Surface-rich aluminum mordenite zeolite, its preparation method and application

Abstract

This invention relates to the field of mordenite synthesis, and discloses surface-rich aluminum mordenite, its preparation method, and applications. The mordenite has a surface Si / Al molar ratio of 2-20 and a bulk Si / Al molar ratio of 5-30, with the ratio of the surface Si / Al molar ratio to the bulk Si / Al molar ratio being below 0.9. The preparation method includes: performing a first crystallization on a first solution with a molar composition of 1SiO2:0.02-0.07Al2O3:0.1-0.5Na2O:0.02-0.3S2:5-50H2O to obtain a first crystallized product; and performing a second crystallization on a second solution (molar composition of 1SiO2:0.03-0.15Al2O3:0.1-0.8Na2O:0.01-0.3S2:5-50H2O) with the first crystallized product. The surface-rich aluminum mordenite provided by this invention is particularly suitable for conversion reaction processes containing macromolecular hydrocarbons.

Description

Technical Field

[0001] This invention relates to the field of mordenite synthesis, specifically to surface-rich aluminum mordenite, its preparation method, and its applications. Background Technology

[0002] Toluene and C9 and above heavy aromatics (C9 + A) Alkyl transfer reactions are an important pathway for increasing xylene production in aromatics plants. Aromatics conversion reactions involve complex processes such as dealkylation of heavy aromatics, disproportionation and alkyl transfer, and benzene ring hydrocracking, generally following an acid-catalyzed carbocation mechanism. Molecular sieve materials are widely used in aromatics conversion processes due to their advantages of tunable pore size and acidity. From the perspective of reactant molecular size matching, molecular sieves with 10-membered or 12-membered ring pore structures are more suitable for aromatics conversion reactions. ZSM-5, MOR, and Beta molecular sieve materials have all been reported as catalysts for aromatics conversion.

[0003] With the diversification of aromatic feedstock production and the trend of integrated oil and chemical production, utilizing low-quality aromatic feedstocks from catalytic gasoline, hydrocracking products, or catalytic reforming to produce benzene, toluene, and xylene is one of the future technological development directions. However, these low-quality aromatic feedstocks often contain large-molecule non-aromatic or polycyclic aromatic hydrocarbon components. These large molecules accumulate on the outer surface and pore sites of the molecular sieve, hindering the diffusion of other monocyclic aromatic molecules and promoting carbon deposition, thereby reducing the reaction performance of the molecular sieve catalyst. Therefore, existing aromatic conversion catalysts have strict limitations on large-molecule non-aromatic and polycyclic aromatic hydrocarbons. To mitigate this adverse effect, the key lies in promoting the rapid hydrocracking of large-molecule components on the outer surface of the molecular sieve and the desorption of small-molecule products. This requires the outer surface of the molecular sieve to have strong acidity and a large number of acidic sites, enabling rapid hydrocracking of large molecules.

[0004] Therefore, designing molecular sieves with acidic gradient distributions is of great significance for optimizing reaction processes, and a series of synthetic methods have been reported in the prior art. For example, CN110856819A discloses a surface-rich aluminum molecular sieve and its preparation method, which involves preparing two gels with different silica-alumina ratios and completing the first step of crystallization separately, then mixing the products from the first step of crystallization and performing a second step of crystallization to obtain a surface-rich aluminum ZSM-48 molecular sieve.

[0005] Although the above method synthesizes surface-rich aluminum molecular sieves, the synthesis method is complex, and the performance of the catalyst in the aromatic conversion reaction needs to be further improved. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of low conversion efficiency of molecular sieves containing large molecular non-aromatic hydrocarbons and / or side-chain cycloalkanes and aromatic components, and easy carbon deposition and deactivation of catalysts in the existing technology. This invention provides a surface-rich aluminum mordenite zeolite, its preparation method and application. This molecular sieve has abundant external surface acidity and moderate internal pore acidity, which can promote the cracking of large molecular hydrocarbon components on the external surface and promote the diffusion and conversion of small molecular hydrocarbon components in the pores.

[0007] To achieve the above objectives, the present invention provides a surface-rich aluminum mordenite zeolite, wherein the surface Si / Al molar ratio of the mordenite is 2-20, the bulk Si / Al molar ratio is 5-30, and the ratio of the surface Si / Al molar ratio to the bulk Si / Al molar ratio is below 0.9.

[0008] Preferably, the mordenite has an adsorption capacity of more than 1% for 1-methyl-tetrahydronaphthalene and an adsorption capacity of more than 3% for toluene.

[0009] A second aspect of this invention provides a method for preparing surface-rich aluminum mordenite zeolite, the method comprising the following steps:

[0010] (1) Provide a first adhesive solution containing a first aluminum source, a first silicon source, a first structure directing agent S1 and a first alkali source, and then perform a first crystallization; the molar composition of the first adhesive solution is 1SiO2:0.02-0.07Al2O3:0.1-0.5Na2O:0.02-0.3S1:5-50H2O;

[0011] (2) Under the first crystallization conditions, the first adhesive solution is subjected to first crystallization to obtain the first crystallization product;

[0012] (3) Mix the second silicon source, the second aluminum source, the second alkali source and the surfactant S2 to obtain the second adhesive solution. The molar composition of the second adhesive solution is 1SiO2:0.03-0.15Al2O3:0.1-0.8Na2O:0.01-0.3S2:5-50H2O;

[0013] (4) Under the second crystallization conditions, the second adhesive solution and the first crystallization product are subjected to a second crystallization to obtain the second crystallization product.

