CN105582995A - Catalyst for catalytically pyrolyzing naphtha to produce propylene, preparation method thereof, and method of catalytically pyrolyzing the naphtha to produce the propylene - Google Patents

Abstract

The invention provides a catalyst for producing propylene by catalytic cracking of naphtha and a preparation method thereof. Based on the total weight of the catalyst, the catalyst contains 50-95% by weight of molecular sieve and 5-50% by weight of matrix; The molecular sieve contains a first molecular sieve, a second molecular sieve and a third 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 third molecular sieve is a small-pore molecular sieve with a maximum pore opening diameter below 0.45nm. 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 2 or more can be obtained.

Description

Catalyst for producing propylene by catalytic cracking of naphtha, preparation method thereof, and method for producing propylene by catalytic cracking of naphtha

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 low propylene yield 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. method.

In order to achieve the above object, the present invention provides a catalyst for producing propylene by catalytic cracking of naphtha, based on the total weight of the catalyst, the catalyst contains 50-95% by weight of molecular sieve and 5-50% by weight of matrix; The molecular sieve contains a first molecular sieve, a second molecular sieve and a third 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 third molecular sieve is a small-pore molecular sieve with a maximum pore opening diameter below 0.45nm.

The present invention also provides a method for preparing a catalyst for catalytic cracking of naphtha to produce propylene, the method comprising: (1) mixing a matrix source, water, and an optional acid solution to form a slurry; (2) mixing molecular sieves or The suspension of molecular sieve and water is mixed with the slurry, and the obtained catalyst mixture is shaped, and optionally dried and calcined; the molecular sieve contains a first molecular sieve, a second molecular sieve and a third molecular sieve, and the first molecular sieve is A molecular sieve with a ten-membered ring two-dimensional elliptical pore structure, the second molecular sieve is a molecular sieve with a twelve-membered ring pore structure, and the third molecular sieve is a small-pore molecular sieve with a maximum pore opening diameter below 0.45nm.

The present invention also provides a method for preparing a catalyst for producing propylene by catalytic cracking of naphtha, the method comprising: (1) mixing a matrix source, water, a first molecular sieve and an optional acid solution to form a slurry; (2) The second molecular sieve and the third molecular sieve or the suspension containing the second molecular sieve and the third molecular sieve and water are mixed with the slurry, and the obtained catalyst mixture is shaped, and optionally dried and calcined; the first molecular sieve is A molecular sieve with a ten-membered ring two-dimensional elliptical pore structure, the second molecular sieve is a molecular sieve with a twelve-membered ring pore structure, and the third molecular sieve is a small-pore molecular sieve with a maximum pore opening diameter below 0.45nm.

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 2 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, and are not intended to limit the present invention.

The invention provides a catalyst for producing propylene by catalytic cracking of naphtha. Based on the total weight of the catalyst, the catalyst contains 50-95% by weight of molecular sieve and 5-50% by weight of matrix; the molecular sieve contains the first A molecular sieve, a second molecular sieve and a third molecular sieve, the first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical pore structure, the second molecular sieve is a molecular sieve with a twelve-membered ring pore structure, and the third molecular sieve It is a small-pore molecular sieve with a maximum pore opening diameter below 0.45nm.

In the catalyst provided by the present invention, the first molecular sieve, the second molecular sieve and the third molecular sieve are used as catalytic cracking active components, so that a higher yield of propylene produced by catalytic cracking of naphtha can be obtained.

According to the present invention, the first molecular sieve has ten-membered ring two-dimensional elliptical channels, preferably with an 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 0.6-0.75 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 silicon-aluminum atom molar ratio (Si/Al) in the second molecular sieve may be 0.1-100:1; preferably 30-80:1.

According to the present invention, preferably, the third molecular sieve is at least one selected from molecular sieves having structures of ATT, ATN, CHA, ITE, STI, and WEN. More preferably, the third molecular sieve is at least one of ITQ-3, SAPO-34 and cancryptite.

According to the present invention, preferably, the weight ratio of the first molecular sieve, the second molecular sieve and the third molecular sieve is 0.1-15:0.1-5:1, preferably 1-10:1-2:1 .

According to the present invention, preferably, based on the total weight of the catalyst, the catalyst contains 60-95% by weight of molecular sieve and 5-40% by weight of matrix.

