Olefin catalytic cracking catalyst for producing propylene, preparation method and application thereof

Abstract

The present invention relates to a catalyst for the catalytic cracking of olefins to produce propylene, a preparation method thereof, and an application thereof. Based on the weight of the catalyst, the catalyst comprises the following components: 59% to 85% of ZSM-5 molecular sieve, 10% to 40% of a binder component, and 0.5% to 5% of a Group VIII transition metal element; the ratio of the acid amount of Bronsted acid and Lewis acid of the catalyst is 1 to 10:1, and the apparent framework density is 0.8 to 2.0 g / mL. When the catalyst is used in the reaction of catalytic cracking of olefins to produce propylene, it has the characteristics of high catalyst activity, good stability, and high selectivity of the product propylene.

Description

Technical Field

[0001] The present invention relates to the field of catalytic cracking, and particularly relates to a catalyst for olefin catalytic cracking to produce propylene, a preparation method thereof, and an application in increasing the production of propylene by olefin catalytic cracking. Background Art

[0002] Due to its special pore structure, pore size, stable framework structure and widely adjustable silica-alumina ratio, ZSM-5 molecular sieve has excellent catalytic performance and can meet the requirements of various reaction processes. For example, in the catalytic cracking process, its molecular shape selectivity is used to improve the octane number of gasoline and the yield of light olefins. It has also been widely used in various petrochemical processes such as hydrocarbon isomerization, alkylation, disproportionation, and etherification. To further improve various catalytic performances, a large number of studies have been carried out on the synthesis and modification of ZSM-5 molecular sieve. For example, ZSM-5 molecular sieve modified by phosphorus or magnesium is used for the methylation of toluene, greatly improving the selectivity of p-xylene. Good progress has also been made in processes such as methanol to propylene (MTP), methanol to gasoline (MTG), toluene shape-selective disproportionation, and benzene alkylation.

[0003] The report on the use of ZSM-5 molecular sieve for the cracking of C 4 and higher olefins first appeared in the 1990s. It was found that the pore structure, crystal size, cation type, etc. of ZSM-5 molecular sieve affect its catalytic performance. It was found that the ZSM-5 molecular sieve catalyst should have a suitable pore size. The pore size should be small enough to prevent the passage of C 4 / C 5 dimerization products, so that they cannot coke in the pores, and at the same time, it should be large enough to allow C 4 / C 5 olefins to carry out cracking reactions in the pores and allow the products ethylene and propylene to pass through smoothly. On the premise that the pore structure of the catalyst has shape selectivity, its acidity is the determining factor for catalytic performance. Research shows that many important shape-selective catalytic reactions, such as hydrocarbon selective cracking, isomerization, alkylation, disproportionation, and aromatic synthesis, alcohol conversion, etc. are all acid-catalyzed. The catalytic activity, selectivity and catalyst life of these reactions are not only related to the acid sites of the catalyst, but also related to the acid type and its distribution. Therefore, the preparation of ZSM-5 molecular sieve catalysts with a suitable acid distribution and pore structure is the research focus of such catalysts for various reactions.

[0004] Due to the strong acidity of the molecular sieve, while olefins are cracked to produce propylene, side reactions such as olefin polymerization chain growth, hydrogen transfer and aromatization will occur, and even coke will form in the pores of the molecular sieve catalyst, covering the reaction active centers, causing the catalyst to quickly deactivate. EP0109059A1 discloses a method for converting C 4 -C 12A method for producing propylene by olefin cracking, wherein ZSM-5 or ZSM-11 molecular sieve is used as a catalyst. US6307117 discloses a method for producing propylene and ethylene by cracking C 4 -C 12 olefins, in which the active component of the catalyst used is a ZSM-5 molecular sieve without protonic acid and containing a Group IB metal. The olefin cracking catalysts reported in the above-mentioned literatures all have defects such as poor product selectivity, poor catalyst stability, easy coking deactivation, and inability to meet long-term operation to varying degrees, so it is difficult to realize industrialization. SUMMARY OF THE INVENTION

[0005] The technical problem to be solved by the present invention is the poor stability of the existing catalysts for olefin catalytic cracking to produce propylene and the low selectivity of propylene. The present invention provides a catalyst for olefin catalytic cracking to produce propylene and a preparation method thereof, as well as the application of the catalyst in increasing the production of propylene by olefin catalytic cracking. When the catalyst of the present invention is used in the reaction of olefin catalytic cracking to produce propylene, it has the characteristics of high catalyst activity, good stability, and high selectivity of the product propylene.

[0006] In the first aspect of the present invention, a catalyst for olefin catalytic cracking to produce propylene is provided, wherein, based on the weight of the catalyst, the catalyst comprises the following components:

[0007] I) 59% to 85% of ZSM-5 molecular sieve;

[0008] II) 10% to 40% of a binder component;

[0009] III) 0.5% to 5% of a Group VIII transition metal element;

[0010] The acid amount ratio of B acid and L acid of the catalyst is 1 to 10:1, and the apparent framework density is 0.8 to 2.0 g / ml.

[0011] In the above technical solution, preferably, the acid amount ratio of B acid and L acid of the catalyst is 3 to 8:1.

[0012] In the above technical solution, preferably, the apparent framework density of the catalyst is 1.0 to 1.6 g / ml.

[0013] In the above technical solution, the SiO 2 / Al 2 O 3 molar ratio of the ZSM-5 molecular sieve in component I) is 50 to 1000, preferably 100 to 1000.

[0014] In the above technical solution, the Group VIII transition metal element in component III) is selected from at least one of Fe, Co, Ni, Ru, Rh, and Pd.