[0014] Preferably, based on silicon dioxide, the weight ratio of the first adhesive to the second adhesive is 2-10:1.

[0015] The third aspect of this invention provides the application of the surface-rich aluminum mordenite zeolite described in the first aspect or the surface-rich aluminum mordenite zeolite prepared by the preparation method described in the second aspect in aromatic hydrocarbon conversion reactions.

[0016] This invention primarily utilizes an in-situ two-step crystallization method, by adjusting the silicon-to-aluminum ratio in the feed (preferably also including adjusting the crystallization conditions), to synthesize alumina-rich silicate molecular sieves in a single step. This molecular sieve possesses abundant external surface acidity and moderate internal pore acidity, making it particularly suitable for conversion reactions containing macromolecular hydrocarbons. Through the above technical solution, the molecular sieve of this invention, due to its alumina-rich outer surface layer, can effectively adsorb and decompose macromolecular components in the raw materials, which is beneficial for improving the conversion of macromolecular components and preventing macromolecular components from clogging the molecular sieve pores and delaying catalyst deactivation. Attached Figure Description

[0017] Figure 1 These are the IGA adsorption curves of mordenite synthesized in Example 2 and Comparative Example 1 for 1-methyl-tetrahydronaphthalene.

[0018] Figure 2 This is the IGA adsorption curve of toluene on mordenite synthesized in Example 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] The first aspect of the present invention provides a surface-rich aluminum mordenite zeolite, wherein the surface Si / Al molar ratio of the mordenite is 2-20, the bulk Si / Al molar ratio is 5-30, and the ratio of the surface Si / Al molar ratio to the bulk Si / Al molar ratio is less than 0.9.

[0021] In this invention, unless otherwise specified, the surface Si / Al molar ratio of the mordenite zeolite is determined by XPS, specifically using an ESCALAB 250 X-ray photoelectron spectrometer manufactured by Thermo Scientific, USA, with an Al K X-ray source. α Spectral peak corrections were performed using C1s as the reference. The bulk Si / Al molar ratio of the mordenite zeolite was determined by ICP. Specifically, the elemental content of the sample was analyzed using a Thermo Scientific IRIS Intrepid II XSP inductively coupled plasma atomic emission spectrometer (ICP-AES). The sample volume was 20-40 mg, and the sample was thoroughly dissolved in 40-80 mL of 40% hydrofluoric acid solution before detection.

[0022] Preferably, the surface Si / Al molar ratio of the mordenite is 3-15, for example, it can be 3, 5, 7, 9, 11, 13, 15, or any value between the two; the bulk Si / Al molar ratio of the mordenite is 7-25, for example, it can be 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, or any value between the two.

[0023] According to a preferred embodiment of the present invention, the ratio of the surface Si / Al molar ratio to the bulk Si / Al molar ratio is 0.3-0.8, for example, it can be 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or any value between the two. This preferred embodiment is more advantageous for improving the reaction processes on the outer surface and within the pores of the molecular sieve.

[0024] According to a preferred embodiment of the present invention, the average grain size of the mordenite is 0.02 μm-10 μm, preferably 0.05 μm-5 μm. In contrast, the average grain size of mordenite in the prior art is generally large. The mordenite of the above-described preferred embodiment of the present invention has the advantages of high external surface area and good diffusion performance.

[0025] In this invention, the average grain size of the mordenite was obtained by TEM testing.

[0026] According to a preferred embodiment of the present invention, the BET surface area of ​​the mordenite is 200-600 m². 2 / g, preferably 250-500m 2 / g. The BET surface area of ​​the mordenite was measured by N2 adsorption-desorption method.

[0027] According to a preferred embodiment of the present invention, the mordenite zeolite has an adsorption capacity of 1% or more for 1-methyl-tetrahydronaphthalene and an adsorption capacity of 3% or more for toluene. More preferably, the mordenite zeolite has an adsorption capacity of 1.5-4% for 1-methyl-tetrahydronaphthalene and an adsorption capacity of 3.5-6% for toluene. This preferred embodiment is more conducive to improving the conversion rate of both macromolecular and small molecule hydrocarbons.

[0028] In this invention, unless otherwise specified, the adsorption capacity of the mordenite zeolite for 1-methyl-tetrahydronaphthalene and toluene was determined by the IGA method. Specifically, an Intelligent Gravimetric Analyzer from Hiden Analytical Ltd. (UK) was used to study the adsorption-desorption behavior. The catalyst was degassed under vacuum at 573 K for 6 hours, and then 1-methyl-tetrahydronaphthalene and toluene vapors were adsorbed onto the catalyst at 298 K. The mass change of the sample during the adsorption process was recorded using a microbalance, and the adsorption-desorption equilibrium results were finally obtained.

[0029] Through the above technical solution, the molecular sieve of the present invention, due to its aluminum-rich outer surface layer, can effectively adsorb and decompose macromolecular components in the raw materials, which is beneficial to improve the conversion of macromolecular components and avoid macromolecular components from clogging the molecular sieve channels and delaying the deactivation of the catalyst.