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 according to the following steps: (1) the matrix source , water and optionally an acid solution are mixed to form a slurry;

(2) mixing molecular sieves or a suspension containing molecular sieves and water with the slurry, forming the obtained catalyst mixture, and optionally drying and roasting;

The molecular sieve contains a first molecular sieve, a second molecular sieve and a third 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 third molecular sieve is a small-pore molecular sieve with a maximum pore opening diameter below 0.45 nm.

According to a more preferred embodiment of the present invention, preferably the catalyst of the present invention is prepared according to the following steps: (1) mixing the substrate source, water, the first molecular sieve and an optional acid solution to form a slurry;

(2) mixing the second molecular sieve and the third molecular sieve or the suspension containing the second molecular sieve and the third molecular sieve and water with the slurry, and forming the obtained catalyst mixture, and performing optional drying and roasting; the second molecular sieve The first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical pore structure, the second molecular sieve is a molecular sieve with a twelve-membered ring pore structure, and the third molecular sieve is a small-pore molecular sieve with a maximum pore opening diameter below 0.45nm .

According to the method of the present invention, the types of the first molecular sieve, the second molecular sieve, and the third molecular sieve have been described in detail in the aforementioned product introduction process, and will not be repeated here.

According to the present invention, preferably, the weight ratio of the first molecular sieve, the second molecular sieve and the third molecular sieve is 0.1-15:0.1-5:1, preferably 1-10:1-2:1 .

According to the present invention, preferably, the matrix source can be a substance that can be transformed into a matrix under the conditions of the calcination in step (2), and the matrix is alumina, silica, amorphous silica-alumina, zirconia At least one of titanium oxide, boron oxide and alkaline earth metal oxide; the addition of the matrix source and the molecular sieve makes the obtained catalyst, based on the total weight of the catalyst, the content of the matrix is 5-50 % by weight, the content of molecular sieve is 50-95% by weight, preferably based on the total weight of the catalyst, the catalyst contains 60-95% by weight of molecular sieve and 5-40% by weight of matrix.

In one embodiment of the present invention, a silica source and an alumina source can be used to prepare the substrate in the catalyst provided by the present invention.

In one embodiment of the present invention, the silicon oxide source may be 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.

In one embodiment of the present invention, the alumina source may be a substance that can be converted into alumina under the conditions of the calcination in step (2). 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.

In one embodiment of the present invention, the sum of the amounts of silica and alumina in the obtained catalyst is recorded as the amount of matrix. In addition, although the molecular sieve contains alumina and silica, the amount of silica and alumina contained in the molecular sieve is still counted as the amount of the molecular sieve, excluding silica and alumina. That is, the content of each component in the catalyst prepared by the method provided by the invention is calculated according to the feeding amount.

In the present invention, the optional acid solution in step (1) may be acidified or not acidified according to the substrate source. In one embodiment, when alumina sol and/or silica sol are used as alumina source or silica source, acid solution acidification may not be used; when pseudo-boehmite and/or kaolin is used, acid solution acidification may be used . The acid solution can be used in an amount such that the pH of the slurry is 1-5, preferably 1.5-4. The acid solution may be selected from water-soluble inorganic and/or organic acids, such as at least one of hydrochloric acid, nitric acid, phosphoric acid and acetic acid.

In the present invention, the amount of water added in step (1) is not particularly limited, as long as the slurry described in step (1) can be obtained. For example, the amount of water added is such that the resulting slurry has a solids content of 5-60% by weight, preferably 10-30% by weight.

In the present invention, there is no particular limitation on the amount of water used to form the suspension in step (2), as long as the suspension described in step (2) can be obtained. For example, the amount of water added is such that the resulting suspension has a solids content of 15-60% by weight, preferably 20-35% by weight.

In the step (2) of the present invention, the catalyst mixture may be in the form of wet mixture, paste mixture, dough or slurry. By said shaping, the catalyst mixture can be shaped into extrudates, tablets, pellets, spheres or microspheroidal particles. For example, when the catalyst mixture is a dough or pasty mixture, the catalyst mixture can be shaped (preferably extruded) to form granules, preferably cylindrical extrusions with a diameter of 1.0-8.0 mm and a length of 2.0-5.0 mm. The extrudates are then dried and calcined. If the catalyst mixture is in the form of a wet mixture, the mixture can be thickened, dried and shaped. The catalyst mixture can also be in the form of a slurry, which can be spray-dried to form microspheres with a particle size of 20-200 microns to achieve the purpose of molding. To facilitate spray drying, the solids content of the catalyst mixture prior to drying may be 10-50% by weight, preferably 20-50% by weight.