[0015] In the second aspect of the present invention, a method for preparing the above catalyst is provided, which includes the following steps:

[0016] a) Prepare the ZSM-5 molecular sieve raw powder;

[0017] b) Knead and mold the raw powder obtained in step a) with a binder, dry it, and perform the first calcination to obtain a molded product;

[0018] c) Treat the molded product obtained in step b) in an alkali solution, and perform the second calcination to obtain a catalyst precursor;

[0019] d) Perform ammonium exchange on the catalyst precursor obtained in step c), and perform the third calcination to obtain an ammonium-exchanged product;

[0020] e) Treat the ammonium-exchanged product obtained in step d) in an acid solution, perform the fourth calcination, load the Group VIII transition metal, and perform the fifth calcination to obtain the catalyst.

[0021] In the above technical solution, the process of preparing the ZSM-5 molecular sieve raw powder in step a) includes: mixing a template agent, an aluminum source, a silicon source, an alkali source, and water evenly, performing hydrothermal crystallization, and drying to obtain the ZSM-5 molecular sieve raw powder.

[0022] In the above technical solution, in the step of preparing the raw powder in step a), the template agent includes at least one of tetraethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, and tetrapropylammonium hydroxide. The aluminum source includes at least one of aluminum nitrate, aluminum sulfate, aluminum phosphate, and sodium aluminate. The silicon source includes at least one of sodium silicate, silica sol, and tetraethyl orthosilicate. The alkali source includes at least one of sodium hydroxide and potassium hydroxide.

[0023] In the above technical solution, among the raw materials used in step a) for preparing the raw powder, the template agent is calculated as NH 4 + , the aluminum source is calculated as Al 2 O 3 , the silicon source is calculated as SiO 2 , the alkali source is calculated as OH - , and the molar ratio of water is: NH 4 + ∶Al 2 O 3 ∶SiO 2 ∶OH - ∶H 2 O = 0.1 - 0.5∶0.001 - 0.02∶1∶0.1 - 0.4∶5 - 10.

[0024] In the above technical solution, in the step a) of preparing the raw powder, the device is preferably an autoclave. The pressure is the autogenous pressure, generally less than or equal to 2 MPa. The conditions for hydrothermal crystallization are as follows: crystallization at 120 - 180 °C for 10 - 60 hours. The product obtained after hydrothermal crystallization can be washed and dried. The conditions for drying are as follows: drying at 80 - 120 °C for 10 - 30 hours.

[0025] In the above technical solution, in step b), the binder is selected from one or more of alumina, aluminum sol, and silica sol. When aluminum sol is used as the binder, the binder component is Al 2 O 3 ; when silica sol is used as the binder, the binder component is SiO 2 .

[0026] In the above technical solution, the conditions for drying in step b) are as follows: drying at 80 - 120 °C for 5 - 10 hours. The conditions for the first calcination are as follows: calcination at 500 - 600 °C for 4 - 8 hours.

[0027] In the above technical solution, in step c), the concentration of the alkali solution is 0.3 - 1.0 mol / L, preferably 0.6 - 1.0 mol / L; the alkali includes at least one selected from sodium hydroxide, sodium carbonate, potassium hydroxide, and potassium carbonate. The treatment can be soaking, and the conditions for the treatment are as follows: the volume ratio of the alkali solution to the formed product is 2:1 - 5:1, the treatment temperature is 70 - 80 °C, and the treatment time is 4 - 8 hours. The treatment is carried out under stirring conditions. After treatment in the alkali solution, it can be washed and dried. The conditions for drying are a temperature of 80 - 120 °C and a time of 4 - 20 hours. The conditions for the second calcination are calcination at 500 - 600 °C for 4 - 8 hours.

[0028] In the above technical solution, the conditions for ammonium exchange in step d) are as follows: the temperature is 80 - 90 °C and the time is 1 - 3 h. The number of ammonium exchange times is 2 - 5 times. The concentration of the ammonium salt aqueous solution in ammonium exchange is 5 wt% - 10 wt%. The ammonium salt is at least one selected from ammonium chloride, ammonium nitrate, and ammonium sulfate. After ammonium exchange, it can be washed and dried. The conditions for drying are as follows: the drying temperature is 80 - 120 °C and the drying time is 6 - 20 hours. The conditions for the third calcination are calcination at 500 - 600 °C for 4 - 8 hours.

[0029] In the above technical solution, the content of the acid in the acid solution in step e) is 2 wt% to 5 wt%; the acid is an organic acid; the organic acid includes at least one selected from citric acid, oxalic acid, acetic acid, and ethanedioic acid. The treatment can be soaking, and the treatment conditions are as follows: the volume ratio of the acid solution to the ammonium exchange product is 2:1 to 5:1, the treatment temperature is 70 to 80 °C, and the treatment time is 4 to 8 hours. The treatment is carried out under stirring conditions. Washing and drying can be carried out after treatment in the acid solution. The drying conditions are: temperature 80 to 120 °C, time 6 to 20 hours. The conditions for the fourth calcination are calcination at 500 to 600 °C for 4 to 8 hours.

[0030] In the above technical solution, the supported Group VIII transition metal in step e) is the equal-volume impregnation method. The impregnating solution is a Group VIII transition metal salt solution. The Group VIII transition metal salt is a soluble salt of a Group VIII transition metal, preferably a nitrate. Calculated as metal ions, the mass concentration of the Group VIII transition metal salt solution is 0.5% to 5%. The impregnation time is 5 to 15 hours. Drying can be carried out after impregnation. The drying is carried out at 80 to 120 °C for 6 to 20 hours. The conditions for the fifth calcination are calcination at 500 to 600 °C for 4 to 8 hours.

[0031] The third aspect of the present invention provides the application of the above catalyst in the catalytic cracking of olefins to produce propylene.

[0032] In the above technical solution, the process of catalytic cracking of olefins to produce propylene is as follows: an olefin raw material contacts with the above catalyst for catalytic cracking of olefins to produce propylene to carry out a reaction, and a propylene product is obtained.

[0033] In the above technical solution, the olefin raw material is at least one selected from C4 to C6 olefins. The reaction conditions are as follows: the reaction temperature is 400 to 600 °C, preferably 420 to 580 °C, the reaction pressure is 0 to 0.3 MPa, preferably 0.01 to 0.2 MPa, and the weight hourly space velocity of the olefin raw material is 1 to 50 h -1 , preferably 2 to 40 h -1 .

