Molecular sieve-based microsphere fluidized bed catalyst, its preparation method and application

Abstract

The application discloses a kind of molecular sieve-based microsphere fluidized bed catalyst and its preparation method and application.The catalyst includes transition metal modified molecular sieve, molecular sieve selects at least one in ZSM-5, ZSM-11, ZSM-12, Silicate-I@ZSM-5, Silicate-I@Y, Silicate-I or Silicate-II type molecular sieve, its outer surface Si / Al molar ratio is greater than 250, bulk Si / Al molar ratio is 30~250;Transition metal is selected from at least one in Mn, Cu, Co or Ni.The catalyst of the application is used in the reaction of aromatic selective shape methylation preparation p-xylene, significantly reduces the abrasion of catalyst, improves the conversion rate of toluene and the selectivity of p-xylene.

Description

Technical Field

[0001] This invention belongs to the field of fluidized bed catalyst technology, specifically relating to a molecular sieve-based microsphere fluidized bed catalyst, its preparation method, and its application. Background Technology

[0002] Aromatic hydrocarbons are the most basic raw materials in the organic chemical industry, widely used in the synthesis of resins, fibers, rubber, dyes, pharmaceuticals, pesticides, and other chemical products. They play a vital role in developing the national economy and improving people's lives, and their production technology is one of the indicators of a country's petrochemical development level. Aromatic hydrocarbons mainly originate from petroleum and coal tar, with benzene, toluene, and xylene being the most important products. Xylene exists in three isomers: ortho-xylene, m-xylene, and para-xylene, with para-xylene having the largest market demand. PX is mainly used to produce terephthalic acid, while PTA is an important raw material for the production of polyester fibers, polyester bottles, and polyester films. OX is mainly used to produce phthalic anhydride, which is widely used in the production of plasticizers, alkyd resins, and dyes. MX is mainly used to produce isophthalic acid and isophthalonitrile, which are then used to produce unsaturated polyester resins and bactericides. The process of alkylating aromatic hydrocarbons to produce xylene can effectively utilize surplus benzene and methanol resources and meet the high market demand for toluene and xylene, making it highly valuable for development.

[0003] CN101417236A discloses a method for preparing a catalyst for the alkylation of toluene and methanol. The method includes: first, subjecting a molecular sieve to ion exchange, then modifying it with alkaline earth metals and rare earth metals, followed by spray molding and further modification with a siloxane compound to obtain the catalyst. This method is complex, and the toluene conversion rate is only about 20%.

[0004] CN107649172A discloses a method for preparing a catalyst for the alkylation of toluene to p-xylene. The method includes: grinding a solid raw material composed of ZSM-5 molecular sieve, silica, a template agent, and ammonium fluoride in a certain proportion at room temperature; then pouring the raw material into a synthesis reactor and heating it for crystallization for a period of time; and finally calcining the obtained product to remove the template agent. However, this catalyst is only suitable for the toluene-methanol alkylation reaction to prepare p-xylene, and the liquid hourly space velocity (WHSV) of the raw material toluene is 1.0 h⁻¹. -1 At that time, the toluene conversion rate was only 24.43%.

[0005] CN106854128B discloses a fluidized bed process for producing paraxylene from toluene and methanol. This process employs multiple circulating fluidized bed reactors connected in series. The toluene feedstock enters entirely from the first reactor, while methanol is divided into multiple streams. These streams are mixed uniformly with the toluene-containing material at each reaction inlet in a mixer before entering the respective reactors for reaction. Each fluidized bed reactor is equipped with a corresponding regenerator to ensure the stability and continuous regeneration of catalyst carbon deposition within the reactor. This technical solution improves methanol utilization by using staged methanol feeding, enabling efficient mixing of methanol and toluene and controlling the optimal amount of catalyst carbon deposition. However, the process involves multiple circulating fluidized bed reactors connected in series, making it complex and difficult to implement. Summary of the Invention

[0006] To address the problems of low activity, numerous byproducts, and low p-xylene yield in existing aromatic shape-selective methylation reactions, this invention provides a molecular sieve-based microsphere fluidized bed catalyst, its preparation method, and its application. When used in the aromatic shape-selective methylation reaction to p-xylene, this catalyst significantly reduces catalyst wear and improves toluene conversion and p-xylene selectivity.

