A layered mordenite zeolite catalyst, its preparation method and use

Abstract

The application discloses a layered mordenite catalyst and a preparation method and application thereof, and the composition of the catalyst comprises the following components: (a) a layered mordenite as a carrier; (b) at least one of a group VIII metal as an active component; the layered mordenite has a lamellar structure in appearance, and single sheet-shaped crystals grow in order along a c-axis, i.e. a sheet thickness direction. The layered mordenite catalyst provided by the application is used for preparing a tetramethylbenzene from heavy aromatic hydrocarbons, has outstanding reaction stability, has low contents of interfering components, i.e. methylindane and methylisobutylbenzene, after the reaction, and is easy to obtain high-purity tetramethylbenzene after separation.

Description

Technical Field

[0001] This invention relates to a layered mordenite zeolite catalyst and its preparation method, as well as its application in the catalytic hydrogenation cracking of C10 aromatics to produce tetramethylbenzene. Background Technology

[0002] Mordenite (MOR) is a type of microporous zeolite catalytic material with parallel elliptical twelve-membered rings (0.65×0.70nm) and eight-membered rings (0.26×0.57nm) straight channels along the c-axis. Due to its excellent catalytic performance in reactions such as toluene disproportionation, hydrocracking, alkylation, aromatic isomerization, and alkyl transfer, it has been widely used in the petrochemical field.

[0003] Traditional methods for synthesizing mordenite zeolite particles result in large particle sizes, typically in the micrometer range (>1 μm), with a small external surface area. This hinders the diffusion and mass transfer of large molecular reactants in catalytic reactions, leading to low catalytic efficiency. Furthermore, secondary reactions easily occur within the micropores, reducing the selectivity of the target product and potentially causing catalyst deactivation due to carbon deposition. Given the drawbacks of micron-sized mordenite zeolite in catalytic reactions, the synthesis of nano-mordenite zeolite with high diffusion properties has become a research hotspot in zeolite synthesis. However, granular nano-mordenite zeolite still suffers from low external surface area and poor accessibility of reactive sites.

[0004] A special synthesis method can be used to synthesize mordenite with a layered morphology. This type of mordenite has a near-two-dimensional structure, a short c-axis dimension, sufficient exposure of acidic sites on the surface, and strong accessibility of macromolecules on the catalyst surface. It is expected to have excellent performance in the hydrogenation cracking reaction of heavy aromatics.

[0005] CN201610908241.5 discloses a method for synthesizing sheet-like nano-mordenite zeolite molecular sieves, which can prepare sheet-like mordenite zeolite with a c-axis thickness of 10-40 nm through hydrothermal synthesis; however, the template agent used has a relatively complex structure. Therefore, using commonly available and inexpensive organic amine template agents to synthesize sheet-like mordenite zeolite with high diffusion performance is more practically significant in industry.

[0006] Currently, the production of mesitylene from C10 heavy aromatics is the most widely used and mature industrial production method. After crystallizing and separating mesitylene from the C10 feedstock, the isomerization reaction of the partial tetramethylbenzene and tetramethylbenzene in the mother liquor can yield mesitylene, thus maximizing the yield of mesitylene. CN202011068678.5 and CN01103144.1 disclose a catalyst preparation method for the isomerization of mixed tetramethylbenzene to mesitylene, using Y, Hβ, MCM-49 or mixed molecular sieves as isomerization catalysts. The concentration of mesitylene in the product is close to or even exceeds the chemical equilibrium composition, and the yield of the target product mesitylene is high. However, the conventional zeolites mentioned above are prone to carbon deposition and deactivation in non-hydroisomerization reactions, resulting in poor reaction stability. In addition, the presence of impurities such as methyl indene in the mixed feedstock makes this method only suitable for the production of high-purity mesitylene and unable to obtain high-purity tetramethylbenzene. Summary of the Invention

[0007] To overcome the problems of poor diffusivity, poor stability, and poor process economy of micron-sized mordenite zeolite in the isomerization reaction of heavy aromatics to tetramethylbenzene in existing technologies, this invention provides a layered mordenite zeolite catalyst, its preparation method, and its application. The layered mordenite zeolite catalyst provided by this invention exhibits high activity and selectivity in the reaction of heavy aromatics to tetramethylbenzene, and also demonstrates strong reaction stability.