[0030] A second aspect of this invention provides a method for preparing surface-rich aluminum mordenite zeolite, the method comprising the following steps:

[0031] (1) Provide a first adhesive solution containing a first aluminum source, a first silicon source, a first structure directing agent S1 and a first alkali source, and then perform a first crystallization; the molar composition of the first adhesive solution is 1SiO2:0.02-0.07Al2O3:0.1-0.5Na2O:0.02-0.3S1:5-50H2O;

[0032] (2) Under the first crystallization conditions, the first adhesive solution is subjected to first crystallization to obtain the first crystallization product;

[0033] (3) Mix the second silicon source, the second aluminum source, the second alkali source and the surfactant S2 to obtain the second adhesive solution. The molar composition of the second adhesive solution is 1SiO2:0.03-0.15Al2O3:0.1-0.8Na2O:0.01-0.3S2:5-50H2O;

[0034] (4) Under the second crystallization conditions, the second adhesive solution and the first crystallization product are subjected to a second crystallization to obtain the second crystallization product.

[0035] This invention primarily utilizes an in-situ two-step crystallization method, by adjusting the silicon-to-alumina ratio in the feed (preferably also including adjusting the crystallization conditions), to synthesize aluminum-rich mordenite in a single step. This molecular sieve possesses abundant acidic sites on its outer surface and moderate acidity within its pores, making it particularly suitable for conversion reaction processes involving macromolecular hydrocarbons.

[0036] According to the present invention, preferably, the molar composition of the first adhesive solution is 1SiO2:0.03-0.06Al2O3:0.1-0.4Na2O:0.02-0.3Si:8-40H2O.

[0037] In the method provided by the present invention, sodium salt may also be added to the first adhesive solution. There is no particular limitation on the amount and type of sodium salt added. The amount of sodium salt added is based on meeting the Na content in the adhesive solution. The type of sodium salt may be sodium chloride.

[0038] According to the present invention, preferably, the molar composition of the second adhesive is 1SiO2:0.04-0.1Al2O3:0.15-0.7Na2O:0.02-0.2S2:5-20H2O.

[0039] The molar composition of the first and second adhesive solutions in the preferred embodiment described above is more conducive to forming a structure in which the silicon-aluminum ratio on the molecular sieve surface is lower than that in the bulk phase.

[0040] In a preferred embodiment, the Si / Al molar ratio in the second adhesive solution is 0.2-0.9 to the Si / Al molar ratio in the first adhesive solution. This preferred embodiment is more conducive to obtaining molecular sieves with better conversion performance and aluminous surface.

[0041] According to the present invention, preferably, the weight ratio of the first adhesive solution to the second adhesive solution, based on silicon oxide, is 2-10:1, more preferably 3-9:1. This preferred embodiment is more advantageous for obtaining molecular sieves with a high degree of crystallinity and a surface rich in aluminum.

[0042] The present invention does not particularly limit the method of providing the first and second adhesive solutions. The materials can be added together or partially mixed first and then added, based on the principle of forming a uniform adhesive solution.

[0043] According to the present invention, preferably, the conditions for the first crystallization include: a temperature of 90-180°C and a time of 10-80 h, more preferably a temperature of 130-175°C and a time of 15-50 h.

[0044] According to the present invention, preferably, the conditions for the second crystallization include: a temperature of 150-220°C and a time of 3-50 h, more preferably a temperature of 160-200°C and a time of 5-30 h.

[0045] According to the present invention, specifically, the first crystallization and the second crystallization can be carried out independently under stirring conditions, and there is no particular limitation on the stirring speed, for example, it can be 50-200 rpm.

[0046] According to the present invention, specifically, the first crystallization and the second crystallization can be carried out independently in a stainless steel high-temperature reactor.

[0047] In the above preferred embodiments, by adjusting the silicon-to-aluminum ratio and the crystallization conditions, the surface-rich silicate zeolite synthesized in one step is more conducive to suppressing the formation of twin molecular sieve crystals with different silicon-to-aluminum ratios.

[0048] Preferably, the temperature of the second crystallization is higher than the temperature of the first crystallization, more preferably 10-50°C higher, for example 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, and any value between the two.

[0049] According to the present invention, preferably, the first aluminum source and the second aluminum source are each independently selected from at least one of alumina, aluminum hydroxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum sol, and aluminum isopropoxide. The first aluminum source and the second aluminum source may be the same or different. Preferably, the second aluminum source is selected from at least one of sodium aluminate, aluminum nitrate, aluminum sol, and aluminum sulfate. The first aluminum source and the second aluminum source may or may not contain water of crystallization; the present invention does not impose any particular limitation on this.

[0050] According to the present invention, preferably, the first silicon source and the second silicon source are each independently selected from at least one of silica, silicon oxide, water glass, silica sol, ethyl silicate, and silica gel, and more preferably from at least one of silica sol, water glass, and silica. The first silicon source and the second silicon source may be the same or different.

[0051] According to the present invention, preferably, the first alkali source and the second alkali source are each independently selected from at least one of sodium hydroxide, potassium hydroxide and ammonia water.

[0052] According to the present invention, the selection range of the first structure directing agent S1 is wide, as long as it can synthesize mordenite. Preferably, the first structure directing agent S1 is selected from at least one of ethylamine, hexylamine, triethanolamine, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetraethylammonium bromide and tetraethylammonium hydroxide.

