammonia complex (0.4 M). Therefore, 10 g of the dealuminated Beta zeolite support was directly impregnated with an equal volume of the saturated solution of the copper-ammonia complex of 12 ml. Other procedures were unchanged. The obtained Cu-Beta zeolite catalyst was named Cu3-Beta24c-CE3.

[0145] In this example, the catalytic performance of the Cu3-Beta24c-CE3 catalyst and its high-temperature calcined sample was evaluated by the reaction of caprolactone gas-phase solid-phase aminolysis to caprolactam. The reaction evaluation results showed that under the same reaction conditions, the caprolactam yield of the Cu3-Beta24c-CE3 catalyst was about 80%; the caprolactam yield of its high-temperature calcined sample (550°C x 3 h) was about 76%. Comparing the reaction results with Comparative Example 2, it can be seen that the notching modification of the dealuminated Beta zeolite support with ethanolamine solution is beneficial to improve the anti-sintering performance of the Cu-Beta zeolite catalyst.

[0146] Comparative Example 4: This example is to illustrate that the copper-silica catalyst prepared by the traditional ammonia evaporation method with amorphous fumed silica (white carbon black, BET specific surface area 286 m 2 / g) as the support has poor anti-sintering ability.

[0147] In this example, the traditional ammonia evaporation method described refers to the method of Example 1 in U.S. Patent US4 440 873 (1984), which is as follows:

[0148] (1) Dissolve 1.14 g of copper nitrate (Cu(NO3)2.3H2O) in 100 ml of water to obtain an aqueous solution containing copper ions, then add 3.6 ml of concentrated aqueous ammonia solution (industrial ammonia water with a NH3 content of 26 wt.%, density 0.89 g / ml) to the solution in a molar ratio of copper ions to ammonia molecules of about 1:10, and make up the volume to 150 ml with water, to obtain a deep blue copper-ammonia complex solution with a pH of 11-12 (complex ion concentration about 30.8 mM. The purpose of making up the volume to 150 ml is to keep the ratio of solution volume to dry basis of silicon dioxide consistent with the literature);

[0149] (2) Add 10 g of fumed silica (dry basis) to the copper-ammonia complex solution and stir at room temperature for 2 h;

[0150] (3) Perform an ammonia distillation treatment (80°C, 6 h) on the reaction mixture of step (2), and when the pH of the mixture drops to 6-7, filter to obtain a solid which is washed three times with deionized water to obtain a solid product;

[0151] (4) Dry the solid product at 120°C for 12 h and calcine at 450°C for 4 h;

[0152] (5) Perform a hydrogen reduction treatment on the calcined solid product. The reduction conditions are 350°C x 2 h, to obtain a copper-silica catalyst, code Cu3-SiO2-CE4.

[0153] The results of the evaluation of the caprolactam gas-solid phase hydrogenation reaction show that under the same reaction conditions, the caprolactam yield of the Cu3-SiO2-CE4 catalyst is 73%; the caprolactam yield of the high-temperature calcined sample (550°C x 3 h) is 62%. The reaction results show that the copper-based catalyst prepared using amorphous silica as a carrier has poor resistance to sintering, and the catalytic activity decreases significantly after high-temperature treatment.

[0154] Comparative Example 5: This example is used to further illustrate that a copper-silica catalyst prepared by loading copper using a traditional ammonia distillation method has poor resistance to sintering.

[0155] Repeat Comparative Example 4, but use 33.3 g of silica sol (30 wt.% SiO2) as a precursor for in-situ generation of 10 g of a silica carrier. In order to keep the ratio of solution volume to dry basis of silica consistent with Comparative Example 3, the amount of water added is changed to 26.7 ml when preparing the copper-ammonia complex solution in step (1). The copper-silica catalyst prepared is code Cu3-SiO2-CE5

[0156] The evaluation results of the caprolactam production reaction by gas-solid phase hydrogenation of caprolactone show that the caprolactam yield of the Cu3-SiO2-CE5 catalyst is 78% under the same reaction conditions; the caprolactam yield of the high-temperature calcined sample (550°C x 3h) is 70%. The reaction results also show that the copper-based catalyst prepared by using amorphous silica as the carrier has poor sintering resistance, and the catalytic activity greatly decreases after high-temperature treatment.

[0157] Comparative Example 6: This example is used to illustrate that the amorphous nature of the silica carrier determines the poor sintering resistance of the copper-silica catalyst.

[0158] In this example, the copper-silica catalyst is prepared by using the improved ammonia evaporation method provided by the present application on the gas phase silica carrier. Specifically as follows:

[0159] Example 1 is repeated, but 10g of the fluted modified hierarchical pore dealuminated Beta zeolite carrier is replaced by 10g (dry basis) of the gas phase silica (white carbon black, BET specific surface area 286m 2 / g, and saturated water absorption of 2.5ml / g), and 10g of the gas phase silica needs 25ml of the copper ammonia complex solution. The concentration of the copper ammonia complex solution required is about 0.19M according to the copper loading of 3wt.%. 11.9ml of the copper ammonia complex saturated solution is diluted to 25ml by using the dilute ammonia water base solution, that is, 25ml of the copper ammonia complex solution with a concentration of 0.19M is obtained. The prepared copper-silica catalyst is coded as Cu3-SiO2-CE6.

[0160] The evaluation results of the caprolactam production reaction by gas-solid phase hydrogenation of caprolactone show that the caprolactam yield of the Cu3-SiO2-CE5 catalyst is 78% under the same reaction conditions; the caprolactam yield of the high-temperature calcined sample (550°C x 3h) is 70%. The reaction results also show that the copper-based catalyst prepared by using amorphous silica as the carrier has poor sintering resistance, and the catalytic activity greatly decreases after high-temperature treatment.

[0161] Example 2: This example is used to illustrate that the Cu-Beta zeolite catalyst preparation method provided by the present application can be used to prepare Cu-Beta zeolite catalysts with different copper loadings by using the fluted modified hierarchical pore dealuminated Beta zeolite as the carrier and using the improved ammonia evaporation method to load copper in the zeolite pores.

[0162] Example 1 was repeated, but the copper loading in the prepared Cu-Beta zeolite catalyst was reduced to 1 wt.% and 2 wt.% successively, and the concentration of the required copper ammonia complex solution was about 0.13 M and 0.25 M successively. 3.9 ml and 7.8 ml of the saturated copper ammonia complex solution were diluted to 12.5 ml with the dilute ammonia water base solution successively, to obtain an equal volume impregnation solution for the Cu-Beta zeolite catalyst with copper loading of 1 wt.% and 2 wt.% successively. In the preparation of the Cu-Beta zeolite catalyst by the improved ammonia evaporation method, the time for the equal volume impregnation treatment of the multi-level hole dealuminated Beta support modified by channelling (Beta24C) at room temperature was changed to 6 h, the temperature and time for the ammonia evaporation treatment were changed to 65 °C and 12 h respectively, the temperature and time for the dehydration drying were changed to 150 °C and 3 h respectively, the subsequent calcination temperature and time were changed to 450 °C and 6 h respectively, the final hydrogen reduction temperature and time were changed to 350 °C and 8 h respectively, and the hydrogen flow rate (volume space velocity) was changed to 1000 h -1 The code of the prepared Cu-Beta zeolite catalyst was Cu1-Beta24C-2 and Cu2-Beta24C-2 successively.

