CN105582996B - The method of catalyst of naphtha catalytic cracking production propylene and preparation method thereof and naphtha catalytic cracking production propylene - Google Patents

Abstract

The invention provides a catalyst for producing propylene by catalytic cracking of naphtha and a preparation method thereof. The catalyst comprises: a regular structure carrier and an active component coating distributed on the inner surface and/or outer surface of the regular structure carrier; the molecular sieve contains A first molecular sieve and a second molecular sieve; the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical pore structure, and the second molecular sieve is a molecular sieve with a twelve-membered ring pore structure. The invention also provides a method for producing propylene by catalytic cracking of naphtha. By adopting the catalyst provided by the invention, the yield of propylene can be increased, and the ratio of propylene/ethylene to 3 or more can be obtained.

Description

Catalyst for producing propylene by catalytic cracking of naphtha, preparation method thereof and naphtha catalysis The method of pyrolysis to produce propylene

technical field

The present invention relates to a catalyst for producing propylene by catalytic cracking of naphtha and a preparation method thereof and a method for producing propylene by catalytic cracking of naphtha, in particular to a catalyst for producing propylene by catalytic cracking of naphtha, a catalyst for preparing naphtha A method for cracking a catalyst for producing propylene and the prepared catalyst, and a method for producing propylene by catalytic cracking of naphtha.

Background technique

Propylene is one of the most widely used basic organic chemical raw materials, mainly used in the production of polypropylene, cumene, acrylonitrile, acrylic acid, etc. At present, propylene mainly comes from ethylene cracking units in petrochemical plants and catalytic cracking units in refineries. With the rapid growth of global demand for propylene, the output of traditional production processes is difficult to meet the demand, so the development of technology to increase the production of propylene has become an important development direction in petrochemical production technology.

Conventional ethylene cracking mainly uses naphtha as raw material to produce ethylene and propylene through steam thermal cracking. Limited by the thermal cracking reaction mechanism, ethylene is generally the main product and propylene is the by-product. The propylene/ethylene ratio is limited to about 0.65, which is higher than At this ratio, the total olefin yield will decrease. This process needs to consume a large amount of high-quality naphtha raw material, which is a process with high energy consumption. Currently 66-70% of propylene is produced by steam thermal cracking technology.

The reaction temperature of catalytic cracking is about 50-200°C lower than that of steam thermal cracking, and the energy consumption is lower. Moreover, the reaction mechanism of catalytic cracking is beneficial to the formation of propylene molecules, so that the yield of propylene produced from naphtha can be increased.

CN101491772A discloses a catalyst for catalytic cracking of naphtha, which comprises the following active components in weight percent: a) 80-99.5% is selected from the intergrowth molecular sieves of ZSM-5 and mordenite, ZSM-5 and zeolite beta At least one of the intergrown molecular sieves or the intergrown molecular sieves of ZSM-5 and Y zeolite; and b) the balance carried thereon is at least one element selected from Group VA elements of the Periodic Table of Elements or its oxides. But the diene yield of ethylene and propylene that can be obtained by this catalyst is still low.

CN102861604A discloses a catalyst for producing olefins by catalytic cracking of naphtha, wherein, based on the weight content of the final catalyst, it contains 60-90% EU-1/ZSM-5 composite molecular sieve and 0.5-3% heteropolyacid. When the catalyst is actually used for catalytic cracking of naphtha, although the yield of ethylene and propylene diene is high, the ratio of propylene/ethylene is still low, and the yield of propylene obtained is small.

It can be seen that, in order to achieve a larger yield of propylene by catalytic cracking of naphtha, a new catalyst for the production of propylene by catalytic cracking of naphtha is needed.

Contents of the invention

The purpose of the present invention is to overcome the problem of small propylene output in the prior art when catalytic cracking of naphtha is used to produce propylene, and to provide a catalyst for producing propylene by catalytic cracking of naphtha and a preparation method thereof and a method for producing propylene by catalytic cracking of naphtha .

In order to achieve the above object, the present invention provides a catalyst for producing propylene by catalytic cracking of naphtha, which catalyst comprises: a regular structure carrier and an active component coating distributed on the inner surface and/or outer surface of the regular structure carrier; Based on the total weight of the catalyst, the content of the active component coating is 10-50% by weight; based on the total weight of the active component coating, the active component coating contains 50-95% by weight molecular sieve and 5-50% by weight of the substrate; the molecular sieve contains a first molecular sieve and a second molecular sieve; the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical channel structure, and the second molecular sieve is a molecular sieve with a ten-membered ring Molecular sieve with binary ring channel structure.

The present invention also provides a method for preparing a catalyst for producing propylene by catalytic cracking of naphtha, the method comprising: (1) mixing and grinding a molecular sieve and an aqueous solvent to obtain a molecular sieve slurry;

(2) mixing the molecular sieve slurry with a matrix source to form an active component coating slurry;

(3) coating the regular structure carrier with the active component coating slurry and drying and roasting;

Wherein, the molecular sieve contains a first molecular sieve and a second molecular sieve; the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical channel structure, and the second molecular sieve is a molecular sieve with a twelve-membered ring channel structure.

