Catalyst for preparing epoxy compound through hydrogen-gas-phase epoxidation of alpha-olefin and preparation method of catalyst

Abstract

The invention relates to a preparation method of an Au / TS-1 catalyst applied to an alpha-olefin hydrogen-gas phase epoxidation reaction, which solves the problem of poor stability (less than 3 hours) of the traditional high-activity Au / TS-1 catalyst in a manner of physically mixing the Au / TS-1 catalyst with a hydrophobic polymer PDVB (polydivinylbenzene) and roasting a fresh TS-1 molecular sieve in a CO / He atmosphere or combining the Au / TS-1 catalyst with the hydrophobic polymer PDVB and the fresh TS-1 molecular sieve. According to the scheme that the TS-1 molecular sieve roasted in the CO / He atmosphere is loaded with Au and then is physically mixed with PDVB, the stability of the catalyst in the propylene hydrogen phase epoxidation reaction can be improved to 100 hours, the PO generation rate is kept at 230 gPOh <-1 > kgCat-1, the catalytic activity and the stability are both considered, and the method is suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalyst preparation and catalytic reaction engineering, and specifically relates to a catalyst used in the gas-phase epoxidation reaction of α-olefins (propylene, 1-butene) in the presence of hydrogen, and is particularly suitable for a catalyst used in the industrial continuous production process of propylene oxide (PO) and a preparation method thereof. Background Art

[0002] Epoxides are important α-olefin derivatives, and their efficient and green synthesis has attracted considerable attention. The vapor-phase epoxidation of α-olefins in the presence of hydrogen holds great promise for industrial applications due to its simplicity, high selectivity, and atom economy. However, catalyst stability issues severely restrict its industrial application.

[0003] The strong adsorption of epoxy compounds on the catalyst surface is a key factor in deactivation. Epoxides bind to titanium hydroxyl or silanol groups through oxygen atoms, occupying active sites and initiating ring-opening side reactions, which reduces selectivity and accelerates carbon deposition. Modification selectively eliminates silanol groups, retains the activity of titanium hydroxyl groups, promotes epoxy compound desorption, and improves catalyst stability. A common post-treatment strategy is to use organosilanes to increase the hydrophobicity of the support, but this inevitably covers the active sites, resulting in a decrease in reaction activity. By changing the calcination atmosphere during catalyst synthesis, a hydrophobic microenvironment is constructed around the active sites, effectively extending the catalyst life while maintaining high activity.

[0004] At present, there are two main types of catalysts used in the gas-phase epoxidation of α-olefins to prepare epoxy compounds: Ni-Ti-based non-precious metal catalysts and Au / titanium silicate molecular sieve-based precious metal catalysts. Ni-Ti-based catalysts are difficult to apply to large-scale industrial production due to their low selectivity and H2 efficiency. CN115845916A discloses an Au / TS-1 catalyst for an epoxidation reaction system. The titanium silicate is prepared by a hydrothermal method without adding any additional substances, avoiding the problem of introducing a binder to cover a portion of the titanium species and affecting the placement of the Au species. By avoiding the secondary side reactions caused by product retention that reduce the catalytic activity and deactivation, the service life of the catalyst is extended. The Au / TS-1 catalyst for the epoxidation reaction system disclosed in CN115845917A controls the hydrothermal crystallization process to prepare a TS-1 catalyst at the micron level with high crystallinity and good titanium distribution, which has good catalytic performance and stability. The Au / TS-1 catalysts for epoxidation reaction systems disclosed in CN112844468A, CN112871205A, and CN112871204A have additives added during the preparation process to enrich titanium and obtain more defect sites, which facilitate the loading of Au and improve the hydrogen efficiency and propylene conversion rate.

[0005] Au / titanium silicate molecular sieve catalysts have high low-temperature activity and selectivity and have the greatest potential for industrial application. However, the main problem they face is poor stability due to Au particle sintering and carbon deposition. Summary of the Invention

[0006] One purpose of the present application is to improve the stability of Au / TS-1 catalyst in the gas-phase epoxidation reaction of α-olefins (propylene, 1-butene) in the presence of hydrogen.