[0053] According to a preferred embodiment of the present invention, the surfactant S2 is selected from at least one of alcohols, anionic surfactants, cationic surfactants, and nonionic surfactants. The alcohol is preferably a C2-C10 alcohol.

[0054] According to the present invention, preferably, the surfactant S2 is selected from at least one of alcohol compounds, sulfate surfactants, sulfonate surfactants, polyoxyethylene fatty acid esters, polyoxyethylene fatty alcohol ethers, polysorbates, and quaternary ammonium compounds.

[0055] According to a more preferred embodiment of the present invention, the surfactant S2 is selected from at least one of ethanol, sodium hexadecylbenzenesulfonate, sodium dodecyl sulfate, sodium hexadecyl sulfate, hexadecylpyridine chloride, Tween 20, Pintodione O, and dodecylimidazole, and more preferably from at least one of sodium hexadecylbenzenesulfonate, sodium dodecyl sulfate, and sodium hexadecyl sulfate. This preferred embodiment is more advantageous in suppressing the nucleation and crystallization of the second adhesive itself.

[0056] According to the present invention, preferably, the method further includes filtering, optionally washing, and then performing ion exchange on the material obtained from the second crystallization.

[0057] Preferably, the ion exchange in this invention is ammonium ion exchange (which can be performed once or multiple times, with washing and drying between multiple times) or hydrogen ion exchange. There are no particular limitations on the specific exchange operation and conditions; it can be carried out using conventional techniques in the art, which will not be elaborated upon here. Preferably, the ion exchange results in a sodium oxide content of less than 0.2% by weight in the obtained mordenite zeolite.

[0058] Through the above technical solution, the molecular sieve of the present invention, due to its aluminum-rich outer surface layer, can effectively adsorb and decompose macromolecular components in the raw materials, which is beneficial to improve the conversion of macromolecular components and avoid macromolecular components from clogging the molecular sieve channels and delaying the deactivation of the catalyst.

[0059] The third aspect of this invention provides the application of the surface-rich aluminum mordenite zeolite described in the first aspect or the surface-rich aluminum mordenite zeolite prepared by the preparation method described in the second aspect in the conversion reaction of components containing macromolecular non-aromatic hydrocarbons and / or side-chain cycloalkane aromatic hydrocarbons.

[0060] The "macromolecule non-aromatic hydrocarbon" mentioned in this invention refers to a non-aromatic hydrocarbon component with a carbon number of not less than 9.

[0061] The mordenite zeolite provided by this invention possesses unique surface properties, making it suitable for conversion reactions involving macromolecular hydrocarbon components. It is particularly well-suited for applications in conversion reactions involving macromolecular non-aromatic hydrocarbons and / or aromatic hydrocarbon components containing side-chain cycloalkanes, and is especially suitable for the BTX-enhancing reaction process involving the conversion of heavy gasoline components or hydrotreated diesel components. This invention is illustrated using the catalytic conversion of heavy gasoline components to BTX-enhancing reaction as an example, but the invention is not limited thereto.

[0062] The mordenite zeolite provided by this invention can be directly applied to the reaction of heavy gasoline components or hydrotreated diesel components. Preferably, it is used in combination with a binder and an active metal component to form a catalyst for the conversion reaction of heavy gasoline components or hydrotreated diesel components. The presence of mordenite zeolite in the catalyst is beneficial for improving its activity and stability. The catalyst offers a wide range of choices regarding the content of each component and the types of binders and active metal components; it can use any available binder (including but not limited to alumina) and active metal component (including but not limited to Mo) in hydrocarbon conversion processes. Preferably, the content of mordenite zeolite in the catalyst is not less than 50% by weight. Preferably, the content of the active metal component in the catalyst is not less than 0.5% by weight.

[0063] According to the application described in this invention, preferably, the catalyst is further reduced in a hydrogen-containing atmosphere before use. This invention does not particularly limit the reduction conditions, and those skilled in the art can select them using conventional techniques.

[0064] The present invention will be described in detail below through examples. In the following examples, the surface silica-to-alumina ratio of the mordenite was obtained by XPS, and the bulk silica-to-alumina molar ratio was determined by ICP. The average grain size of the mordenite was measured by TEM. The BET specific surface area of ​​the molecular sieve was measured by N2 adsorption-desorption. The adsorption capacity of 1-methyl-tetrahydronaphthalene and toluene was measured by IGA; the specific test methods are as described above.

[0065] In the following examples and comparative examples, Tween 20 is a commercially available product from Aladdin Company under the brand name Tween 20, with a molecular weight of 522.

[0066] Unless otherwise specified, all percentages in the following examples and comparative examples refer to mass percentages.

[0067] Example 1

[0068] Solution A was prepared by dissolving 25 g of sodium hydroxide, 20 g of NaCl, and 25 g of tetraethylammonium hydroxide in 150 g of deionized water. Solution B was prepared by dissolving 225 g of silica sol (SiO2 content 40%) in solution A. Solution C was prepared by dissolving 38 g of aluminum sol (alumina content 20%) in 70 g of water. Solution D was prepared by slowly adding solution C to solution B. The mixture was stirred vigorously at room temperature for 4 hours to obtain a silica-alumina gel. The silica-alumina gel was then added to a stainless steel high-temperature reactor and crystallized at 160 °C for 40 hours with stirring at 180 rpm to obtain a primary crystallization product E.