The present invention also provides the catalyst prepared by the method provided by the present invention.

The present invention also provides a method for producing propylene by catalytic cracking of naphtha, the method comprising: under the reaction conditions of catalytic cracking of naphtha, contacting naphtha and water with a catalyst to obtain a propylene product, wherein the catalyst Including the catalyst provided by the present invention.

By adopting the catalyst provided by the invention, the yield of propylene can be increased, and the ratio of propylene/ethylene to 3 or more can be obtained.

Other features and advantages of the present invention will be described in detail in the following detailed description.

detailed description

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, not to limit the present invention.

In the present invention, the term regular structure catalyst is used to refer to a catalyst comprising a regular structure carrier and an active component coating distributed on the inner surface and/or outer surface of the carrier; the regular structure carrier is a carrier with a regular structure such as a honeycomb carrier; the regular structure The reactor is a fixed-bed reactor filled with a structured catalyst as a catalyst bed.

The invention provides a catalyst for producing propylene by catalytic cracking of naphtha, which catalyst comprises: a regular structure carrier and an active component coating distributed on the inner surface and/or outer surface of the regular structure carrier; the total weight of the catalyst is As a benchmark, the content of the active component coating is 10-50% by weight; based on the total weight of the active component coating, the active component coating contains 50-95% by weight of molecular sieve and 5 -50% by weight of the matrix; the molecular sieve contains a first molecular sieve and a second molecular sieve; the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical channel structure, and the second molecular sieve is a molecular sieve with a twelve-membered ring channel structure of molecular sieves.

In the present invention, the molecular sieve containing the first molecular sieve and the second molecular sieve is used as the cracking active component, so that a high yield of propylene produced by catalytic cracking of naphtha can be obtained.

According to a preferred embodiment of the present invention, the active component coating includes two layers, an inner layer and an inner layer, wherein the inner layer contains the first molecular sieve, and the outer layer contains the second molecular sieve. Wherein, the inner layer refers to the layer in contact with the peripheral wall of the regular structure carrier; the outer layer refers to the layer arranged on the inner layer, which is close to the center of the pipe.

According to the present invention, it is preferred to contain 50-95% by weight of the first molecular sieve and 5-50% by weight of the matrix based on the total weight of the active component coating in the inner layer; % by weight of the second molecular sieve and 5-50% by weight of the matrix.

In the present invention, the inner layer coating adopts the first molecular sieve as the catalytic cracking active component, the outer layer coating adopts the second molecular sieve as the catalytic cracking active component, and the first molecular sieve and the second molecular sieve and the matrix are respectively made into active components. The sub-coating is distributed on the regular structure carrier to form a regular structure catalyst, and a higher yield of propylene produced by catalytic cracking of naphtha can be obtained.

According to the present invention, the first molecular sieve is a molecular sieve having a ten-membered ring two-dimensional elliptical pore structure, preferably with a pore opening diameter of 0.45-0.56 nanometers.

According to the present invention, preferably, the first molecular sieve is a molecular sieve with a FER structure and/or a molecular sieve with an MFS structure. The structure types FER and MFS refer to the molecular sieve structure named by the International Zeolite Association (IZA), which is used to describe the spatial topology of the pores in the molecular sieve. The molecular sieves of the FER structure include ZSM-35 zeolite, Ferrierite zeolite, FU-9 zeolite, ISI-6 zeolite, NU-23 zeolite and Sr-D zeolite, etc., and the molecular sieves of the MFS structure include ZSM-57 zeolite and COK-5 zeolite Wait.

Preferably, the first molecular sieve is at least one of ZSM-35 zeolite, Ferrierite zeolite, FU-9 zeolite, ISI-6 zeolite, NU-23 zeolite, Sr-D zeolite, ZSM-57 zeolite and COK-5 zeolite.

According to the present invention, preferably, the first molecular sieve is a mixture of a molecular sieve with a FER structure and a molecular sieve with an MFS structure. More preferably, the weight ratio of the molecular sieve with the FER structure to the molecular sieve with the MFS structure is 0.1-10:1, more preferably 1-5:1.

More preferably, the molecular sieve of the FER structure is at least one of ZSM-35 zeolite, Ferrierite zeolite, FU-9 zeolite, ISI-6 zeolite, NU-23 zeolite and Sr-D zeolite, more preferably ZSM-35 zeolite, At least one of Ferrierite zeolite and FU-9 zeolite.

More preferably, the molecular sieve with MFS structure is at least one of ZSM-57 zeolite and COK-5 zeolite.

