CN103785454B - A kind of catalytic cracking catalyst and preparation method thereof - Google Patents

Abstract

A catalytic cracking catalyst and a preparation method thereof, the catalyst is characterized in that it comprises the following components, by weight percentage: (a) 15% to 65% of natural minerals; (b) 10% to 30% of oxides; and (c) 25%~75% phosphorus-containing silicon-rich β molecular sieve, in which the phosphorus content is 1~10% by weight based on P ₂ O ₅ , and its ²⁷ Al? MAS? In NMR, the ratio of the peak area of the resonance signal with a chemical shift of 40±3ppm to the peak area of the resonance signal with a chemical shift of 54±3ppm is greater than or equal to 1, and the ratio of the peak area of the resonance signal with a chemical shift of 0±3ppm to -12±3ppm and the percentage of the total peak area is less than or equal to 10%. The preparation method comprises preparing the phosphorus-containing silicon-rich β molecular sieve, beating the silicon-rich molecular sieve with the natural minerals, oxides and/or oxide precursors, and spray drying. The catalyst is used for catalytic cracking of naphtha and has higher yield of low-carbon olefins.

Description

Catalytic cracking catalyst and preparation method thereof

technical field

The invention relates to a fluidized catalyst for catalytic cracking to produce olefins, in particular to a fluidized catalyst modified with phosphorus-containing beta molecular sieve for producing ethylene, propylene and butene through catalytic cracking process with naphtha as raw material.

Background technique

Ethylene, propylene and butene are very important chemical raw materials. At present, naphtha steam cracking is mainly used in the world to produce these low-carbon olefins. This method has many shortcomings such as high reaction temperature and high energy consumption. In order to overcome these problems, a lot of research on catalytic cracking technology has been carried out at home and abroad. It is expected that through the introduction of catalysis, on the one hand, the reaction temperature can be appropriately reduced, coking and energy consumption can be reduced, and on the other hand, the yield of low-carbon olefins can also be increased, making it more flexible. adjust product distribution. One catalyst is a molecular sieve-containing catalyst.

The Institute of Materials and Chemistry of the Japan Industrial Technology Institute and the Japan Chemical Industry Association jointly developed La/ZSM-5 (10%La/ZSM-5) with a mass fraction of La loaded at 10% as a catalyst. The latest ACO ^TM (Advanced Catalytic Olefins) process developed by KBR Corporation of the United States and SK Energy Corporation of Korea uses a microsphere ZSM-5 molecular sieve catalyst as its proprietary catalyst.

CN102371171A discloses a fluidized bed catalyst for catalytic cracking to produce olefins. The composition of the catalyst includes, by weight percentage: 1) 0.5-15.0% is selected from at least one of phosphorus, rare earth or alkaline earth metal oxides; 4) 85.0-95.0% is selected from ZSM-5-containing zeolite synthesized in situ Microspheres composed of molecular sieves with a particle size of 10-200 μm. The catalyst can remarkably increase the conversion rate of naphtha and the yield of ethylene and propylene when the catalyst is used for catalytic decomposition of naphtha.

CN102371172A discloses a fluidized bed catalyst for catalytic cracking to produce olefins. The composition of the catalyst includes, by weight percentage: 1) 15.0-60.0% kaolin; 2) 10.0-30.0% at least one selected from silicon oxide or aluminum oxide; 3) 0.5-15.0% selected from phosphorus, rare earth or at least one of alkaline earth metal oxides; 4) 25.0-70.0% is selected from ZSM-5 zeolite synthesized by directing agent method with a grain size of 200-1000nm. When the catalyst is used in catalytic cracking of naphtha, it can significantly increase the conversion rate of naphtha and the yield of ethylene and propylene.

The catalyst containing ZSM-5 molecular sieve can increase the yield of ethylene and propylene. Another commonly used molecular sieve is β molecular sieve, which can improve the yield of butene. CN1179994A A method for modifying zeolite beta, which basically consists of the following steps: ( ₁ ) Na2O content of Na2O on the zeolite is less than 0.1% by weight by exchanging Naβ zeolite with ammonium ion; Use acid treatment to remove part of the skeleton aluminum, so that the silicon-aluminum ratio is greater than 50; (3) mix the above-mentioned dealuminated β zeolite with phosphoric acid or phosphate, and then dry it, so that the amount of P ₂ O ₅ on the obtained zeolite is 2-5% by weight; (4) The product obtained in step (3) is hydrothermally calcined at 450-650° C. for 0.5-4 hours under a steam atmosphere. However, the catalyst prepared from zeolite obtained by this method still has the problem of low yield of light olefins (ethylene, propylene and butene) when it is used for cracking naphtha to prepare light olefins.