[0007] Another object of the present application is to simultaneously improve the stability and catalytic activity of the Au / TS-1 catalyst in the gas-phase epoxidation reaction of α-olefins (propylene, 1-butene) in the presence of hydrogen.

[0008] A method for preparing an Au / TS-1 catalyst comprises: 1) calcining an uncalcined TS-1 molecular sieve in a mixed atmosphere containing CO to obtain a modified TS-1 molecular sieve;

[0009] 2) The modified TS-1 molecular sieve is mixed with an aqueous solution containing a gold compound, and a first solid is obtained after filtering and washing. The first solid is then dried and reduced to obtain an Au / TS-1 catalyst.

[0010] The fresh TS-1 molecular sieve is an uncalcined solid containing silicon and titanium. The silicon-titanium molar ratio of the fresh TS-1 molecular sieve is 50-250.

[0011] The Au / TS-1 catalyst prepared in this application is used in a reaction system for preparing epoxy compounds from α-olefins.

[0012] The Au / TS-1 catalyst obtained by the above method is calcined in a CO atmosphere. The obtained Au / TS-1 catalyst has good stability and can maintain a high production rate of epoxy compounds for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the XRD pattern of the catalyst in Example 1 of the present application;

[0014] Figure 2 This is the BET diagram of the catalyst in Example 1 of the present application;

[0015] Figure 3 This is the contact angle diagram of the catalyst in Example 1 of this application. DETAILED DESCRIPTION

[0016] The following is a further detailed description of the catalyst for preparing epoxides from α-olefins and the preparation method thereof, according to the present application. This does not limit the scope of this application, which is defined by the claims. Certain specific details are disclosed to provide a comprehensive understanding of each disclosed embodiment. However, those skilled in the relevant art will appreciate that embodiments may be implemented without one or more of these specific details, using other materials, and the like.

[0017] Unless the context requires otherwise, in the specification and claims, the terms "include" and "comprising" should be understood as having an open and inclusive meaning, that is, "including, but not limited to".

[0018] The terms "embodiment," "one embodiment," "another embodiment," or "certain embodiments" mentioned in the specification mean that the specific features, structures, or characteristics described in connection with the embodiment are included in at least one embodiment. Therefore, "embodiment," "one embodiment," "another embodiment," or "certain embodiments" do not necessarily all refer to the same embodiment. Moreover, specific features, structures, or characteristics may be combined in any manner in one or more embodiments. Each feature disclosed in the specification may be replaced by any alternative feature that can provide the same, equal, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equal or similar features.

[0019] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which specific conditions are not specified, are generally based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, all percentages, ratios, proportions, or parts are by weight.

[0020] The units of weight-volume percentage in the present invention are well known to those skilled in the art, for example, refer to the weight of the solute in 100 ml of solution.

[0021] In the present invention, the concentration unit "M" of a solution represents mol / L.

[0022] “TS-1” in this application refers to titanium silicate molecular sieve.

[0023] The "silicon-titanium molar ratio" refers to the molar ratio of silicon to titanium in the molecular sieve.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0025] In one aspect, a method for preparing an Au / TS-1 catalyst for preparing an epoxy compound from an α-olefin comprises: 1) calcining an uncalcined TS-1 molecular sieve as a template in a mixed gas containing CO to obtain a modified TS-1 molecular sieve;

[0026] 2) The modified TS-1 molecular sieve is mixed with an aqueous solution containing a gold compound to obtain a mixture, the mixture is filtered and washed to obtain a first solid, and the first solid is further dried and reduced to obtain an Au / TS-1 catalyst.

[0027] The TS-1 molecular sieve without calcining the template agent is a molecular sieve before calcining. That is, the TS-1 molecular sieve without calcining the template agent contains the template agent.

[0028] The silicon-titanium molar ratio of fresh TS-1 molecular sieve is 50-250.

[0029] The template agent includes one or a mixture of at least two of ethylenediamine, tetraethylammonium hydroxide, n-butylamine, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium bromide and tetrabutylammonium bromide.