According to a preferred embodiment of the present invention, preferably the molecular sieve of the FER structure is a mixture of ZSM-35 zeolite and Ferrierite zeolite, more preferably the weight ratio of the two is 2-5:1; the molecular sieve of the MFS structure is The mixture of ZSM-57 zeolite and COK-5 zeolite, more preferably the weight ratio of the two is 2-5:1.

In the present invention, the silicon-aluminum atomic molar ratio (Si/Al) of the first molecular sieve may be 0.1-100:1; preferably 30-80:1.

According to the present invention, preferably, the opening diameter of the pores of the second molecular sieve is 0.65-0.7 nanometers. More preferably, the second molecule is selected from at least one molecular sieve having a structure of AET, AFR, AFS, AFI, BEA, BOG, CFI, CON, GME, IFR, ISV, LTL, MEI, MOR, OFF and SAO kind. Particularly preferably, the second molecular sieve is at least one of Beta, SAPO-5, SAPO-40, SSZ-13, CIT-1, ITQ-7, ZSM-18, mordenite and gmelinite.

In the present invention, the molar ratio of silicon to aluminum atoms in the second molecular sieve may be 0.1-100:1.

According to the present invention, preferably, the weight ratio of the first molecular sieve to the second molecular sieve is 1-15:1, preferably 1.5-7:1.

According to the present invention, preferably, based on the total weight of the active component coating, the active component coating contains 54-90% by weight of molecular sieve and 10-46% by weight of matrix.

According to the present invention, preferably, based on the total weight of the catalyst, the content of the active component coating is 15-30% by weight.

According to the invention, the structured support can be used to provide a catalyst bed in a fixed bed reactor. The carrier with regular structure can be a whole carrier block with a hollow channel structure formed inside, a catalyst coating can be distributed on the inner wall of the channel, and the channel space can be used as a fluid flow space. Preferably, the structured carrier is selected from a monolithic carrier with a parallel channel structure open at both ends. The structured carrier may be a honeycomb structured carrier with honeycomb-shaped openings in the cross-section (referred to as honeycomb carrier).

According to the present invention, preferably, the pore density of the cross-section of the regular structure carrier is 6-140 holes/cm2, preferably 20-100 holes/cm2; the cross-sectional area of each hole is 0.4-10 mm2, It is preferably 2-7 square millimeters; the opening ratio is 50-80%. The shape of the hole can be square (or winged square, that is, there are wings with vertical sides facing inward at the center of the four sides in the square hole, and its length is 1/5-2/5 of the side length of the square), regular triangle, regular six One of polygonal, circular and corrugated.

According to the present invention, preferably, the regular structure support may be selected from at least one of cordierite honeycomb support, mullite honeycomb support, alumina honeycomb support and metal alloy honeycomb support.

According to the present invention, preferably, the substrate may be selected from at least one of alumina, silica, amorphous silica-alumina, zirconia, titania, boria and alkaline earth metal oxides.

Catalysts that meet the aforementioned requirements of the present invention can all achieve the purpose of the present invention, and the present invention has no special requirements for its preparation method. According to a preferred embodiment of the present invention, the catalyst is prepared as follows: (1) molecular sieve and Aqueous solvents are mixed and ground to obtain a molecular sieve slurry;

(2) mixing the molecular sieve slurry with a matrix source to form an active component coating slurry;

(3) coating the regular structure carrier with the active component coating slurry and drying and roasting;

Wherein, the molecular sieve contains a first molecular sieve and a second molecular sieve; the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical channel structure, and the second molecular sieve is a molecular sieve with a twelve-membered ring channel structure.

According to a more preferred embodiment of the present invention, the method of the present invention prepares the catalyst according to the following steps: (1) the first molecular sieve and the second molecular sieve are respectively mixed with an aqueous solvent and ground to obtain the first molecular sieve slurry and the second molecular sieve slurry;

(2) mixing the first molecular sieve slurry and the second molecular sieve slurry with a substrate source respectively to form a first active component coating slurry and a second active component coating slurry;

(3) Coating the structured structure carrier with the first active component coating slurry, drying and roasting, and then coating the structured structure carrier distributed with the first active component coating with the second active component coating slurry, Dry and roast.

According to the present invention, preferably, the added amount of the matrix source and the molecular sieve is such that in the obtained active component coating, based on the total weight of the active component coating, the content of the matrix is 5-50 wt. %, the content of molecular sieve is 50-95% by weight.

In the method provided by the present invention, the matrix source is used to provide the matrix in the prepared active component, which is not particularly required in the present invention. It should be noted that when the matrix is silica and/or alumina, although the molecular sieve contains alumina and silica, the amount of silica and alumina contained in the molecular sieve is still counted as the The amount of molecular sieve, excluding silica and alumina. That is, the content of each component in the active component prepared by the method provided by the invention is calculated according to the feeding amount.

According to the present invention, the diameter _d90 of molecular sieve particles in the molecular sieve slurry in step (1) is 1-10 microns, such as 5-10 microns, and the solid content of the molecular sieve slurry is 15-70% by weight, such as 50-65% by weight %, the aqueous solvent is water such as deionized water.