[0008] The first aspect of this invention provides a layered mordenite zeolite catalyst, the catalyst comprising:

[0009] (a) A carrier containing layered mordenite zeolite;

[0010] (b) Using at least one of Group VIII metals as the active component;

[0011] The layered mordenite has a lamellar structure, with individual lamellar crystals growing orderly along the c-axis, i.e., the thickness direction of the lamellar crystals.

[0012] Furthermore, the silicon-aluminum molar ratio of the layered mordenite, calculated as silicon oxide / alumina, is 5 to 50, preferably 5 to 20.

[0013] Furthermore, the specific surface area of ​​the layered mordenite is 300–450 m². 2 / g, preferably 350-430m 2 / g; external specific surface area is 100-200m² 2 / g, preferably 150-200m 2 / g.

[0014] Furthermore, the thickness of the individual sheet-like crystal, i.e., the c-axis thickness, is 30-150 nm.

[0015] Furthermore, the relative crystallinity of the layered mordenite is 85%–95%.

[0016] Furthermore, the carrier containing layered mordenite contains layered mordenite and alumina.

[0017] Furthermore, in the carrier containing layered mordenite, the content of layered mordenite accounts for 50% to 95% of the dry weight of the carrier, preferably 70% to 90%; and the content of alumina accounts for 5% to 50% of the dry weight of the carrier, preferably 10% to 30%.

[0018] Furthermore, the Group VIII metal is preferably platinum and / or palladium.

[0019] Furthermore, in the catalyst, the mass content of Group VIII metals is 0.01% to 2%, preferably 0.1% to 0.5%, based on the mass of the catalyst.

[0020] A second aspect of this invention provides a method for preparing the above-mentioned layered mordenite zeolite catalyst, specifically comprising the following steps:

[0021] (1) Mix silicon source, aluminum source a, alkali source, template agent T1 / T2 and water, and adjust the pH value of the system to 8.5-12.5 to obtain crystallization solution;

[0022] (2) The crystallization solution obtained in step (1) is crystallized, ammonium exchanged, dried and calcined to obtain hydrogen-type layered mordenite.

[0023] (3) The hydrogen-type layered mordenite obtained in step (2) is mixed with aluminum source b, shaped, dried and calcined to obtain a catalyst support;

[0024] (4) At least one of the group VIII metals is loaded onto the catalyst support prepared in step (3) to obtain the catalyst.

[0025] Further, the silicon source mentioned in step (1) is selected from, but not limited to, at least one of water glass, silica sol, silica, and silicon dioxide; the aluminum source a is selected from, but not limited to, at least one of aluminum sulfate, sodium aluminate, aluminum nitrate, and aluminum isopropoxide; the alkali source is selected from, at least one of sodium hydroxide and potassium hydroxide. The template agent T1 is selected from one or more of tetraethylammonium bromide, tetraethylammonium hydroxide, tetrapropylammonium bromide, and tetrapropylammonium hydroxide; and the template agent T2 is selected from one or more of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0026] Further, in step (1), the silicon source, alkali source and aluminum source a are dissolved in water to prepare material A; template agent T1, template agent T2 and alkali source are added to water to prepare material B; and material B is slowly added to material A.

[0027] Further, in the crystallization solution of step (1), the silicon source is SiO2, the aluminum source a is Al2O3, and the molar ratio of each material is SiO2 / Al2O3 = 5~50, T / SiO2 = 0.01~0.65, T1 / T2 = 0.1~2, H2O / SiO2 = 5~30, OH - / SiO2=0.1~0.5; where OH - This represents both the alkali source and the alkali used to adjust the pH.

[0028] Furthermore, in step (1), the pH of the system is adjusted by dropping a strong alkaline solution.

[0029] Furthermore, the crystallization treatment conditions in step (2) are crystallization at 120–240°C for 3–120 hours.

[0030] Further, in step (2), after crystallization, the sodium-type layered molecular sieve is obtained by conventional solid-liquid separation, washing, drying, and calcination. The solid-liquid separation, washing, drying, and calcination are all conventional and well-known processes familiar to those skilled in the art, without any special limitations. For example, a method of filtering the obtained mixture can be used for separation. Here, the filtration, washing, and drying can be performed in any manner conventionally known in the art. Specifically, for example, the filtration can be performed by simply vacuum filtering the obtained product mixture. For example, washing can be performed using deionized water and / or ethanol. For example, the drying temperature can be 40–250°C, preferably 60–150°C, and the drying time can be 4–30 hours, preferably 4–20 hours. The drying can be carried out under normal pressure or under reduced pressure. The roasting can be carried out in any manner conventionally known in the art, for example, the roasting temperature is generally 300–800°C, preferably 400–650°C, and the roasting time is generally 1–12 hours, preferably 2–8 hours. Furthermore, the roasting is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.