[0030] The mixed gas containing CO includes CO and inert gas. Inert gas refers to gas that does not react with other substances at high temperatures, such as He.

[0031] In certain embodiments, in the mixed gas containing CO, the volume ratio of CO to inert gas is 1:(5-20).

[0032] Optionally, the mixed gas containing CO includes CO and He, and the volume ratio of CO to He is 1:(8-12); for example, the volume ratio of CO to He is 1:10.

[0033] The CO content in the calcination atmosphere is too low, and the template agent in the pores is not completely decomposed, resulting in pore blockage and the Ti active sites inside cannot be utilized.

[0034] By calcining the uncalcined TS-1 molecular sieve in a CO / He atmosphere, CO is selectively adsorbed and decomposed with the template in the molecular sieve pores to form carbon species that partially cover the surface hydroxyl groups, reducing the strong adsorption of epoxy compounds in the pores while retaining the pore space required for the active center.

[0035] In certain embodiments, the calcination temperature is 300-700°C. Alternatively, the calcination temperature is 400-600°C, for example, about 500°C.

[0036] Preferably, the heating rate during the calcination process is 1-5°C / min. Alternatively, the heating rate during the calcination process is 1-3°C / min. Controlling the heating rate during the calcination process can effectively control the pore structure of the molecular sieve and prevent the molecular sieve from collapsing.

[0037] By calcining in the above-mentioned CO2-containing mixed atmosphere under the above-mentioned conditions, the ultra-thin carbon layer can be controlled to optimize the pore structure, selectively cover the surface hydroxyl groups to weaken the side reactions, and the modified molecular sieve ensures the integrity of the initial structure, avoiding the influence of possible structural defects on the performance effect.

[0038] Optionally, the roasting time is 2-6 hours.

[0039] The uncalcined TS-1 molecular sieve of the template agent in step (1) is calcined and naturally cooled to obtain a modified TS-1 molecular sieve with an average pore size of 0.5-0.6 nm and a pore volume of 0.10-0.25 cm 3 / g.

[0040] Alternatively, the average pore size of the modified TS-1 molecular sieve obtained by calcining at a temperature of about 500°C is about 0.5 nm, and the pore volume is about 0.22 cm 3 / g.

[0041] In certain embodiments, in step (2), the concentration of the aqueous solution of the gold-containing compound is 0.01-2 mol / L. Alternatively, the concentration of the aqueous solution of the gold-containing compound is 0.01-0.1 mol / L.

[0042] The dosage of the gold-containing compound aqueous solution and the dosage of the modified TS-1 molecular sieve are such that the Au loading amount is 0.05-1% of the total mass of the catalyst.

[0043] The gold-containing compound may be chloroauric acid.

[0044] In step (2), the pH of the mixture of the modified TS-1 molecular sieve and the aqueous solution containing the gold compound is adjusted to 5-9. During the mixing process, the temperature is controlled at 20-70°C.

[0045] Optionally, the pH of the mixture of the modified TS-1 molecular sieve and the aqueous solution containing the gold compound is adjusted to 5-8.

[0046] Controlling the pH within the above range can achieve a close distribution of Au-Ti species. If the acidity is too high or too low, different Au species will be formed and the size of Au particles will also be affected, which in turn affects the selectivity of the final catalyst.

[0047] The substance for adjusting pH may be carbonate or sodium hydroxide, and preferably, cesium carbonate is used.

[0048] In certain embodiments, in step (2), the drying temperature is 20-120° C. Alternatively, the drying temperature is 20-100° C.

[0049] The drying time can be determined by the drying temperature to remove the solvent of the catalyst and control it to a certain range. Optionally, the drying temperature is 1-12 hours, or 6-12 hours.

[0050] After the mixture of step (2) is filtered, it is washed until the solid does not contain chloride ions. Silver nitrate solution can be used to detect whether there is precipitation to determine whether the solid contains chloride ions.