In the present invention, the drying method and conditions of the catalyst mixture are well known to those skilled in the art, for example, the drying method may be air drying, oven drying, or blast drying. Preferably, in step (2), the drying temperature can be from room temperature to 400°C, preferably 100-350°C; the drying time is at least 0.5 hours, preferably 0.5-60 hours.

In the present invention, the calcination conditions of the catalyst mixture can also be known to those skilled in the art. Generally speaking, the calcination temperature is 400-700°C, preferably 450-650°C; the calcination time is at least 0.5 hours, preferably 0.5-100 hours, more preferably 0.5-10 hours.

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

According to the present invention, based on the total weight of the catalyst, the catalyst contains 50-95% by weight of molecular sieve and 5-50% by weight of matrix; the molecular sieve contains a first molecular sieve, a second molecular sieve and a third molecular sieve, and the The first molecular sieve is a molecular sieve with a ten-membered ring two-dimensional elliptical channel structure, the second molecular sieve is a molecular sieve with a twelve-membered ring channel structure, and the third molecular sieve is a small hole with a maximum channel opening diameter below 0.45nm Molecular sieve.

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 naphtha feed is The weight hourly space velocity 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. 28 grams of pseudo-boehmite (Shandong Aluminum Plant, containing 20 grams on a dry basis) and 50 grams of deionized water were mixed under stirring, and 3.6 grams of concentrated hydrochloric acid (chemically pure, produced by Beijing Chemical Plant) was added with a concentration of 36% by weight. Stir and acidify for 1 hour, then raise the temperature to 60°C and acidify for 1 hour, and the pH value is 3.0. When the temperature drops below 40°C, add 50 grams of ZSM-35 zeolite (Shanghai Zhuoyue Chemical Co., Ltd., Si/Al molar ratio = 60:1), 20 grams of Beta zeolite (self-made, Si/Al molar ratio = 50: 1) and SAPO-34 molecular sieve 10 grams (Tianjin Kemesite Technology Development Co., Ltd., Si/Al molar ratio = 0.25: 1) suspension (solid content is 20% by weight), after mixing, stir for 1 hour to obtain the catalyst mixture .

The catalyst mixture was extruded and pelletized by a single-screw extruder, dried in the sun at room temperature, dried at 120°C for 5 hours, and then calcined at 480°C for 1 hour to obtain the catalyst.

The composition of the catalyst is calculated according to the feed: ZSM-35, Beta and SAPO-34 molecular sieve contents are respectively 50% by weight, 20% by weight and 10% by weight, and the content of alumina is 20% by weight.

(2) Propylene production. The catalyst prepared in (1) is loaded into a fixed-bed reactor, and naphtha (containing 1% by weight of olefins, 56% by weight of alkanes, 32% by weight of cycloalkanes, 11% by weight of aromatics, and 0.5% by weight of basic nitrogen μg/g) and water were injected into the fixed bed reactor after being preheated at 250°C. Among them, the weight hourly space velocity of naphtha injection is 2.3hr ^-1 , and the water/oil feed weight ratio is 0.46. The reaction temperature is 520° C., and the pressure is 0.2 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. 32 grams of Ferrierite zeolite molecular sieve (Si/Al molar ratio=50:1), 32 grams of mordenite molecular sieve (Shanghai Shentan Environmental Protection New Material Co., Ltd., Si/Al molar ratio=80:1) and 30 grams of ITQ-3 Molecular sieves (self-made, Si/Al molar ratio = 10:1) were mechanically mixed, and then silica sol (solid content: 30% by weight) containing 6 grams of silicon dioxide was added, and the catalyst was obtained by tableting.

The catalyst composition is calculated according to the feed: the contents of Ferrierite zeolite, mordenite molecular sieve and ITQ-3 molecular sieve are 32 wt%, 32 wt% and 30 wt%, and the content of silicon oxide matrix is 6 wt%.

