Molecular sieve-based microsphere fluidized bed catalyst as well as preparation method and application thereof

Abstract

The invention discloses a molecular sieve-based microsphere fluidized bed catalyst as well as a preparation method and application thereof. The catalyst comprises a transition metal modified molecular sieve, the molecular sieve is selected from at least one of ZSM-5, ZSM-11, ZSM-12, Silicate-I (at) ZSM-5, Silicate-I (at) Y, Silicate-I or Silicate-II type molecular sieves, the Si / Al molar ratio of the outer surface of the transition metal modified molecular sieve is larger than 250, and the Si / Al molar ratio of a body is 30-250; the transition metal is selected from at least one of Mn, Cu, Co or Ni. The catalyst disclosed by the invention is used in a reaction for preparing p-xylene through shape-selective methylation of aromatic hydrocarbon, so that the abrasion of the catalyst is remarkably reduced, and the conversion rate of toluene and the selectivity of p-xylene are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fluidized bed catalysts, and in particular relates to a molecular sieve-based microsphere fluidized bed catalyst and a preparation method and application thereof. Background Art

[0002] Aromatics are the most basic raw materials for the organic chemical industry. They are widely used in chemical products such as synthetic resins, fibers, rubber, dyes, medicines, pesticides, etc. They play an important role in developing the national economy and improving people's lives. Their production technology is one of the signs of a country's petrochemical development level. Aromatics are mainly derived from petroleum and coal tar, and the most important products are benzene, toluene and xylene. There are three isomers of xylene, namely o-xylene, m-xylene and p-xylene. Among them, p-xylene has 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, dyes, etc.; MX is mainly used to produce isophthalic acid and isophthalonitrile, which are then used to produce unsaturated polyester resins and fungicides. The process of preparing xylene by alkylation of aromatics can not only effectively utilize excess benzene and methanol resources, but also meet the high market demand for toluene and xylene, and has a high development value.

[0003] CN101417236A discloses a method for preparing a catalyst for the alkylation of toluene and methanol. The method comprises: the molecular sieve is first subjected to ion exchange, then modified with alkaline earth metals and rare earth metals, spray-formed, and then modified with a siloxane compound to obtain a catalyst. The preparation process of the method is complicated, and the conversion rate of toluene is only about 20%.

[0004] CN107649172A discloses a method for preparing a catalyst for the alkylation of toluene to produce p-xylene. The method comprises: grinding a solid raw material composed of ZSM-5 molecular sieve, silicon dioxide, template and ammonium fluoride in a certain proportion at room temperature, then pouring the raw material into a synthesis reactor and heating and crystallizing it for a period of time, and then roasting the obtained product to remove the template. However, the catalyst is only suitable for the alkylation reaction of toluene and methanol to produce p-xylene, and the liquid space velocity (WHSV) of the raw toluene is 1.0h -1 The toluene conversion rate was only 24.43%.

[0005] CN106854128B discloses a fluidized bed process for preparing paraxylene from toluene and methanol, which adopts a reaction form of multiple circulating fluidized bed reactors in series, all raw toluene enters from the first reactor, and methanol is divided into multiple strands, which are mixed evenly with toluene-containing materials in a mixer at each reaction inlet before entering each reactor for reaction, and each fluidized bed reactor is equipped with a corresponding regenerator to ensure the stability and continuous regeneration of the carbon deposit amount of the catalyst in the reactor. This technical solution uses methanol to feed in stages, so that methanol and toluene are efficiently mixed, and the optimal carbon deposit amount of the catalyst is controlled, thereby improving the utilization rate of methanol, but this technical solution adopts a series process of multiple circulating fluidized bed reactors, and the process is complicated and difficult to implement. Summary of the invention

[0006] In view of the problems of low activity, many by-products, low yield of p-xylene, etc. in the prior art in the process of shape-selective methylation of aromatics, the present invention provides a molecular sieve-based microsphere fluidized bed catalyst and its preparation method and application. The catalyst of the present invention is used in the reaction of preparing p-xylene by shape-selective methylation of aromatics, which can significantly reduce the attrition of the catalyst and improve the conversion rate of toluene and the selectivity of p-xylene.