[0051] The reduction treatment in step (2) can be carried out using a common method in the prior art to obtain the Au / TS-1 catalyst.

[0052] The reduction treatment is carried out in a reducing atmosphere at a temperature of 100-250° C. Optionally, the reduction treatment is carried out for 1-4 hours.

[0053] The reducing agent in the reducing atmosphere mainly includes H2 gas.

[0054] The heating rate during the reduction treatment is 0.5-3°C / min.

[0055] The silicon-titanium molar ratio of fresh TS-1 molecular sieve is 50-250, and the specific surface area is 400-550m 2 / g.

[0056] Fresh TS-1 molecular sieve can be prepared by existing methods, preferably by ultraviolet light-assisted method.

[0057] In certain embodiments, the method for preparing TS-1 molecular sieve without calcining the template agent comprises:

[0058] (1) mixing a template, a silicon source, a titanium source, and water to obtain a mixed solution I;

[0059] (2) irradiating the mixed solution I of step (1) with a light source containing ultraviolet light to obtain a mixed solution II;

[0060] (3) The mixed solution II is crystallized, solid-liquid separated, and dried to obtain the titanium silicate molecular sieve of the uncalcined template agent.

[0061] The light source is a mixed ultraviolet light with a wavelength of 10-400nm. Alternatively, the light source is a mixed long-wave ultraviolet light with a wavelength of 320-400nm.

[0062] During the mixing process of step (1) and step (2), the temperature is higher than 0°C and lower than 100°C; more preferably, the mixing temperature is higher than 10°C and lower than 35°C.

[0063] The template includes one or a mixture of at least two of ethylenediamine, tetraethylammonium hydroxide, n-butylamine, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium bromide, and tetrabutylammonium bromide. The silicon source includes tetraethyl orthosilicate and / or silica sol. The titanium source includes tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate, titanium trichloride, and titanium tetrachloride, or a mixture of at least two of them.

[0064] The molar ratio of the template to the silicon source is: Si / template=(0.1-50):1.

[0065] In step (3), the crystallization temperature is higher than 100°C and lower than 200°C.

[0066] In step (3), the drying temperature is 40-120°C; more preferably, the drying temperature should be 70-90°C.

[0067] The Au / TS-1 catalyst finally obtained has an Au loading of 0.05-1 wt % and an Au particle size of 2-5 nm.

[0068] The Au / TS-1 catalyst obtained by the above method is applied to the reaction system of preparing epoxy compounds from α-olefins. Compared with the conventional Au / TS-1 catalyst in the prior art, the stability is improved to 30 hours, and the generation rate of epoxy compounds (such as PO) does not decrease significantly.

[0069] On the other hand, a method for preparing an Au / TS-1 catalyst for preparing epoxy compounds from α-olefins comprises mixing the Au / TS-1 catalyst with a hydrophobic polymer PDVB to obtain a hydrophobically modified Au / TS-1 catalyst.

[0070] PDVB is the abbreviation of polydivinylbenzene polymer, which is a polymer material formed by the polymerization of divinylbenzene monomers.

[0071] The Au / TS-1 catalyst can be prepared by any method in the prior art. Preferably, the Au / TS-1 catalyst is prepared using the above method.

[0072] The hydrophobic properties of the hydrophobically modified Au / TS-1 catalyst and PDVB reduce the adsorption of water on the catalyst surface in the reaction system for preparing epoxy compounds from α-olefins, thereby reducing the number of hydroxyl groups on the surface of the molecular sieve, inhibiting the adsorption of epoxy compounds on the surface of the molecular sieve and further side reactions, and generating carbon deposits covering the active sites.

[0073] The mass ratio of Au / TS-1 catalyst to PDVB is 1:(0.25-5). Preferably, the mass ratio of Au / TS-1 catalyst to PDVB is 1:(0.5-2), for example, the mass ratio of the two is 1:1.

[0074] The Au / TS-1 catalyst and the hydrophobic polymer PDVB were mechanically stirred and mixed at a stirring rate of 100-300 r / min.

