A composite disproportionation catalyst for the disproportionation of ethylene and 1-butene to propylene and its preparation method

Abstract

This invention proposes a composite disproportionation catalyst for the disproportionation of ethylene and 1-butene to propylene. The catalyst comprises 1%-49% by mass of WO3 / SiO2 catalyst, 50%-98% by mass of element I modified molecular sieve catalyst, and the remainder as a binder. The preparation method involves impregnating the WO3 / SiO2 catalyst and the element I modified molecular sieve catalyst, then mixing and molding the two catalysts to obtain the composite catalyst. Metal II is then used to modify the composite catalyst to obtain the final composite disproportionation catalyst. The molecular sieve in this composite disproportionation catalyst has a unique pore structure, which greatly enhances its carbon-holding capacity and promotes the chemical reaction in a direction favorable to propylene formation. Metal II modification significantly inhibits the acid catalytic activity of the composite disproportionation catalyst, suppresses side reactions, achieves high reactant conversion and propylene selectivity, and also exhibits good reaction stability, thus enhancing the reaction advantages for disproportionation to propylene.

Description

Technical Field

[0001] This invention belongs to the field of disproportionation catalyst technology, specifically relating to a composite disproportionation catalyst for the disproportionation of ethylene and 1-butene to propylene and its preparation method. Background Technology

[0002] Olefin disproportionation is a process for converting olefins. It allows for the conversion of relatively surplus, low-value-added olefins into high-value-added olefin products. Furthermore, the self-disproportionation of 1-butene can generate ethylene and hexene. In the self-disproportionation of 1-butene, inhibiting the double bond isomerization reaction can increase the yields of ethylene and hexene. Therefore, olefin disproportionation allows for flexible control of the formation of target products according to market demand, making it an important and efficient pathway for converting olefin resources. Catalysts for olefin disproportionation can be homogeneous or heterogeneous. Heterogeneous olefin catalysts are generally compounds of W, Mo, Re, etc., supported on inert supports, typically SiO2, Al2O3, TiO2, SiO2-Al2O3, or phosphoaluminates.

[0003] Patent CN1490289A discloses a method for producing propylene by butene disproportionation, using a fixed-bed catalyst with SiO2 as a support and WO3 supported, and the catalyst has a specific surface area of ​​270-550 m². 2 / gram, at a reaction temperature of 250-450℃, a reaction pressure of 0-10MPa, and a liquid hourly space velocity of 0.1-1.0h. -1 Under certain conditions, a disproportionation reaction occurs to produce propylene.

[0004] Patent CN200810043969.1 relates to a catalyst for the synthesis of propylene from ethylene and butene. By employing a catalyst for the synthesis of propylene from ethylene and butene, comprising, by weight, the following components: (a) 1 to 30 parts of tungsten oxide; (b) 70 to 99 parts of MCM-22 molecular sieve support, the technical solution effectively solves the problems of low propylene selectivity and short catalyst life in previous technologies, and can be used in the industrial production of propylene from ethylene and butene.

[0005] Patent CN101172241B relates to a method for producing propylene from butene disproportionation. This invention uses mesoporous WO3 / SBA-15 molecular sieves to produce propylene in a fixed-bed reactor at a reaction temperature of 0-550℃, a reaction pressure of 0-35MPa, and a liquid hourly space velocity of 0.1-10h. -1 Under certain conditions, butene disproportionation produces propylene, wherein the catalyst mainly comprises 60%-99% all-silica SBA-15 molecular sieve and the balance tungsten oxide by weight percentage. This technical solution mainly solves the problem of low catalyst activity in existing technologies and can be used in the industrial production of propylene from olefin disproportionation.

[0006] The aforementioned patents are mainly applied to the disproportionation reaction of butene and ethylene, and the research focuses on the modification and purification based on a single support. Currently, there is little research on the modification and design of catalysts for the disproportionation production of propylene based on composite supports. Existing catalysts applied to the disproportionation reaction of butene and ethylene all have the disadvantages of low catalyst activity and propylene selectivity, low reactant conversion rate, and insufficient reaction stability. Therefore, this invention provides a composite disproportionation catalyst for the disproportionation of ethylene and 1-butene to propylene and its preparation method. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention proposes a composite disproportionation catalyst for the disproportionation of ethylene and 1-butene to propylene and its preparation method. The purpose is to prepare a composite disproportionation catalyst by mixing WO3 / SiO2 catalyst and element I modified molecular sieve catalyst, and then modifying the composite catalyst with metal II. This solves the problems of low disproportionation catalyst activity, low propylene selectivity, low reactant conversion rate, and insufficient reaction stability.

[0008] This invention discloses a composite disproportionation catalyst for the disproportionation of ethylene and 1-butene to propylene, the components and mass fractions of which are as follows:

[0009] WO3 / SiO2 catalyst: 1%-49%;

[0010] Element I modified molecular sieve catalysts: 50%-98%;

[0011] The remainder is adhesive.

[0012] Preferably, the WO3 loading in the WO3 / SiO2 catalyst has a mass fraction of 1%-20%.

[0013] Preferably, the mass fraction of element I loaded in the element I modified molecular sieve catalyst is 0.01%-10%, and element I is one or more of rare earth metals and elements IIIA-VA, preferably La, Ce, Nd, Y, P, Ga, Sn, and Bi; the molecular sieve in the element I modified molecular sieve catalyst is one or more of MCM-22 group molecular sieves, Y-type molecular sieves, β molecular sieves, HMS series molecular sieves, SBA series molecular sieves, and ZSM-5 molecular sieves, wherein the silicon-to-aluminum ratio of MCM-22 group molecular sieves is 10-50, the silicon-to-aluminum ratio of Y-type molecular sieves is 2-10, the silicon-to-aluminum ratio of β molecular sieves is 6-100, the silicon-to-aluminum ratio of ZSM-5 molecular sieves is 60-300, and the HMS series molecular sieves and SBA series molecular sieves are all silicon.