According to a preferred embodiment of the present invention, the molecular sieve particle diameters _d90 of the first molecular sieve slurry and the second molecular sieve slurry in step (1) are each 1-10 microns, such as 5-10 microns, and the first The solid content of the molecular sieve slurry and the second molecular sieve slurry are each 15-70 wt%, such as 50-65 wt%, and the aqueous solvent is water such as deionized water.

According to the present invention, preferably, based on the total weight of the active component coating slurry obtained in step (2), the content of the molecular sieve is 3-60% by weight, preferably 10-40% by weight, so The total content of the matrix source based on the matrix is 0.3-18% by weight, preferably 4-15% by weight.

According to a preferred embodiment of the present invention, based on the respective total weights of the first active component coating slurry and the second active component coating slurry, the first molecular sieve (or second molecular sieve) The contents are each 3-60% by weight, preferably 10-40% by weight, and the total content of the substrate source is 0.3-18% by weight, preferably 4-15% by weight.

According to a preferred embodiment of the present invention, the types and amounts of substrate sources for forming the first active component coating slurry and the second active component coating slurry can be the same or different, and can be selected according to actual needs.

According to the present invention, the active component coating slurry in step (2) may further contain a dispersant, and the weight ratio of the dispersant to the molecular sieve is less than 0.2 and greater than 0; preferably 0.0005-0.015:1.

According to a preferred embodiment of the present invention, the weight ratio of the dispersant to the first molecular sieve in the first active component coating slurry in step (2) is 0.0005-0.015:1, and the second active component The weight ratio of the dispersant to the second molecular sieve in the component coating slurry is 0.0006-0.002:1.

According to the present invention, the dispersant in step (2) is selected from compounds containing at least one of polyhydroxy, polyvinyl and polycarboxylic acid groups, such as polyethylene glycol, glycerol, polyvinyl alcohol Or one or more of polyacrylic acid, preferably polyethylene glycol and/or polyacrylic acid.

According to the present invention, in step (3), the catalyst provided by the present invention can be prepared by distributing the active component coating slurry on the inner surface and/or outer surface of the structured carrier by various coating methods. The coating method can be water coating method, dipping method or spraying method. The specific operation of coating can be carried out with reference to the method described in CN1199733C. The coating temperature is preferably 10-70°C, more preferably 15-35°C, the coating pressure is preferably -0.04 MPa to 0.4 MPa, and the coating time is preferably 0.1-100 seconds.

According to the present invention, the structured carrier coated with the active component coating slurry is dried and calcined. The drying method and conditions are well known to those skilled in the art, for example, the drying method may be air drying, oven drying, and blast drying. Preferably, in step (3), the drying temperature can be from room temperature to 300°C, preferably 100-200°C; the drying time is at least 0.5 hours, preferably 1-10 hours.

According to the present invention, the conditions of the calcination in step (3) can also be known to those skilled in the art, generally speaking, the temperature of the calcination is 400-800°C, preferably 500-700°C; The time is at least 0.5 hours, preferably 1-10 hours.

According to the present invention, the types of molecular sieves have been described in detail above, and will not be repeated here.

According to the present invention, when the matrix is silicon oxide, the matrix source may be a silicon oxide source, preferably the silicon oxide source is silicon oxide or a natural ore with a silicon oxide content greater than 45% by weight. Preferably, the silica source may be at least one of layered clay, diatomaceous earth, expanded perlite, silicalite, silica sol, macroporous silica and silica gel.

According to the present invention, when the substrate is alumina, the substrate source may be an alumina source, and the alumina source may be a substance that can be converted into alumina under the calcination conditions in step (3). Preferably, the alumina source is one or more of hydrated alumina, alumina sol and pseudoboehmite; the hydrated alumina is boehmite, pseudoboehmite, trihydrate At least one of alumina and amorphous aluminum hydroxide.

The present invention also provides the catalyst prepared by the method provided by the present invention.

According to the present invention, the catalyst comprises a regular structure carrier and an active component coating distributed on the inner surface and/or outer surface of the regular structure carrier; based on the total weight of the catalyst, the content of the active component coating is 10-50% by weight; based on the total weight of the active component coating, the active component coating contains 50-95% by weight of molecular sieve and 5-50% by weight of the matrix; the molecular sieve contains the first A molecular sieve and a second molecular sieve; the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical pore structure, and the second molecular sieve is a molecular sieve with a twelve-membered ring pore structure.

The present invention also provides a method for producing propylene by catalytic cracking of naphtha, the method comprising: under the reaction conditions of catalytic cracking of naphtha, contacting naphtha and water with a catalyst to obtain a propylene product, wherein the catalyst Including the catalyst provided by the present invention.