[0075] The stirring and mixing time is not limited, as long as the two are fully mixed. Optionally, the stirring and mixing time is 1-20 minutes, or 1-10 minutes.

[0076] In certain embodiments, the number average molecular weight of PDVB is 10,000-200,000.

[0077] The particle size of PDVB is 5-50 μm. Preferably, the particle size of PDVB is 15-30 μm, such as about 20 μm.

[0078] By mixing the Au / TS-1 catalyst prepared in the present application with PDVB, the problems of pore blockage and water-induced deactivation are solved simultaneously, achieving a balance between stability and activity.

[0079] After Au / TS-1 prepared by calcination in a CO atmosphere is mixed with PDVB, the catalyst stability can be improved to 100 hours compared with the conventional Au / TS-1 catalyst in the prior art, and the PO generation rate is slightly reduced, taking into account both catalytic activity and stability, and is more suitable for industrial production applications.

[0080] The catalyst preparation method disclosed herein involves mixing an Au / TS-1 catalyst with PDVB, leveraging PDVB's hydrophobic properties to mitigate the negative effects of water on the catalyst. The Au / TS-1 catalyst, prepared by calcining the TS-1 molecular sieve in a CO atmosphere, suppresses pore clogging through the controlled pore blocking of the fresh molecular sieve, achieving a comprehensive balance between epoxy production rate and stability. Further mixing with PDVB further enhances both epoxy production rate and stability.

[0081] The catalyst preparation process does not require complex equipment or expensive raw materials; physical mixing and calcination are conventional processes. PDVB is inexpensive and suitable for large-scale industrial production. It is not only suitable for the vapor-phase epoxidation of propylene in the presence of hydrogen, but also exhibits similar effects in the epoxidation of other α-olefins, such as 1-butene.

[0082] In another aspect, the catalyst prepared by any of the above schemes of the present application is used in a reaction system for preparing epoxy compounds from α-olefins.

[0083] The α-olefin may be propylene or n-butene.

[0084] A method for preparing an epoxy compound from an α-olefin comprises reacting an α-olefin, oxygen and hydrogen under the action of an Au / TS-1 catalyst prepared by any of the above methods to obtain an epoxy compound, wherein the reaction temperature is 100-250°C.

[0085] In the reaction raw materials, the volume ratio of α-olefin, hydrogen and oxygen is 1:1:1.

[0086] The amount of catalyst used is 0.1-5g.

[0087] The reaction raw materials also contain nitrogen, and the volume ratio of α-olefin to nitrogen is about 1:7.

[0088] The pressure during the reaction process is controlled at 0.1-0.5 MPa.

[0089] During the reaction, the gas space velocity is 5000-50000h -1 For example, about 14000h -1 .

[0090] Under the action of the above catalyst in this application, the propylene is epoxidized to propylene oxide (PO) at a production rate of 130-300 g under the above conditions. PO h -1 kg Cat -1 The catalyst can act stably for 3-250 hours.

[0091] The catalyst of the present invention and its catalytic effect are further described below with reference to specific examples. The substances used in the following examples are all chemically pure.

[0092] In the following examples, fresh TS-1 molecular sieve was prepared using the method of Example 3 of patent CN201910341872.7. The silicon-titanium molar ratio was 200, and the specific surface area was 430 m 2 / g, pore diameter 0.50nm, pore volume 0.22cm 3 / g.

[0093] Chloroauric acid (HAuCl4·4H2O): analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0094] Polydivinylbenzene (PDVB): A nonporous polymer was prepared according to the protocol “Synthesis of nonporous PDVB” in the supporting information of the literature (Science, 2022, 377(6604):406-410). It is a light yellow solid with a particle size of 20 μm and a contact angle of 160°.

[0095] Cesium carbonate, silver nitrate, propylene, hydrogen, oxygen, and nitrogen: all were analytical grade or industrial grade.