[0034] Compared with the prior art, the present invention has significant advantages and outstanding effects, which are specifically as follows:

[0035] (1) The olefin catalytic cracking catalyst for producing propylene of the present invention, based on the weight of the catalyst, comprises the following components: a) 59% - 85% of ZSM-5 molecular sieve; b) 10% - 40% of binder component; c) 0.5% - 5% of Group VIII transition metal element; the acid amount ratio of B acid and L acid of the catalyst is 1 - 10:1, and the apparent framework density is 0.8 - 2.0 g / ml. The present invention increases the ratio of B / L acid in the catalyst and simultaneously reduces the apparent framework density of the catalyst. The obtained catalyst has a more abundant pore structure, promotes the diffusion of reaction intermediates and products, and reduces side reactions, thereby improving the catalyst stability, olefin conversion rate, and selectivity of the product propylene. In addition, the product P / E (propylene / ethylene mass ratio) is increased.

[0036] (2) In the present invention, in the catalyst preparation method, after modifying the molecular sieve with an alkali solution and an acid solution, the acidic characteristics of the catalyst are adjusted, the B / L acid ratio is increased, and at the same time, the apparent framework density of the prepared catalyst is significantly reduced, generating a more abundant pore structure and accelerating the diffusion of reaction intermediates and products. The catalyst prepared by this method is used in the olefin catalytic cracking for producing propylene, and the catalyst has the characteristics of high activity, good stability, high selectivity of the product propylene, and a large product P / E.

[0037] (3) In the present invention, in the application of the catalyst in the olefin catalytic cracking for producing propylene, it has the characteristics of high activity, good stability, high selectivity of the product propylene, and a large product P / E. At the initial stage of the reaction, the olefin conversion rate can reach 78%, the propylene selectivity can reach 48%, and the P / E can reach 4.4; during the long-term operation of the reaction for 80 hours, the olefin conversion rate can reach 77%, the propylene selectivity can reach 46%, and the product P / E can (propylene / ethylene mass ratio) reach 4.6. The catalyst has good stability and achieves good technical effects. Description of the Drawings

[0038] Figure 1 It is the pyridine adsorption infrared spectrum of the catalyst obtained in Example 1;

[0039] Figure 2 It is the XRD pattern of the molecular sieve raw powder obtained in Example 1;

[0040] Figure 3 It is the XRD pattern of the molecular sieve raw powder obtained in Comparative Example 1;

[0041] Figure 4 It is the pyridine adsorption infrared spectrum of the catalyst obtained in Comparative Example 1. Detailed Embodiments

[0042] The present invention will be further described below through examples.

[0043] In the context of this specification, XRD analysis was carried out on a Rigaku D / MAX-1400X type polycrystalline X-ray diffractometer, with a graphite monochromator, Cu Kα radiation, tube voltage 40 kV, tube current 40 mA, and scanning speed 15°·min -1 , and the scanning range 2θ was 5 - 50°.

[0044] In the context of this specification, the pyridine adsorption infrared spectrum was analyzed and determined by an IFS-88IR type infrared spectrometer from Bruker Corporation. Specifically: after the sample was ground fine, a bulk tablet was pressed, with a diameter of 2 cm and the whole tablet weight being 11 - 14 mg. Then it was placed in a sample tube and desorbed at 300 °C for 4 hours under a vacuum of 10 -2 Pa to remove moisture and other impurities in the sample. After cooling, the sample was placed in pyridine saturated vapor for adsorption, and then spectra were taken after heating to different temperatures of 150 °C, 200 °C, 250 °C, 300 °C, and 350 °C and equilibrating for 10 minutes. After 300 °C, the spectrum tended to be stable. In the obtained spectrum, the peak near the wavenumber 1449 cm -1 corresponds to the L acid center of the catalyst, and the peak near the wavenumber 1544 cm -1 corresponds to the B acid center of the catalyst. The acid amount ratio of B acid to L acid (B acid / L acid) is the ratio of the infrared absorption peak areas near 1544 cm -1 and near 1449 cm -1 .

[0045] In the context of this specification, the silicon-aluminum molar ratio SiO 2 / Al 2 O 3 was calculated by analyzing the elemental composition of the solid sample using a Magix X type fluorescence spectrometer from Philips Company of the Netherlands, with an operating voltage of 40 kV and an operating current of 40 mA.

[0046] In the context of this specification, the apparent skeletal density was measured using an AutoPore V 9600 type fully automatic mercury porosimeter from Micromeritics Instrument Corporation of the United States. The maximum pressure for high-pressure analysis was 60000 psia (413685 kPa), and the minimum diameter for high-pressure pore size analysis was 4 nm.

[0047] In the context of this specification, it was calculated according to the following formula:

[0048] Olefin conversion rate (%) = (1 - mass of olefin in product / mass of olefin in raw material) × 100%;

[0049] Propylene selectivity (%) = mass of propylene produced in product / (mass of olefin in raw material - mass of remaining olefin after reaction) × 100%;

[0050] Product P / E = mass of propylene produced in the product / mass of ethylene produced in the product.

[0051] [Example 1]

[0052] a) Preparation of ZSM-5 molecular sieve raw powder

[0053] Tetramethylammonium bromide is used as template, aluminum nitrate is used as aluminum source, silica sol is used as silicon source, sodium hydroxide is used as alkali source, and the molar ratio of tetramethylammonium bromide, aluminum nitrate, silica sol, alkali and water is: NH 4 + :Al 2 O 3 ∶SiO 2 :OH - :H 2 O=0.2:0.001:1:0.2:5, after fully mixing and stirring, transfer to an autoclave, crystallize at 180°C for 10 hours under autogenous pressure, and then cool. The synthesized product is filtered, washed with water, and dried at 80°C for 30 hours to obtain ZSM-5 molecular sieve raw powder.