[0031] Further, in step (2), the ammonium exchange temperature is 50–90°C, the ammonium exchange time is 2–10 h / time, and the number of ammonium exchanges is 2–4 times. The ammonium salt is selected from at least one of ammonium nitrate, ammonium chloride, and ammonium sulfate, and the mass concentration of the ammonium salt solution is 5%–20%. The ammonium salt solution is mixed with the sodium-type layered zeolite solid obtained in step (2) at a mass ratio of 5–10:1. After the ammonium exchange is completed, the sample is filtered and washed with deionized water.

[0032] Further, after the ammonium exchange step (2) is completed, the drying temperature is 50–150°C, preferably 80–120°C, and the drying time is 10–24 hours. This drying can be carried out under normal pressure or under reduced pressure. The calcination can be carried out in any manner conventionally known in the art, with a calcination temperature of 450–650°C and a calcination time of 1–12 hours, preferably 2–6 hours. Additionally, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.

[0033] Further, in step (3), the amount of hydrogen-type layered mordenite added is 50% to 95% of the dry weight of the catalyst support, preferably 70% to 90%; the amount of aluminum source b added, calculated as alumina, is 5% to 50% of the dry weight of the catalyst support, preferably 10% to 30%.

[0034] Further, the aluminum source b in step (3) can be selected from one or more of boehmite, boehmite, and aluminum hydroxide, preferably boehmite. The molding can be carried out using conventional molding methods, such as extrusion molding. During the molding process, conventional molding aids can be added, such as extrusion aids and pectinic acids. The extrusion aid is a substance that is beneficial to extrusion molding, and can be selected from one or more of starch, hydroxymethyl cellulose, and guar gum powder, preferably guar gum powder, and its addition amount is 1.0% to 10.0% of the dry basis weight of the catalyst carrier, preferably 1.0% to 5.0%. The pectinic acid in the pectinic acid solution can be selected from one or more of hydrochloric acid, nitric acid, acetic acid, citric acid, and tartaric acid, preferably nitric acid; the addition amount of pectinic acid solution and aluminum source b according to the mass ratio is 0.9 to 1.5, preferably 1.0 to 1.3; the concentration of pectinic acid solution is 0.5wt% to 5.0wt%, preferably 1.5wt% to 4.0wt%.

[0035] Furthermore, the drying conditions described in step (3) are 50℃~200℃ for 1h~48h; the calcination conditions are 300℃~600℃ for 0.5h~10.0h.

[0036] Further, the Group VIII metal precursor in step (4) is selected from metal salts, preferably at least one of palladium chloride, palladium nitrate, ammonium chloropalladate, ammonium chloropalladate, platinum nitrate, chloroplatinic acid, ammonium chloroplatinate, tetraammonium dichloroplatinate, and ammonium chloroplatinate.

[0037] Further, the mass content of the Group VIII noble metal in step (4) on the catalyst is 0.01% to 2%, preferably 0.1% to 0.5%.

[0038] Further, after loading the metal in step (4), the catalyst is obtained by drying and calcining. The drying conditions are 50℃~200℃ for 1h~48h; the calcination conditions are 300℃~600℃ for 0.5h~10.0h.

[0039] Furthermore, the loading method described in step (4) can be one or both of the impregnation method and the ion exchange method.

[0040] The third aspect of the present invention provides the application of the above-mentioned layered mordenite zeolite catalyst in the production of high-purity tetramethylbenzene from C10 aromatics.

[0041] In the above technical solution, the C10 aromatics feedstock is a reformed C10 aromatics feedstock after hydrogenation.

[0042] In the above technical solution, the C10 aromatics feedstock is a tetramethylbenzene-rich fraction with a distillation range of 190-205℃ obtained by distillation separation.

[0043] In the above technical solution, the hydrogenated reformed C10 aromatics feedstock contains, by weight percentage, 4.0%–15.5% mesitylene, 10.0%–20.0% pseudotetramethylbenzene, 4.5%–15.0% methyltetramethylbenzene, 1.0%–5.0% methylindene, 0.5%–5.0% methyl isobutylbenzene, and 39.5%–80.0% other components.