According to the present invention, preferably, the reaction conditions for catalytic cracking of naphtha include: the temperature is 520-590° C., the pressure is 0.1-0.2 MPa, the water/oil feed weight ratio is 0.3-2, and the catalyst uses active components According to the coating meter, the weight hourly space velocity of naphtha feed is 2-40h ^-1 .

According to the present invention, preferably, the naphtha contains 0.5-1.5% by weight of olefins, 40-60% by weight of alkanes, 20-40% by weight of naphthenes and 10-20% by weight of aromatics.

The present invention will be described in detail below by way of examples.

The properties of gas phase products in the following examples were determined by gas chromatography using an instrument of HP6890 type from Agilent Company. Yield and selectivity were calculated by the following formulas:

Yield = (target product (C ₂ ⁼ +C ₃ ⁼ ) generated amount/reactant feed amount) × 100%

Selectivity = (target product (C ₂ ⁼ ~ C ₄ ⁼ ) formation amount/reactant conversion amount) × 100%

Example 1

This example is used to illustrate the preparation method of the catalyst provided by the present invention and the method for producing propylene by catalytic cracking of naphtha.

(1) Preparation of catalyst. Mix 56.2 grams of ZSM-35 molecular sieve (Shanghai Zhuoyue Chemical Co., Ltd., Si/Al molar ratio = 30:1) with 56.2 grams of deionized water, and wet ball mill to form a molecular sieve slurry. The molecular sieve particle diameter d90 = 10 microns. Add 28.4 grams of aluminum sol (containing 22% by weight of alumina, produced by Sinopec Catalyst Qilu Branch) in the slurry, stir for 10 minutes, add 1.5 grams of polyethylene glycol solution (the weight percent of polyethylene glycol solution is 2% by weight), Stir for 20 minutes to obtain the first active component coating slurry 1.

The first active component coating slurry 1 is coated with a cordierite honeycomb carrier (the carrier pore density is 100 holes/square centimeter, the cross-sectional area of each hole is 7 square millimeters, the porosity is 80%, and the shape of the holes is a square ), dried at 120° C. for 5 hours and calcined at 500° C. for 5 hours to obtain catalyst precursor 1, wherein the active component coating content was 15% by weight.

Mix 30 grams of Beta molecular sieve (self-made, Si/Al molar ratio = 100:1) with 30 grams of deionized water, and wet ball mill to form a molecular sieve slurry. The particle diameter of the molecular sieve is d90 = 10 microns, and the solid content is 50% by weight. Add 15.0 grams of aluminum sol (containing 22% by weight of alumina, produced by Sinopec Catalyst Qilu Branch) in the slurry, stir for 10 minutes, add 1.0 grams of polyethylene glycol solution (the weight percent of polyethylene glycol solution is 2% by weight), Stir for 20 minutes to obtain the second active component coating slurry 2.

The catalyst precursor 1 was coated with the second active component coating slurry 2, dried at 120°C for 5 hours and calcined at 500°C for 5 hours, wherein the content of the outer active component coating was 9% by weight. Based on the total weight of the active component coating: the molecular sieve content is 90% by weight, and the matrix (aluminum oxide) content is 10% by weight.

(2) Propylene production. The catalyst prepared in (1) was used as a catalyst bed to form a structured reactor, wherein the total weight of the active component coating was 62.5 grams. Naphtha (containing 1% by weight of olefins, 56% by weight of alkanes, 32% by weight of naphthenes, 11% by weight of aromatics, and 0.5 μg/g of basic nitrogen) and water were preheated at 250°C and injected into the above-mentioned regular structure reactor. The heavy hourly space velocity of naphtha injection (relative to the total weight of active component coating) is 25 hr ^-1 , and the weight ratio of water/oil feed is 0.46. The reaction temperature is 520° C., and the pressure is 0.1 MPa. The reaction results are shown in Table 1.

Example 2

This example is used to illustrate the preparation method of the catalyst provided by the present invention and the method for producing propylene by catalytic cracking of naphtha.

(1) Preparation of catalyst.

Mix 32 grams of Ferrierite zeolite molecular sieve (Zeolyst International, Si/Al molar ratio = 10:1) with 20 grams of deionized water, and wet ball mill to form a slurry. The particle diameter of the molecular sieve in the slurry is d90 = 8 microns; in the slurry Add 150 grams of peptized pseudo-boehmite (containing 18% by weight of alumina, the pH value is 2.8, the product of Sinopec Catalyst Qilu Branch), stirred for 15 minutes; added 3.2 grams of polyacrylic acid solution (the weight percent of polyacrylic acid solution is 1 weight %), the amount of polyacrylic acid solution added is 10% by weight of the molecular sieve weight, and stirred for 30 minutes to obtain the first active component coating slurry 1.

The first active component coating slurry 1 is coated with a cordierite honeycomb carrier (the carrier pore density is 80 holes/square centimeter, the cross-sectional area of each hole is 5 square millimeters, the porosity is 60%, and the shape of the hole is a circle shape), dried at 120°C for 5 hours and calcined at 500°C for 5 hours to obtain catalyst precursor 1, wherein the active component coating content was 10% by weight.