[0007] The first aspect of this invention provides a molecular sieve-based microsphere fluidized bed catalyst, the catalyst comprising a transition metal modified molecular sieve, wherein the molecular sieve is selected from at least one of ZSM-5, ZSM-11, ZSM-12, Silicate-I@ZSM-5, Silicate-I@Y, Silicate-I, or Silicate-II type molecular sieves, preferably ZSM-5 or ZSM-11; the Si / Al molar ratio on the outer surface of the molecular sieve is greater than 250, and the Si / Al molar ratio in the molecular sieve body is 30 to 250; the transition metal is selected from at least one of Mn, Cu, Co, or Ni, preferably Mn.

[0008] In the above technical solution, the Si / Al molar ratio on the outer surface of the molecular sieve is preferably 300 to ∞, more preferably 350 to ∞, and even more preferably 500 to ∞. The Si / Al molar ratio in the molecular sieve body is preferably 80 to 250, more preferably 150 to 250.

[0009] In the above technical solution, the average particle size of the catalyst is 15-100 μm.

[0010] In the above technical solution, the catalyst wear index is 1.0%-4.8% / 4 hours, preferably 1.0%-2.5% / 4 hours.

[0011] In the above technical solution, the catalyst further includes a binder and a matrix. The matrix is ​​at least one selected from diatomaceous earth, kaolin, clay, and ceramic clay; the binder is at least one selected from silicon dioxide, titanium dioxide, or alumina.

[0012] In the above technical solution, the transition metal modified molecular sieve contains 1% to 30% of the molecular sieve mass as oxides.

[0013] In the above technical solution, based on the weight of the catalyst and expressed as a mass fraction, the catalyst comprises: 40% to 90% transition metal modified molecular sieve, 5% to 35% binder (based on oxides) and 5% to 25% matrix.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, comprising the following steps:

[0015] (1) Molecular sieves are modified by transition metals to obtain modified molecular sieves;

[0016] (2) The modified molecular sieve is added to an organic solvent and mixed to form slurry A;

[0017] (3) Add the binder and matrix to water to form slurry B;

[0018] (4) Mix slurry A and slurry B and then sequentially perform slurrying, spray granulation and calcination to obtain the catalyst.

[0019] In the above technical solution, in step (1), the molecular sieve is an ammonium-type molecular sieve. The preparation method of the molecular sieve is not particularly limited and can be prepared according to conventional methods in the art. The molecular sieve is at least one selected from ZSM-5, ZSM-11, ZSM-12, Silicate-I@ZSM-5, Silicate-I@Y, Silicate-I, or Silicate-II type molecular sieves. The Si / Al molar ratio on the outer surface of the molecular sieve is greater than 250, preferably 300 to ∞, more preferably 350 to ∞, and even more preferably 500 to ∞; the Si / Al molar ratio on the molecular sieve body is 30 to 250, preferably 80 to 250, and more preferably 150 to 250.

[0020] In the above technical solution, in step (1), the molecular sieve (the primary structure of microspheres) has a size of 100-1200 nm.

[0021] In the above technical solution, in step (1), the transition metal is selected from at least one of Mn, Cu, Co, or Ni, preferably Mn. The method of transition metal modification is conventional impregnation or ion exchange, preferably equal-volume impregnation. The transition metal salt used for impregnation is selected from at least one of nitrate or ammonium salts of transition metals, preferably nitrate. The transition metal salt (calculated as oxide) accounts for 1% to 30% of the molecular sieve mass.

[0022] In the above technical solution, in step (2), the organic solvent is a straight-chain alkane with ≥5 carbon atoms, preferably at least one of n-hexane and n-heptane.

[0023] In the above technical solution, in step (2), the amount of organic solvent added is 1% to 80% of the mass of the modified molecular sieve, preferably 10% to 50%.