Contents of the invention

One of the objectives of the present invention is to provide a fluidized bed catalyst for catalytic cracking to olefins, which has excellent hydrothermal stability and better product selectivity.

The second object of the present invention is to provide a preparation method of the catalyst.

A catalyst for producing olefins by catalytic cracking, comprising the following components by weight percentage: (a) 15%~65% of natural minerals; (b) 10%~30% of oxides; and (c) 25%~ 75% phosphorus-containing silicon-rich β molecular sieve; the phosphorus-containing silicon-rich β molecular sieve has a phosphorus content of 1 to 10% by weight in terms of P ₂ O ₅ , and in the ²⁷ AlMASNMR of the molecular sieve, the chemical shift is (40 ± 3) The ratio of the peak area of the resonance signal in ppm to the peak area of the resonance signal with a chemical shift of (54±3)ppm is greater than or equal to 1, and the peak area of the resonance signal with a chemical shift of (0±3)ppm and a chemical shift of (-12±3)ppm The percentage of the sum to the total peak area is less than or equal to 10%.

The silicon-aluminum molar ratio (Si/Al) of the phosphorus-containing silicon-rich β molecular sieve (also known as phosphorus-containing silicon-rich β molecular sieve) is 12-100. The preparation method comprises the step of treating the original powder of β molecular sieve in the temperature range of 200°C to 800°C through at least two non-overlapping temperature ranges from low to high to remove the template agent, dealuminate, and then carry out phosphorus modification. .

The phosphorus-containing silicon-rich β molecular sieve provided by the present invention has a phosphorus content of 1-10% by weight based on P ₂ O ₅ , and is characterized in that, in the ²⁷ AlMASNMR of the molecular sieve, the chemical shift is 40 ± 3ppm. The ratio of the peak area of the resonance signal with a shift of 54ppm±3ppm is greater than or equal to 1, and the percentage of the sum of the peak areas of the resonance signal with a chemical shift of 0±3ppm and a chemical shift of -12ppm±3ppm to the total peak area is less than or equal to 10%.

The phosphorus-containing silicon-rich β molecular sieve provided by the present invention has a phosphorus content of 1-10% by weight, preferably 1-8% by weight, based on P ₂ O ₅ .

In the phosphorus-containing silicon-rich β molecular sieve provided by the present invention, the ratio of the peak area of the resonance signal with a chemical shift of 40 ± 3 ppm to the peak area of the resonance signal with a chemical shift of 54 ppm ± 3 ppm in ²⁷ AlMASNMR is greater than or equal to 1, preferably greater than or equal to 2, for example, 2 to a value in 5; the chemical shift is 0 ± 3ppm and the chemical shift is -12ppm ± 3ppm The percentage of the resonance signal peak area of the total peak area is preferably less than 10%, preferably less than or equal to 6%, for example 1 A value of -6%.

The above-mentioned phosphorous-containing silicon-rich β molecular sieve provided by the present invention is prepared by treating the original powder of β molecular sieve in a temperature range from 200°C to 800°C through at least two non-overlapping temperature ranges from low to high to remove Carry out the step of phosphorus modification after template agent, preferred step comprises:

(1) Exchanging the sodium-type β molecular sieve with ammonium so that the Na ₂ O content on the molecular sieve is less than 0.2% by weight;

(2) After drying the molecular sieve obtained in step (1), treat it at a temperature range of 200-400°C for at least 0.5 hours, and then heat it up to a temperature range of 500-800°C within at most 2 hours and treat it for at least 0.5 hours to remove the template agent;

(3) Treating the product obtained in step (2) with a dealumination agent solution with a weight concentration of 1-20% at a temperature of 25-100°C;

(4) Introducing phosphorus-containing compounds to modify molecular sieves;

(5) Baking at 400-800°C for at least 0.5 hours.

Compared with the modification process of the existing β molecular sieve, the main difference between the preparation method provided by the present invention is that the modification method of the present invention is to process the original powder of β molecular sieve (sodium type β molecular sieve containing an organic template) from low to high After the non-overlapping temperature ranges are processed to remove the templating agent by roasting, the beta zeolite is chemically dealuminated and then modified with phosphorus.