(2) Propylene production. The catalyst prepared in (1) is loaded into a fixed-bed reactor, and naphtha (containing 1% by weight of olefins, 56% by weight of alkanes, 32% by weight of cycloalkanes, 11% by weight of aromatics, and 0.5% by weight of basic nitrogen μg/g) and water were injected into the fixed bed reactor after being preheated at 250°C. Among them, the weight hourly space velocity of naphtha injection is 36.5hr ^-1 , and the water/oil feed weight ratio 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. 21 grams of pseudo-boehmite (catalyst Nanjing branch, containing 15 grams of dry basis), 32 grams of kaolin (catalyst Qilu branch, containing 25 grams of dry basis) and 90 grams of deionized water were mixed under stirring, and 4.0 grams of Concentrated nitric acid (chemically pure, produced by Beijing Chemical Plant) was stirred and acidified for 1 hour, then the temperature was raised to 60° C. for 1 hour, and the pH value was 2.8. When the temperature drops below 40°C, add 50 grams of ZSM-57 molecular sieve (Si/Al molar ratio = 80:1), 5 grams of SSZ-13 molecular sieve (Si/Al molar ratio = 40:1) and 5 grams of calcium Nepheline (Kailong Mining Co., Ltd., Si/Al molar ratio = 3:1) suspension (solid content: 35% by weight), mixed and stirred for 1 hour to obtain a catalyst mixture.

The catalyst mixture is spray-dried using a ^{NiroBowenNozzleTowerTM} type spray dryer, the spray-drying pressure is 8.5MPa to 9.5MPa, the inlet temperature is below 500°C, and the outlet temperature is about 150°C. The microspheres obtained by spray drying were first dried at 150°C for 1 hour, and then calcined at 480°C for 1 hour to obtain the catalyst.

The catalyst composition is calculated according to the feed: the content of ZSM-57 zeolite, SSZ-13 molecular sieve and cancryptite is 50 wt%, 5 wt% and 5 wt%, and the content of matrix (alumina+kaolin) is 40 wt%.

(2) Propylene production. Naphtha (containing 1% by weight of olefins, 56% by weight of alkanes, 32% by weight of naphthenes, 11% by weight of aromatics, 0.5 μg/g of basic nitrogen) and water are preheated at 250°C and injected into the fluidized bed in the reactor. The catalyst prepared in (1) was fed into the fluidized bed reactor in a fluidized state, wherein the weight hourly space velocity of naphtha injection was 4.6 hr ^-1 , and the water/oil feed weight ratio was 1.61. The reaction temperature is 590° C. and the pressure is 0.1 MPa. 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

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.

Prepare the catalyst, prepare the catalyst according to the method of Example 6, the difference is that the first molecular sieve is fed separately from the second molecular sieve and the third molecular sieve, as follows:

(1) Preparation of catalyst. 21 grams of pseudo-boehmite (catalyst Nanjing branch, containing 15 grams on a dry basis), 50 grams of the first molecular sieve (FU-9 zeolite (silicon-aluminum atomic molar ratio is 50) and ZSM-57 zeolite (silicon-aluminum atomic molar ratio) ratio is 30), the weight ratio of the two is 5:1), 32 grams of kaolin (catalyst Qilu branch, containing 25 grams on a dry basis) and 183 grams of deionized water are mixed under stirring, and 8.1 grams of concentrated nitric acid (chemically pure , produced by Beijing Chemical Plant) was stirred and acidified for 1 hour, then heated to 60° C. for 1 hour, and the pH value was 2.8. When the temperature drops below 40°C, add 5 grams of SSZ-13 molecular sieve (Si/Al molar ratio = 40:1) and 5 grams of cancryptite (Kailong Mining Co., Ltd., Si/Al molar ratio = 3:1). ) suspension (solid content is 35% by weight), mixed and then stirred for 1 hour to obtain a catalyst mixture.

The catalyst mixture is spray-dried using a ^{NiroBowenNozzleTowerTM} type spray dryer, the spray-drying pressure is 8.5MPa to 9.5MPa, the inlet temperature is below 500°C, and the outlet temperature is about 150°C. The microspheres obtained by spray drying were first dried at 150°C for 1 hour, and then calcined at 480°C for 1 hour to obtain the catalyst.

The catalyst composition is calculated according to the feed: the content of the first molecular sieve, SSZ-13 molecular sieve and canignite is 50% by weight, and the content of 5% by weight and 5% by weight matrix (alumina+kaolin) is 40% by weight.