[0069] 23g of silica (SiO2 content 85%), 8g of sodium hydroxide, 17g of aluminum sulfate octahydrate, 7g of sodium dodecyl sulfate, and 50g of deionized water were mixed to obtain solution F. Solution F was added to the primary crystallization product E, and the mixture was heated to 190℃ for 2 hours and crystallized for 10 hours to obtain the secondary crystallization product.

[0070] The obtained secondary crystallization product was filtered, and the filter cake was exchanged with a 5% ammonium nitrate aqueous solution at 90°C for 4 hours (liquid-solid weight ratio of 5:1). It was then filtered and washed until neutral, and the exchange was repeated 3 times. The product MOR-1 was obtained by drying at 120°C for 8 hours. The results are shown in Table 1.

[0071] Example 2

[0072] Solution A was prepared by dissolving 30 g of sodium hydroxide, 15 g of NaCl, and 60 g of tetraethylammonium bromide in 280 g of deionized water. Solution B was prepared by dissolving 275 g of silica sol (40% SiO2 content) in solution A. Solution C was prepared by dissolving 38 g of aluminum sol (20% aluminum oxide) in 70 g of water. Solution D was prepared by slowly adding solution C to solution B. The mixture was stirred vigorously at room temperature for 4 hours to obtain a silica-alumina gel. The silica-alumina gel was then added to a stainless steel high-temperature reactor and crystallized at 160 °C for 30 hours with stirring at 180 rpm to obtain a primary crystallization product E.

[0073] 49g of silica sol (SiO2 content 40%), 8g of sodium hydroxide, 3.9g of sodium aluminate (alumina 54%, sodium oxide 40%), 5g of sodium cetylbenzenesulfonate, and 30g of deionized water were mixed to obtain solution F. Solution F was added to the primary crystallization product E, and the mixture was heated to 190℃ for 2 hours and crystallized for 10 hours to obtain the secondary crystallization product.

[0074] The obtained secondary crystallization product was filtered, and the filter cake was exchanged with a 5% ammonium nitrate aqueous solution at 90°C for 4 hours (liquid-solid weight ratio 5:1). It was then filtered and washed until neutral, and the exchange process was repeated three times. The product MOR-2 was obtained by drying at 120°C for 8 hours. The results are shown in Table 1. The IGA adsorption curves of MOR-2 for 1-methyl-tetrahydronaphthalene and for toluene are shown in Table 1. Figure 1 and Figure 2 As shown, compared with DMOR-1 prepared in Comparative Example 1, it has a significantly higher adsorption capacity for 1-methyl-tetrahydronaphthalene and toluene.

[0075] Example 3

[0076] Solution A was prepared by dissolving 30 g of sodium hydroxide, 15 g of NaCl, and 90 g of tetraethylammonium bromide in 450 g of deionized water. Solution B was prepared by dissolving 325 g of silica sol (40% SiO2 content) in solution A. Solution C was prepared by dissolving 38 g of aluminum sol (20% aluminum oxide) in 70 g of water. Solution D was prepared by slowly adding solution C to solution B. The mixture was stirred vigorously at room temperature for 4 hours to obtain a silica-alumina gel. The silica-alumina gel was then added to a stainless steel high-temperature reactor and crystallized at 160 °C for 30 hours with stirring at 180 rpm to obtain a primary crystallization product E.

[0077] 83g of water glass (SiO2 content 30%), 6g of sodium hydroxide, 4.3g of sodium aluminate (alumina 54%, sodium oxide 40%), 8g of sodium cetylbenzenesulfonate, and 20g of deionized water were mixed to obtain solution F. Solution F was added to the primary crystallization product E, and the mixture was heated to 190℃ for 2 hours and crystallized for 10 hours to obtain the secondary crystallization product.

[0078] The obtained secondary crystallization product was filtered, and the filter cake was exchanged with a 5% ammonium nitrate aqueous solution at 90°C for 4 hours (liquid-solid weight ratio of 5:1). It was then filtered and washed until neutral, and the exchange was repeated 3 times. The product MOR-3 was obtained by drying at 120°C for 8 hours. The results are shown in Table 1.

[0079] Example 4

[0080] Solution A was prepared by dissolving 25 g of sodium hydroxide, 20 g of NaCl, and 120 g of tetraethylammonium bromide in 900 g of deionized water. Solution B was prepared by dissolving 400 g of silica sol (40% SiO2 content) in solution A. Solution C was prepared by dissolving 38 g of aluminum sol (20% aluminum oxide) in 70 g of water. Solution D was prepared by slowly adding solution C to solution B. The mixture was stirred vigorously at room temperature for 4 hours to obtain a silica-alumina gel. The silica-alumina gel was then added to a stainless steel high-temperature reactor and crystallized at 160 °C for 30 hours with stirring at 180 rpm to obtain a primary crystallization product E.

[0081] 74 g of silica sol (SiO2 content 40%), 10 g of sodium hydroxide, 4.3 g of sodium aluminate (alumina 54%, sodium oxide 40%), 8 g of Tween 20, and 30 g of deionized water were mixed to obtain solution F. Solution F was added to the primary crystallization product E, and the mixture was heated to 190 °C for 2 hours and crystallized for 10 hours to obtain the secondary crystallization product.