[0024] In the above technical solution, in step (2), the matrix is ​​at least one of diatomaceous earth, kaolin, clay, and ceramic clay; the binder is at least one of silicon dioxide, silica sol, titanium dioxide, alumina, and alumina sol.

[0025] In the above technical solution, in step (2), the amount of matrix added is 40% to 90% of the mass of the modified molecular sieve, and the amount of binder added, calculated as oxide, is 5% to 35% of the mass of the modified molecular sieve.

[0026] In the above technical solution, in step (4), the mass ratio of slurry A to slurry B is 2:1 to 1:5, preferably 2:1 to 1:1.

[0027] In the above technical solution, in step (4), the pulping conditions are as follows: the colloid mill line speed is 5 to 50 m / s, and the pulping time is 0.5 to 2 hours, preferably 1 to 2 hours.

[0028] In the above technical solution, in step (4), the spray granulation conditions are as follows: inlet temperature 180~250℃, preferably 200~220℃, outlet temperature 120~180℃, preferably 140~160℃.

[0029] In the above technical solution, the roasting conditions in step (4) are as follows: 450~650℃, preferably 500~600℃, roasting for 3~8 hours, preferably 4~5 hours.

[0030] A third aspect of the present invention provides a method for producing p-xylene by shape-selective methylation of aromatic hydrocarbons, comprising: reacting an aromatic hydrocarbon feedstock with a methylating agent under the action of the above-mentioned catalyst to generate p-xylene.

[0031] In the above technical solution, the aromatic raw material is at least one of benzene or toluene, and the methylating agent is at least one of methanol, dimethyl ether, methylamine, and chloromethane.

[0032] In the above technical solution, the reaction temperature is 400-650℃, preferably 450-550℃; the reaction pressure is 0.05-5.0MPa, preferably 0.1-2.0MPa.

[0033] In the above technical solution, the molar ratio of aromatic feedstock to methylating reagent is 1:10 to 10:1, preferably 1:5 to 5:1; the total weight hourly space velocity of aromatic feedstock and methylating reagent is 1 to 10 h⁻¹. -1 Preferably 3-6 hours -1 The molar ratio of water to aromatics is 0 to 5, preferably 1 to 3.

[0034] In the above technical solution, the methylation fluidized bed reactor for the catalyst is either a single-stage fluidized bed reactor or a multi-stage fluidized bed reactor.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] 1. This invention involves modifying a high-silicon-to-alumina ratio molecular sieve with a silicon-rich surface using a transition metal, then dispersing it in straight-chain alkanes with ≥5 carbon atoms to form slurry A. A matrix and binder are mixed to form slurry B. Slurry A and slurry B are then mixed, spray-granulated, and calcined to prepare a fluidized bed catalyst. The organic solvent in this invention fully disperses the molecular sieve, ensuring thorough and uniform mixing with the binder in the subsequent slurrying step. This results in more regular sprayed spherical shapes, and the synergistic effect of each step leads to lower catalyst wear. This catalyst is used in the alkylation of aromatics to prepare p-xylene, improving the conversion rate and selectivity of toluene, achieving high methanol utilization, low byproduct content, and producing a high concentration of p-xylene. This method is simple, effective, easy to operate, and has low energy and material consumption, making it suitable for industrial production of p-xylene.

[0037] 2. The fluidized bed catalyst of the present invention includes a transition metal modified molecular sieve, wherein the molecular sieve is a high silica-alumina ratio and a silica-rich surface. The catalyst has a low wear index and can significantly reduce catalyst wear and improve the conversion rate of toluene and the selectivity of p-xylene in the shape-selective methylation of aromatics. Attached Figure Description

[0038] Figure 1 Here is a SEM image of the catalyst obtained in Example 1;

[0039] Figure 2 The image shows the SEM image of the catalyst obtained in Comparative Example 1. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments.

[0041] In this invention, scanning electron microscope (SEM) images of the catalyst samples were observed using a Zeiss-Merlin scanning electron microscope at an accelerating voltage of 20 kV. The size of more than 100 microspheres selected from a random field of view was observed and measured to determine the average size of the microsphere catalyst.