[0054] b) 70 g of the above ZSM-5 molecular sieve raw powder, 40 g of binder alumina and 30 g of 5% dilute nitric acid were kneaded, extruded into strips, dried at 80° C. for 10 hours, and then calcined at 500° C. for 8 hours to obtain a molded product.

[0055] c) The obtained shaped product was placed in a 0.6 mol / L sodium hydroxide solution at 70°C and stirred for 4 hours, with the volume ratio of the alkali solution to the shaped product being 2:1. After washing and drying at 80°C for 20 hours, the shaped product was calcined at 600°C for 4 hours to obtain a catalyst precursor.

[0056] d) The obtained catalyst precursor was ammonium exchanged in a 5 wt% aqueous solution of ammonium nitrate at 90°C for 1 hour. The number of ammonium exchanges was 5. After washing and drying at 120°C for 6 hours, it was calcined at 500°C for 8 hours.

[0057] e) placing the obtained ammonium exchange product in a 2wt% citric acid solution at 70°C and stirring for 4 hours, with the volume ratio of the acid solution to the ammonium exchange product being 3:1, washing, drying at 80°C for 120 hours, and calcining at 500°C for 8 hours. Using an equal volume impregnation method, the above catalyst is impregnated in a 2wt% ferric nitrate solution for 5 hours, dried at 120°C for 6 hours, and then calcined at 500°C for 8 hours to obtain the desired catalyst for catalytic cracking of olefins to increase propylene production.

[0058] Figure 1 The pyridine adsorption infrared spectrum of the catalyst obtained in Example 1. The acid ratio of B acid to L acid in the catalyst is 9:1, and the apparent skeleton density is 1.2 g / ml.

[0059] The catalyst comprises: a) 60% of ZSM-5 molecular sieve; b) 38% of binder component; and c) 2% of metal element Fe.

[0060] The silicon-aluminum molar ratio of the ZSM-5 molecular sieve in the catalyst component is SiO 2 / Al 2 O 3 is 1000.

[0061] The XRD pattern of the obtained ZSM-5 molecular sieve raw powder is shown in Figure 2 .

[0062] The fixed-bed catalytic reaction device was used to evaluate the olefin catalytic cracking reaction activity of the prepared catalyst with n-butene as the olefin raw material. The process conditions used in the investigation were: 0.6 g catalyst, reaction temperature of 500 °C, reaction pressure of 0.02 MPa, and weight space velocity of olefin raw material of 20 h -1 .

[0063] The results of the reaction at 2 h and 80 h are listed in Table 1.

[0064] [Example 2]

[0065] a) Preparation of ZSM-5 molecular sieve raw powder

[0066] Tetrapropylammonium bromide is used as template, aluminum sulfate is used as aluminum source, water glass is used as silicon source, potassium hydroxide is used as alkali source, and the molar ratio of tetrapropylammonium bromide, aluminum sulfate, water glass, alkali and water is: NH 4 + :Al 2 O 3 ∶SiO 2 :OH - :H 2 O=0.5:0.01:1:0.4:10, transfer to an autoclave after sufficient mixing and stirring, crystallize at 120°C for 60 hours under autogenous pressure, and then cool. Filter the synthesized product, wash with water, and dry at 120°C for 10 hours to obtain ZSM-5 molecular sieve raw powder.

[0067] b) 70 g of the ZSM-5 molecular sieve raw powder and 75 g of the binder silica sol (SiO 2 The mixture was kneaded with a weight content of 40%, extruded into strips, dried at 120° C. for 5 hours, and then calcined at 600° C. for 4 hours to obtain a molded product.

[0068] c) The obtained shaped product was placed in a 1.0 mol / L sodium carbonate solution at 80°C and stirred for 8 hours, with the volume ratio of the alkali solution to the shaped product being 3:1. After washing and drying at 120°C for 4 hours, the shaped product was calcined at 500°C for 8 hours to obtain a catalyst precursor.

[0069] d) The obtained catalyst precursor was subjected to ammonium exchange in an aqueous solution of 10 wt% ammonium sulfate at 80 °C for 2 hours. The ammonium exchange was carried out twice in total. After washing and drying at 80 °C for 20 hours, it was calcined at 600 °C for 4 hours.

[0070] e) The obtained ammonium-exchanged product was placed in a 5 wt% oxalic acid solution at 80 °C and stirred for 8 hours. The volume ratio of the acid solution to the ammonium-exchanged product was 5:1. After washing and drying at 120 °C for 6 hours, it was calcined at 600 °C for 4 hours. Using the equal-volume impregnation method, the above catalyst was impregnated in a 5% cobalt nitrate solution for 15 hours, dried at 80 °C for 20 hours, and then calcined at 600 °C for 4 hours to obtain the catalyst for increasing the production of propylene by olefin catalytic cracking as required.

[0071] The acid amount ratio of Bronsted acid and Lewis acid in the catalyst is 5:1, and the apparent skeletal density is 1.6 g / mL.

[0072] The composition of the catalyst is as follows: a) 64% ZSM-5 molecular sieve; b) 31% binder component; c) 5% metal element Co.

[0073] In the catalyst component, the silicon-aluminum molar ratio of the ZSM-5 molecular sieve is SiO 2 / Al 2 O 3 is 100. The XRD pattern of the obtained ZSM-5 molecular sieve raw powder is similar Figure 2 .

[0074] Using a fixed-bed catalytic reaction device, with 1-pentene as the raw material, the prepared catalyst was evaluated for the reaction activity of olefin catalytic cracking to produce propylene. The process conditions investigated were as follows: 0.6 g of the catalyst was loaded, the reaction temperature was 600 °C, the reaction pressure was 0.02 MPa, and the weight hourly space velocity of the olefin raw material was 40 h -1 .

[0075] The results of the reaction for 2 h and 80 h are listed in Table 1.