[0082] The obtained secondary crystallization product was filtered, and the filter cake was exchanged with a 5% ammonium nitrate aqueous solution at 90°C for 4 hours (liquid-solid weight ratio of 5:1). It was then filtered and washed until neutral, and the exchange was repeated 3 times. The product MOR-4 was obtained by drying at 120°C for 8 hours. The results are shown in Table 1.

[0083] Example 5

[0084] Solution A was prepared by dissolving 30 g of sodium hydroxide, 15 g of NaCl, and 130 g of tetraethylammonium bromide in 300 g of deionized water. Solution B was prepared by dissolving 450 g of silica sol (40% SiO2 content) in solution A. Solution C was prepared by dissolving 38 g of aluminum sol (20% aluminum oxide) in 70 g of water. Solution D was prepared by slowly adding solution C to solution B. The mixture was stirred vigorously at room temperature for 4 hours to obtain a silica-alumina gel. The silica-alumina gel was then added to a stainless steel high-temperature reactor and crystallized at 160 °C for 30 hours with stirring at 180 rpm to obtain a primary crystallization product E.

[0085] 35g of silica (85% SiO2 content), 10g of sodium hydroxide, 3.5g of sodium aluminate (54% aluminum oxide, 40% sodium oxide), 6g of dodecyl imidazole, and 60g of deionized water were mixed to obtain solution F. Solution F was added to the primary crystallization product E, and the mixture was heated to 190℃ for 2 hours and crystallized for 10 hours to obtain the secondary crystallization product.

[0086] The obtained secondary crystallization product was filtered, and the filter cake was exchanged with a 5% ammonium nitrate aqueous solution at 90°C for 4 hours (liquid-solid weight ratio of 5:1). It was then filtered and washed until neutral, and the exchange was repeated 3 times. The product MOR-5 was obtained by drying at 120°C for 8 hours. The results are shown in Table 1.

[0087] Example 6

[0088] Solution A was prepared by dissolving 30 g of sodium hydroxide, 15 g of NaCl, and 60 g of tetraethylammonium bromide in 280 g of deionized water. Solution B was prepared by dissolving 275 g of silica sol (40% SiO2 content) in solution A. Solution C was prepared by dissolving 38 g of aluminum sol (20% aluminum oxide) in 70 g of water. Solution D was prepared by slowly adding solution C to solution B. The mixture was stirred vigorously at room temperature for 4 hours to obtain a silica-alumina gel. The silica-alumina gel was then added to a stainless steel high-temperature reactor and crystallized at 160 °C for 30 hours with stirring at 180 rpm to obtain a primary crystallization product E.

[0089] 23g of silica (85% SiO2 content), 7g of sodium hydroxide, 5.2g of sodium aluminate (54% aluminum oxide, 40% sodium oxide), 5g of sodium cetylbenzenesulfonate, and 50g of deionized water were mixed to obtain solution F. Solution F was added to the primary crystallization product E, and the mixture was heated to 190℃ for 2 hours and crystallized for 10 hours to obtain the secondary crystallization product.

[0090] The obtained secondary crystallization product was filtered, and the filter cake was exchanged with a 5% ammonium nitrate aqueous solution at 90°C for 4 hours (liquid-solid weight ratio of 5:1). It was then filtered and washed until neutral, and the exchange was repeated 3 times. The product MOR-6 was obtained by drying at 120°C for 8 hours. The results are shown in Table 1.

[0091] Example 7

[0092] Molecular sieves were synthesized according to the method in Example 2, except that the secondary crystallization temperature was 175°C, resulting in the product MOR-7.

[0093] Examples 8-9

[0094] Molecular sieves were synthesized according to the method in Example 2, except that the amount of sodium hydroxide added during the secondary crystallization process was 5 grams and 10 grams, respectively, to obtain products MOR-8 and MOR-9.

[0095] Examples 10-11

[0096] Molecular sieves were synthesized according to the method in Example 2, except that the amount of sodium hexadecylbenzenesulfonate added during the secondary crystallization process was 8 g and 12 g, respectively, to obtain products MOR-10 and MOR-11.

[0097] Example 12

[0098] Molecular sieves were prepared according to the method in Example 2, except that the crystallization temperature of the second crystallization stage was 160°C, and the crystallized product MOR-12 was obtained. The results are shown in Table 1.

[0099] Comparative Example 1

[0100] Solution A was prepared by dissolving 30 g of sodium hydroxide, 22 g of NaCl, and 52 g of tetraethylammonium hydroxide in 200 g of deionized water. Solution B was prepared by dissolving 250 g of silica sol (40% SiO2 content) in solution A. Solution C was prepared by dissolving 38 g of aluminum sol (20% aluminum oxide) in 120 g of water. Solution D was prepared by slowly adding solution C to solution B. The mixture was stirred vigorously at room temperature for 4 hours to obtain a silica-alumina gel. The silica-alumina gel was then added to a stainless steel high-temperature reactor and crystallized at 160 °C for 40 hours with stirring at 180 rpm to obtain the crystallized product DMOR-1. The results are shown in Table 1.