[0044] In the above technical solution, the tetramethylbenzene-rich fraction with a distillation range of 190℃ to 205℃, by mass fraction, comprises 10.0% to 21.5% mesitylene, 20.0% to 38.5% metatetramethylbenzene, 10.0% to 25.5% methyltetramethylbenzene, 2.0% to 6.3% methyl indene, 2.0% to 8.2% methyl isobutylbenzene, and 0% to 56.0% other components.

[0045] Furthermore, the catalyst evaluation was carried out in a fixed-bed reactor.

[0046] Furthermore, the reaction conditions are: reaction temperature 350–500℃, reaction pressure 2.0–4.0 MPa, and volume hourly space velocity 1.0–3.0 h⁻¹. -1 Hydrogen-to-oil ratio 400-800.

[0047] Furthermore, the catalyst used needs to be reduced and activated before use, that is, the metal oxide on the support is converted into an active metal under a reducing atmosphere. The reduction and activation conditions are as follows: hydrogen partial pressure 0.1 MPa to 5.0 MPa, reaction temperature 100℃ to 350℃, and volume hourly space velocity 50 h⁻¹. -1 ~300h -1 The restoration time is 1 to 12 hours.

[0048] Compared with the prior art, the method of the present invention has the following advantages:

[0049] (1) In the catalyst of the present invention, layered nanofiber zeolite is provided as a support. The appearance is a layered structure, and the individual plate crystals grow in an orderly manner along the c-axis, that is, the thickness direction of the plate. It has a high specific surface area and external surface area, high accessibility of active sites, and strong carbon-holding capacity. As a catalyst support, it is beneficial to the dispersion and stability of active components in the production of high-purity tetramethylbenzene from C10 aromatics. After being combined with active components, it is used to produce high-purity tetramethylbenzene under hydrogen reaction conditions. It has high anti-carbon deposition performance, good reaction stability, and is more suitable for continuous industrial production.

[0050] (2) The catalyst preparation method provided by the present invention utilizes a dual template agent to prepare highly crystalline layered nanofiber zeolite under a specific material ratio. Combined with the loading of metal active components, the prepared catalyst has dual-function catalytic reaction characteristics and is highly reactive in the hydrogenation cracking of heavy aromatics.

[0051] (3) The catalyst of the present invention is used in the production of high-purity tetramethylbenzene from C10 aromatics. The reaction stability is outstanding. Moreover, the content of the interfering components methyl indane and methyl isobutylbenzene that affect the subsequent separation of tetramethylbenzene is low after the reaction, and high-purity tetramethylbenzene can be easily obtained after separation. Attached Figure Description

[0052] Figure 1 This is an electron microscope image of layered mordenite from Example 1;

[0053] Figure 2 The XRD pattern of layered mordenite zeolite in Example 1;

[0054] Figure 3 This is a scanning electron microscope image of zeolite for Comparative Example 1. Detailed Implementation

[0055] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited by these specific embodiments, but is determined by the claims.

[0056] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0057] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0058] It should be noted that the two or more aspects (or embodiments) disclosed in the context of this specification can be arbitrarily combined with each other, and the resulting technical solutions (such as methods or systems) are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0059] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, unless being based on weight would not be in accordance with the common understanding of those skilled in the art.

[0060] In this invention, the XRD determination of layered mordenite was performed on a D8 Advance SS powder X-ray diffractometer from Bruker GmbH, Germany, with a Cu Kα ray source, tube voltage of 40 kV, tube current of 300 mA, and scan rate of 5° / min.

[0061] In this invention, the method for determining relative crystallinity is to use commercial mordenite zeolite (SiO2 / Al2O3 = 16) from the catalyst factory of Nankai University as a standard sample. This sample has high crystallinity, which is assumed to be 100%. Then, the sum of the intensities of eight strong line peaks with d values ​​of 9.11, 6.60, 4.52, 3.98, 3.46, 3.38, 3.23, and 2.89 on the X-ray diffraction pattern is compared, that is, the sum of the peak areas of the sample is divided by the sum of the peak areas of the standard sample.

[0062] In this invention, scanning electron microscopy (SEM) tests were performed on a Nova Nano SEM 450 from FEI Corporation in the United States, with an accelerating voltage of 30 kV.