(2) Propylene production. Naphtha (containing 1% by weight of olefins, 56% by weight of alkanes, 32% by weight of naphthenes, 11% by weight of aromatics, 0.5 μg/g of basic nitrogen) and water are preheated at 250°C and injected into the fluidized bed in the reactor. The catalyst prepared in (1) was fed into the fluidized bed reactor in a fluidized state, wherein the weight hourly space velocity of naphtha injection was 4.6 hr ^-1 , and the water/oil feed weight ratio was 1.61. The reaction temperature is 590° C. and the pressure is 0.1 MPa. The reaction results are shown in Table 1.

Comparative example 1

According to the method of Example 1, the difference is that the ZSM-35 zeolite and the SAPO-34 molecular sieve are 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 and the SAPO-34 molecular sieve are replaced by the same amount of ZSM-35 zeolite, that is, all the molecular sieves are the first molecular sieves.

Comparative example 3

According to the method of Example 1, the difference is that the ZSM-35 zeolite and the Beta zeolite are replaced by the same amount of SAPO-34 molecular sieves, that is, all the molecular sieves are the third molecular sieves.

As can be seen from the data results in Table 1, the catalyst provided by the present invention contains the first molecular sieve, the second molecular sieve and the third molecular sieve, and can obtain high ethylene and propylene yields in carrying out catalytic cracking of naphtha to produce propylene, and Wherein the ratio of propylene/ethylene is greater than 2, which can realize more propylene production.

Table 1

Claims (13)

1. naphtha catalytic cracking produces the catalyst of propylene, taking the gross weight of this catalyst as benchmark,The matrix of the molecular sieve that this catalyst contains 50-95 % by weight and 5-50 % by weight; Described molecular sieve containsThe first molecular sieve, the second molecular sieve and type three-molecular screen alternating, described the first molecular sieve is for having ten-ring two dimensionThe molecular sieve of ellipse duct structure, described the second molecular sieve is the molecule with twelve-ring pore passage structureSieve, described type three-molecular screen alternating is the small pore molecular sieve of maximum duct opening diameter below 0.45nm.

2. catalyst according to claim 1, wherein,

The molecular sieve that described the first molecular sieve is FER structure and/or the molecular sieve of MFS structure, preferably instituteState the mixture of the molecular sieve of molecular sieve that the first molecular sieve is described FER structure and MFS structure, itsIn, the weight ratio of the molecular sieve of the molecular sieve of FER structure and MFS structure is 0.1-10:1, is preferably1-5:1; The molecular sieve of described FER structure be ZSM-35 zeolite, Ferrierite zeolite, FU-9 zeolite,At least one in ISI-6 zeolite, NU-23 zeolite and Sr-D zeolite, be preferably ZSM-35 zeolite,One in Ferrierite zeolite and FU-9 zeolite; The molecular sieve of MFS structure be ZSM-57 zeolite andAt least one in COK-5 zeolite; More preferably, the molecular sieve of described FER structure is that ZSM-35 boilsThe mixture of stone and Ferrierite zeolite; The molecular sieve of described MFS structure be ZSM-57 zeolite andThe mixture of COK-5 zeolite;

The duct opening diameter of described the second molecular sieve is 0.6-0.75 nanometer, be preferably be selected from there is AET,AFR、AFS、AFI、BEA、BOG、CFI、CON、GME、IFR、ISV、LTL、MEI、At least one in the molecular sieve of MOR, OFF and SAO structure;

Described type three-molecular screen alternating be selected from there is ATT, ATN, CHA, ITE, STI and WEN structureAt least one in molecular sieve.

3. catalyst according to claim 1, wherein, described the first molecular sieve, described secondThe weight ratio of molecular sieve and described type three-molecular screen alternating is 0.1-15:0.1-5:1.

4. catalyst according to claim 1, wherein, taking the gross weight of this catalyst as benchmark,The matrix of the molecular sieve that this catalyst contains 60-95 % by weight and 5-40 % by weight.

5. catalyst according to claim 1, wherein, described matrix is selected from aluminium oxide, oxidationAt least one in silicon, amorphous aluminum silicide, zirconia, titanium oxide, boron oxide and alkaline earth oxide.