[0096] Example 1

[0097] Preparation of Au / TS-1 catalyst

[0098] 10 g of fresh TS-1 molecular sieve was placed in a quartz tube reactor, and a CO / He mixed gas (CO and He volume ratio 1:10) was introduced. The temperature was raised to 500 °C at 2 °C / min, and the mixture was calcined for 4 h. After cooling, the modified TS-1 molecular sieve was obtained.

[0099] Take 10g of modified TS-1 molecular sieve and add 8mL of 0.02g / mL chloroauric acid solution. Add 1mol / L cesium carbonate solution dropwise while stirring to adjust the pH to 7.2. React in the dark at 30℃ for 6 hours, stand in the dark for 12 hours, filter, wash until there is no chloride ion, and dry at 30℃ for 10 hours.

[0100] The dried solid was reduced in a reaction atmosphere (the reaction gas included H2) at 200°C for 2 hours (heating rate 1°C / min) to obtain an Au / TS-1 catalyst with an Au loading of 0.5%.

[0101] The catalyst prepared in this example was subjected to X-ray diffraction (XRD) analysis, N2 adsorption-desorption (Nitrogen adsorption-desorption, BET) analysis, and contact angle (Contact Angle Measurement) analysis. The results are shown in the accompanying figures. Figure 1 The XRD diffraction pattern shown in the figure shows that the catalyst is of MFI configuration, and no relevant diffraction peaks of Au, Ti, and C are found, indicating that the Au, Ti, and C oligomers are highly dispersed. Figure 2 As shown in the BET diagram, the catalyst has a higher adsorption-desorption curve mainly at low pressure, indicating that the catalyst mainly contains microporous structure. The curve distribution of the catalyst after CO calcination is similar to that of the conventionally treated molecular sieve, and no micropore blockage is found. Figure 3 The contact angle diagram shown in the figure indicates that the hydrophobicity of the catalyst surface is enhanced after CO calcination. This hydrophobicity can effectively promote the desorption of epoxy compounds, thereby improving the stability of α-olefin epoxidation while ensuring the selectivity of epoxy compounds.

[0102] Example 2

[0103] Preparation of Au / TS-1 catalyst

[0104] The steps and process parameters for preparing the Au / TS-1 catalyst in this example are the same as those in Example 1, except that the calcination temperature is adjusted to 400°C.

[0105] Example 3

[0106] Preparation of Au / TS-1 catalyst

[0107] The steps and process parameters for preparing the Au / TS-1 catalyst in this example are the same as those in Example 1, except that the calcination temperature is adjusted to 600°C.

[0108] Example 4

[0109] Preparation of Au / TS-1 catalyst

[0110] The steps and process parameters for preparing the Au / TS-1 catalyst in this example were the same as those in Example 1, except that the amount of chloroauric acid solution was adjusted to 1 mL (0.02 g / mL), and finally an Au / TS-1 catalyst with an Au loading of 0.3% was obtained.

[0111] Example 5

[0112] Preparation of Au / TS-1 catalyst

[0113] The steps and process parameters for preparing the Au / TS-1 catalyst in this example were the same as those in Example 1, except that the amount of chloroauric acid solution was adjusted to 3 mL (0.02 g / mL), and finally an Au / TS-1 catalyst with an Au loading of 0.8% was obtained.

[0114] Example 6

[0115] 10 g of the Au / TS-1 catalyst prepared by calcination in air atmosphere in Comparative Example 1 was mixed with 10 g of PDVB and stirred at 100 r / min for 3 minutes to obtain a mixed catalyst.

[0116] Example 7

[0117] 10 g of the Au / TS-1 catalyst prepared by calcination in air atmosphere in Comparative Example 1 was mixed with 5 g of PDVB and stirred at 100 r / min for 3 minutes to obtain a mixed catalyst.

[0118] Example 8

[0119] 20 g of the Au / TS-1 catalyst prepared by calcination in air atmosphere in Comparative Example 1 was mixed with 10 g of PDVB and stirred at 100 r / min for 3 minutes to obtain a mixed catalyst.

[0120] Example 9

[0121] 10 g of the Au / TS-1 catalyst prepared in Example 1 was mixed with 10 g of PDVB and stirred at 100 r / min for 5 minutes to obtain a mixed catalyst.