In the preparation method provided by the present invention, in the step (1), the sodium β molecular sieve is a sodium β molecular sieve obtained by conventional crystallization (eg USP3,308,069, CNZL00107486.5). The sodium content in the so-called sodium-type β molecular sieve is 4-6% by weight in terms of sodium oxide. The process of ammonium exchange to reduce sodium content is preferably exchanged at room temperature to 100°C for at least 0.5 hours according to the weight ratio of molecular sieve: ammonium salt: H ₂ O = 1: (0.1-1): (5-10) , preferably after 0.5-2 hours of filtration, such an ammonium exchange process can be repeated 1-4 times, so that the Na ₂ O content on the molecular sieve is less than 0.2% by weight. Said ammonium salt can be common inorganic ammonium salt, can be selected from one of ammonium chloride, ammonium sulfate or ammonium nitrate or their mixture.

In the preparation method of the phosphorus-containing silicon-rich β molecular sieve provided by the present invention, the step (2) is a process of treating the molecular sieve obtained in the step (1) and removing the template agent in different temperature ranges from low temperature to high temperature. Said treatment is carried out in the interval of 200°C to 800°C, through at least two non-overlapping temperature intervals from low to high, the said low temperature interval is 200-400°C, preferably 300-350°C, The high temperature range is 500-800°C, preferably 500-600°C. For example, the said treatment is to roast the molecular sieve with Na ₂ O content less than 0.2% by weight after the ammonium exchange in step (1) after drying at 200-400°C, preferably 300-350°C for at least 0.5 hours, preferably 1-350°C. 12 hours, and then heating up to a temperature range of 500-800° C. for at least 0.5 hours, preferably 1 to 8 hours, within at most 2 hours, preferably within 1 hour. In step (2), it is also possible to treat at 120-180°C for at least 1 hour before the above-mentioned two temperature ranges to fully remove moisture.

In the preparation method of phosphorus-containing silicon-rich β molecular sieve provided by the present invention, said step (3) is a process of treating the product obtained in step (2) with a dealumination agent solution at a temperature of 25-100°C. In step (2), the amount of dealumination agent is added empirically according to the degree of dealumination required, usually the treatment time is 1-6 hours for zeolite beta, and the preferred weight concentration of dealumination agent solution is 1-20%. Said dealuminizing agent is selected from organic acids (including ethylenediaminetetraacetic acid, oxalic acid, citric acid, sulfosalicylic acid), inorganic acids (including fluosilicic acid, hydrochloric acid, sulfuric acid, nitric acid), organic and inorganic salts ( Including ammonium oxalate, ammonium fluoride, ammonium fluorosilicate, ammonium fluoroborate), the chemical dealumination process can be carried out once or several times.

In the preparation method of phosphorus-containing silicon-rich β molecular sieve provided by the present invention, in step (4), a phosphorus-containing compound is introduced to modify the product of step (3). Said phosphorus-containing compound is selected from phosphoric acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate or ammonium phosphate or a mixture thereof. The modification process mentioned in step (4) can be carried out by impregnation. Wherein said impregnating can be that the dealuminated molecular sieve and the calculated amount of phosphorus-containing compound aqueous solution are beaten and dried uniformly at room temperature to 95°C.

In the preparation method of phosphorus-containing silicon-rich β molecular sieve provided by the present invention, step (5) is to roast the phosphorus-containing β molecular sieve product obtained in step (4) at 400-800°C, preferably 500-600°C, for at least 0.5 hours, Preferably 0.5-8 hours. Wherein said roasting process can adopt dry roasting or wet roasting, and said wet roasting is preferably carried out under 1-100%, more preferably 100% water vapor atmosphere.

The natural minerals mentioned therein are for example clay, including one of kaolin, halloysite, montmorillonite, diatomaceous earth, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite and retortite, etc. or a mixture of several. Based on the total amount of catalyst, the content of natural minerals is 15%-65%, preferably 20%-55%.

The oxide is selected from one or a mixture of two or more of silicon oxide, aluminum oxide, zirconia, titanium oxide, amorphous silicon aluminum and aluminum phosphate materials, and the oxide is preferably from its corresponding sol state Substances, such as one or more of silica sol, aluminum sol, peptized pseudo-boehmite, silica-alumina sol, and phosphorus-containing aluminum sol. Based on the total amount of the catalyst, the content of the oxide is 10% to 30%, preferably 12% to 28%.