[0101] Comparative Example 2

[0102] Molecular sieves were prepared according to the method in Example 2, except that no surfactant was added in the second crystallization stage, and the crystallized product DMOR-2 was obtained. The results are shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] As can be seen from the results in Table 1, the surface-rich aluminum mordenite zeolite synthesized using Example 2 of the present invention has a high specific surface area and a high adsorption capacity for macromolecules 1-methyl-tetrahydronaphthalene and toluene.

[0107] Application Example 1

[0108] 30 grams of mordenite MOR-1 synthesized in Preparation Example 1 were weighed and mixed with 15 grams of pseudoboehmite (70% alumina content). An appropriate amount of nitric acid aqueous solution was added, and the mixture was extruded and calcined at 500°C for 3 hours. An equal volume of ammonium molybdate solution was impregnated and calcined at 550°C for 3 hours to obtain a catalyst with a Mo content of 3% by weight.

[0109] Weigh 5 grams of catalyst and load it into a fixed-bed reactor. Introduce hydrogen at a rate of 100 mL / min, pressurize to 3 MPa, heat to 400°C and hold at that temperature for 3 hours. Then cool to 380°C and, after the temperature stabilizes, introduce catalytic gasoline C9 at a rate of 15 grams / hour. + Mixture, in which catalytic gasoline C9 + The composition is as follows: non-aromatic hydrocarbons: 8%, indene series: 5%, ethylbenzene: 30%, trimethylbenzene: 35%, tetramethylbenzene: 10%, dimethyl ethylbenzene: 7%, naphthalene series: 2%, C 11 + The reaction rate was 3%. The results are shown in Table 2.

[0110] Application Examples 2-12

[0111] The catalyst was prepared and the raw materials were evaluated according to the method in Example 1, except that the molecular sieves used were MOR2-MOR12.

[0112] Application Comparative Example 1-2

[0113] The catalyst was prepared and the raw materials were evaluated according to the method in Example 1, except that DMOR-1 and DMOR-2 molecular sieves were used respectively.

[0114] Table 2

[0115]

[0116]

[0117] As can be seen from the results in Table 2, the surface-rich alumina mordenite zeolite synthesized in this invention has a higher conversion rate when treating mixed raw materials containing macromolecular aromatics or non-aromatics.

[0118] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A surface-rich aluminum mordenite zeolite, wherein the surface Si / Al molar ratio of the mordenite is 2-20, the bulk Si / Al molar ratio is 5-30, and the ratio of the surface Si / Al molar ratio to the bulk Si / Al molar ratio is below 0.9; The preparation of the surface-rich aluminum mordenite zeolite includes the following steps: (1) Provide a first adhesive solution containing a first aluminum source, a first silicon source, a first structure directing agent S1 and a first alkali source, and then perform a first crystallization; the molar composition of the first adhesive solution is 1SiO2:0.02-0.07Al2O3:0.1-0.5Na2O:0.02-0.3S1:5-50H2O; (2) Under the first crystallization conditions, the first adhesive solution is subjected to first crystallization to obtain the first crystallized product; (3) Mix the second silicon source, the second aluminum source, the second alkali source and the surfactant S2 to obtain the second adhesive solution. The molar composition of the second adhesive solution is 1SiO2:0.03-0.15Al2O3:0.1-0.8Na2O:0.01-0.3S2:5-50H2O; (4) Under the second crystallization conditions, the second adhesive solution and the first crystallization product are subjected to a second crystallization to obtain the second crystallization product; The conditions for the first crystallization include: a temperature of 90-180℃ and a time of 10-80h; The conditions for the second crystallization include: a temperature of 150-220℃ and a time of 3-50h.

2. The mordenite according to claim 1, wherein, The surface Si / Al molar ratio of the mordenite is 3-15, and the bulk Si / Al molar ratio of the mordenite is 7-25.

3. The mordenite according to claim 1, wherein, The ratio of the surface Si / Al molar ratio to the bulk Si / Al molar ratio is 0.3-0.

8.

4. The mordenite according to any one of claims 1-3, wherein, The average grain size of the mordenite is 0.02 μm-10 μm; and / or the mordenite has a BET surface area of 200-600 m 2 / g.

5. The mordenite according to claim 4, wherein, The average grain size of the mordenite is 0.05 μm-5 μm; And / or, the BET surface area of ​​the mordenite is 250-500 m². 2 / g.

6. The mordenite according to any one of claims 1-3, wherein, The mordenite has an adsorption capacity of more than 1% for 1-methyl-tetrahydronaphthalene and more than 3% for toluene.

7. The mordenite according to claim 6, wherein, The mordenite has an adsorption capacity of 1.5-4% for 1-methyl-tetrahydronaphthalene and 3.5-6% for toluene.

8. A method for preparing surface-rich aluminum mordenite zeolite, the method comprising the following steps: (1) Provide a first adhesive solution containing a first aluminum source, a first silicon source, a first structure directing agent S1 and a first alkali source, and then perform a first crystallization; the molar composition of the first adhesive solution is 1SiO2:0.02-0.07Al2O3:0.1-0.5Na2O:0.02-0.3S1:5-50H2O; (2) Under the first crystallization conditions, the first adhesive solution is subjected to first crystallization to obtain the first crystallized product; (3) Mix the second silicon source, the second aluminum source, the second alkali source and the surfactant S2 to obtain the second adhesive solution. The molar composition of the second adhesive solution is 1SiO2:0.03-0.15Al2O3:0.1-0.8Na2O:0.01-0.3S2:5-50H2O; (4) Under the second crystallization conditions, the second adhesive solution and the first crystallization product are subjected to a second crystallization to obtain the second crystallization product; The conditions for the first crystallization include: a temperature of 90-180℃ and a time of 10-80h; The conditions for the second crystallization include: a temperature of 150-220℃ and a time of 3-50h.