[0163] The evaluation results of the caprolactam gas-solid phase hydrogenation amination of caprolactone showed that under the same reaction conditions, the caprolactam yield of the Cu1-Beta24C-2 catalyst was 83%, and the caprolactam yield of the Cu2-Beta24C-2 catalyst was 85%.

[0164] Example 3: This example is used to further illustrate that the Cu-Beta zeolite catalyst preparation method provided by the improved ammonia evaporation method for loading copper in the zeolite pores with the channelling modified multi-level hole dealuminated Beta zeolite as the carrier can be used to prepare Cu-Beta zeolite catalysts with different copper loadings. However, when preparing Cu-Beta zeolite catalysts with copper loading higher than 3 wt.%, it is appropriate to use a multiple loading scheme to prepare the catalyst.

[0165] Example 1 was repeated, but the copper loading in the prepared Cu-Beta zeolite catalyst was increased to 4wt.% and 6wt.% respectively, and the concentration of the required copper-ammonia complex solution was calculated to be about 0.50M and 0.76M respectively. Obviously, the required copper-ammonia complex concentrations are both higher than the concentration of the copper-ammonia complex saturated solution prepared with the dilute ammonia water base solution (0.4M). We tried to dissolve the copper-ammonia complex with industrial ammonia water instead of the dilute ammonia water base solution, and the maximum concentration of the copper-ammonia complex solution obtained was about 0.5M. Although the copper-ammonia complex solution with a high concentration of about 0.5M can be prepared by dissolving the copper-ammonia complex with industrial ammonia water, the ammonia / copper ion molar ratio of the solution is more than 24:1, the basicity is strong, and the ammonia gas volatilization is serious, i.e. it is not conducive to the protection of the crystal structure of the dealuminated Beta zeolite and the operation. This indicates that the Cu-Beta zeolite catalyst with a high copper loading cannot be obtained by one-time equal-volume impregnation and ammonia evaporation operation on the given multi-level pore dealuminated Beta zeolite support with the modified ammonia evaporation method. In view of this, the dilute ammonia water base solution is used to dilute the copper-ammonia complex saturated solution, and the Cu-Beta zeolite catalyst with a copper loading of 4wt.% and 6wt.% respectively is prepared by multiple equal-volume impregnation and ammonia evaporation operations. For the preparation of the catalyst with a copper loading of 4wt.%, two-time equal-volume impregnation and ammonia evaporation operations can be performed, such as 1wt.%+3wt.% and 2wt.%+2wt.%; for the preparation of the catalyst with a copper loading of 6wt.%, two-time (3wt.%+3wt.%) or three-time (2wt.%+2wt.%+2wt.%) operations can be performed. In order to be simple, in this example, the Cu-Beta zeolite catalyst with a copper loading of 4wt.% and 6wt.% respectively is prepared by two-time (2wt.%+2wt.% and 3wt.%+3wt.%) operations. The impregnation solution with a copper-ammonia complex concentration of 0.25M is required to be 12.5ml for loading 2wt.% of copper on the multi-level pore dealuminated Beta zeolite support with the modified ammonia evaporation method, and the impregnation solution with a copper-ammonia complex concentration of 0.38M is required to be 12.5ml for loading 3wt.% of copper on the multi-level pore dealuminated Beta zeolite support with the modified ammonia evaporation method. Among them, the 0.25M impregnation solution is obtained by diluting 7.8ml of the copper-ammonia complex saturated solution with the dilute ammonia water base solution, and the 0.38M impregnation solution is directly obtained by using the copper-ammonia complex saturated solution. When the multi-level pore dealuminated Beta support with the modified ammonia evaporation method is subjected to equal-volume impregnation at room temperature, the impregnation time is changed to 6h, the ammonia evaporation temperature and time are changed to 85℃ and 3h respectively, the dehydration and drying temperature and time are changed to 120℃ and 5h respectively, the subsequent calcination temperature and time are changed to 550℃ and 2h respectively, the final hydrogen reduction temperature and time are changed to 500℃ and 2h respectively, and the hydrogen flow (volume space velocity) is changed to 20h -1(The feed was controlled by a mass flow meter after mixing with an appropriate amount of nitrogen). The prepared Cu-Beta zeolite catalysts were designated as Cu4-Beta24C-3 and Cu6-Beta24C-3, respectively.

[0166] Evaluation results of the gas-solid phase hydroammoniation of caprolactone to caprolactam showed that, under the same reaction conditions, the caprolactam yield was 88% with the Cu4-Beta24C-3 catalyst and 87% with the Cu6-Beta24C-3 catalyst.

[0167] Example 4: This example illustrates that when preparing Cu-Beta zeolite catalysts according to the improved ammonia stripping method provided by the present invention, it is permissible to use Beta zeolite matrix with different crystal sizes to prepare dealubilized Beta zeolite supports.

[0168] Example 1 was repeated, but in the first step of preparing the dealuminized Beta zeolite support, a Beta zeolite matrix with a silicon-aluminum oxide molar ratio (SiO2 to Al2O3 molar ratio) of 22 was synthesized using the hydrothermal crystallization method (with ammonium fluoride additive) provided in the published literature J. Mater. Sci. 41 (2006) 1861-1864 as the raw material for preparing the hierarchical porous dealuminized Beta zeolite support. After conventional filtration, washing, drying (80℃, 24h) and calcination to remove the template agent (600℃, 3h), the synthesized Beta zeolite matrix was observed by TEM to have an average grain size of 1μm, belonging to large-grained Beta zeolite; XRD analysis showed no impurities; and its BET specific surface area was calculated to be approximately 480 m² using nitrogen physical adsorption data. 2 The molar ratio of silicon-aluminum oxides (SiO2 to Al2O3) was approximately 23, as measured by XRF, which meets the technical requirements of this invention for the Beta zeolite matrix. The large-grained hierarchical porous dealubilized Beta zeolite support (code-named Beta23c) prepared using this Beta zeolite matrix has a microporous specific surface area accounting for approximately 70% of the total specific surface area, and a silicon-aluminum oxide molar ratio (SiO2 to Al2O3) of 735 (>700). Based on this, following the procedure in step 2 of Example 1, the above-mentioned large-grained hierarchical porous dealubilized Beta zeolite support (Beta23c) was subjected to a pore-knocking modification treatment with an aqueous solution of ethanolamine to obtain a pore-knocking modified large-grained hierarchical porous dealubilized Beta zeolite support, named Beta23C; further, following the procedure in step 3 of Example 1, copper was loaded into the zeolite channels using a modified ammonia stripping method to prepare a Cu-Beta zeolite catalyst with a copper content of 3 wt.%, code-named Cu3-Beta23C-4.