The preparation method of the catalyst provided by the invention comprises beating natural minerals, oxides and/or precursors of oxides together with phosphorus-containing silicon-rich β molecular sieves, and then spray-drying and calcining the slurry, the oxide precursors For example, the sol of the oxide, the oxide sol can be used as a binder in the catalyst preparation process so that the final catalyst has suitable mechanical strength and anti-wear performance. The amount of each component is such that the final catalyst contains, based on the total weight of the catalyst, 15% to 65% of natural minerals, 10% to 30% of oxides and 25% to 75% of phosphorus-containing silicon-rich β molecular sieves, Preferably, the amount of natural minerals, oxides and/or oxide precursors and phosphorus-containing silicon-rich β molecular sieves makes the composition of the catalyst: the content of natural minerals is 20% by weight to 55% by weight; The content of the phosphorus-silicon-rich molecular sieve is 30%-70% by weight, and the content of the oxide is 12-28% by weight. The precursor of the oxide is, for example, one or more of silica sol, alumina sol, peptized pseudo-boehmite, silica-alumina sol, and phosphorus-containing aluminum sol.

The present invention also provides a method for producing olefins by catalytic cracking of naphtha, which includes the step of contacting and reacting naphtha with a catalytic cracking catalyst in a fluidized bed reactor or a riser reactor, wherein the catalytic cracking catalyst The fluidized bed catalyst for producing olefins by catalytic cracking provided by the present invention. The olefins are ethylene, propylene and butene, the naphtha is straight run naphtha, its boiling range is usually 40~180°C, the conditions of the contact reaction include: the reaction temperature is 600-750°C, the contact reaction The reaction time is 0.1-10 seconds, and the weight hourly space velocity is 0.1-10 h ^-1 . Water vapor is preferably introduced during the reaction process. The ratio of water vapor to naphtha is: 0.1-10:1, for example, 0.2-5:1.

The invention provides a fluidized bed catalyst for catalytic cracking of naphtha to produce olefins, which contains a new type of β molecular sieve, which has more excellent hydrothermal stability and more Good low carbon olefin selectivity. The method for producing olefins by catalytic cracking of naphtha provided by the invention has higher yields of ethylene, propylene and butene.

detailed description

The following examples will further illustrate the present invention, but do not limit the present invention thereby.

In each example and comparative example, the content of Na ₂ O, Fe ₂ O ₃ , Co ₂ O ₃ , NiO, CuO, Mn ₂ O ₃ , ZnO, SnO ₂ , Al ₂ O ₃ , SiO ₂ in each sample β molecular sieve The content is determined by X-ray fluorescence method (see "Petrochemical Analysis Method (RIPP Experimental Method)", edited by Yang Cuiding, etc., Science Press, published in 1990). ²⁷ AlMASNMR was tested by Bruker Advance III 500MHz nuclear magnetic resonance instrument, and the peak area of each peak was calculated by the integration method after the resonant peak spectrum was divided into peaks and fitted. The properties of the raw materials used are as follows: Kaolin (Suzhou Kaolin Company, solid content 75%), halloysite (Sanhe Bai Mine, Zunyi, Guizhou, solid content 75%), retortite (Hubei Zhongxiang retort mine, solid content 75%) %), montmorillonite (Hongshi Bentonite Company, Chaoyang City, Liaoning Province, solid content 75%), pseudoboehmite (Shandong Aluminum Company, solid content 65%), aluminum sol (Qilu Catalyst Branch, alumina content 22.5%), silica sol (Qingdao Ocean Chemical Co., Ltd., silicon oxide content 25.5%, pH value 3.0), phosphorus-containing aluminum sol (P content 16%, Al content 8%, pH value 2.0). The above contents are all percentages by weight.

Example 1

Naβ molecular sieve (produced by Qilu Catalyst Factory, SiO ₂ /Al ₂ O ₃ =25 molar ratio, sodium oxide content 4.5% by weight, the same below) was exchanged and washed with NH ₄ Cl solution until the Na ₂ O content was lower than 0.2% by weight, filtered Obtain filter cake; dry, the obtained sample is roasted at 350°C for 2 hours, then heated to 550°C for 40 minutes, and roasted at 550°C for 4 hours to remove the template agent; take 100Kg (dry basis) of the above molecular sieve and add water to prepare a solid content of 10 Weight % molecular sieve slurry, add 20 kg of oxalic acid during stirring, heat up to 80°C and stir for 1 hour, filter and wash until the filtrate is neutral; add 9 kg of H ₃ PO ₄ (concentration 85% by weight, the same below) to dissolve in 50 kg of water, and The molecular sieve filter cake was mixed, impregnated and dried; the obtained sample was roasted at 550°C for 2 hours, that is, the molecular sieve provided by the present invention, denoted as F-1. The physical property data and ²⁷ AlMASNMR peak area ratio of the samples are listed in Table 1.