[0042] In this invention, the key performance indicators (KPIs) for the shape-selective methylation of aromatics include aromatic conversion rate and p-xylene selectivity. Aromatic conversion rate refers to the proportion of aromatic feedstock converted in a single pass through the reactor, expressed as a weight percentage. p-xylene selectivity refers to the weight percentage of p-xylene in the product. The specific expressions for each KPI are as follows:

[0043]

[0044]

[0045]

Example 1

[0046] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (average size 1μm) with an outer surface Si / Al molar ratio of 560 and a bulk Si / Al molar ratio of 160 was impregnated with 20g of manganese nitrate solution with a MnO content of 3% to obtain Mn-modified ZSM-5 molecular sieve.

[0047] (2) Add Mn-modified ZSM-5 molecular sieve powder to 10g n-heptane solution (the mass ratio of Mn-modified ZSM-5 molecular sieve to n-heptane is 2:1), stir for 2 hours to form slurry A-1;

[0048] (3) Add kaolin (accounting for 20% of the mass of Mn-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 13% of the mass of Mn-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry B-1;

[0049] (4) Mix slurry A-1 and slurry B-1 with a mass ratio of 1:1, then transfer them to a colloid mill for pulping (colloid mill linear speed of 20 m / s, pulping time of 2 hours), spray granulation (inlet temperature of 200℃, outlet temperature of 140℃), and then calcine at 550℃ for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat1.

[0050] SEM images of catalyst Cat1 are shown below. Figure 1 The average particle size is 50-100 μm, and the wear index is 1.9% / 4 hours.

[0051]

Example 2

[0052] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (average size 1μm) with an outer surface Si / Al molar ratio of 860 and a bulk Si / Al molar ratio of 160 was impregnated with 20g of manganese nitrate solution with a MnO content of 3% to obtain Mn-modified ZSM-5 molecular sieve.

[0053] (2) Add Mn-modified ZSM-5 molecular sieve powder to n-hexane solution (mass ratio of Mn-modified ZSM-5 molecular sieve to n-hexane 2:1) and stir for 1 hour to form slurry A-2;

[0054] (3) Add kaolin (accounting for 20% of the mass of Mn-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 13% of the mass of Mn-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry B-2.

[0055] (4) Mix slurry A-2 and slurry B-2 with a mass ratio of 1:1 and then perform slurrying (same as in Example 1) and spray granulation (same as in Example 1) in sequence. Then, calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat2.

[0056] The average particle size of catalyst Cat2 is 50-100 μm, and the wear index is 1.0% / 4 hours.

[0057]

Example 3

[0058] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (average size 1μm) with an outer surface Si / Al molar ratio of 560 and a bulk Si / Al molar ratio of 160 was impregnated with 20g of cobalt nitrate solution with a CoO content of 3% to obtain Co-modified ZSM-5 molecular sieve.

[0059] (2) Add the metal-modified molecular sieve powder to 10g of n-heptane solution (the mass ratio of Co-modified ZSM-5 molecular sieve to n-heptane is 2:1), stir for 2 hours to form slurry A-3;

[0060] (3) Add kaolin (accounting for 25% of the mass of Co-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 15% of the mass of Co-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry B-3;

[0061] (4) Mix slurry A-3 and slurry B-3 in a mass ratio of 1:1, then transfer them to a gel mill for pulping (same as in Example 1) and spray granulation (same as in Example 1), and then calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat3.

[0062] The average particle size of the catalyst Cat3 is 50–100 μm, and the wear index is 2.9% / 4 hours.

[0063]

Example 4

[0064] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (size 1μm) with an outer surface Si / Al molar ratio of 260 and a bulk Si / Al molar ratio of 160 was impregnated with 20g of cobalt nitrate solution with a CoO content of 3% to obtain Co-modified ZSM-5 molecular sieve.