[0169] The evaluation results of caprolactam production reaction by gas-solid phase hydrogenation of caprolactone show that the caprolactam yield of Cu3-Beta23C-4 catalyst is 86% under the same reaction conditions.

[0170] Example 5: This example is used to illustrate that when the Cu-Beta zeolite catalyst is prepared by using the modified multi-level pore dealuminated Beta zeolite as the carrier and loading copper in the pores by the improved ammonia evaporation method, the degree of modification of the multi-level pore dealuminated Beta zeolite can be regulated by changing the modification conditions of the ethanolamine solution.

[0171] The example 1 is repeated, but in the second step, when the hydroxyl pocket of the multi-level pore dealuminated Beta zeolite carrier is modified by using the aqueous solution of ethanolamine, the concentration of the aqueous ethanolamine solution is changed to 0.16 M, the ratio of the modification liquid volume to the multi-level pore dealuminated Beta zeolite carrier (Beta24C) feeding amount (liquid-solid ratio) is changed to 10:1, the immersion temperature is changed to 50°C, and the immersion time is changed to 0.5 h. After the modification of the hydroxyl pocket is completed, the reaction material is filtered to recover the solid product, then the solid product is repeatedly washed with deionized water until it is neutral, and then the solid product is dried (overnight at 110°C) and calcined (at 550°C for 3 h) to prepare the modified multi-level pore dealuminated Beta zeolite carrier. It is sealed and stored for later use. According to the weight loss estimation, the average number of framework silicon atoms (calculated as SiO2) removed from the lattice defect sites of the hydroxyl pocket of the dealuminated Beta zeolite carrier is 1.5 silicon atoms, and the desiliconization amount is increased. It is illustrated that the above-mentioned treatment conditions strengthen the modification treatment of the hydroxyl pocket, and increase the geometric space of the lattice defect sites of the hydroxyl pocket of the multi-level pore dealuminated Beta zeolite. On this basis, the copper content of 3wt.% of the Cu-Beta zeolite catalyst is prepared by loading copper in the pores of the modified carrier by the improved ammonia evaporation method, and is named as Cu3-Beta24C-5.

[0172] The evaluation results of caprolactam production reaction by gas-solid phase hydrogenation of caprolactone show that the caprolactam yield of Cu3-Beta24C-5 catalyst is 89% under the same reaction conditions; and the caprolactam yield of the sample of Cu3-Beta24C-5 catalyst calcined at 550°C is 88%.

[0173] Example 6: This example is used to further illustrate that when the Cu-Beta zeolite catalyst is prepared by using the modified multi-level pore dealuminated Beta zeolite as the carrier and loading copper in the pores by the improved ammonia evaporation method, the degree of modification of the multi-level pore dealuminated Beta zeolite can be regulated by changing the modification conditions of the ethanolamine solution.

[0174] Example 1 was repeated, but in the second step, the hydroxy pocket channelling modification treatment of the hierarchical pore dealuminated Beta zeolite support was carried out using an aqueous solution of ethanolamine, the concentration of the aqueous ethanolamine solution was changed to 0.30 M, the liquid to solid ratio was changed to 2:1, and the impregnation temperature was changed to 20°C, and the impregnation time was changed to 1 h. After the completion of the channelling modification, the reaction mass was filtered to recover the solid product, which was then repeatedly washed with deionized water until it was neutral, and then dried (overnight at 110°C) and calcined (at 550°C for 3 h) to produce the channelling-modified hierarchical pore dealuminated Beta zeolite support. The product was stored in a sealed container for later use. The average number of framework silicon atoms (in terms of SiO2) chiselled out from the hydroxy pocket lattice defect sites of the dealuminated Beta zeolite support was estimated to be 0.9 silicon atoms based on the weight loss, and the dealumination amount was reduced, indicating that the above-mentioned channelling modification condition combination weakened the channelling modification treatment. On this basis, the copper content of 3 wt.% Cu-Beta zeolite catalyst was prepared by using the improved ammonia evaporation method to load copper in the pore channel, and was named Cu3-Beta24C-6.

[0175] The evaluation results of the caprolactam gas-solid phase hydrogenation reaction show that under the same reaction conditions, the caprolactam yield of the Cu3-Beta24C-6 catalyst is 85%; the caprolactam yield of the high-temperature calcined sample (550°C x 3h) is 84%.

[0176] Example 7: This example is used to illustrate that when the improved ammonia evaporation method provided by the present application is used to prepare a Cu-Beta zeolite catalyst, different Beta zeolite matrices with different molar ratios of silicon-aluminum oxide (molar ratio of SiO2 to Al2O3) can be used to prepare the channelling-modified hierarchical pore dealuminated Beta zeolite support. When a Beta zeolite matrix with a higher molar ratio of silicon-aluminum oxide (molar ratio of SiO2 to Al2O3) is used, a relatively mild channelling modification condition combination should be used. Conversely, the opposite is also true.

[0177] Example 1 was repeated, but in the first step of preparing the hierarchical pore dealuminated Beta zeolite support, a Beta zeolite matrix with a molar ratio of silicon-aluminum oxide (molar ratio of SiO2 to Al2O3) of 60 was synthesized by the hydrothermal crystallization method provided in US Patent US3308069 (1967) as the raw material for preparing the hierarchical pore dealuminated Beta zeolite support. After the synthesized Beta zeolite matrix was subjected to conventional filtration, washing, drying (at 170°C for 3 h), and calcination to remove the template agent (at 500°C for 8 h), TEM observation showed that the average grain size of the Beta zeolite matrix was close to 100 nanometers, which belonged to a nano-Beta zeolite; XRD examination showed that there were no any impurities in the Beta zeolite matrix, and the BET specific surface area of the Beta zeolite matrix was calculated to be about 530 m 2The molar ratio of silicon-aluminum oxides (molar ratio of SiO2to Al2O3) of the Beta zeolite matrix is about 57, which meets the technical requirements of the Beta zeolite matrix of the present application.