Mix and beat natural minerals, phosphorus-containing silicon-rich β molecular sieve F-1, binder sol and water, spray-dry the obtained slurry into particles with a diameter of 40-150 microns and roast them at a temperature of 500°C. The time is 1 hour, and the catalyst C1 provided by the present invention is obtained. The physical property data, dosage and ²⁷ AlMASNMR peak area ratio of the phosphorus-containing silicon-rich β molecular sieve used are listed in Table 1. The types and amounts of natural minerals, and the types and amounts of binders are listed in Table 2 and Table 3, respectively.

Example 2

Naβ molecular sieve (produced by Qilu Catalyst Factory, SiO ₂ /Al ₂ O ₃ =25) was exchanged and washed with NH ₄ Cl solution until the Na ₂ O content was less than 0.2% by weight, and filtered to obtain a filter cake; dried, and the obtained sample was roasted at 350°C Treat for 2 hours, then heat up to 550°C for 40 minutes and roast for 4 hours to remove the template agent; take 100 kg (dry basis) of the above-mentioned molecular sieve and add water to prepare a molecular sieve slurry with a solid content of 10% by weight, and add fluosilicic acid (concentration 30 %) 10 kg, heated to 60°C and stirred for 1 hour, filtered and washed with water until the filtrate was neutral; added 10 kg (NH ₃ ) ₂ HPO ₄ (concentration 85% by weight) dissolved in 90 kg of water, mixed with the above molecular sieve filter cake, impregnated and dried; The obtained sample was calcined at 550° C. for 2 hours, that is, the molecular sieve provided by the present invention, denoted as F-2. The physical property data and ²⁷ AlMASNMR peak area ratio of the samples are listed in Table 1.

Mix and beat natural minerals, phosphorus-containing silicon-rich β molecular sieve F-2, binder sol and water, spray-dry the obtained slurry into particles with a diameter of 40-150 microns and roast them at a temperature of 500°C. The time is 1.5 hours, and the catalyst C2 provided by the present invention is obtained. The physical property data, dosage and ²⁷ AlMASNMR peak area ratio of the phosphorus-containing silicon-rich β molecular sieve used are listed in Table 1. The types and amounts of natural minerals, and the types and amounts of binders are listed in Table 2 and Table 3, respectively.

Example 3

Naβ molecular sieve (produced by Qilu Catalyst Factory, SiO ₂ /Al ₂ O ₃ =25) was exchanged and washed with NH ₄ Cl solution until the Na ₂ O content was less than 0.2% by weight, and filtered to obtain a filter cake; dried, and the obtained sample was roasted at 350°C Treat for 2 hours, then heat up to 550°C for 40 minutes and roast for 4 hours to remove the template agent; take 100 kg (dry basis) of the above molecular sieve and add water to prepare a molecular sieve slurry with a solid content of 10% by weight, and add 2 kg of ammonium fluorosilicate during stirring , heated to 60°C and stirred for 1 hour, filtered and washed with water until the filtrate was neutral; added 14 kg of H ₃ PO ₄ (concentration 85% by weight), dissolved in 90 kg of water, mixed with the above molecular sieve filter cake, impregnated and dried; the obtained sample was roasted at 550°C 2 hours, namely the molecular sieve F-3 provided by the present invention. The physical property data and ²⁷ AlMASNMR peak area ratio of the samples are listed in Table 1.

Mix and beat natural minerals, phosphorus-rich silicon-rich β molecular sieve F-3, binder sol and water, spray-dry the obtained slurry into particles with a diameter of 40-150 microns and roast them at a temperature of 500°C. The time is 1 hour, and the catalyst C3 provided by the present invention is obtained. The physical property data, dosage and ²⁷ AlMASNMR peak area ratio of the phosphorus-containing silicon-rich β molecular sieve used are listed in Table 1. The types and amounts of natural minerals, and the types and amounts of binders are listed in Table 2 and Table 3, respectively.