[0076]

Example 3

[0077] a) Preparation of ZSM-5 molecular sieve raw powder

[0078] Using tetrapropylammonium hydroxide as the template agent, sodium aluminate as the aluminum source, tetraethyl orthosilicate as the silicon source, and sodium hydroxide as the base source, the molar ratio of tetrapropylammonium hydroxide, sodium aluminate, tetraethyl orthosilicate, base, and water is: NH 4 + ∶Al 2 O 3 ∶SiO 2 ∶OH - ∶H 2O = 0.1∶0.00125∶1∶0.1∶8. After thorough mixing and stirring, it is transferred into an autoclave and crystallized at 150 °C for 30 hours under autogenous pressure, and then cooled. The synthesized product is filtered by suction, washed with water, and dried at 100 °C for 20 hours to obtain the ZSM-5 molecular sieve raw powder.

[0079] b) Knead 80 g of the above-mentioned ZSM-5 molecular sieve raw powder and 80 g of binder aluminum sol (Al 2 O 3 with a weight content of 25%), extrude into strips, dry at 100 °C for 8 hours, and then calcine at 550 °C for 6 hours to obtain the formed product.

[0080] c) Place the obtained formed product in a 0.8 mol / L sodium carbonate solution at 80 °C and stir for 6 hours. The volume ratio of the alkali solution to the formed product is 5∶1. After washing and drying at 120 °C for 4 hours, calcine at 600 °C for 6 hours to obtain the catalyst precursor.

[0081] d) Exchange the ammonium of the obtained catalyst precursor in a 10 wt% aqueous ammonium chloride solution at 85 °C for 1.5 hours. The ammonium exchange is carried out 4 times in total. After washing and drying at 120 °C for 6 hours, calcine at 550 °C for 6 hours.

[0082] e) Place the obtained ammonium-exchanged product in a 3 wt% oxalic acid solution at 75 °C and stir for 6 hours. The volume ratio of the acid solution to the ammonium-exchanged product is 2∶1. After washing and drying at 120 °C for 6 hours, calcine at 550 °C for 7 hours. Using the equal-volume impregnation method, impregnate the above catalyst in a 3% nickel nitrate solution for 10 hours, dry at 100 °C for 10 hours, and then calcine at 550 °C for 6 hours to obtain the catalyst for increasing the production of propylene by catalytic cracking of olefins as required.

[0083] The acid amount ratio of B acid and L acid in the catalyst is 3∶1, and the apparent framework density is 1.0 g / mL.

[0084] The composition of the catalyst is as follows: a) 77.6% of ZSM-5 molecular sieve; b) 19.4% of binder component; c) 3% of metal element Ni.

[0085] The silica-alumina molar ratio SiO 2 / Al 2 O 3 of the ZSM-5 molecular sieve in the catalyst component is 800. The XRD pattern of the obtained ZSM-5 molecular sieve raw powder is similar Figure 2 .

[0086] Using a fixed-bed catalytic reaction device, with 1-hexene as the raw material, the prepared catalyst was evaluated for the reaction activity of olefin catalytic cracking to produce propylene. The process conditions investigated were as follows: 0.6 g of the catalyst was loaded, the reaction temperature was 400 °C, the reaction pressure was 0.3 MPa, and the weight hourly space velocity of the olefin raw material was 2 h -1 .

[0087] The results of the reaction for 2 h and 80 h are listed in Table 1.

[0088]

Example 4

[0089] a) Preparation of ZSM-5 molecular sieve raw powder

[0090] Using tetraethylammonium bromide as the template agent, aluminum phosphate as the aluminum source, sodium silicate as the silicon source, and potassium hydroxide as the base source, the molar ratio of tetraethylammonium bromide, aluminum phosphate, sodium silicate, base, and water was: NH 4 + ∶Al 2 O 3 ∶SiO 2 ∶OH - ∶H 2 O = 0.2∶0.002∶1∶0.2∶10. After thorough mixing and stirring, it was transferred to an autoclave and crystallized at 160 °C for 15 hours under autogenous pressure and then cooled. The synthesized product was filtered by suction, washed with water, and dried at 90 °C for 25 hours to obtain the ZSM-5 molecular sieve raw powder.

[0091] b) Knead 80 g of the above ZSM-5 molecular sieve raw powder and 50 g of binder silica sol (SiO 2 weight content 40%), extrude into pellets, dry at 80 °C for 10 hours, and then calcine at 500 °C for 8 hours to obtain the formed product.

[0092] c) Place the obtained formed product in a 0.6 mol / L sodium carbonate solution at 75 °C and stir for 8 hours. The volume ratio of the alkali solution to the formed product is 4∶1. After washing and drying at 100 °C for 6 hours, calcine at 550 °C for 8 hours to obtain the catalyst precursor.

[0093] d) Exchange the obtained catalyst precursor with 5 wt% ammonium nitrate aqueous solution at 80 °C for 2 hours. The ammonium exchange was carried out 3 times in total. After washing and drying at 100 °C for 10 hours, calcine at 600 °C for 4 hours.

[0094] e) The obtained ammonium exchange product was placed in a 70°C 5 wt% citric acid solution and stirred for 4 hours, with the volume ratio of the acid solution to the ammonium exchange product being 2:1. After washing and drying at 100°C for 10 hours, it was calcined at 500°C for 6 hours. By adopting an equal volume impregnation method, the above catalyst was impregnated in a 0.5% cobalt nitrate solution for 10 hours, dried at 100°C for 10 hours, and then calcined at 550°C for 6 hours to obtain the desired catalyst for catalytic cracking of olefins to increase the production of propylene.

[0095] The acid amount ratio of B acid to L acid in the catalyst is 6:1, and the apparent skeleton density is 1.2 g / ml.

[0096] The catalyst comprises: a) 77.9% ZSM-5 molecular sieve; b) 21.6% binder component; and c) 0.5% metal element Co.

[0097] The silicon-aluminum molar ratio of the ZSM-5 molecular sieve in the catalyst component is SiO 2 / Al 2 O 3 The XRD pattern of the obtained ZSM-5 molecular sieve raw powder is similar to Figure 2 .