9. The method according to claim 8, wherein, The molar composition of the first adhesive solution is 1SiO2: 0.03-0.06Al2O3: 0.1-0.4Na2O: 0.02-0.3Si: 8-40H2O; And / or, the molar composition of the second adhesive is 1SiO2:0.04-0.1Al2O3:0.15-0.7Na2O:0.02-0.2S2:5-20H2O.

10. The method according to claim 8, wherein, The ratio of the Si / Al molar ratio in the second adhesive solution to the Si / Al molar ratio in the first adhesive solution is 0.2-0.

9.

11. The method according to any one of claims 8-10, wherein, Based on silicon dioxide, the weight ratio of the first adhesive to the second adhesive is 2-10:

1.

12. The method according to any one of claims 8-10, wherein, The conditions for the first crystallization include: a temperature of 130-175℃ and a time of 15-50h; And / or, the conditions for the second crystallization include: a temperature of 160-200°C and a time of 5-30 hours.

13. The method according to any one of claims 8-10, wherein, The temperature of the second crystallization is higher than that of the first crystallization.

14. The method according to claim 13, wherein, The temperature of the second crystallization is 10-50°C higher than that of the first crystallization.

15. The method according to any one of claims 8-10, wherein, The first aluminum source and the second aluminum source are each independently selected from at least one of alumina, aluminum hydroxide, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum sol, and aluminum isopropoxide; And / or, the first silicon source and the second silicon source are each independently selected from at least one of silica, silicon dioxide, water glass, silica sol, ethyl silicate and silica gel; And / or, the first alkali source and the second alkali source are each independently selected from at least one of sodium hydroxide, potassium hydroxide and ammonia water; And / or, the first structure directing agent S1 is selected from at least one of ethylamine, hexylamine, triethanolamine, tetrapropylammonium bromide, tetrapropylammonium hydroxide, tetraethylammonium bromide, and tetraethylammonium hydroxide; And / or, the surfactant S2 is selected from at least one of alcohols, anionic surfactants, cationic surfactants and nonionic surfactants.

16. The method according to any one of claims 8-10, wherein, The second aluminum source is selected from at least one of sodium aluminate, aluminum nitrate, aluminum sol, and aluminum sulfate; And / or, the first silicon source and the second silicon source are each independently at least one of silica sol, water glass and silica; And / or, the surfactant S2 is selected from at least one of ethanol, sodium hexadecylbenzenesulfonate, sodium dodecyl sulfate, sodium hexadecyl sulfate, hexadecylpyridine chloride, Tween 20, Pintodione O, and dodecyl imidazole.

17. The method according to any one of claims 8-10, wherein, The surfactant S2 is selected from at least one of sodium hexadecylbenzenesulfonate, sodium dodecyl sulfate, and sodium hexadecyl sulfate.

18. The method according to any one of claims 8-10, wherein, The method also includes ion exchange of the material obtained from the second crystallization.

19. The method according to claim 18, wherein, The ion exchange process results in a sodium oxide content of less than 0.2% by weight in the prepared mordenite zeolite.

20. The application of the surface-rich aluminate mordenite zeolite according to any one of claims 1-7 or the surface-rich aluminate mordenite zeolite prepared by the method according to any one of claims 9-19 in the conversion reaction of macromolecular non-aromatic hydrocarbons and / or side-chain cycloalkane aromatic hydrocarbon components.

21. Application of surface-rich aluminum mordenite zeolite in the conversion reaction of macromolecular non-aromatic hydrocarbons and / or side-chain cycloalkane aromatic components; wherein the surface Si / Al molar ratio of the mordenite zeolite is 2-20, the bulk Si / Al molar ratio is 5-30, and the ratio of the surface Si / Al molar ratio to the bulk Si / Al molar ratio is below 0.9; the average grain size of the mordenite zeolite is 0.02μm-10μm; and the BET surface area of ​​the mordenite zeolite is 200-600 m². 2 / g; the adsorption capacity of the mordenite for 1-methyl-tetrahydronaphthalene is above 1%, and the adsorption capacity for toluene is above 3%.

22. The application according to claim 21, wherein, The surface Si / Al molar ratio of the mordenite is 3-15, and the bulk Si / Al molar ratio of the mordenite is 7-25.

23. The application according to claim 21, wherein, The ratio of the surface Si / Al molar ratio to the bulk Si / Al molar ratio is 0.3-0.

8.

24. The application according to any one of claims 21-23, wherein, The average grain size of the mordenite is 0.05 μm-5 μm; And / or, the BET surface area of ​​the mordenite is 250-500 m². 2 / g.

25. The application according to any one of claims 21-23, wherein, The mordenite has an adsorption capacity of 1.5-4% for 1-methyl-tetrahydronaphthalene and 3.5-6% for toluene.

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