[0007] The first aspect of the present invention provides a molecular sieve-based microsphere fluidized bed catalyst, which includes 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 molecular sieves, preferably ZSM-5 or ZSM-11; the Si / Al molar ratio of the outer surface of the molecular sieve is greater than 250, and the Si / Al molar ratio of 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 of the molecular sieve outer surface is preferably 300-∞, more preferably 350-∞, and more preferably 500-∞. The Si / Al molar ratio of the molecular sieve body is preferably 80-250, and more preferably 150-250.

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

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

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

[0012] In the above technical solution, in the transition metal modified molecular sieve, the transition metal accounts for 1% to 30% of the mass of the molecular sieve in terms of oxide.

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

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

[0015] (1) The molecular sieve is modified by a transition metal to obtain a modified molecular sieve;

[0016] (2) adding the modified molecular sieve into an organic solvent and mixing to form a slurry A;

[0017] (3) adding a binder and a matrix into water to form a slurry B;

[0018] (4) Slurry A and slurry B are mixed and then slurried, spray granulated and calcined in sequence to obtain the catalyst.

[0019] In the above technical scheme, in step (1), the molecular sieve is an ammonium type molecular sieve, and 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 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 of the outer surface of the molecular sieve is greater than 250, preferably 300~∞, more preferably 350~∞, and more preferably 500~∞; the Si / Al molar ratio of the molecular sieve body is 30~250, preferably 80~250, and more preferably 150~250.

[0020] In the above technical solution, in step (1), the size of the molecular sieve (primary structure of microspheres) is 100 to 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 in the art, preferably isovolumetric impregnation. The transition metal salt used for impregnation is selected from at least one of nitrates or ammonium salts of transition metals, preferably nitrates. The transition metal salt (in terms of oxide) accounts for 1% to 30% of the mass of the molecular sieve.

[0022] In the above technical solution, in step (2), the organic solvent is a straight-chain alkane with a carbon number ≥ 5, 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; and the binder is at least one of silicon dioxide, silica sol, titanium dioxide, aluminum oxide, and aluminum sol.

[0025] In the above technical solution, in step (2), the amount of the matrix added is 40% to 90% of the mass of the modified molecular sieve, and the amount of the binder added in terms of 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 beating conditions are as follows: the colloid mill line speed is 5 to 50 m / s, and the beating 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°C, preferably 200-220°C, outlet temperature 120-180°C, preferably 140-160°C.

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

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

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

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

[0033] In the above technical scheme, the molar ratio of the aromatic hydrocarbon raw material to the methylating agent is 1:10 to 10:1, preferably 1:5 to 5:1; the total weight space velocity of the aromatic hydrocarbon raw material and the methylating agent is 1 to 10h -1 , preferably 3 to 6 hours -1 ; The molar ratio of water to aromatic hydrocarbon is 0 to 5, preferably 1 to 3.

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

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention is to modify the surface silicon-rich high silicon-aluminum ratio molecular sieve with transition metal, and then disperse it in a straight-chain alkane with a carbon number of ≥5 to form slurry A, mix the matrix and the binder to form slurry B, and then mix slurry A with slurry B, spray granulate, and prepare a fluidized bed catalyst after roasting. The organic solvent of the present invention fully disperses the molecular sieve so that it can be fully and evenly mixed with the binder in the subsequent beating step, and the spheres sprayed out are more regular. The various steps cooperate with each other to reduce the catalyst wear. The catalyst of the present invention is used for the alkylation of aromatics to prepare p-xylene, improve the conversion rate of toluene and the selectivity of p-xylene, have high methanol utilization, and have a low by-product content in the product, generating a high concentration of p-xylene. The method of the present invention has the advantages of being simple and effective, easy to operate, and having low energy and material consumption, and can be used in the industrial production of p-xylene.

[0037] 2. The fluidized bed catalyst of the present invention comprises a transition metal modified molecular sieve, wherein the molecular sieve is a molecular sieve with a high silicon-aluminum ratio and a silicon-rich surface, and the catalyst has a low attrition index. When used in the reaction of aromatics shape-selective methylation to produce p-xylene, the catalyst can significantly reduce the attrition of the catalyst, and improve the conversion rate of toluene and the selectivity of p-xylene. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0039] Figure 2 This is the SEM image of the catalyst obtained in Comparative Example 1. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0041] In the present invention, a scanning electron microscope image of the catalyst sample is observed on a Zeiss Merlin scanning electron microscope at an accelerating voltage of 20 kV. The sizes of more than 100 microsphere particles selected in a random field of view are observed and measured to measure the average size of the microsphere catalyst.