[0122] Example 10

[0123] The method for preparing the mixed catalyst in this embodiment is substantially the same as that in Example 9 in terms of steps and process parameters, except that the volume ratio of CO to He in the atmosphere for calcining the fresh TS-1 molecular sieve in Example 1 is 1:5.

[0124] Example 11

[0125] The method for preparing the mixed catalyst in this embodiment is substantially the same as that in Example 9 in terms of steps and process parameters, except that the volume ratio of CO to He in the atmosphere for calcining the fresh TS-1 molecular sieve in Example 1 is 1:20.

[0126] Comparative Example 1

[0127] Method for preparing Au / TS-1 catalyst

[0128] 10 g of fresh TS-1 molecular sieve was placed in a quartz tube reactor, and the temperature was raised to 500 °C at 2 °C / min in an air atmosphere, and calcined for 4 hours to obtain TS-1 molecular sieve;

[0129] TS-1 molecular sieve was added to 8 mL of 0.02 g / mL chloroauric acid solution, and 1 mol / L cesium carbonate solution was added dropwise with stirring to adjust the pH to 7.2. The mixture was reacted at 30°C in the dark for 6 hours, and allowed to stand in the dark for 12 hours. The mixture was filtered and washed until there was no chloride ion, and dried at 30°C for 10 hours.

[0130] The dried solid was reduced in a reaction atmosphere (reaction gas including H2) at 200°C for 2 hours (heating rate 1°C / min) to obtain an Au / TS-1 catalyst with an Au loading of 0.5%.

[0131] Experimental example

[0132] Activity test and stability test of the catalysts prepared in Examples 1-11 and Comparative Example 1

[0133] Propylene gas-phase epoxidation in the presence of hydrogen was tested in a fixed-bed reactor (8 mm inner diameter). The catalyst was sieved to 80-100 mesh and loaded at 0.15 g. The reaction conditions were: reaction temperature 200°C, reaction pressure 0.1 MPa, feed gas volume ratio propylene:hydrogen:oxygen:nitrogen = 1:1:1:7, gas space velocity 14,000 h-1. -1 The products were analyzed using an online gas chromatograph (GC 7890) with a Porapak T capillary column (30 m × 0.32 mm × 0.25 μm) and an FID detector. The PO formation rate was calculated using propylene as the internal standard, and stability was measured as the reaction time at which the PO formation rate dropped to 30% of the initial value (this calculation method is commonly used in the field to assess stability).

[0134]

[0135] H2 efficiency = N po / (N H2,in -N H2,out )×100%, N po is the amount of propylene oxide produced, N H2,in , N H2,out The amount of hydrogen entering the gas and the amount of hydrogen discharged after the reaction.

[0136] From the above results, it can be concluded that the catalyst prepared in this application has the following beneficial effects compared with the conventional Au / TS-1 catalyst prepared in the prior art (Comparative Example 1):

[0137] The stability is significantly improved: compared with the stability of the traditional Au / TS-1 catalyst (<3 hours), the stability of the catalyst prepared by the method of the present application in the reaction system of propylene to propylene oxide is increased to more than 30 hours. The stability of the catalysts in Examples 6-8 (traditional Au / TS-1 catalyst mixed with PDVB) reaches 200 hours, and the stability of the catalysts in Examples 9-11 (Au / TS-1 catalyst prepared by the method of the present application mixed with PDVB) reaches 100 hours, meeting the basic requirements of industrial continuous production.

[0138] Activity and stability balance: Example 1-5 (catalyst prepared by calcining fresh TS-1 in CO atmosphere) improves stability while maintaining a high PO generation rate (300g PO h -1 kg Cat -1 ); The catalyst of Examples 9-11 (Au / TS-1 catalyst prepared by the method of the present application mixed with PDVB) slightly reduced activity (230g PO h -1 kg Cat -1 ) significantly improves stability, solving the problem of balancing activity and stability in existing technologies.