Example 4

Naβ molecular sieve (produced by Qilu Catalyst Factory, SiO ₂ /Al ₂ O ₃ =25) was exchanged and washed with NH ₄ Cl solution until the Na ₂ O content was less than 0.2% by weight, and filtered to obtain a filter cake; dried, and the obtained sample was roasted at 350°C Treat for 2 hours, then heat up to 550°C for 40 minutes and roast for 4 hours to remove the template agent; take 100 kg (dry basis) of the above-mentioned molecular sieve and add water to prepare a molecular sieve slurry with a solid content of 10% by weight, add 30 kg of ammonium oxalate during stirring, and heat up Stir at 60°C for 1 hour, filter and wash until the filtrate is neutral; add 6 kg of NH ₃ H ₂ PO ₄ to dissolve in 90 kg of water, mix with the above-mentioned molecular sieve filter cake, immerse and dry; the obtained sample is roasted at 550°C for 2 hours, which is the invention The provided molecular sieve is denoted as F-4. The physical property data and ²⁷ AlMASNMR peak area ratio of the samples are listed in Table 1.

Mix and beat natural minerals, phosphorus-rich silicon-rich β molecular sieve F-4, binder sol and water, spray-dry the obtained slurry into particles with a diameter of 40-150 microns and roast them at a temperature of 500°C. The time is 2 hours, and the catalyst C4 provided by the present invention is obtained. For the phosphorus-containing silicon-rich β molecular sieve used, the pseudo-boehmite is peptized with 31% by weight of hydrochloric acid, and the molar ratio of the hydrochloric acid to the pseudo-boehmite expressed as alumina is 0.20. The physical property data and dosage and ²⁷ AlMASNMR peak area ratios are listed in Table 1. The types and amounts of natural minerals, and the types and amounts of binders are listed in Table 2 and Table 3, respectively.

Comparative example 1

Prepare phosphorus-containing β molecular sieve according to the method of CN1179994A: add 100g (dry basis) Naβ molecular sieve into 2000ml of 4% by weight ammonium sulfate solution, stir and exchange at 90°C for 1h, filter and exchange again in the same way, filter, filter cake and React 500ml of 3% by weight fluorosilicate H ₂ SiF ₆ solution at 60°C for 2 hours, then filter, and mix the filter cake with 14g of phosphoric acid with a concentration of 85% by weight and 3g of pseudo-boehmite (Al2O3 content of 67% by weight) Mix the formed mixture evenly, dry it in an oven at 110°C, put it into a tubular muffle furnace and roast it with steam at 550°C for 2h, the weight space velocity of the steam is 2h ^-1 , and the molecular sieve of Comparative Example 1 is obtained Recorded as DF-1.

Mix natural minerals, phosphorus-modified β-molecular sieve DF-2, binder sol, and water for beating, spray-dry the obtained slurry into particles with a diameter of 40-150 microns and roast (500°C for 1.5 hours), Catalyst D1 is obtained. The physical property data, dosage and ²⁷ AlMASNMR peak area ratio of the phosphorus-modified β molecular sieve used are listed in Table 1. The types and amounts of natural minerals, and the types and amounts of binders are listed in Table 2 and Table 3, respectively. The spray drying temperature, calcination temperature and time are listed in Table 4.

Comparative example 2

The Naβ molecular sieve was treated according to the method of Example 1, but the aluminum extraction treatment was not carried out before the phosphorus modification, and the molecular sieve of Comparative Example 2 was obtained, which was recorded as DF-2.

Mix and beat natural minerals, phosphorus-modified β molecular sieve DF-2, binder sol and water, spray-dry the obtained slurry into particles with a diameter of 40-150 microns and roast (500°C for 1 hour), Catalyst D2 is obtained. The physical property data, dosage and ²⁷ AlMASNMR peak area ratio of the phosphorus-modified β molecular sieve used are listed in Table 1. The types and amounts of natural minerals, and the types and amounts of binders are listed in Table 2 and Table 3, respectively. The spray drying temperature, calcination temperature and time are listed in Table 4. The composition of Catalyst D2 is listed in Table 5.

Comparative example 3

Exchange and wash the β molecular sieve with NH ₄ Cl solution until the Na ₂ O content is less than 0.2% by weight, filter to obtain a filter cake; dry, and roast at 550°C for 4 hours to remove the template agent; take 100g (dry basis) of the above molecular sieve and add water to prepare Molecular sieve slurry with a solid content of 10% by weight, add 20g of oxalic acid during stirring, heat up to 80°C and stir for 1h, filter and wash until the filtrate is neutral; add 9gH ₃ PO ₄ (concentration 85% by weight) to dissolve in 50g of water, and mix with the molecular sieve filter cake Dipping and drying; the obtained sample was calcined at 550° C. for 2 hours, that is, the comparative molecular sieve provided by the present invention, denoted as DF-3.