[0065] (2) Add the metal-modified molecular sieve powder to 10g of n-heptane solution (the mass ratio of Co-modified ZSM-5 molecular sieve to n-heptane is 2:1), stir for 2 hours to form slurry A-4;

[0066] (3) Add kaolin (accounting for 20% of the mass of Co-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 23% of the mass of Co-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry B-4;

[0067] (4) Mix slurry A-4 and slurry B-4 in a mass ratio of 1:1, then transfer them to a gel mill for pulping (same as in Example 1) and spray granulation (same as in Example 1), and then calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat4.

[0068] The average particle size of catalyst Cat4 is 50–100 μm, and the wear index is 3.1% / 4 hours.

[0069]

Example 5

[0070] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (size 1μm) with an outer surface Si / Al molar ratio of 360 and a bulk Si / Al molar ratio of 80 was impregnated with 20g of manganese nitrate solution with a MnO content of 5% to obtain Mn-modified ZSM-5 molecular sieve.

[0071] (2) Add the metal-modified sieve powder to the n-hexane solution (the mass ratio of Mn-modified molecular sieve to n-hexane is 2:1) and stir for 1 hour to form slurry A-5;

[0072] (3) Add kaolin (30% of the mass of Mn-modified ZSM-5 molecular sieve) and silica sol (25 wt% SiO2 content, 25% of the mass of Mn-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry B-5;

[0073] (4) Mix slurry A-5 and slurry B-5 in a mass ratio of 1:1 and then perform slurrying (same as in Example 1) and spray granulation (same as in Example 1) in sequence. Then, calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat5.

[0074] The average particle size of catalyst Cat5 is 90-100 μm, and the wear index is 1.0% / 4 hours.

[0075]

Example 6

[0076] (1) 10g of ammonium-type ZSM-11 molecular sieve powder (size 1μm) with an outer surface Si / Al molar ratio of 560 and a bulk Si / Al molar ratio of 160 was impregnated with 10g of manganese nitrate solution with a MnO content of 6% to obtain Mn-modified ZSM-11 molecular sieve.

[0077] (2) Add the metal-modified molecular sieve powder to 10g of n-heptane solution (the mass ratio of Mn-modified ZSM-11 molecular sieve to n-heptane is 2:1), stir for 2 hours to form slurry A-6;

[0078] (3) Add kaolin (60% of the mass of Mn-modified ZSM-11 molecular sieve) and silica sol (25wt% SiO2 content, 13% of the mass of Mn-modified ZSM-11 molecular sieve) to water and stir evenly to form slurry B-6.

[0079] (4) Mix slurry A-6 and slurry B-6 in a mass ratio of 1:1, then transfer them to a gel mill for pulping (same as in Example 1) and spray granulation (same as in Example 1), and then calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat6.

[0080] The catalyst Cat1 has an average particle size of 60–100 μm and an attrition index of 2.1% / 4 hours.

[0081]

Example 7

[0082] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (average size 1μm) with an outer surface Si / Al molar ratio of 860 and a bulk Si / Al molar ratio of 160 was impregnated with 20g of manganese nitrate solution with a MnO content of 3% to obtain Mn-modified ZSM-5 molecular sieve.

[0083] (2) Add Mn-modified ZSM-5 molecular sieve powder to n-hexane solution (mass ratio of Mn-modified ZSM-5 molecular sieve to n-hexane 1:1) and stir for 1 hour to form slurry A-7;

[0084] (3) Add kaolin (accounting for 20% of the mass of Mn-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 13% of the mass of Mn-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry B-7.

[0085] (4) Mix slurry A-7 and slurry B-7 in a mass ratio of 1:1 and then perform slurrying (same as in Example 1) and spray granulation (same as in Example 1) in sequence. Then, calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat7.

[0086] The average particle size of the catalyst Cat7 is 60-90 μm, and the attrition index is 2.2% / 4 hours.

[0087]

Example 8

[0088] Compared to Example 2, the only difference is that the amount of hexane added was changed, and the mass ratio of Mn-modified ZSM-5 molecular sieve to hexane was 4:1. This yielded the catalyst Cat8.

[0089] The average particle size of the catalyst Cat8 is 60–100 μm, and the wear index is 1.2% / 4 hours.