[0098] The fixed-bed catalytic reaction device was used to evaluate the olefin catalytic cracking reaction activity of the prepared catalyst with n-butene as the raw material. The process conditions used in the investigation were: 0.6 g catalyst, reaction temperature of 580 °C, reaction pressure of 0.01 MPa, and weight space velocity of olefin raw material of 50 h -1 .

[0099] The results of the reaction at 2 h and 80 h are listed in Table 1.

[0100] [Example 5]

[0101] a) Preparation of ZSM-5 molecular sieve raw powder

[0102] Tetrapropylammonium hydroxide is used as template, aluminum nitrate is used as aluminum source, silica sol is used as silicon source, sodium hydroxide is used as alkali source, and the molar ratio of tetrapropylammonium hydroxide, aluminum nitrate, silica sol, alkali and water is: NH 4 + :Al 2 O 3 ∶SiO 2 :OH - :H 2 O=0.1:0.005:1:0.2:6, after being fully mixed and stirred, transferred into an autoclave, crystallized at 180°C for 10 hours under autogenous pressure, and then cooled. The synthesized product was filtered, washed with water, and dried at 120°C for 10 hours to obtain ZSM-5 molecular sieve raw powder.

[0103] b) Knead 85 g of the above-mentioned ZSM-5 molecular sieve raw powder, 25 g of binder alumina and 32 g of 5% dilute nitric acid, extrude into strips, dry at 80 °C for 10 hours, and then calcine at 600 °C for 4 hours to obtain a formed product.

[0104] c) Place the obtained formed product in a 0.8 mol / L sodium hydroxide solution at 75 °C and stir for 4 hours. The volume ratio of the alkali solution to the formed product is 3:1. After washing and drying at 120 °C for 4 hours, calcine at 600 °C for 4 hours to obtain a catalyst precursor.

[0105] d) Exchange the ammonium of the obtained catalyst precursor in a 10 wt% aqueous ammonium sulfate solution at 90 °C for 1.5 hours. The ammonium exchange is carried out 3 times in total. After washing and drying at 120 °C for 6 hours, calcine at 500 °C for 8 hours.

[0106] e) Place the obtained ammonium-exchanged product in a 5 wt% acetic acid solution at 70 °C and stir for 6 hours. The volume ratio of the acid solution to the ammonium-exchanged product is 5:1. After washing and drying at 120 °C for 6 hours, calcine at 500 °C for 8 hours. Using the equal-volume impregnation method, impregnate the above catalyst in a 2% palladium nitrate solution for 8 hours, dry at 120 °C for 6 hours, and then calcine at 550 °C for 8 hours to obtain the required catalyst for increasing the production of propylene by olefin catalytic cracking.

[0107] The acid amount ratio of B acid and L acid in the catalyst is 5:1, and the apparent framework density is 1.5 g / mL.

[0108] The composition of the catalyst is as follows: a) 74% of ZSM-5 molecular sieve; b) 24% of binder component; c) 2% of metal element Pd.

[0109] The molar ratio of silicon to aluminum SiO 2 / Al 2 O 3 in the ZSM-5 molecular sieve in the catalyst components is 200. The XRD pattern of the obtained ZSM-5 molecular sieve raw powder is similar Figure 2 .

[0110] Using a fixed-bed catalytic reaction device, with n-butene as the raw material, the catalytic activity of the prepared catalyst for olefin catalytic cracking to produce propylene was evaluated. The process conditions investigated were: 0.6 g of catalyst was loaded, the reaction temperature was 420 °C, the reaction pressure was 0.02 MPa, and the weight hourly space velocity of the olefin raw material was 40 h -1 .

[0111] The results of the reaction for 2 h and 80 h are listed in Table 1.

[0112]

Example 6

[0113] a) Preparation of ZSM-5 molecular sieve raw powder

[0114] Using tetraethylammonium bromide as the template agent, aluminum nitrate as the aluminum source, silica sol as the silicon source, and sodium hydroxide as the base source, the molar ratio of tetraethylammonium bromide, aluminum nitrate, silica sol, base, and water is: NH 4 + ∶Al 2 O 3 ∶SiO 2 ∶OH - ∶H 2 O = 0.2∶0.001∶1∶0.2∶5. After thorough mixing and stirring, it is transferred to an autoclave and crystallized at 180 °C for 10 hours under autogenous pressure and then cooled. The synthesized product is filtered by suction, washed with water, and dried at 80 °C for 30 hours to obtain the as-synthesized ZSM-5 zeolite powder.

[0115] b) Knead 70 g of the above-mentioned as-synthesized ZSM-5 zeolite powder, 40 g of binder alumina, and 30 g of 5% dilute nitric acid, extrude into pellets, dry at 80 °C for 10 hours, and then calcine at 500 °C for 8 hours to obtain the formed product.

[0116] c) Place the obtained formed product in a 0.3 mol / L sodium hydroxide solution at 70 °C and stir for 4 hours. The volume ratio of the alkali solution to the formed product is 2∶1. After washing and drying at 80 °C for 20 hours, it is calcined at 600 °C for 4 hours to obtain the catalyst precursor.

[0117] d) Exchange the ammonium of the obtained catalyst precursor in a 5 wt% ammonium nitrate aqueous solution at 90 °C for 1 hour. The number of ammonium exchange times is 5 times. After washing and drying at 120 °C for 6 hours, it is calcined at 500 °C for 8 hours.

[0118] e) Place the obtained ammonium-exchanged product in a 2 wt% citric acid solution at 70 °C and stir for 4 hours. The volume ratio of the acid solution to the ammonium-exchanged product is 3∶1. After washing and drying at 80 °C for 120 hours, it is calcined at 500 °C for 8 hours. Using the equal-volume impregnation method, impregnate the above catalyst in a 2 wt% iron nitrate solution for 5 hours, dry at 120 °C for 6 hours, and then calcine at 500 °C for 8 hours to obtain the catalyst for enhancing propylene production by catalytic cracking of olefins as required.

[0119] The acid amount ratio of Bronsted acid and Lewis acid in the catalyst is 2∶1, and the apparent framework density is 0.8 g / mL.