The physical property data and ²⁷ AlMASNMR peak area ratio of the samples are listed in Table 1.

Table 1

Table 2

Catalyst number Natural Mineral Types Dosage, kg C1 Retort Clay and Kaolin Clay Retort Clay 40, Kaolin Clay 40 C2 halloy stone 53.3 C3 Montaude 26.7 C4 Kaolin 13.3 D1 Retort Clay and Kaolin Clay Retort Clay 40, Kaolin Clay 40 D2 Retort Clay and Kaolin Clay Retort Clay 40, Kaolin Clay 40

table 3

Table 4

Catalyst number Spray drying tail gas temperature/℃ Calcination temperature/℃ Roasting time/h C1 180 500 1 C2 170 500 1.5 C3 180 500 1 C4 175 500 2 D1 180 500 1.5 D2 170 500 1

Example 5

The samples prepared in the above examples and comparative examples were aged at 820°C and 100% water vapor for 17 hours and evaluated on a fluidized bed device. The evaluation conditions were reaction temperature 650°C and weight space velocity of 1.0 ^hours The amount of oil is 1.56g, the weight ratio of water to oil is 4:1, the raw material oil is straight-run naphtha, the initial boiling point is 45.5°C, and the final boiling point is 166.5°C. The specific composition is shown in Table 5. The reaction results are shown in Table 6.

table 5

carbon number n-alkane Isoparaffin Olefin Naphthenic Aromatics 2 0.02 0.00 0.00 0.00 0.00 3 0.21 0.00 0.00 0.00 0.00 4 0.95 0.20 0.02 0.00 0.00 5 2.24 1.16 0.03 0.55 0.00 6 3.89 2.47 0.03 5.28 0.60 7 5.98 3.08 0.04 10.55 1.86 8 7.24 5.36 0.00 10.77 5.36 9 6.57 4.53 0.00 9.80 2.43 10 2.10 3.90 0.00 1.27 0.26 11 0.19 0.88 0.00 0.04 0.01 12 0.01 0.03 0.00 0.00 0.00 total 29.40 21.61 00.12 38.24 10.52

In table 5, it is the weight percent composition

Table 6

The productivity mentioned therein is calculated based on the raw material feed.

Product yield = product output (weight) / naphtha feed amount (weight) × 100%

The conversion rate is the sum of the yields of hydrocarbon products with carbon numbers less than or equal to 4 in the molecule, the yields of hydrogen and coke.

It can be seen from the data in Table 6 that the modified molecular sieve provided by the present invention has better activity stability and low olefin yield. Compared with the comparative example, the catalyst provided by the present invention with phosphorus-containing silicon-rich β molecular sieve as the active component can effectively increase the yield of low-carbon olefins of cracked products while improving the hydrocarbon cracking ability, ethylene, propylene and butene The productive rate of productive rate has improved substantially.

Claims (17)