[0090]

Example 9

[0091] The only difference from Example 2 is that an equal amount of n-heptane was used instead of n-hexane. This yielded catalyst Cat9.

[0092] The average particle size of the catalyst Cat9 is 70–100 μm, and the wear index is 1.1% / 4 hours.

[0093]

Example 10

[0094] Compared to Example 2, the only difference is that the mass ratio of slurry A to slurry B is changed, and slurry A-10 and slurry B-10 with a mass ratio of 1:5 are mixed to obtain catalyst Cat10.

[0095] The average particle size of the catalyst Cat10 is 80–100 μm, and the wear index is 0.8% / 4 hours.

[0096] Comparative Example 1

[0097] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (size 1μm) with an outer surface Si / Al molar ratio of 560 and a bulk Si / Al molar ratio of 160 was impregnated with 20g of manganese nitrate solution with a MnO content of 3% to obtain Mn-modified ZSM-5 molecular sieve.

[0098] (2) Add Mn-modified ZSM-5 molecular sieve powder to cumene (the mass ratio of Mn-modified ZSM-5 molecular sieve to cumene is 2:1), stir for 2 hours to form slurry DA-1;

[0099] (3) Add kaolin (20% of the mass of Mn-modified ZSM-5 molecular sieve) and silica sol (25wt% SiO2 content, 13% of the mass of Mn-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry DB-1.

[0100] (4) Mix slurry DA-1 and slurry DB-l in a mass ratio of 1:1 and transfer them to a gel mill for pulping (same as in Example 1) and spray granulation (same as in Example 1). Then, calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere catalyst DCatl.

[0101] See the SEM image of catalyst DCat1. Figure 2 Its average particle size is 60-100 μm, and its wear index is 7.9% / 4 hours.

[0102] Comparative Example 2

[0103] (1) 10g of ammonium-type silicon-rich ZSM-5 molecular sieve powder with an outer surface Si / Al molar ratio of 560 and a bulk Si / Al molar ratio of 160 (size 1μm) was impregnated with 20g of manganese nitrate solution with a MnO content of 3% to obtain Mn-modified ZSM-5 molecular sieve.

[0104] (2) Add Mn-modified ZSM-5 molecular sieve powder to ethanol (the mass ratio of Mn-modified ZSM-5 molecular sieve to ethanol is 2:1) and stir for 2 hours to form slurry DA-2.

[0105] (3) Add kaolin (accounting for 20% of the mass of Mn-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 13% of the mass of Mn-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry DB-2.

[0106] (4) Mix slurry DA-2 and slurry DB-2 in a mass ratio of 1:1 and transfer them to a gel mill for pulping (same as in Example 1) and spray granulation (same as in Example 1). Then, calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere catalyst DCat2.

[0107] The catalyst DCat2 has an average particle size of 15–100 μm and an attrition index of 8.3% / 4 hours.

[0108] Comparative Example 3

[0109] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (size 1μm) with an outer surface Si / Al molar ratio of 160 and a bulk Si / Al molar ratio of 160 was impregnated with 20g of manganese nitrate solution with a MnO content of 3% to obtain Mn-modified ZSM-5 molecular sieve.

[0110] (2) Add Mn-modified ZSM-5 molecular sieve powder to n-heptane solution (the mass ratio of Mn-modified ZSM-5 molecular sieve to n-heptane is 2:1, stir for 2 hours to form slurry DA-3);

[0111] (3) Add kaolin (20% of the mass of Mn-modified ZSM-5 molecular sieve) and silica sol (25wt% SiO2 content, 13% of the mass of Mn-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry DB-3.

[0112] (4) Mix slurry DA-3 and slurry DB-3 in a mass ratio of 1:1 and transfer them to a gel mill for pulping (same as in Example 1) and spray granulation (same as in Example 1). Then, calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere catalyst Dcat3.

[0113] The catalyst Dcat3 has an average particle size of 60–80 μm and an attrition index of 4.9% / 4 hours.