[0139] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for preparing an Au / TS-1 catalyst for preparing an epoxy compound from an α-olefin, comprising: 1) TS-1 molecular sieve without calcining the template agent is calcined in a mixed gas containing CO to obtain a modified TS-1 molecular sieve; 2) mixing the modified TS-1 molecular sieve with an aqueous solution containing a gold compound to obtain a mixture, filtering and washing the mixture to obtain a first solid, and then drying and reducing the first solid to obtain an Au / TS-1 catalyst. Preferably, in the Au / TS-1 catalyst, the Au loading amount is 0.05-1% of the total mass of the catalyst.

2. The preparation method according to claim 1, characterized in that The mixed gas containing CO includes CO and an inert gas. In the mixed gas containing CO, the volume ratio of CO to the inert gas is 1:(5-20); Preferably, the mixed gas containing CO comprises CO and He, and the volume ratio of CO to He is 1:(8-12); More preferably, the volume ratio of CO to He is 1:

10.

3. The preparation method according to claim 1 or 2, characterized in that The calcination temperature is 300-700℃; Preferably, the calcination temperature is 400-600°C; Preferably, the calcination temperature is about 500°C; More preferably, the heating rate during the calcination process is 1-5°C / min.

4. The preparation method according to any one of claims 1 to 3, characterized in that The pH of the mixture of the modified TS-1 molecular sieve and the aqueous solution containing the gold compound is adjusted to 5-9; Preferably, the pH of the mixture of the modified TS-1 molecular sieve and the aqueous solution containing the gold compound is adjusted to 5-8; Preferably, during the mixing process, the temperature is controlled at 20-70°C; More preferably, in step (2), the concentration of the aqueous solution of the gold-containing compound is 0.01-2 mol / L (preferably, 0.01-0.1 mol / L).

5. The preparation method according to any one of claims 1 to 4, characterized in that The silicon-titanium molar ratio of fresh TS-1 molecular sieve is 50-250; preferably, the specific surface area is 400-550m 2 / g.

6. The preparation method according to claim 1, characterized in that Reduction treatment is carried out at a temperature of 100-250° C. in a reducing atmosphere, wherein the reducing agent in the reducing atmosphere includes H2 gas; Preferably, the reduction treatment is performed for 1-4 hours; More preferably, the heating rate during the reduction treatment is 0.5-3°C / min.

7. A hydrophobically modified Au / TS-1 catalyst comprising: The preparation method of claim 1 obtains a hydrophobically modified Au / TS-1 catalyst by mixing the Au / TS-1 catalyst with a polydivinylbenzene polymer; Preferably, the number average molecular weight of the polydivinylbenzene polymer is 10,000-200,000; Preferably, the particle size of the polydivinylbenzene polymer is 5-50 μm; More preferably, the particle size of the polydivinylbenzene polymer is 15-30 μm (preferably 20 μm).

8. The preparation method according to claim 7, characterized in that The mass ratio of Au / TS-1 catalyst to polydivinylbenzene polymer is 1:(0.25-5); Preferably, the mass ratio of Au / TS-1 catalyst to polydivinylbenzene polymer is 1:(0.5-2); More preferably, the mass ratio of the Au / TS-1 catalyst to the polydivinylbenzene polymer is 1:

1.

9. A method for preparing an epoxy compound from an α-olefin, comprising reacting an α-olefin, oxygen, and hydrogen in the presence of an Au / TS-1 catalyst obtained by the preparation method according to any one of claims 1 to 6 or a hydrophobically modified Au / TS-1 catalyst according to claim 7 or 8 to obtain an epoxy compound, wherein: Reaction temperature 100-250°C; Preferably, the α-olefin is selected from propylene or n-butene; Preferably, the volume ratio of α-olefin, hydrogen and oxygen is 1:1:

1.

10. The preparation method according to claim 9, characterized in that The reaction feed also contains nitrogen, and the volume ratio of α-olefin to nitrogen is about 1:7; Preferably, the pressure during the reaction is controlled at 0.1-0.5 MPa; During the reaction, the gas space velocity is 5000-50000h -1 .

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