[0042] In the present invention, the indicators of interest in the aromatics shape-selective methylation reaction include aromatics conversion rate and para-xylene selectivity. Among them, aromatics conversion rate refers to the proportion of aromatics raw materials converted after passing through the reactor once, which is expressed in weight percentage herein; para-xylene selectivity refers to the weight percentage of para-xylene in the product. The specific expressions of each indicator are as follows:

[0043]

[0044]

[0045] [Example 1]

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

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

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

[0049] (4) Slurry A-1 and slurry B-1 were mixed in a mass ratio of 1:1, and then transferred to a colloid mill for beating (colloid mill linear speed of 20 m / s, beating time of 2 hours), spray granulation (inlet temperature of 200°C, outlet temperature of 140°C), and then calcined at 550°C for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat1.

[0050] The SEM image of catalyst Cat1 is shown in Figure 1 , average particle size is 50-100μm, and abrasion index is 1.9% / 4 hours.

[0051] [Example 2]

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

[0053] (2) adding the Mn-modified ZSM-5 molecular sieve powder into the n-hexane solution (the mass ratio of the Mn-modified ZSM-5 molecular sieve to the n-hexane is 2:1) and stirring for 1 hour to form a slurry A-2;

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

[0055] (4) Slurry A-2 and slurry B-2 in a mass ratio of 1:1 were mixed, and then pulped (same as in Example 1) and spray granulated (same as in Example 1) in sequence, and then calcined 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 um, and the abrasion index is 1.0% / 4 hours.

[0057] [Example 3]

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

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

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

[0061] (4) Slurry A-3 and slurry B-3 in a mass ratio of 1:1 were mixed, and then transferred to a rubber mill for slurrying (same as in Example 1) and spray granulation (same as in Example 1), and then calcined at 550° C. for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat3.

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

[0063] [Example 4]

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

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

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

[0067] (4) Slurry A-4 and slurry B-4 in a mass ratio of 1:1 were mixed, and then transferred to a rubber mill for slurrying (same as in Example 1) and spray granulation (same as in Example 1), and then calcined 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 abrasion index is 3.1% / 4 hours.

[0069] [Example 5]

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

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

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

[0073] (4) Slurry A-5 and slurry B-5 in a mass ratio of 1:1 were mixed, and then pulped (same as in Example 1) and spray granulated (same as in Example 1) in sequence, and then calcined 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 um, and the abrasion index is 1.0% / 4 hours.

[0075] [Example 6]

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

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

[0078] (3) adding kaolin (accounting for 60% of the mass of the Mn-modified ZSM-11 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 13% of the mass of the Mn-modified ZSM-11 molecular sieve) into water and stirring evenly to form slurry B-6;

[0079] (4) Slurry A-6 and slurry B-6 in a mass ratio of 1:1 were mixed, and then transferred to a rubber mill for slurrying (same as in Example 1) and spray granulation (same as in Example 1), and then calcined at 550°C for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat6.

[0080] The average particle size of catalyst Cat1 is 60 to 100 μm, and the attrition index is 2.1% / 4 hours.

[0081] [Example 7]

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

[0083] (2) adding the Mn-modified ZSM-5 molecular sieve powder into the n-hexane solution (the mass ratio of the Mn-modified ZSM-5 molecular sieve to the n-hexane is 1:1) and stirring for 1 hour to form a slurry A-7;

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

[0085] (4) Slurry A-7 and slurry B-7 in a mass ratio of 1:1 were mixed, and then pulped (same as in Example 1) and spray granulated (same as in Example 1) were performed in sequence, and then calcined at 550° C. for 5 hours to obtain the molecular sieve-based microsphere fluidized bed catalyst Cat7.

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

[0087] [Example 8]

[0088] Compared with Example 2, the only difference is that the amount of the organic solvent n-hexane added is changed, and the mass ratio of the Mn-modified ZSM-5 molecular sieve to n-hexane is 4:1. Catalyst Cat8 is obtained.

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

[0090] [Example 9]

[0091] Compared with Example 2, the only difference is that an equal amount of n-heptane is used to replace n-hexane, thereby obtaining catalyst Cat9.