Mix 32 grams of mordenite molecular sieve (Shanghai Shentan Environmental Protection New Material Co., Ltd., Si/Al molar ratio = 80:1) with 30 grams of deionized water, wet ball mill to form molecular sieve slurry, molecular sieve particle diameter d90 = 10 microns, solid The content is 50% by weight. Add 122 grams of aluminum sol (containing 22% by weight of alumina, produced by Sinopec Catalyst Qilu Branch) in the slurry, stir for 10 minutes, add 1.0 grams of polyethylene glycol solution (the weight percent of polyethylene glycol solution is 2% by weight), Stir for 20 minutes to obtain the second active component coating slurry 2.

The second active component coating slurry 2 was coated on the catalyst precursor 1, dried at 120°C for 5 hours and calcined at 500°C for 5 hours, wherein the content of the outer active component coating was 10% by weight. Based on the total weight of the active component coating: the molecular sieve content is 54% by weight, and the matrix (aluminum oxide) content is 46% by weight.

(2) Propylene production. The catalyst prepared in (1) was used as a catalyst bed to form a structured reactor, wherein the total weight of the active component coating was 59 grams. Naphtha (containing 1% by weight of olefins, 56% by weight of alkanes, 32% by weight of naphthenes, 11% by weight of aromatics, and 0.4 μg/g of basic nitrogen) and water were preheated at 250°C and injected into the above-mentioned regular structure reactor. The heavy hourly space velocity of naphtha injection (relative to the total weight of the active component coating) is 36.5 hr ^-1 , and the weight ratio of water/oil feed is 0.96. The reaction temperature is 570° C. and the pressure is 0.1 MPa. The reaction results are shown in Table 1.

Example 3

This example is used to illustrate the preparation method of the catalyst provided by the present invention and the method for producing propylene by catalytic cracking of naphtha.

(1) Preparation of catalyst. Mix 70 grams of ZSM-57 molecular sieve (Si/Al molar ratio = 80:1) with 60 grams of distilled water, and wet ball mill it into a slurry. The particle diameter of the molecular sieve in the slurry is d90 = 5 microns; add 143 grams of acidic silica sol to the slurry (containing silicon oxide 21% by weight, product of Sinopec Catalyst Qilu Branch Company), stirred for 60 minutes; Added polyethylene glycol and polyacrylic acid mixed solution 12.6 grams (polyethylene glycol and polyacrylic acid weight percentages are divided into 3% by weight and 5% by weight) , and stirred for 30 minutes to obtain the first active component coating slurry 1.

The first active component coating slurry 1 is coated with a cordierite honeycomb carrier (the carrier pore density is 20 holes/square centimeter, the cross-sectional area of each hole is 2 square millimeters, the porosity is 75%, and the shape of the hole is a circle shape), dried at 120°C for 5 hours and calcined at 500°C for 5 hours to obtain catalyst precursor 1, wherein the active component coating content was 20% by weight.

Mix 10 grams of SSZ-13 (Si/Al molar ratio = 40:1) with 10 grams of deionized water, and wet ball mill to form a molecular sieve slurry. The particle diameter of the molecular sieve is d90 = 10 microns, and the solid content is 50% by weight. Add 20 grams of silica sol (containing 21% by weight of silicon oxide, produced by Sinopec Catalyst Qilu Branch) in the slurry, stir for 10 minutes, add 1.0 grams of polyethylene glycol solution (the weight percent of polyethylene glycol solution is 2% by weight), Stir for 20 minutes to obtain the second active component coating slurry 2.

The second active component coating slurry 2 was coated on the catalyst precursor 1, dried at 120° C. for 5 hours and calcined at 500° C. for 5 hours, wherein the content of the outer active component coating was 10% by weight.

Based on the total weight of the active component coating: the molecular sieve content is 70% by weight, and the matrix (silicon oxide) content is 30% by weight.

(2) Propylene production. The catalyst prepared in (1) was used as a catalyst bed to form a regular structure reactor, wherein the total weight of the active component coating was 100 grams. Naphtha (containing 1% by weight of olefins, 56% by weight of alkanes, 32% by weight of naphthenes, 11% by weight of aromatics, and 0.6 μg/g of basic nitrogen) and water were preheated at 250°C and injected into the regular structure reactor. Among them, the heavy hourly space velocity of naphtha injection (relative to the total weight of the active component coating) was 4.6 hr ^-1 , and the weight ratio of water/oil feed was 1.61. The reaction temperature is 590° C., and the pressure is 0.2 Pa. The reaction results are shown in Table 1.

Example 4

According to the method cracking naphtha of embodiment 3, difference is that the first molecular sieve is replaced by ZSM-35 zeolite (silicon-aluminum atomic molar ratio is 30) and COK-5 zeolite (silicon-aluminum atomic molar ratio is 50) in the catalyst, And the weight ratio of the two is 1:1.