[0178] The Beta zeolite matrix is used for desilication treatment with sodium hydroxide solution and dealumination treatment with concentrated nitric acid to prepare a hierarchical pore dealuminated Beta zeolite carrier. In the preparation of the hierarchical pore Beta zeolite matrix by desilication treatment with alkali treatment of sodium hydroxide solution, the desilication weight loss is about 5.22 wt.%. In the preparation of the hierarchical pore dealuminated Beta zeolite carrier by dealumination treatment with acid treatment of the hierarchical pore Beta zeolite matrix with concentrated nitric acid solution, a hierarchical pore dealuminated Beta zeolite carrier (code Beta57c) with a molar ratio of silicon-aluminum oxides (molar ratio of SiO2to Al2O3) of 910 (> 900) is obtained. The degree of dealumination of the carrier meets the requirements of the present application. In the second step, the hydroxyl pit of the hierarchical pore dealuminated Beta zeolite carrier is modified by pit chiseling treatment with an aqueous solution of ethanolamine. The concentration of the aqueous ethanolamine solution is changed to 0.02 M, the liquid-solid ratio is changed to 20:1, the impregnation temperature is changed to 80°C, and the impregnation time is changed to 5 h. After the pit chiseling modification is completed, the reaction material is filtered to recover the solid product, which is then repeatedly washed with deionized water until it is neutral, and then dried (overnight at 110°C) and calcined (at 550°C for 3 h) to obtain the dealuminated Beta zeolite modified by pit chiseling. It is sealed and stored for use. According to the weight loss, the average number of framework silicon atoms (in terms of SiO2) chiseled out of the hydroxyl pit lattice defect site of the dealuminated Beta zeolite carrier is 1.3 silicon atoms, and the desilication amount increases, indicating that the above-mentioned combination of pit chiseling modification conditions has strengthened the pit chiseling modification treatment for the hierarchical pore dealuminated Beta zeolite carrier with a small number of hydroxyl pits. The pit chiseling modified hierarchical pore dealuminated Beta zeolite carrier obtained is named Beta57C. Further, according to the method of the third step of Example 1, copper is loaded in the zeolite pores by improved ammonia evaporation to prepare a Cu-Beta zeolite catalyst with a copper content of 3 wt.%. In the impregnation of the carrier with an equal volume of saturated solution of copper-ammonia complex at room temperature, the impregnation time is changed to 2 h. In the ammonia evaporation, micro-negative pressure ammonia evaporation is used, the ammonia evaporation temperature is 50°C, and the ammonia evaporation time is 48 h. In the dehydration and drying of the material after ammonia evaporation, the drying temperature and time are changed to 100°C and 48 h, respectively. The subsequent calcination temperature and time are changed to 350°C and 24 h, respectively. The final hydrogen reduction treatment temperature, time and hydrogen flow (volume space velocity) are changed to 300°C, 20 h and 2000 h -1 , respectively, and the catalyst code is Cu3-Beta57C-7.

[0179] The evaluation results of the caprolactam gas-solid phase hydrogenation reaction show that under the same reaction conditions, the caprolactam yield of the Cu3-Beta57C-7 catalyst is 84%.

[0180] Example 8: This example is used to further illustrate that, when preparing Cu-Beta zeolite catalyst by improved ammonia desorption method provided by the present application, it is allowed to use Beta zeolite matrix with different silica alumina molar ratio (molar ratio of Si02 to Al203) to prepare the multi-level pore dealuminated Beta zeolite support with channeled modification. When using Beta zeolite with higher silica alumina molar ratio (molar ratio of Si02 to Al203) as the matrix, it is appropriate to use a relatively mild channeled modification condition combination. Conversely, the same is true.

[0181] Example 7 was repeated, but in the second step, when the hydroxyl channeled modification treatment was performed on the dealuminated Beta zeolite support using an aqueous solution of ethanolamine, the liquid-solid ratio was changed to 100:1 and the immersion time was changed to 24 h. After the channeled modification was completed, the reaction material was filtered to recover the solid product, which was then repeatedly washed with deionized water until it was neutral, and then dried (overnight at 110°C) and calcined (at 550°C for 3 h) to obtain the channeled modified dealuminated Beta zeolite. It was sealed and stored for later use. According to the weight loss estimation, the average number of framework silicon atoms (in terms of Si02) channeled out from the hydroxyl channeled modification of the dealuminated Beta zeolite support was 2.3 silicon atoms, and the desiliconization amount increased significantly, indicating that the above channeled modification condition combination strengthened the channeled modification treatment for the multi-level pore dealuminated Beta zeolite support with a small number of hydroxyl channels. On this basis, the channeled modified multi-level pore dealuminated Beta zeolite obtained was used as the support to prepare a Cu-Beta zeolite catalyst according to the method of Example 1, Step 3, and the code of the catalyst was Cu3-Beta57C-8.

[0182] The evaluation results of the caprolactam gas-solid phase hydrogenation reaction showed that, under the same reaction conditions, the caprolactam yield of the Cu3-Beta57C-8 catalyst was 83%.

[0183] Example 9: This example is used to further illustrate that, when preparing Cu-Beta zeolite catalyst by improved ammonia desorption method provided by the present application, it is allowed to use Beta zeolite matrix with different silica alumina molar ratio (molar ratio of Si02 to Al203) to prepare the multi-level pore dealuminated Beta zeolite support with channeled modification. When using Beta zeolite with higher silica alumina molar ratio (molar ratio of Si02 to Al203) as the matrix, it is appropriate to use a relatively mild channeled modification condition combination. Conversely, the same is true.

[0184] Example 1 was repeated, but in the first step of preparing the hierarchical-pore dealuminated Beta zeolite carrier, firstly, Beta zeolite precursors with silica-alumina molar ratios (molar ratio of SiO2 to Al2O3) of 15, 20, 40, 80 and 100 were synthesized by a hydrothermal crystallization method provided in Chinese Invention Patent CN1108275C (application date 10 September 1999) as raw materials for preparing the dealuminated Beta zeolite carrier. After the synthesized Beta zeolite precursors were subjected to conventional filtration, washing, drying (110°C, 12h) and calcination to remove the template agent (540°C, 6h), TEM observation showed that the average crystal size thereof belonged to the nanometer level and the small crystal (less than 1 μm) level. With the increase of the silica-alumina molar ratio, the crystal size increased; XRD examination did not find any impurity crystal therein, and the BET specific surface area thereof calculated from the nitrogen physical adsorption data was higher than 500 m2 / g; and XRF measurement showed that the silica-alumina molar ratios (molar ratio of SiO2 to Al2O3) thereof were 14, 18, 38, 72 and 94, respectively, which met the technical requirements of the Beta zeolite precursor according to the present application. 2 Example 2 was repeated, but in the first step of preparing the hierarchical-pore dealuminated Beta zeolite carrier, firstly, Beta zeolite precursors with silica-alumina molar ratios (molar ratio of SiO2 to Al2O3) of 15, 20, 40, 80 and 100 were synthesized by a hydrothermal crystallization method provided in Chinese Invention Patent CN1108275C (application date 10 September 1999) as raw materials for preparing the dealuminated Beta zeolite carrier. After the synthesized Beta zeolite precursors were subjected to conventional filtration, washing, drying (110°C, 12h) and calcination to remove the template agent (540°C, 6h), TEM observation showed that the average crystal size thereof belonged to the nanometer level and the small crystal (less than 1 μm) level. With the increase of the silica-alumina molar ratio, the crystal size increased; XRD examination did not find any impurity crystal therein, and the BET specific surface area thereof calculated from the nitrogen physical adsorption data was higher than 500 m 2 / g, and XRF measurement showed that the silica-alumina molar ratios (molar ratio of SiO2 to Al2O3) thereof were 14, 18, 38, 72 and 94, respectively, which met the technical requirements of the Beta zeolite precursor according to the present application.