[0120] The composition of the catalyst is: a) 60% ZSM-5 zeolite; b) 38% binder component; c) 2% metal element Fe.

[0121] The silicon-aluminum molar ratio SiO 2 / Al 2 O 3 in the ZSM-5 zeolite in the catalyst component is 1000.

[0122] The XRD pattern of the obtained ZSM-5 zeolite as-synthesized powder is similar Figure 2 .

[0123] The catalyst evaluation method is the same as that in Example 1, and the reaction results are listed in Table 1.

[0124]

Comparative Example 1

[0125] a) Preparation of ZSM-5 zeolite as-synthesized powder

[0126] Using tetrapropylammonium hydroxide as the template agent, sodium aluminate as the aluminum source, tetraethyl orthosilicate as the silicon source, and sodium hydroxide as the base source, the molar ratio of tetrapropylammonium hydroxide, sodium aluminate, tetraethyl orthosilicate, base, and water is: NH 4 + ∶Al 2 O 3 ∶SiO 2 ∶OH - ∶H 2 O = 0.1∶0.00125∶1∶0.1∶8. After thorough mixing and stirring, it is transferred to an autoclave and crystallized at 150 °C for 30 hours under autogenous pressure and then cooled. The synthesized product is filtered by suction, washed with water, and dried at 100 °C for 20 hours to obtain ZSM-5 zeolite as-synthesized powder.

[0127] b) Knead 80 g of the above ZSM-5 zeolite as-synthesized powder and 80 g of binder aluminosol (Al 2 O 3 weight content 25%), extrude into pellets, dry at 100 °C for 8 hours, and then calcine at 550 °C for 6 hours to obtain the formed product.

[0128] c) Exchange the obtained formed product with 10 wt% ammonium chloride aqueous solution at 85 °C for 1.5 hours, perform ammonium exchange 4 times, wash, dry at 120 °C for 6 hours, and then calcine at 550 °C for 6 hours.

[0129] d) Place the obtained ammonium-exchanged product in a 3 wt% oxalic acid solution at 75 °C and stir for 6 hours. The volume ratio of the acid solution to the ammonium-exchanged product is 2∶1. Wash, dry at 120 °C for 6 hours, and then calcine at 550 °C for 7 hours. Using the equal-volume impregnation method, impregnate the above catalyst in a 3% nickel nitrate solution for 10 hours, dry at 100 °C for 10 hours, and then calcine at 550 °C for 6 hours to obtain the catalyst for increasing propylene production by catalytic cracking of olefins as required.

[0130] Figure 4 It is the pyridine adsorption infrared spectrum of the catalyst obtained in Comparative Example 1. The acid amount ratio of B acid and L acid in the catalyst is 0.5∶1, and the apparent framework density is 2.02 g / mL.

[0131] The catalyst comprises: a) 77.6% of ZSM-5 molecular sieve; b) 19.4% of binder component; and c) 3% of metal element Ni.

[0132] The silicon-aluminum molar ratio of the ZSM-5 molecular sieve in the catalyst component is SiO 2 / Al 2 O 3 is 800.

[0133] The XRD pattern of the obtained ZSM-5 molecular sieve raw powder is shown in Figure 3 .

[0134] The catalyst evaluation method is the same as in Example 3, and the reaction results are listed in Table 1.

[0135] [Comparative Example 2]

[0136] a) Preparation of ZSM-5 molecular sieve raw powder

[0137] Tetrapropylammonium hydroxide is used as the template, sodium aluminate is used as the aluminum source, tetraethyl orthosilicate is used as the silicon source, and sodium hydroxide is used as the alkali source. The molar ratio of tetrapropylammonium hydroxide, sodium aluminate, tetraethyl orthosilicate, alkali, and water is: NH 4 + :Al 2 O 3 ∶SiO 2 :OH - :H 2 O=0.1∶0.00125∶1∶0.1∶8, transfer to an autoclave after sufficient mixing and stirring, crystallize at 150℃ for 30 hours under autogenous pressure, and then cool. Filter the synthesized product, wash with water, and dry at 100℃ for 20 hours to obtain ZSM-5 molecular sieve raw powder.

[0138] b) 80 g of the ZSM-5 molecular sieve raw powder and 80 g of the binder aluminum sol (Al 2 O 3 The mixture was kneaded with a weight content of 25%, extruded into strips, dried at 100°C for 8 hours, and then calcined at 550°C for 6 hours to obtain a molded product.

[0139] c) The obtained shaped product was placed in a 0.8 mol / L sodium carbonate solution at 80°C and stirred for 6 hours, with the volume ratio of the alkali solution to the shaped product being 5:1. After washing and drying at 120°C for 4 hours, the shaped product was calcined at 600°C for 6 hours to obtain a catalyst precursor.

[0140] d) The obtained catalyst precursor was ammonium exchanged in a 10 wt% aqueous solution of ammonium chloride at 85°C for 1.5 hours, for a total of 4 times, washed, dried at 120°C for 6 hours, and calcined at 550°C for 6 hours.

[0141] e) By adopting the equal-volume impregnation method, the obtained ammonium-exchanged product was impregnated in a 3% nickel nitrate solution for 10 hours, dried at 100 °C for 10 hours, and then calcined at 550 °C for 6 hours to obtain the catalyst for enhancing the production of propylene by catalytic cracking of olefins as required.

[0142] The ratio of Bronsted acid to Lewis acid in the catalyst is 0.7:1, and the apparent skeletal density is 2.1 g / mL.

[0143] The composition of the catalyst is as follows: a) 77.6% of ZSM-5 molecular sieve; b) 19.4% of binder component; c) 3% of metal element Ni.

[0144] In the catalyst component, the molar ratio of silicon to aluminum in the ZSM-5 molecular sieve is SiO 2 / Al 2 O 3 is 800.

[0145] The catalyst evaluation method is the same as that in Example 3, and the reaction results are listed in Table 1.