1. A catalyst for producing olefins by catalytic cracking of naphtha, consisting of the following components in weight percent: (a) 15% to 65% natural minerals; (b) 10% to 30% oxides and; (c) 25% to 75% phosphorus-containing silicon-rich β molecular sieve, the phosphorus content of the phosphorus-containing silicon-rich β molecular sieve is 1 to 10% by weight in terms of P ₂ O ₅ , and in the ²⁷ AlMASNMR of the molecular sieve, the chemical shift The ratio of the peak area of the resonance signal of 40±3ppm to the peak area of the resonance signal of the chemical shift of 54±3ppm is greater than or equal to 1, and the sum of the peak areas of the resonance signal of the chemical shift of 0±3ppm and the chemical shift of -12±3ppm accounts for the total peak area The percentage is less than 10%; The natural minerals include one or more of kaolin, montmorillonite, diatomite, attapulgite, sepiolite, halloysite, hydrotalcite, bentonite and rectorite; the oxide One or more selected from silica, alumina, zirconia, titania and amorphous silica-alumina. 2 . The catalyst according to claim 1 , characterized in that, the phosphorus content in the phosphorus-containing silicon-rich β molecular sieve is 1-8% by weight based on P ₂ O ₅ . 3. The catalyst according to claim 1, characterized in that, said phosphorus-containing silicon-rich β molecular sieve, said ²⁷ AlMASNMR, chemical shift is 40 ± 3ppm resonance signal peak area and chemical shift is 54ppm ± 3ppm resonance The signal peak area ratio is greater than or equal to 2. 4. The catalyst according to claim 1, characterized in that, the phosphorus-containing silicon-rich β molecular sieve, in the said ²⁷ AlMASNMR, the chemical shift is 0 ± 3ppm and the chemical shift is the resonance signal peak of -12ppm ± 3ppm The percentage of the sum of the areas to the total peak area is less than or equal to 6%. 5. The catalyst according to claim 1, characterized in that the silicon-aluminum molar ratio of the phosphorus-containing silicon-rich β molecular sieve is 12-100. 6. The method for preparing the catalyst according to any one of claims 1 to 5, comprising preparing the phosphorus-containing silicon-rich β molecular sieve, combining the phosphorus-containing silicon-rich molecular sieve with the natural minerals, oxides and/or Or the oxide precursor is beaten and spray-dried; wherein the preparation method of the phosphorus-containing silicon-rich β molecular sieve includes the raw powder of the β molecular sieve in the temperature range of 200 ° C to 800 ° C, through at least two non-overlapping temperatures from low to high Interval treatment to remove the templating agent, dealumination, and impregnation for phosphorus modification. 7. according to the described catalyst preparation method of claim 6, it is characterized in that, the preparation process of described phosphorus-containing silicon-rich β molecular sieve is as follows: ( ₁ ) The Na2O content on the molecular sieve is less than 0.2% by weight by exchanging the sodium type β molecular sieve with ammonium; (2) After drying the molecular sieve obtained in step (1), treat it at a temperature range of 200-400°C for at least 0.5 hours, and then heat it up to a temperature range of 500-800°C within at most 2 hours and treat it for at least 0.5 hours to remove the template agent; (3) Treating the product obtained in step (2) with a dealumination agent solution at a temperature of 25-100° C.; (4) Impregnating and introducing phosphorus-containing compounds to modify the molecular sieve; (5) Baking at 400-800°C for at least 0.5 hours. 8. according to the described catalyst preparation method of claim 7, wherein, said ammonium exchange is according to the weight ratio of molecular sieve: ammonium salt: H ₂ O=1: (0.1～1): (5～10) at room temperature to The process of filtering after exchange at 100°C for at least 0.5 hours, this process should be carried out at least once. 9. The method for catalyst preparation according to claim 7, wherein said phosphorus-containing compound is selected from one of phosphoric acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate or ammonium phosphate or a mixture thereof. 10. The catalyst preparation method according to claim 7, characterized in that before step (2), the product of step (1) is treated at 120-180° C. for at least 1 hour. 11. The catalyst preparation method according to claim 7, wherein said dealumination agent is selected from organic acids, inorganic acids, organic salts or inorganic salts, and said step (3) is carried out once or several times. 12. according to the described catalyst preparation method of claim 11, wherein, said organic acid is selected from ethylenediaminetetraacetic acid, oxalic acid, citric acid or sulfosalicylic acid, and said inorganic acid is selected from fluosilicic acid, Hydrochloric acid, sulfuric acid or nitric acid, said organic salt is ammonium oxalate, and said inorganic salt is ammonium fluoride, ammonium fluorosilicate or ammonium fluoroborate. 13. The catalyst preparation method according to claim 7, wherein said dealumination agent has a weight concentration of 1-20%. 14. according to the described catalyst preparation method of claim 7, wherein, said modification of said step (4) adopts impregnation mode to carry out, said impregnation mode is the molecular sieve after dealumination and the phosphorus-containing The compound aqueous solution is beaten evenly at room temperature to 95°C, and then dried. 15. according to the described catalyst preparation method of claim 7, wherein, the said calcination process of step (5) is calcination under steam atmosphere. 16. according to the described catalyst preparation method of claim 7, it is characterized in that, described natural mineral matter is clay, and described oxide precursor is aluminum phosphate, aluminum sol, peptized pseudo-boehmite, silica sol , one or more of silica-alumina sol and phosphorus-containing aluminum sol. 17. A method for catalytic cracking to produce olefins, comprising contacting hydrocarbon oil with a catalyst in a fluidized bed reactor or a riser reactor, characterized in that, the catalyst is any one of claims 1 to 5 The catalyst mentioned above, the hydrocarbon oil is naphtha, the contact temperature is 600-750°C, and the weight hourly space velocity is 0.1-10h ^-1 .