[0063] In this invention, the specific surface area and external surface area are measured on a Micrometrics ASAP-2010 physical adsorption instrument. N2 is the adsorbed gas, adsorbed at liquid nitrogen temperature (-196℃) and desorbed at room temperature. The specific surface area and external specific surface area are calculated based on the amount of N2 desorbed according to the BET model.

[0064] The catalyst of this invention was evaluated using a 100ml fixed-bed adiabatic reactor with a catalyst loading of 60ml. The catalyst underwent reduction and activation treatment before feeding. The product composition was analyzed 2 hours after the initial reaction.

[0065] Example 1

[0066] The preparation steps of the catalyst in this embodiment are as follows:

[0067] (1) Mordenite zeolite was prepared by hydrothermal synthesis: Silica, sodium hydroxide, and sodium aluminate were dissolved in water to prepare material A; tetraethylammonium bromide, hexadecyltrimethylammonium bromide, and sodium hydroxide were dissolved in water to prepare material B. Under vigorous stirring, material B was slowly added dropwise to material A, and the pH of the solution was adjusted to 12 by adding 10wt% sodium hydroxide aqueous solution. The mixture was stirred thoroughly. The silicon source was calculated as SiO2, the aluminum source a as Al2O3, and the alkali source as OH... - The molar ratios of the materials are calculated as follows: SiO2 / Al2O3 = 18.19, T / SiO2 = 0.03, T1 / T2 = 1.8, H2O / SiO2 = 12.57, OH... - / SiO2=0.20. After thorough mixing at room temperature, the resulting gel was crystallized at 170℃ for 5 hours, filtered, washed, dried at 120℃, and calcined at 550℃ to obtain a sodium-type zeolite sample. Using a 10wt% ammonium nitrate solution as the ammonium exchanger, the sodium-type zeolite was subjected to ammonium exchange three times at 90℃ under a solid-liquid ratio of 1:10. After filtration, washing, drying at 120℃, and calcining at 550℃, hydrogen-type layered mordenite was obtained.

[0068] The XRD pattern of layered mordenite is shown below. Figure 2 Appearance and morphology Figure 1 It has a plate-like structure, with individual plate-shaped crystals growing orderly along the c-axis, i.e., the thickness direction of the plate. The thickness of an individual plate-shaped crystal is between 90-120 nm along the c-axis, and the relative crystallinity is 93.8%. The silicon-aluminum molar ratio of the layered mordenite is 15.2, calculated as silicon oxide / alumina.

[0069] (2) Take 100g of hydrogen-type mordenite, 20g of pseudoboehmite, 5g of guar gum powder, 24g of 2.5wt.% nitric acid solution, and an appropriate amount of water, mix thoroughly, and then extrude into cylindrical strips (1.8mm in diameter). After drying at 120℃ for 8 hours and calcining at 550℃ for 3 hours, the catalyst support is obtained. The amount of hydrogen-type layered mordenite molecular sieve added is 87.7% of the dry weight of the catalyst support; the amount of aluminum source added is 17.5% of the dry weight of the catalyst support; the amount of extrusion aid added is 4.4% of the dry weight of the catalyst support; and the amount of nitric acid solution added is 1.0 to 1.3 of the mass ratio of aluminum source b to the total feed.

[0070] (3) Pt with a loading weight ratio of 0.1wt% was obtained by equal volume impregnation on the support, and after drying at 120℃ for 8 hours and calcining at 450℃ for 4 hours, catalyst CAT-1 was obtained.

[0071] The hydrocracking feedstock is selected from the tetramethylbenzene-rich fraction of reformed C10 aromatics with a distillation range of 190℃ to 205℃, and by weight percentage, it consists of 19.75% mesitylene, 36.36% paratetramethylbenzene, 23.62% methyltetramethylbenzene, 5.50% methyl indene, 7.39% methyl isobutylbenzene, and 7.38% other components.

[0072] The hydrocracking reaction conditions for the catalyst were: reaction temperature 400℃, reaction pressure 3.5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500. The catalyst obtained in Example 1 needs to be reduced and activated before use, that is, the metal oxide on the support is converted into an active metal under a reducing atmosphere. The reduction and activation conditions are as follows: hydrogen partial pressure 0.5 MPa, reduction temperature 400 °C, and volume hourly space velocity 120 h⁻¹. -1 The reduction time was 12 hours. The product composition was analyzed 2 hours after the reaction was started, and the results are shown in Table 1.