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

[0093] [Example 10]

[0094] Compared with 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 are mixed at a mass ratio of 1:5 to obtain catalyst Cat10.

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

[0096] [Comparative Example 1]

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

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

[0099] (3) adding kaolin (accounting for 20% of the mass of the Mn-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 13% of the mass of the Mn-modified ZSM-5 molecular sieve) into water and stirring evenly to form slurry DB-1;

[0100] (4) Slurry DA-1 and slurry DB-1 in a mass ratio of 1:1 were mixed and transferred to a rubber mill for slurrying (same as in Example 1) and spray granulation (same as in Example 1), and then calcined at 550° C. for 5 hours to obtain the molecular sieve-based microsphere catalyst DCat1.

[0101] The SEM image of catalyst DCat1 is shown in Figure 2 The average particle size is 60-100 μm, and the abrasion index is 7.9% / 4 hours.

[0102] [Comparative Example 2]

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

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

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

[0106] (4) Slurry DA-2 and slurry DB-2 in a mass ratio of 1:1 were mixed and transferred to a rubber mill for slurrying (same as in Example 1) and spray granulation (same as in Example 1), and then calcined at 550° C. for 5 hours to obtain the molecular sieve-based microsphere catalyst DCat2.

[0107] The average particle size of the catalyst DCat2 is 15 to 100 μm, and the attrition index is 8.3% / 4 hours.

[0108] [Comparative Example 3]

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

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

[0111] (3) adding kaolin (accounting for 20% of the mass of the Mn-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 13% of the mass of the Mn-modified ZSM-5 molecular sieve) into water and stirring evenly to form slurry DB-3;

[0112] (4) Slurry DA-3 and slurry DB-3 in a mass ratio of 1:1 were mixed and transferred to a rubber mill for slurrying (same as in Example 1) and spray granulation (same as in Example 1), and then calcined at 550° C. for 5 hours to obtain the molecular sieve-based microsphere catalyst Dcat3.

[0113] The average particle size of catalyst Dcat3 is 60 to 80 μm, and the attrition index is 4.9% / 4 hours.

[0114] [Comparative Example 4]

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

[0116] (2) 1 g of tetramethyl orthosilicate was prepared into a methanol solution, impregnated into Mn-modified ZSM-5 molecular sieve powder, and stirred for 2 hours to form a slurry DA-4;

[0117] (3) adding kaolin (accounting for 20% of the mass of the Mn-modified ZSM-5 molecular sieve) and silica sol (SiO2 content of 25wt%, accounting for 13% of the mass of the Mn-modified ZSM-5 molecular sieve) into water and stirring evenly to form slurry DB-4;

[0118] (4) Slurry DA-4 and slurry DB-4 in a mass ratio of 1:1 were mixed and transferred to a rubber mill for slurrying (same as in Example 1) and spray granulation (same as in Example 1), and then calcined at 550° C. for 5 hours to obtain the molecular sieve-based microsphere catalyst Dcat4.

[0119] The average particle size of catalyst Dcat4 is 50 to 130 μm, and the attrition index is 8.3% / 4 hours.

[0120] [Comparative Example 5]

[0121] (1) 10 g of ammonium ZSM-5 molecular sieve (size: 1 μm) powder 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 the ZSM-5 molecular sieve) and silica sol (SiO2 content: 25%, accounting for 13% of the mass of the ZSM-5 molecular sieve) and an appropriate amount of water were mixed, and the resulting slurry was formed by spray drying (same as in Example 1) to obtain spherical particles with a diameter of 10-150 μm, which were calcined at 550° C. for 5 hours to form raw powder I;

[0122] (2) An equal volume of the original powder I is immersed in a manganese nitrate solution containing 20 g of MnO and 3% of MnO, stirred evenly, dried for 10 h, and then calcined at 550° C. for 5 h to obtain the molecular sieve-based microsphere catalyst DCat5.