[0185] The five above-mentioned Beta zeolite matrices were used to prepare hierarchical pore dealuminated Beta zeolite carriers by alkali desilication with sodium hydroxide solution and acid dealumination with concentrated nitric acid solution. In the preparation of hierarchical pore Beta zeolite by alkali desilication with sodium hydroxide solution, the five Beta zeolite matrices were in the order of low to high in the molar ratio of silicon-aluminum oxides (the molar ratio of SiO2 to Al2O3), and the weight loss of desilication was 7.31, 7.99, 8.88, 9.79, and 10.31%, respectively. In the preparation of hierarchical pore dealuminated Beta zeolite carrier by acid dealumination with concentrated nitric acid solution, five dealuminated Beta zeolite carriers, Beta14c, Beta18c, Beta38c, Beta72c, and Beta94c, were obtained, and the molar ratio of silicon-aluminum oxides (the molar ratio of SiO2 to Al2O3) was 730, 755, 850, 843, and 916, respectively, all of which met the technical requirements of dealuminated Beta zeolite carriers. On this basis, the above-mentioned hierarchical pore dealuminated Beta zeolite carriers were subjected to channelling modification treatment with an aqueous solution of ethanolamine according to the method of the second step of Example 1. The channelling modification treatment conditions were as follows: the concentration of the aqueous solution of ethanolamine was changed to 0.01 M, the liquid-solid ratio was changed to 20:1, the impregnation temperature was changed to 80°C, and the impregnation time was changed to 3h. After the channelling modification was completed, the reaction material was filtered to recover the solid product, which was then repeatedly washed with deionized water until it was neutral, and then dried (overnight at 110°C) and calcined (at 550°C for 3h) to obtain channelling-modified hierarchical pore dealuminated Beta zeolite carriers, which were named Beta14C, Beta18C, Beta38C, Beta72C, and Beta94C. They were sealed and stored for later use. According to the weight loss, the average number of framework silicon atoms (calculated as SiO2) chiselled out from the hydroxyl channelling lattice defect sites of the dealuminated Beta zeolite carriers in the above-mentioned channelling-modified hierarchical pore dealuminated Beta zeolite carriers was 0.2, 0.3, 0.4, 0.8, and 1.1, respectively. That is, the above-mentioned channelling modification condition combination was not sufficient for the channelling modification of the hierarchical pore dealuminated Beta zeolite carriers prepared from the Beta zeolite matrices with a lower molar ratio of silicon-aluminum oxides (the molar ratio of SiO2 to Al2O3).

[0186] Further, according to the method of the third step of Example 1, copper was loaded in the zeolite pores by the improved ammonia evaporation method to prepare a Cu-Beta zeolite catalyst with a copper content of 3wt.%. In this process, when the carrier was impregnated with a saturated solution of copper-ammonia complex at room temperature, the impregnation time was changed to 1h. In the ammonia evaporation, the ammonia evaporation temperature was 90°C, and the ammonia evaporation time was 1h. In the dehydration and drying of the material after ammonia evaporation, the drying temperature and time were changed to 200°C and 1h, respectively. The subsequent calcination temperature and time were changed to 550°C and 1h, respectively. Finally, the hydrogen reduction treatment temperature, time, and hydrogen flow rate were changed to 550°C, 1h, and 5h, respectively. -1(Cu3-Beta14C-9, Cu3-Beta18C-9, Cu3-Beta38C-9, Cu3-Beta72C-9 and Cu3-Beta94C-9, respectively).

[0187] The anti-sintering deactivation performance of the above catalysts and their 550°C calcined (3h) samples were evaluated by using caprolactam gas-solid phase hydrogenation to caprolactam reaction. The results showed that under the same reaction conditions, the catalytic activity of Cu3-Beta14C-9, Cu3-Beta18C-9, Cu3-Beta38C-9, Cu3-Beta72C-9 and Cu3-Beta94C-9 catalysts after high temperature calcination decreased by about 3%, 3%, 3%, 4% and 5%, respectively.

[0188] Example 10: This example is used to further illustrate that when preparing Cu-Beta zeolite catalysts by using the improved ammonia evaporation method provided by the present application, it is allowed to use Beta zeolite matrices with different silica-alumina molar ratios (molar ratio of SiO2 to Al2O3) to prepare the channeled modified dealuminated Beta zeolite carriers. When using Beta zeolite with a higher silica-alumina molar ratio (molar ratio of SiO2 to Al2O3) as the matrix, it is appropriate to use a relatively mild channeled modification condition combination. Conversely, the same is true.

[0189] Example 9 was repeated, but when using aqueous ethanolamine solution to channeled modify different hierarchical pore dealuminated Beta zeolite carriers in the second step, the concentration of the aqueous ethanolamine solution was changed to 0.08M. After the channeled modification was completed, the reaction material was filtered to recover the solid product, which was then repeatedly washed with deionized water until it was neutral, and then dried (overnight at 110°C) and calcined (550°C, 3h) to obtain channeled modified hierarchical pore dealuminated Beta zeolite carriers, designated as Beta14C, Beta18C, Beta38C, Beta72C and Beta94C. They were sealed and stored for later use. According to the weight loss, the average number of framework silicon atoms (in terms of SiO2) channeled out of the hydroxyl channeled lattice defect sites of the dealuminated Beta zeolite carriers in the above channeled modified dealuminated Beta zeolite matrices was 0.6, 0.8, 1.0, 1.6 and 1.8, respectively. That is, the above channeled modification condition combination improved the degree of desilication modification of different carriers.

[0190] The catalysts prepared by using the improved ammonia evaporation method on the above channeled modified hierarchical pore dealuminated Beta zeolite carriers were designated as Cu3-Beta14C-10, Cu3-Beta18C-10, Cu3-Bet38C-10, Cu3-Beta72C-10 and Cu3-Beta94C-10, respectively.

[0191] The anti-sintering deactivation performance of the above catalysts and their samples calcined at 550°C (3h) was evaluated by using caprolactone gas solid phase hydrogenation amination reaction to prepare caprolactam. The results showed that under the same reaction conditions, the decline in catalytic activity of Cu3-Beta14C-10, Cu3-Beta18C-10, Cu3-Beta38C-10, Cu3-Beta72C-10 and Cu3-Beta94C-10 catalysts after high-temperature calcination was about 2%, 3%, 2%, 3% and 5%, respectively.