[0114] Comparative Example 4

[0115] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (size 1μm) with an outer surface Si / Al molar ratio of 160 and a bulk Si / Al molar ratio of 160 was impregnated with 20g of manganese nitrate solution with a MnO content of 3% to obtain Mn-modified ZSM-5 molecular sieve.

[0116] (2) Prepare a methanol solution with 1g of tetramethyl orthosilicate, impregnate it with Mn-modified ZSM-5 molecular sieve powder, and stir for 2 hours to form slurry DA-4.

[0117] (3) Add kaolin (20% of the mass of Mn-modified ZSM-5 molecular sieve) and silica sol (25wt% SiO2 content, 13% of the mass of Mn-modified ZSM-5 molecular sieve) to water and stir evenly to form slurry DB-4.

[0118] (4) Mix slurry DA-4 and slurry DB-4 in a mass ratio of 1:1 and transfer them to a gel mill for pulping (same as in Example 1) and spray granulation (same as in Example 1). Then, calcine at 550°C for 5 hours to obtain the molecular sieve-based microsphere catalyst Dcat4.

[0119] The catalyst Dcat4 has an average particle size of 50–130 μm and an attrition index of 8.3% / 4 hours.

[0120] Comparative Example 5

[0121] (1) 10g of ammonium-type ZSM-5 molecular sieve powder (size 1μm) with an outer surface Si / Al molar ratio of 560 and a bulk Si / Al molar ratio of 160, kaolin (accounting for 20% of the mass of ZSM-5 molecular sieve), silica sol (SiO2 content of 25%, accounting for 13% of the mass of ZSM-5 molecular sieve) and an appropriate amount of water were mixed and the slurry was spray-dried and shaped (same as Example 1) to obtain spherical particles with a diameter of 10-150μm, which were then calcined at 550℃ for 5 hours to form raw powder I;

[0122] (2) The original powder I was impregnated in a solution of 20g of 3% manganese nitrate with MnO content, stirred evenly, dried for 10h, and then calcined at 550℃ for 5h to obtain the molecular sieve-based microsphere catalyst DCat5.

[0123] The catalyst Dcat5 has an average particle size of 10–150 μm and an attrition index of 9.3% / 4 hours.

[0124] Table 1. Physicochemical properties of the catalysts obtained in each example.

[0125]

[0126]

[0127]

Application Example 1

[0128] A fluidized bed reactor was used, with 40g of fluidized bed catalysts Cat1-Cat10 and DCat1-DCat5 respectively. Toluene and methanol were mixed at a molar ratio of 1:1, vaporized, and uniformly dispersed at room temperature before entering the catalyst fluidization zone of the reactor. The reaction was carried out at a temperature of 500℃, a pressure of 0.05MPa, and a weight hourly space velocity of 5.0h⁻¹. -1 The reaction was carried out under certain conditions, and a gaseous product stream was obtained after the reaction. After cooling, the stream was passed into a gas-liquid separator for separation. The liquid product was sampled and analyzed. The evaluation results are shown in Table 2.

[0129] Table 2 Evaluation results of the catalysts obtained in each example

[0130]

[0131]

[0132] The specific embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including combining the 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 molecular sieve-based microsphere fluidized bed catalyst for the shape-selective methylation of aromatics to p-xylene, the catalyst comprising a transition metal modified molecular sieve, wherein the molecular sieve is selected from at least one of ZSM-5, ZSM-11, ZSM-12, Silicate-I@ZSM-5, Silicate-I@Y, Silicate-I, or Silicate-II type molecular sieves; the Si / Al molar ratio on the outer surface of the molecular sieve is greater than 250, and the Si / Al molar ratio in the molecular sieve bulk is 30~250; the transition metal is selected from at least one of Mn, Cu, Co, or Ni; the attrition index of the catalyst is 1.0%-4.8% / 4 hours; based on the weight of the catalyst, the catalyst comprises, by mass fraction: 40%~90% transition metal modified molecular sieve, 5%~35% binder (calculated as oxides) and 5%~25% matrix; The matrix is ​​at least one of diatomaceous earth, kaolin, and ceramic clay; the binder is at least one of silicon dioxide, titanium dioxide, or alumina; and in the transition metal modified molecular sieve, the transition metal accounts for 1% to 30% of the molecular sieve mass as an oxide.