Example 5

According to the method cracking naphtha of embodiment 3, difference is that in the catalyst, the first molecular sieve is replaced by Ferrierite zeolite (silicon-aluminum atomic molar ratio is 50) and ZSM-57 zeolite (silicon-aluminum atomic molar ratio is 80), and two The weight ratio of the latter is 2:1.

Example 6

According to the method cracking naphtha of embodiment 3, difference is that in the catalyst, the first molecular sieve is replaced by FU-9 zeolite (silicon-aluminum atomic molar ratio is 50) and ZSM-57 zeolite (silicon-aluminum atomic molar ratio is 30), And the weight ratio of the two is 5:1.

Example 7

According to the method cracking naphtha of embodiment 4, difference is, ZSM-35 zeolite is by ZSM-35 zeolite (silicon-aluminum atomic molar ratio is 30) and Ferrierite zeolite (silicon-aluminum atomic molar ratio is 30) in the catalyst in the first molecular sieve ) mixture, the weight ratio of the two is 3:1; COK-5 zeolite is replaced by a mixture of ZSM-57 zeolite (silicon-aluminum atomic molar ratio is 50) and COK-5 zeolite (silicon-aluminum atomic molar ratio is 50) , the weight ratio of the two is 4:1.

Example 8

Carry out according to the method for embodiment 3, difference is, after the first active component coating slurry and the second active component coating slurry are mixed, carry out coating regular structure carrier, then carry out drying and calcining, the temperature of drying and calcining Same as Example 3, the total time of drying and firing is the same as the total time of drying and firing after coating in Example 3, and the rest of the conditions are the same.

Example 9

Carried out according to the method of Example 3, the difference is that the structured structure carrier is first coated with the second active component coating slurry, then dried and calcined, and then coated with the first active component coating slurry, Carry out drying and roasting then, the temperature of drying and roasting is identical with embodiment 3, all the other conditions are identical.

Comparative example 1

According to the method of Example 1, the difference is that the ZSM-35 molecular sieve is replaced by the same amount of Beta zeolite, that is, all the molecular sieves are the second molecular sieves.

Comparative example 2

According to the method of Example 1, the difference is that the Beta zeolite is replaced by an equal amount of ZSM-35 molecular sieves, that is, all the molecular sieves are the first molecular sieves.

Comparative example 3

Carry out according to the method for embodiment 3, difference is that the catalyst used is prepared as follows:

Mix 56.2 grams of ZSM-5 molecular sieve (manufactured by Nankai University, Si/Al molar ratio = 30:1) with 56.2 grams of deionized water, and wet ball mill to form a molecular sieve slurry. The particle diameter of the molecular sieve is d90 = 10 microns, and the solid content is 50 weight%. 28.4 grams of aluminum sol (containing 22% by weight of alumina, produced by Sinopec Catalyst Qilu Branch) was added to the slurry, and stirred for 20 minutes to obtain a mixture slurry which was then extruded.

Catalyst composition: ZSM-5 molecular sieve content is 90% by weight, matrix (alumina) content is 10% by weight.

Table 1

As can be seen from the data results in Table 1, in a preferred embodiment of the present invention, the catalyst provided by the invention adopts a regular structure carrier and a double-layer active component coating distributed on the inner surface and/or outer surface of the regular structure carrier; The inner molecular sieve has a ten-membered ring two-dimensional elliptical channel structure, preferably one of FER or MFS structures, and the outer layer is a molecular sieve with twelve-membered ring channels. In the production of propylene by catalytic cracking of naphtha, high yields of ethylene and propylene can be obtained, and wherein the ratio of propylene/ethylene is greater than 3, so that more propylene can be produced.

Claims (21)