[0073] Example 2

[0074] The catalyst preparation method in this embodiment is the same as in Example 1, except that the support is loaded with 0.1 wt.% Pd, and the catalyst is calcined at 450°C for 4 hours to obtain catalyst CAT-2. The hydrogenation evaluation process conditions of the raw materials and catalyst used in the reaction are the same as in Example 1, and the results are shown in Table 1.

[0075] Example 3

[0076] The preparation and evaluation methods of the catalyst in this embodiment are the same as in Example 1, except that the template agent T2 in the mordenite synthesis crystallization mother liquor is replaced with an equal amount of tetraethylenepentamine to prepare catalyst CAT-3. The individual plate-like crystals of the catalyst support layered mordenite zeolite have a c-axis thickness between 80-140 nm and a crystallinity of 91.3%.

[0077] Example 4

[0078] The preparation and evaluation methods of the catalyst in this embodiment are the same as in Example 1, except that the proportion of the template agent in the mother liquor for mordenite synthesis crystallization is adjusted. The total amount of T1 tetraethylammonium bromide and T2 hexadecyltrimethylammonium bromide remains unchanged, and the molar ratio of T1 / T2 is adjusted to 1:1 to prepare catalyst CAT-4. The thickness of a single lamellar crystal of the catalyst support layered mordenite is between 90-120 nm along the c-axis, and the crystallinity is 87.5%.

[0079] Comparative Example 1

[0080] The method for synthesizing mordenite in this comparative example:

[0081] (1) Mordenite zeolite was prepared by hydrothermal synthesis: A solution A was prepared by dissolving a measured amount of silica, sodium hydroxide, and sodium aluminate in water; a solution B was prepared by dissolving tetraethylammonium bromide and sodium hydroxide in water. Under vigorous stirring, solution B was slowly added dropwise to solution A, and the pH of the solution was adjusted to 12 by adding 10 wt% sodium hydroxide aqueous solution. The mixture was stirred thoroughly. The silicon source was calculated as SiO2, the aluminum source a as Al2O3, and the alkali source as OH... - The molar ratios of the materials are calculated as follows: SiO2 / Al2O3 = 18.19, T / SiO2 = 0.03, H2O / SiO2 = 12.57, OH... - / SiO2=0.20. After thorough mixing at room temperature, the resulting gel was crystallized at 170℃ for 5 hours, filtered, washed, dried at 120℃, and calcined at 550℃ to obtain a sodium-type zeolite sample. Using a 10wt% ammonium nitrate solution as the ammonium exchanger, the above sodium-type zeolite was subjected to ammonium exchange three times at 90℃ under a solid-liquid ratio of 1:10. After filtration, washing, drying at 120℃, and calcining at 550℃, hydrogen-type mordenite was obtained. The morphology of the mordenite is shown in […]. Figure 3 The morphology is an irregular micron-sized structure. The silica-alumina molar ratio of the silica zeolite is 15.5, calculated as silica / alumina.

[0082] The hydrogen-type mordenite support molding, active component Pt loading and loading amount were the same as in Example 1, and catalyst DCAT-1 was prepared.

[0083] The catalyst evaluation materials and evaluation conditions were the same as in Example 1, and the results are shown in Table 1.

[0084] Comparative Example 2

[0085] In this comparative example, conventional Hβ zeolite was used as the support material, and the silica-alumina ratio was the same as that of the mordenite in Example 1. The zeolite support molding, Pt loading, and loading amount were the same as in the example, resulting in catalyst DCAT-2.

[0086] The catalyst evaluation materials and evaluation conditions were the same as in Example 1, and the results are shown in Table 1.

[0087] Table 1. Physicochemical properties of layered mordenite zeolite and evaluation results of corresponding catalysts in the examples and comparative examples.

[0088]

[0089] As can be seen from the results in Table 1, the catalyst prepared by using layered nanofiber zeolite as a support in this invention exhibits outstanding reaction stability in the hydrogenation cracking reaction of reformed heavy aromatics. Moreover, the content of interfering components methylindene and methyl isobutylbenzene is low after the reaction, and high-purity tetramethylbenzene can be easily obtained after separation.