[0123] The average particle size of catalyst Dcat5 is 10 to 150 μm, and the attrition index is 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, and 40 g of fluidized bed catalysts Cat1-Cat10 and DCat1-DCat5 were loaded respectively. Toluene and methanol were mixed in a molar ratio of 1:1 at room temperature, gasified, and evenly dispersed, and then entered the catalyst fluidization zone of the reactor. The reaction temperature was 500 ° C, the reaction pressure was 0.05 MPa, and the weight space velocity was 5.0 h -1 The reaction was carried out under the conditions of , and a gas product flow was obtained after the reaction. After cooling, it 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 case

[0130]

[0131]

[0132] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A molecular sieve-based microsphere fluidized bed catalyst, the catalyst comprising a transition metal modified molecular sieve, the molecular sieve being selected from at least one of ZSM-5, ZSM-11, ZSM-12, Silicate-I@ZSM-5, Silicate-I@Y, Silicate-I or Silicate-II molecular sieves, preferably ZSM-5 or ZSM-11; the Si / Al molar ratio of the outer surface of the molecular sieve is greater than 250, and the Si / Al molar ratio of 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.

2. The catalyst according to claim 1, characterized in that: The Si / Al molar ratio of the outer surface of the molecular sieve is 300-∞, preferably 500-∞; and / or the Si / Al molar ratio of the molecular sieve body is 80-250, preferably 150-250.

3. The catalyst according to claim 1, characterized in that: The attrition index of the catalyst is 1.0%-4.8% / 4 hours, preferably 1.0%-2.5% / 4 hours.

4. The catalyst according to claim 1, characterized in that: The catalyst comprises a binder and a matrix; the matrix is ​​at least one of diatomaceous earth, kaolin, clay, and ceramic clay; and / or the binder is at least one of silicon dioxide, titanium dioxide, or aluminum oxide; Preferably, based on the weight of the catalyst, in terms of mass fraction, the catalyst comprises: 40% to 90% of transition metal modified molecular sieve, 5% to 35% of binder in terms of oxide, and 5% to 25% of matrix.

5. The catalyst according to claim 1, characterized in that: In the transition metal modified molecular sieve, the transition metal accounts for 1% to 30% of the molecular sieve mass in terms of oxide.

6. A method for preparing a catalyst according to any one of claims 1 to 5, comprising the following steps: (1) The molecular sieve is modified by a transition metal to obtain a modified molecular sieve; (2) adding the modified molecular sieve into an organic solvent and mixing to form a slurry A; (3) adding a binder and a matrix into water to form a slurry B; (4) Slurry A and slurry B are mixed and then slurried, spray granulated and calcined in sequence to obtain the catalyst.

7. The preparation method according to claim 6, characterized in that: In step (1), the size of the molecular sieve is 100 to 1200 nm; and / or, in step (1), the method of transition metal modification is impregnation or ion exchange, preferably isovolumetric impregnation.

8. The preparation method according to claim 6, characterized in that: In step (2), the organic solvent is a straight-chain alkane with a carbon number ≥ 5, preferably at least one of n-hexane and n-heptane; and / or the amount of the organic solvent added is 1% to 80% of the mass of the modified molecular sieve, preferably 10% to 50%.

9. The preparation method according to claim 6, characterized in that: In step (4), the mass ratio of slurry A to slurry B is 2:1 to 1:5, preferably 2:1 to 1:1; And / or, in step (4), the beating conditions are as follows: the colloid mill line speed is 5 to 50 m / s, and the beating time is 0.5 to 2 hours, preferably 1 to 2 hours; And / or, in step (4), the spray granulation conditions are as follows: inlet temperature 180-250°C, preferably 200-220°C, outlet temperature 120-180°C, preferably 140-160°C; And / or, in step (4), the calcination conditions are as follows: 450-650° C., preferably 500-600° C., for 3-8 hours, preferably 4-5 hours.

10. 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 1-5, the aromatic raw material reacts with the methylating agent to produce para-xylene.

11. The method according to claim 10, characterized in that: The aromatic hydrocarbon raw material is at least one of benzene and toluene, and the methylating agent is at least one of methanol, dimethyl ether, methylamine and methyl chloride.

12. The method according to claim 10 or 11, characterized in that: The reaction conditions are as follows: the reaction temperature is 400-650°C, preferably 450-550°C; the reaction pressure is 0.05-5.0MPa, preferably 0.1-2.0MPa; the molar ratio of the aromatic hydrocarbon raw material to the methylating agent is 1:10-10:1, preferably 1:5-5:1; the total weight space velocity is 1-10h -1 , preferably 3 to 6 hours -1 ; The molar ratio of water to aromatic hydrocarbons is 0 to 5.

Images