1. A catalyst for producing propylene by catalytic cracking of naphtha, the catalyst comprising: a regular structure carrier and an active component coating distributed on the inner surface and/or outer surface of the regular structure carrier; based on the total weight of the catalyst , the content of the active component coating is 10-50% by weight; based on the total weight of the active component coating, the active component coating contains 50-95% by weight of molecular sieve and 5-50 % by weight of matrix; the molecular sieve contains a first molecular sieve and a second molecular sieve; the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical channel structure, and the second molecular sieve is a molecular sieve with a twelve-membered ring channel structure Molecular sieve, the first molecular sieve is a mixture of a molecular sieve with a FER structure and a molecular sieve with an MFS structure, and the second molecular sieve is selected from a molecular sieve with AET, AFR, AFS, AFI, BEA, BOG, CFI, CON, GME, IFR, ISV, At least one of molecular sieves with structures of LTL, MEI, MOR, OFF and SAO, the weight ratio of the first molecular sieve to the second molecular sieve is 1-15:1. 2. The catalyst according to claim 1, wherein the active component coating comprises two layers, an inner layer and an inner layer, wherein the inner layer contains the first molecular sieve and the outer layer contains the second molecular sieve. 3. The catalyst according to claim 2, wherein, based on the total weight of the inner layer active component coating, it contains the first molecular sieve of 50-95% by weight and the matrix of 5-50% by weight; the outer layer active component coating Based on the total weight, it contains 50-95% by weight of the second molecular sieve and 5-50% by weight of the matrix. 4. The catalyst according to any one of claims 1-3, wherein the weight ratio of the molecular sieve of the FER structure and the molecular sieve of the MFS structure is 0.1-10:1; the molecular sieve of the FER structure is ZSM-35 zeolite, At least one of Ferrierite zeolite, FU-9 zeolite, ISI-6 zeolite, NU-23 zeolite and Sr-D zeolite; the molecular sieve of MFS structure is at least one of ZSM-57 zeolite and COK-5 zeolite. 5. The catalyst according to claim 4, wherein the weight ratio of the molecular sieve with the FER structure to the molecular sieve with the MFS structure is 1-5:1. 6. The catalyst according to claim 4, wherein the molecular sieve of the FER structure is at least one of ZSM-35 zeolite, Ferrierite zeolite and FU-9 zeolite. 7. The catalyst according to claim 6, wherein the molecular sieve of the FER structure is a mixture of ZSM-35 zeolite and Ferrierite zeolite. 8. The catalyst according to claim 4, wherein the molecular sieve of the MFS structure is a mixture of ZSM-57 zeolite and COK-5 zeolite. 9. The catalyst according to any one of claims 1-3, wherein the opening diameter of the pores of the second molecular sieve is 0.6-0.75 nanometers. 10. The catalyst according to any one of claims 1-3, wherein, based on the total weight of the active component coating, the active component coating contains 54-90% by weight of molecular sieves and 10 - 46% by weight of substrate; the content of the active component coating is 15-30% by weight, based on the total weight of the catalyst. 11. The catalyst according to any one of claims 1-3, wherein the structured support is selected from a monolithic support having a parallel pore structure open at both ends. 12. The catalyst according to any one of claims 1-3, wherein the pore density of the cross-section of the regular structure support is 6-140 holes/square centimeter, and the cross-sectional area of each hole is 0.4-10 square millimeters , The porosity is 50-80%. 13. The catalyst according to any one of claims 1-3, wherein the structured carrier is selected from at least one of cordierite honeycomb carrier, mullite honeycomb carrier, alumina honeycomb carrier and metal alloy honeycomb carrier kind. 14. The catalyst according to any one of claims 1-3, wherein the substrate is selected from the group consisting of alumina, silica, amorphous silica-alumina, zirconia, titania, boria and alkaline earth metal oxides at least one. 15. a method for preparing a catalyst for producing propylene from naphtha catalytic cracking according to claim 1, the method comprising: (1) mixing and grinding the molecular sieve and an aqueous solvent to obtain a molecular sieve slurry; (2) mixing the molecular sieve slurry with a matrix source to form an active component coating slurry; (3) coating the regular structure carrier with the active component coating slurry and drying and roasting; Wherein, the molecular sieve contains a first molecular sieve and a second molecular sieve; the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical channel structure, and the second molecular sieve is a molecular sieve with a twelve-membered ring channel structure. 16. The method of claim 15, wherein the method comprises: (1) mixing and grinding the first molecular sieve and the second molecular sieve respectively with an aqueous solvent to obtain the first molecular sieve slurry and the second molecular sieve slurry; (2) mixing the first molecular sieve slurry and the second molecular sieve slurry with a substrate source respectively to form a first active component coating slurry and a second active component coating slurry; (3) Coating the structured structure carrier with the first active component coating slurry, drying and roasting, and then coating the structured structure carrier distributed with the first active component coating with the second active component coating slurry, Dry and roast. 17. The method according to claim 15, wherein, in step (1), the molecular sieve particle diameter d90 in the molecular sieve slurry is 1-10 microns, and the solid content of the molecular sieve slurry is 15-70% by weight, the The aqueous solvent is deionized water. 18. The method according to claim 15, wherein the active component coating slurry in step (2) further contains a dispersant, and the weight ratio of the dispersant to the molecular sieve is less than 0.2 and greater than zero. 19. A catalyst prepared by the process of any one of claims 15-18. 20. A method for producing propylene by catalytic cracking of naphtha, the method comprising: under the reaction conditions of catalytic cracking of naphtha, contacting naphtha and water with a catalyst to obtain a propylene product, characterized in that the catalyst comprises The catalyst according to any one of claims 1-14 and 19. 21. The method according to claim 20, wherein the catalytic cracking reaction conditions of the naphtha include: a temperature of 520-590°C, a pressure of 0.1-0.2MPa, a water/oil feed weight ratio of 0.3-2, The catalyst is calculated based on the active component coating, and the weight hourly space velocity of the naphtha feed is 2-40h ^-1 .