Claims

1. A layered mordenite zeolite catalyst, said catalyst comprising: (a) A carrier containing layered mordenite zeolite; (b) Using at least one of Group VIII metals as the active component; The layered mordenite has a lamellar structure, with individual lamellar crystals growing orderly along the c-axis, i.e., the thickness of the lamellar crystals, i.e., the c-axis thickness, is 80–140 nm. The layered mordenite zeolite is prepared using a dual template agent, wherein template agent T1 is selected from one or more of tetraethylammonium bromide, tetraethylammonium hydroxide, tetrapropylammonium bromide, and tetrapropylammonium hydroxide, and template agent T2 is selected from one or more of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

2. The layered mordenite zeolite catalyst according to claim 1, characterized in that, The specific surface area of ​​the layered mordenite is 300–450 m². 2 / g; external specific surface area is 100-200m² 2 / g.

3. The layered mordenite zeolite catalyst according to claim 1, characterized in that, The specific surface area of ​​the layered mordenite is 350–430 m². 2 / g; external specific surface area is 150-200 m² 2 / g.

4. The layered mordenite zeolite catalyst according to claim 1, characterized in that, The relative crystallinity of the layered mordenite is 85%–95%.

5. The layered mordenite zeolite catalyst according to claim 1, characterized in that, The Group VIII metal is platinum and / or palladium; the mass content of the Group VIII metal is 0.01% to 2% based on the mass of the catalyst.

6. The layered mordenite zeolite catalyst according to claim 1, characterized in that, The Group VIII metal is platinum and / or palladium; the mass content of the Group VIII metal is 0.1% to 0.5% based on the mass of the catalyst.

7. A method for preparing the layered mordenite zeolite catalyst according to any one of claims 1-6, specifically comprising the following steps: (1) Mix silicon source, aluminum source a, alkali source, template agent T1, template agent T2 and water, and adjust the pH value of the system to 8.5-12.5 to obtain crystallization solution; (2) The crystallization solution obtained in step (1) is crystallized, ammonium exchanged, dried and calcined to obtain hydrogen-type layered mordenite; (3) The hydrogen-type layered mordenite obtained in step (2) is mixed with aluminum source b, shaped, dried and calcined to obtain a catalyst support; (4) At least one of the group VIII metals is loaded onto the catalyst support prepared in step (3) to obtain the catalyst.

8. The preparation method according to claim 7, characterized in that, The silicon source mentioned in step (1) is selected from at least one of water glass, silica sol, silica, and silicon dioxide; the aluminum source a is selected from at least one of aluminum sulfate, sodium aluminate, aluminum nitrate, and aluminum isopropoxide; and the alkali source is selected from at least one of sodium hydroxide and potassium hydroxide.

9. The preparation method according to claim 7, characterized in that, In the crystallization solution of step (1), the silicon source is SiO2, the aluminum source a is Al2O3, and the molar ratios of each material are SiO2 / Al2O3 = 5~50, (T1+T2) / SiO2 = 0.01~0.65, T1 / T2 = 0.1~2, H2O / SiO2 = 5~30, OH - / SiO2=0.1~0.

5.

10. The preparation method according to claim 7, characterized in that, The crystallization conditions in step (2) are crystallization at 120-240℃ for 3-120 hours.

11. The preparation method according to claim 7, characterized in that, The amount of hydrogen-type layered mordenite added in step (3) is 50% to 95% of the dry weight of the catalyst support; the amount of aluminum source b added, calculated as alumina, is 5% to 50% of the dry weight of the catalyst support.

12. The preparation method according to claim 7, characterized in that, The amount of hydrogen-type layered mordenite added in step (3) is 70% to 90% of the dry weight of the catalyst support; the amount of aluminum source b added, calculated as alumina, is 10% to 30% of the dry weight of the catalyst support.

13. The application of the layered mordenite zeolite catalyst according to any one of claims 1-6 in the production of high-purity tetramethylbenzene from C1-decane aromatics.

14. The application according to claim 13, characterized in that, The C10 aromatics feedstock is hydrogenated reformed C10 aromatics; by weight percentage, it contains 4.0-15.5% mesitylene, 10.0-20.0% pseudotetramethylbenzene, 4.5-15.0% methyltetramethylbenzene, 1.0-5.0% methyl indene, 0.5-5.0% methyl isobutylbenzene, and 39.5-80.0% other components.

15. The application according to claim 13, characterized in that, The reaction conditions for this application are: reaction temperature 350–500℃, reaction pressure 2.0–4.0 MPa, and volume hourly space velocity (VHSV) 1.0–3.0 h⁻¹. -1 Hydrogen-to-oil ratio 400-800.

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