2. The catalyst according to claim 1, characterized in that: The molecular sieve is ZSM-5 or ZSM-11.

3. The catalyst according to claim 1, characterized in that: The transition metal is Mn.

4. The catalyst according to claim 1, characterized in that: The Si / Al molar ratio on the outer surface of the molecular sieve is 300~∞; and / or, the Si / Al molar ratio on the molecular sieve body is 80~250.

5. The catalyst according to claim 4, characterized in that: The Si / Al molar ratio on the outer surface of the molecular sieve is 500~∞; and / or, the Si / Al molar ratio on the molecular sieve body is 150~250.

6. The catalyst according to claim 1, characterized in that: The catalyst has an attrition index of 1.0%-2.5% / 4 hours.

7. A method for preparing the catalyst according to any one of claims 1-6, comprising the following steps: (1) Molecular sieves are modified by transition metals to obtain modified molecular sieves; (2) The modified molecular sieve is added to an organic solvent and mixed to form slurry A; (3) Add the binder and matrix to water to form slurry B; (4) Mix slurry A and slurry B and then sequentially perform slurrying, spray granulation and calcination to obtain the catalyst.

8. The preparation method according to claim 7, characterized in that: In step (1), the molecular sieve size is 100~1200 nm; and / or, in step (1), the method of transition metal modification is impregnation or ion exchange.

9. The preparation method according to claim 8, characterized in that: The method for modifying transition metals is equal-volume impregnation.

10. The preparation method according to claim 7, characterized in that: In step (2), the organic solvent is a straight-chain alkane with ≥5 carbon atoms; and / or, the amount of organic solvent added is 1% to 80% of the mass of the modified molecular sieve.

11. The preparation method according to claim 10, characterized in that: The organic solvent is at least one of n-hexane and n-heptane; and / or, the amount of organic solvent added is 10% to 50% of the mass of the modified molecular sieve.

12. The preparation method according to claim 7, characterized in that: In step (4), the mass ratio of slurry A to slurry B is 2:1 to 1:5; And / or, in step (4), the pulping conditions are as follows: the colloid mill linear speed is 5~50 m / s, and the pulping time is 0.5~2 hours; And / or, in step (4), the spray granulation conditions are as follows: inlet temperature 180~250℃, outlet temperature 120~180℃; And / or, in step (4), the roasting conditions are as follows: roasting at 450~650℃ for 3~8 hours.

13. The preparation method according to claim 12, characterized in that: In step (4), the mass ratio of slurry A to slurry B is 2:1 to 1:1; And / or, in step (4), the pulping time is 1 to 2 hours; And / or, in step (4), the spray granulation conditions are as follows: inlet temperature 200~220 ℃, outlet temperature 140~160 ℃; And / or, in step (4), the roasting conditions are as follows: roasting at 500~600℃ for 4~5 hours.

14. A method for preparing p-xylene by shape-selective methylation of aromatic hydrocarbons, comprising: Under the action of any one of the catalysts described in claims 1-6, the aromatic feedstock reacts with the methylating agent to generate p-xylene.

15. The method according to claim 14, characterized in that: The aromatic raw material is at least one of benzene or toluene, and the methylating agent is at least one of methanol, dimethyl ether, methylamine, and chloromethane.

16. The method according to claim 14 or 15, characterized in that: The reaction conditions are as follows: reaction temperature 400~650 ℃; reaction pressure 0.05~5.0 MPa; molar ratio of aromatic feedstock to methylating reagent 1:10~10:1; total weight hourly space velocity 1~10 h⁻¹. -1 The molar ratio of water to aromatics is 0-5.

17. The method according to claim 16, characterized in that: The reaction conditions are as follows: reaction temperature 450~550 ℃; reaction pressure 0.1~2.0 MPa; molar ratio of aromatic feedstock to methylating reagent 1:5~5:1; total weight hourly space velocity 3~6 h⁻¹. -1 .

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