[0192] Example 11: This example is used to illustrate that when the improved ammonia evaporation method provided by the present application is used to prepare Cu-Beta zeolite catalyst, it allows the use of Beta zeolite matrixes with different silica alumina molar ratios (molar ratio of SiO2 to Al2O3) to prepare the channeled modified hierarchical pore dealuminated Beta zeolite carrier. However, when the channeled modified hierarchical pore dealuminated Beta zeolite carrier is prepared using a Beta zeolite matrix with a higher silica alumina molar ratio (molar ratio of SiO2 to Al2O3), it is suitable for preparing Cu-Beta zeolite catalysts with lower copper loading.

[0193] Example 1 was repeated, but in the first step of preparing the hierarchical pore dealuminated Beta zeolite carrier, a Beta zeolite matrix with a silica alumina molar ratio (molar ratio of SiO2 to Al2O3) of 100 was synthesized by the hydrothermal crystallization method provided by Chinese Invention Patent CN1108275C (application date 1999.9.10) as the raw material for preparing the hierarchical pore dealuminated Beta zeolite carrier. After the synthesized Beta zeolite matrix was treated by conventional filtration, washing, drying (200°C, 3h) and calcination to remove the template (500°C, 8h), TEM observation showed that its average crystal size belonged to the small crystal (less than 1 μm) level. XRD examination showed that there were no any impurity crystals in it, and its BET specific surface area calculated from its nitrogen physical adsorption data was higher than 530 m 2 / g, and XRF measurement showed that its silica alumina molar ratio (molar ratio of SiO2 to Al2O3) was 94, which met the technical requirements of the Beta zeolite matrix of the present application.

[0194] The Beta zeolite mother substance was first treated with sodium hydroxide solution to prepare a hierarchical pore Beta zeolite mother substance, and then treated with concentrated nitric acid solution to prepare a hierarchical pore dealuminated Beta zeolite carrier with a molar ratio of silicon-aluminum oxide (molar ratio of SiO2 to Al2O3) of 916 (> 900) (coded as Beta94c), which meets the technical requirements of the present application. On this basis, the hierarchical pore dealuminated Beta zeolite carrier was modified by using an aqueous solution of ethanolamine according to the method of the second step of Example 1 to obtain a notched modified hierarchical pore dealuminated Beta zeolite carrier, which is named as Beta94C. Further, a Cu-Beta zeolite catalyst with a copper content of 6 wt.% was prepared according to the improved ammonia evaporation method according to the method of the third step of Example 1, which is twice equal volume impregnation and twice ammonia evaporation. The concentration of the copper-ammonia complex solution used in the twice equal volume impregnation is 0.38 M. Since the concentration of the 0.38 M copper-ammonia complex solution is very close to the concentration of the saturated solution of the copper-ammonia complex prepared by using the dilute ammonia water base solution, 12.5 ml of the 0.4 M saturated solution of the copper-ammonia complex was directly used for equal volume impregnation of the Beta94C carrier. The prepared catalyst is coded as Cu6-Beta94C-11.

[0195] The anti-sintering deactivation performance of the catalyst and the sample thereof calcined at 550°C (3h) was evaluated by using caprolactam gas-solid phase hydrogenation reaction. The results showed that under the same reaction conditions, the catalytic activity (caprolactam yield) of the Cu6-Beta94C-11 catalyst after high temperature calcination decreased by 7%.

[0196] Example 12: This example is used to illustrate that when the Cu-Beta zeolite catalyst is prepared by using the catalyst preparation method provided by the present application, which is to use the notched modified hierarchical pore dealuminated Beta zeolite as the carrier and use the improved ammonia evaporation method to load copper in the pore channel, the degree of desilication of the zeolite mother substance and the amount of mesopore generated can be adjusted by changing the alkali treatment conditions of the sodium hydroxide solution, so as to adjust the sintering resistance and activity of the catalyst.

[0197] Example 1 was repeated, but in the preparation of the hierarchical pore dealuminated Beta zeolite carrier in the first step, the concentration of the sodium hydroxide solution was changed to 0.3 M, the liquid-solid ratio was changed to 5:1 (ml / g), the desilication temperature was 30°C, and the desilication time was 20 min. The determination results showed that the desilication weight loss of the zeolite mother substance was 9.11%, and the micropore specific surface area of the hierarchical pore zeolite mother substance accounted for about 77% of the total specific surface area. The Cu-Beta zeolite catalyst prepared on this basis is coded as Cu3-Beta24C-12. In the caprolactam gas-solid phase hydrogenation reaction, the caprolactam yield of the catalyst was 85%, and the caprolactam yield of the sample thereof calcined at 550°C (3h) decreased by less than 2%.

[0198] Example 13: This example is used to further illustrate that in the preparation of Cu-Beta zeolite catalyst using the improved ammonia evaporation method to load copper in the pore channel of the multi-pore dealuminated Beta zeolite carrier modified by channelling, the degree of desilication and the amount of mesopore generated in the zeolite matrix can be adjusted by changing the alkali treatment conditions of the sodium hydroxide solution, so as to adjust the sintering resistance and activity of the catalyst.

[0199] Example 1 was repeated, but in the preparation of the multi-pore dealuminated Beta zeolite carrier in the first step, the concentration of the sodium hydroxide solution was changed to 0.05 M, the liquid-solid ratio was changed to 20:1 (ml / g), the desilication temperature was 55°C, and the desilication time was 60 min. The measurement results showed that the weight loss of desilication of the zeolite matrix was 7.22%, and the micropore specific surface area of the multi-pore zeolite matrix accounted for about 76% of the total specific surface area. The Cu-Beta zeolite catalyst prepared on this basis was designated as Cu3-Beta24C-13. In the gas-solid phase hydrogenation of caprolactone, the caprolactam yield of the catalyst was 86%, and the caprolactam yield of the sample calcined at 550°C (3 h) decreased by less than 1%.

[0200] Example 14: This example is used to further illustrate that in the preparation of Cu-Beta zeolite catalyst using the improved ammonia evaporation method to load copper in the pore channel of the multi-pore dealuminated Beta zeolite carrier modified by channelling, the degree of desilication and the amount of mesopore generated in the zeolite matrix can be adjusted by changing the alkali treatment conditions of the sodium hydroxide solution, so as to adjust the sintering resistance and activity of the catalyst.

[0201] Example 1 was repeated, but in the preparation of the multi-pore dealuminated Beta zeolite carrier in the first step, the concentration of the sodium hydroxide solution was changed to 0.05 M, the liquid-solid ratio was changed to 20:1 (ml / g), the desilication temperature was 55°C, and the desilication time was 60 min. The measurement results showed that the weight loss of desilication of the zeolite matrix was 7.22%, and the micropore specific surface area of the multi-pore zeolite matrix accounted for about 76% of the total specific surface area. The Cu-Beta zeolite catalyst prepared on this basis was designated as Cu3-Beta24C-13. In the gas-solid phase hydrogenation of caprolactone, the caprolactam yield of the catalyst was 86%, and the caprolactam yield of the sample calcined at 550°C (3 h) decreased by less than 1%.