6. prepare the method that naphtha catalytic cracking produces the catalyst of propylene, the method comprises:

(1) substrate source, water and optional acid solution are mixed, form slurries;

(2), by molecular sieve or contain molecular sieve and the suspension of water mixes with described slurries, obtainCatalyst mixture carries out moulding, the dry and roasting of the line option of going forward side by side;

Described molecular sieve contains the first molecular sieve, the second molecular sieve and type three-molecular screen alternating, described the first moleculeSieve is for having the molecular sieve of ten-ring two-dimensional elliptic type pore passage structure, and described the second molecular sieve is for having 12The molecular sieve of membered ring channel structure, described type three-molecular screen alternating be maximum duct opening diameter 0.45nm withUnder small pore molecular sieve.

7. prepare the method that naphtha catalytic cracking produces the catalyst of propylene, the method comprises:

(1) substrate source, water, the first molecular sieve and optional acid solution are mixed, form slurries;

(2) by the second molecular sieve and type three-molecular screen alternating or contain the second molecular sieve and type three-molecular screen alternating andThe suspension of water mixes with described slurries, and the catalyst mixture obtaining carries out moulding, the line option of going forward side by sideBe dried and roasting;

Described the first molecular sieve is the molecular sieve with ten-ring two-dimensional elliptic type pore passage structure, described secondMolecular sieve is the molecular sieve with twelve-ring pore passage structure, and described type three-molecular screen alternating is maximum duct openingThe small pore molecular sieve of diameter below 0.45nm.

8. according to the method described in claim 6 or 7, wherein, described the first molecular sieve is FER knotThe molecular sieve of the molecular sieve of structure and/or MFS structure, preferably described the first molecular sieve is described FER structureMolecular sieve and the mixture of the molecular sieve of MFS structure, wherein, the molecular sieve of FER structure and MFSThe weight ratio of the molecular sieve of structure is 0.1-10:1, is preferably 1-5:1; The molecular sieve of described FER structureFor ZSM-35 zeolite, Ferrierite zeolite, FU-9 zeolite, ISI-6 zeolite, NU-23 zeolite and Sr-DAt least one in zeolite, is preferably in ZSM-35 zeolite, Ferrierite zeolite and FU-9 zeoliteA kind of; The molecular sieve of MFS structure is at least one in ZSM-57 zeolite and COK-5 zeolite; MorePreferably, the molecular sieve of described FER structure is the mixture of ZSM-35 zeolite and Ferrierite zeolite;The molecular sieve of described MFS structure is the mixture of ZSM-57 zeolite and COK-5 zeolite;

The duct opening diameter of described the second molecular sieve is 0.6-0.75 nanometer, be preferably be selected from there is AET,AFR、AFS、AFI、BEA、BOG、CFI、CON、GME、IFR、ISV、LTL、MEI、At least one in the molecular sieve of MOR, OFF and SAO structure;

Described type three-molecular screen alternating be selected from there is ATT, ATN, CHA, ITE, STI and WEN structureAt least one in molecular sieve.

9. according to the method described in claim 6 or 7, wherein, described the first molecular sieve, describedThe weight ratio of two molecular sieves and described type three-molecular screen alternating is 0.1-15:0.1-5:1.

10. according to the method described in claim 6 or 7, wherein, described substrate source is in step (2)The condition of described roasting under can change the material of matrix into, described matrix be aluminium oxide, silica,At least one in amorphous aluminum silicide, zirconia, titanium oxide, boron oxide and alkaline earth oxide; InstituteIn the catalyst that the addition of stating substrate source and molecular sieve makes to obtain, taking the gross weight of this catalyst as baseStandard, the content of matrix is 5-50 % by weight, the content of molecular sieve is 50-95 % by weight.

11. catalyst that made by the method described in any one in claim 6-10.

12. 1 kinds of naphtha catalytic crackings produce the method for propylene, and the method comprises: split in naphtha catalysisSeparate under reaction condition, naphtha contacted with catalyst with water, obtain propylene product, it is characterized in that,Described catalyst comprises the catalyst described in any one in claim 1-5 and 11.

13. methods according to claim 12, wherein, described naphtha catalytic cracking reaction barPart comprises: temperature is 520-590 DEG C, and pressure is 0.1-0.2MPa, and water/oily feed weight ratio is 0.3-2,Naphtha feed weight (hourly) space velocity (WHSV) is 2-40h^-1。