[0146] Table 1

[0147]

Claims

1. A catalyst for the catalytic cracking of olefins to produce propylene, based on the weight of the catalyst, comprises the following components: I) 59% - 85% of ZSM-5 molecular sieve; II) 10% - 40% of binder component; III) 0.5% - 5% of Group VIII transition metal element; The ratio of the amount of Brønsted acid to Lewis acid of the catalyst is 1 - 10:1, and the apparent framework density is 0.8 - 2.0 g / mL.

2. The catalyst according to claim 1, characterized in that, the ratio of the amount of Brønsted acid to Lewis acid of the catalyst is 3 - 8:1, and the apparent framework density is 1.0 - 1.6 g / mL.

3. The catalyst according to claim 1, characterized in that, The SiO of the ZSM-5 molecular sieve in Component I 2 / Al 2 O 3 molar ratio is 50 to 1000; and / or, the Group VIII transition metal element in component III) is selected from at least one of Fe, Co, Ni, Ru, Rh and Pd.

4. The catalyst according to claim 1, characterized in that, The SiO 2 / Al 2 O 3 molar ratio of the ZSM-5 molecular sieve in Component I) is 100 to 1000.

5. A preparation method of the catalyst according to any one of claims 1 - 4, characterized in that, comprises the following steps: a) Prepare the ZSM-5 molecular sieve raw powder; b) Knead and shape the raw powder obtained in step a) with the binder, dry, and perform the first calcination to obtain a shaped product; c) Treat the shaped product obtained in step b) in an alkali solution, perform the second calcination to obtain a catalyst precursor; d) Perform ammonium exchange on the catalyst precursor obtained in step c), perform the third calcination to obtain an ammonium-exchanged product; e) Treat the ammonium-exchanged product obtained in step d) in an acid solution, perform the fourth calcination, load the Group VIII transition metal, and perform the fifth calcination to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that, the process of preparing the ZSM-5 molecular sieve raw powder in step a) includes: mixing the template agent, aluminum source, silicon source, alkali source, and water evenly, performing hydrothermal crystallization, and drying to obtain the ZSM-5 molecular sieve raw powder.

7. The preparation method according to claim 6, characterized in that, the template agent includes at least one of tetraethylammonium bromide, tetraethylammonium bromide, tetrapropylammonium bromide, and tetrapropylammonium hydroxide; and / or, the aluminum source includes at least one of aluminum nitrate, aluminum sulfate, aluminum phosphate, and sodium aluminate; and / or, the silicon source includes at least one of water glass, silica sol, and tetraethyl orthosilicate: and / or, the alkali source includes at least one of sodium hydroxide and potassium hydroxide.

8. The preparation method according to claim 6, characterized in that, In the raw materials for preparing the ZSM-5 molecular sieve precursor powder in step a), the template agent is calculated as NH 4 + ; the aluminum source is calculated as Al 2 O 3 ; the silicon source is calculated as SiO 2 ; the alkali source is calculated as OH - ; and the molar ratio of water is: NH 4 + : Al 2 O 3 : SiO 2 : OH - : H 2 O = 0.1 - 0.5: 0.001 - 0.02: 1: 0.1 - 0.4: 5 - 10; and / or, the conditions of the hydrothermal crystallization are: crystallizing at 120 - 180 °C for 10 - 60 hours.

9. The preparation method according to claim 5, characterized in that, in step b), the binder is selected from one or more of alumina, aluminum sol, and silica sol; and / or, the conditions of drying in step b) are: drying at 80 - 120 °C for 5 - 10 hours; and / or, the conditions of the first calcination in step b) are: calcining at 500 - 600 °C for 4 - 8 hours.

10. The preparation method according to claim 5, characterized in that, The concentration of the alkali solution described in step c) is 0.3 to 1.0 mol / L; the alkali includes at least one selected from sodium hydroxide, sodium carbonate, potassium hydroxide, and potassium carbonate; and / or, the treatment in step c) is soaking, and the conditions of the treatment are as follows: the volume ratio of the alkali solution to the formed product is 2:1 to 5:1, the treatment temperature is 70 to 80 °C, and the treatment time is 4 to 8 hours; and / or, the conditions of the second calcination in step c) are calcination at 500 to 600 °C for 4 to 8 hours.

11. The preparation method according to claim 10, characterized in that, the concentration of the alkali solution described in step c) is 0.6 to 1.0 mol / L.

12. The preparation method according to claim 5, characterized in that, the conditions of the ammonium exchange in step d) are: the temperature is 80 to 90 °C, and the time is 1 to 3 h.

13. The preparation method according to claim 12, characterized in that, the number of ammonium exchange times is 2 to 5 times.

14. The preparation method according to claim 12, characterized in that, the concentration of the ammonium salt aqueous solution in the ammonium exchange is 5 wt% to 10 wt%; the ammonium salt is at least one selected from ammonium chloride, ammonium nitrate, and ammonium sulfate; and / or, the conditions of the third calcination are calcination at 500 to 600 °C for 4 to 8 hours.

15. The preparation method according to claim 5, characterized in that, the acid content in the acid solution in step e) is 2 wt% to 5 wt%; the acid is an organic acid; the organic acid includes at least one selected from citric acid, oxalic acid, acetic acid, and ethanedioic acid; and / or, the treatment in step e) is soaking, and the treatment conditions are as follows: the volume ratio of the acid solution to the ammonium exchange product is 2:1 to 5:1, the treatment temperature is 70 to 80 °C, and the treatment time is 4 to 8 hours; and / or, the conditions of the fourth calcination in step e) are calcination at 500 to 600 °C for 4 to 8 hours.

16. The preparation method according to claim 5, characterized in that, the loading of the Group VIII transition metal in step e) is the equal volume impregnation method; and / or, the conditions of the fifth calcination are calcination at 500 to 600 °C for 4 to 8 hours.

17. Use of the catalyst according to any one of claims 1 to 4 or the catalyst prepared by the preparation method according to any one of claims 5 to 16 in the catalytic cracking of olefins to produce propylene.

Images