[0202] Example 15: This example is used to further illustrate that in the preparation of Cu-Beta zeolite catalyst using the improved ammonia evaporation method to load copper in the pore channel of the multi-pore dealuminated Beta zeolite carrier modified by channelling, the degree of desilication and the amount of mesopore generated in the zeolite matrix can be adjusted by changing the alkali treatment conditions of the sodium hydroxide solution, so as to adjust the sintering resistance and activity of the catalyst.

[0203] Example 1 was repeated, but in the first step of preparing the hierarchical pore dealuminated Beta zeolite support, the concentration of sodium hydroxide solution was changed to 0.01 M, the liquid to solid ratio was changed to 30:1 (ml / g), the desilication temperature was 60 °C, and the desilication time was 180 min. The results of the measurements showed that the desilication weight loss of the zeolite mother phase was 5.56%, and the micropore specific surface area of the hierarchical pore zeolite mother phase was about 76% of the total specific surface area. The Cu-Beta zeolite catalyst prepared on this basis was designated Cu3-Beta24C-15. In the gas-solid phase hydrogenation of caprolactone, the caprolactam yield of this catalyst was 83%, and the caprolactam yield of the sample thereof calcined at 550 °C (3 h) decreased by less than 1%.

Claims

1. A method for preparing an anti-sintering Cu-Beta zeolite catalyst, characterized in that, The steps are as follows: The first step is to prepare a multi-level porous dealuminolite Beta zeolite support. (1) Select Beta zeolite parent material The aforementioned Beta zeolite matrix refers to silica-alumina Beta zeolite that meets the following requirements: 1) The Beta zeolite matrix is ​​free of impurities; 2) The Beta zeolite matrix has good crystallinity, i.e., the BET specific surface area value of the Beta zeolite matrix measured by nitrogen physical adsorption method is ≥450m². 2 / g;3) The molar ratio of silicon and aluminum oxides in the Beta zeolite matrix, i.e., the molar ratio of SiO2 to Al2O3, is in the range of 15-100; (2) Preparation of multi-level porous Beta zeolite matrix Multi-level porous Beta zeolite matrix was prepared by alkaline treatment and desilication of Beta zeolite matrix with sodium hydroxide solution, with the following parameter requirements: The concentration range of sodium hydroxide aqueous solution is 0.01-0.5M; The ratio of the volume of sodium hydroxide aqueous solution to the amount of Beta zeolite parent material, i.e., the liquid-solid ratio, ranges from 2:1 to 30:1, and the unit of the liquid-solid ratio is ml / g. The temperature range for the desilication reaction is 15℃-60℃; The desilication reaction time ranges from 10 to 180 minutes; (3) Preparation of multi-level porous dealuminolite Beta zeolite support A hierarchical porous dealuminated Beta zeolite support was prepared by acid dealumination based on a hierarchical porous Beta zeolite matrix. The required molar ratio of silicon and aluminum oxides, i.e., the molar ratio of SiO2 to Al2O3, in the prepared hierarchical porous dealuminated Beta zeolite support is ≥700. The second step involves using an aqueous solution of ethanolamine to perform pore-forming modification on the hydroxyl groups of the hierarchical porous dealuminolized Beta zeolite support. Hollowing modification of hydroxyl groups was carried out using an aqueous solution impregnation method, with the following parameter requirements: The concentration range of the ethanolamine solution is 0.01M-0.4M; The ratio of ethanolamine solution to hierarchical porous dealuminolized Beta zeolite support, i.e., the liquid-solid ratio, ranges from 1:1 to 100:1, and the unit of the liquid-solid ratio is ml / g. The impregnation temperature range is 20℃-100℃; The soaking time ranges from 0.5 h to 24 h; The third step involves loading copper into the pores of a hierarchical, dealuminolized Beta zeolite support using a modified ammonia stripping method to prepare a Cu-Beta zeolite catalyst. The specific steps are as follows: (1) Preparation of dilute ammonia water base solution and saturated solution of copper ammonia complex: Prepare a dilute ammonia water base solution with pH value of 11-12 by diluting 4.4g of industrial ammonia water containing 25-28wt.% NH3 with 100ml of deionized water, and store it in a sealed container for later use; then, according to the molar ratio of copper ions to ammonia molecules of 1:4, use copper nitrate trihydrate as a soluble copper compound to react with industrial ammonia water to synthesize copper ammonia complex; finally, dissolve the copper ammonia complex in dilute ammonia water base solution at room temperature to prepare a saturated solution of copper ammonia complex, and store it in a sealed container for later use; the concentration of copper ammonia complex ions in the saturated solution of copper ammonia complex is 0.4M; (2) Impregnating the zeolite support with an equal volume of copper ammonia complex solution: First, determine the saturated water absorption rate of the zeolite support, and calculate the amount of copper ammonia complex solution to impregnate the zeolite support with an equal volume; then, calculate the required concentration of the copper ammonia complex solution according to the copper loading of the Cu-Beta zeolite catalyst to be prepared; when the calculated concentration is equal to 0.4 M, directly impregnate the zeolite support with the saturated solution of copper ammonia complex with an equal volume; when the calculated concentration is less than 0.4 M, dilute the saturated solution of copper ammonia complex with dilute ammonia water base solution appropriately, and then impregnate the zeolite support with an equal volume. When the calculated value is higher than 0.4M, the concentration of the copper ammonia complex solution for a single equal-volume impregnation should be recalculated according to multiple equal-volume impregnations. The copper ammonia complex solution of the required concentration should be prepared using dilute ammonia water base solution and saturated copper ammonia complex solution for each equal-volume impregnation. After each impregnation, the zeolite carrier must be subjected to ammonia stripping treatment; the equal-volume impregnation is carried out at room temperature in a closed container; the equal-volume impregnation time ranges from 0.5 to 24 hours. (3) Ammonia stripping treatment: The ammonia stripping process is carried out under normal or reduced pressure; the temperature and time range for ammonia stripping are 50-100℃ and 0.5-48h. (4) Dehydration and drying treatment after ammonia stripping: The drying temperature and time ranges are 100-200℃ and 0.5-48h, respectively; (5) Roasting treatment after ammonia stripping: Roasting is carried out in an air atmosphere, with roasting temperature and time ranging from 350-650℃ and 0.5-24h, respectively; The catalyst precursor was obtained by calcination. (6) Hydrogen reduction treatment of catalyst precursor: The reduction temperature, time and hydrogen volume hourly space velocity ranged from 280-600℃, 0.5-20h and 1-2000h, respectively. -1 The catalyst precursor is reduced with hydrogen to become Cu-Beta zeolite catalyst.

2. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 1, characterized in that, The steps are as follows: In step (1), the molar ratio of silicon aluminum oxide in the Beta zeolite matrix, i.e., the molar ratio of SiO2 to Al2O3, is in the range of 20-80.

3. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 2, characterized in that, The steps are as follows: In step (1), the molar ratio of silicon aluminum oxide in the Beta zeolite matrix, i.e., the molar ratio of SiO2 to Al2O3, is in the range of 25-60.

4. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 1, characterized in that, The steps are as follows: In step (2), when preparing hierarchical porous Beta zeolite matrix by alkaline treatment and desilication of Beta zeolite matrix with sodium hydroxide solution, the following parameters are required: The concentration range of sodium hydroxide aqueous solution is 0.05-0.4M; The liquid-solid ratio between the volume of sodium hydroxide aqueous solution and the amount of Beta zeolite parent material fed is in the range of 3:1-20:1, and the unit of liquid-solid ratio is ml / g; The temperature range for the desilication reaction is 20℃-55℃; The desilication reaction time ranges from 15 to 120 minutes.

5. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 4, characterized in that, The steps are as follows: In step (2), when preparing hierarchical porous Beta zeolite matrix by alkaline treatment and desilication of Beta zeolite matrix with sodium hydroxide solution, the following parameters are required: The concentration range of sodium hydroxide aqueous solution is 0.1-0.3M; The liquid-solid ratio between the volume of sodium hydroxide aqueous solution and the amount of Beta zeolite parent material fed is in the range of 5:1-15:1, and the unit of liquid-solid ratio is ml / g; The temperature range for the desilication reaction is 25℃-45℃; The desilication reaction time ranges from 20 to 60 minutes.

6. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 1, characterized in that, The steps are as follows: In step (2), when preparing multi-level porous Beta zeolite matrix by alkaline treatment and desilication of Beta zeolite matrix with sodium hydroxide solution, the specific steps are as follows: First, the Beta zeolite matrix is ​​pretreated by drying and calcination. The drying temperature range is 80-200℃ and the drying time is 3-24h. The calcination temperature range is 500℃-600℃ and the calcination time is 3-8h. Secondly, the pretreated Beta zeolite matrix is ​​subjected to desilication treatment, including: heating the sodium hydroxide solution to the desilication reaction temperature, then adding the pretreated Beta zeolite matrix to the sodium hydroxide solution according to the liquid-solid ratio, and reacting under stirring conditions; finally, after the reaction is completed, the reactants are immediately cooled, and the solid product is recovered by solid-liquid separation, then the solid product is washed with water until the pH value is neutral, then dried at 80-200℃ for 3-24h, and calcined at 500℃-600℃ for 1-6h to obtain a hierarchical porous Beta zeolite matrix.

7. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 1, characterized in that, In step (3), the required molar ratio of silicon aluminum oxide to Al2O3 in the multi-level porous dealuminolite Beta zeolite support is ≥800.

8. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 7, characterized in that, In step (3), the required molar ratio of silicon aluminum oxide to Al2O3 in the multi-level porous dealuminolite Beta zeolite support is ≥900.

9. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 1, characterized in that, In step (3), when preparing a hierarchical porous dealuminolized Beta zeolite support by acid dealuminolization of the hierarchical porous Beta zeolite matrix using concentrated nitric acid aqueous solution, the specific steps are as follows: 13M concentrated nitric acid was used as the dealumination acid solution, with a liquid-to-solid ratio of 20:1 (ml / g). The dealumination reaction was carried out at 95℃ for 20 hours. After the dealumination reaction, the solid product was first recovered by solid-liquid separation, then washed with water until the pH value was neutral, dried at 80-200℃ for 3-24 hours, and calcined at 500℃-600℃ for 3-8 hours to obtain the multi-porous dealumination Beta zeolite support.

10. The method for preparing the anti-sintering Cu-Beta zeolite catalyst according to claim 1, characterized in that, In the second step, the hydroxyl groups of the hierarchical porous dealuminolized Beta zeolite support are modified by aqueous solution impregnation using an aqueous solution of ethanolamine. The parameters are as follows: The concentration range of the ethanolamine solution is 0.02M-0.3M; The ratio of ethanolamine solution to hierarchical porous dealuminolized Beta zeolite support, i.e., the liquid-solid ratio, ranges from 2:1 to 50:1, and the unit of the liquid-solid ratio is ml / g. The impregnation temperature range is 30℃-90℃; The soaking time ranges from 1 hour to 10 hours.

11. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 10, characterized in that, In the second step, the hydroxyl groups of the hierarchical porous dealuminolized Beta zeolite support are modified by aqueous solution impregnation using an aqueous solution of ethanolamine. The parameters are as follows: The concentration range of the ethanolamine solution is 0.03M-0.16M; The ratio of ethanolamine solution to hierarchical porous dealuminolized Beta zeolite support, i.e., the liquid-solid ratio, ranges from 3:1 to 20:1, and the unit of the liquid-solid ratio is ml / g. The impregnation temperature range is 40℃-80℃; The soaking time ranges from 2 to 5 hours.

12. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 1, characterized in that, In step 3 (2), the immersion time for equal volume is in the range of 1-12 hours; In the third step (3), the temperature and time range for ammonia stripping are 60-90℃ and 1-24h; In the third step (4), the drying temperature and time ranges are 110-170℃ and 1-24h, respectively; In the third step (5), the roasting temperature and time ranges are 400-600℃ and 1-12h, respectively; In step 3 (6), the reduction temperature, time, and hydrogen volume hourly space velocity ranges are 300-550℃, 1-15h, and 10-1500h, respectively. -1 .

13. The method for preparing an anti-sintering Cu-Beta zeolite catalyst according to claim 12, characterized in that, In step 3 (2), the immersion time for equal volume is in the range of 2-6 hours; In the third step (3), the temperature and time range for ammonia stripping are 65-85℃ and 3-12h; In the third step (4), the drying temperature and time ranges are 120-150℃ and 3-12h, respectively; In the third step (5), the roasting temperature and time ranges are 450-550℃ and 2-6h, respectively; In step 3 (6), the reduction temperature, time, and hydrogen volume hourly space velocity ranges are 350-500℃, 2-8h, and 20-1000h, respectively. -1 .

14. The Cu-Beta zeolite catalyst prepared by the method of any one of claims 1-13 is used to catalyze the gas-solid phase hydroammoniation of caprolactone to caprolactam.

15. The application according to claim 14, characterized in that, The reaction conditions are as follows: reaction temperature range is 120-350℃, reaction pressure range is 0.01-2 atm, and feed space velocity of caprolactone ranges from 0.1 to 5 h⁻¹. -1 The suitable ranges for the molar ratios of amine-ester, hydrogen-ester, and water-ester are 1-50, 5-70, and 0-100, respectively.

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