[0014] Preferably, the binder is one or more of SB powder, silica, water glass, and guar gum powder.

[0015] The present invention discloses a method for preparing a composite disproportionation catalyst for the disproportionation of ethylene and 1-butene to propylene, comprising the following steps:

[0016] (1) Preparation of WO3 / SiO2 catalyst

[0017] SiO2 was dried in an oven at 150℃ and weighed for later use. The amount of soluble tungsten salt required for loading was calculated, and the soluble tungsten salt was weighed and added to pure water for ultrasonic vibration for 10 min to obtain a soluble tungsten salt aqueous solution. After the dried SiO2 was placed at room temperature, the soluble tungsten salt aqueous solution was added and the mixture was vibrated on an ultrasonic instrument for 2 h or more, and then allowed to stand for 24 h to obtain SiO2 loaded with tungsten salt. That is, tungsten salt is adsorbed on SiO2 to catalyze the disproportionation reaction and improve catalytic activity. The SiO2 loaded with tungsten salt was placed in a crucible and dried in a drying oven at 120℃ for 12 h. After drying, it was calcined in a muffle furnace and cooled to room temperature to obtain the WO3 / SiO2 catalyst.

[0018] (2) Preparation of element I modified molecular sieve catalyst

[0019] Molecular sieves were dried in an oven at 150°C to obtain raw molecular sieve powder, which was weighed and set aside. The amount of element I soluble salt required for loading was calculated, and the element I soluble salt was weighed and added to pure water for ultrasonic vibration for 10 min to obtain an aqueous solution of element I soluble salt. After the raw molecular sieve powder was placed at room temperature, the aqueous solution of element I soluble salt was added, and the mixture was vibrated on an ultrasonic instrument for 2 h or more, and then allowed to stand for 24 h to obtain an element I loaded mixture, i.e., element I is adsorbed on the molecular sieve to improve the disproportionation performance of the catalyst. The element I loaded mixture was placed in a crucible and dried in a drying oven at 120°C for 12 h. The dried element I loaded mixture was then calcined in a muffle furnace and cooled to room temperature to obtain the element I modified molecular sieve catalyst.

[0020] (3) Element I modified molecular sieve catalyst and WO3 / SiO2 catalyst were mixed and molded.

[0021] After drying the element-modified molecular sieve catalyst, WO3 / SiO2 catalyst, and binder in a 180℃ drying oven for 2 hours, the components were weighed according to the following ratio: molecular sieve catalyst: WO3 / SiO2 catalyst = 50%-98%: 1%-49%, with the remainder being binder. Nitric acid with a water-to-powder ratio of 0.4 and a mass concentration of 4% was weighed and prepared. The element-modified molecular sieve catalyst, WO3 / SiO2 catalyst, and binder were mixed evenly in a mortar, and then nitric acid was added dropwise while stirring until the nitric acid was completely added to obtain a binder mixture. The binder mixture was kneaded into shape and left to stand for 8 hours or more. The kneaded binder mixture was then placed in a 180℃ drying oven and dried for 3 hours. After drying, it was removed and calcined in a muffle furnace to obtain the composite catalyst.

[0022] (4) Modification of the composite catalyst using a metal II soluble salt solution.

[0023] The composite catalyst was dried in an oven at 150°C and weighed for later use. The amount of element II soluble salt required for loading was calculated, and the element II soluble salt was weighed and added to pure water for ultrasonic vibration for 10 min to obtain an element II soluble salt aqueous solution. After the dried composite catalyst was placed at room temperature, the element II soluble salt aqueous solution was added and placed on an ultrasonic instrument for vibration for 2 h or more. After standing for 24 h, the element II loaded mixture was obtained. The element II loaded mixture was placed in a crucible and dried in a drying oven at 120°C for 12 h. The dried element II loaded mixture was then placed in a muffle furnace for calcination and cooled to room temperature to obtain the composite disproportionation catalyst. The mass ratio of the composite disproportionation catalyst to the metal element added was 85:15-99.9999:0.0001, with a preferred ratio of 85:15-99.9:0.1.

[0024] Preferably, the soluble tungsten salt is selected from its alkali metal salt or ammonium salt; the element I soluble salt is selected from its nitrate, sulfate or ammonium salt; and the metal II soluble salt is selected from its nitrate, sulfate or ammonium salt.

[0025] Preferably, the soluble tungsten salt and soluble salt in steps (1), (2) and (4) are calculated as m = (f × z) / ((1-z) × x × y); where x is the purity of the soluble salt, y is the mass fraction of tungsten trioxide or element I or element II contained in the soluble salt, z is the mass fraction of the catalyst loaded, f is the mass of SiO2 or molecular sieve or composite catalyst, and m is the mass of the soluble salt.

[0026] Preferably, the calcination temperature of the load mixture in steps (1), (2) and (4) is 400℃-600℃ and the calcination time is 4h-6h, with the preferred calcination conditions being 420℃-550℃ and 4.5h-6h; the calcination temperature of the binder mixture in step (3) is 400℃-700℃ and the calcination time is 2h-6h, with the preferred calcination conditions being 450℃-600℃ and 3h-6h.

[0027] Preferably, in step (4), metal II is one or more of alkali metals, alkaline earth metals and metals IIB, preferably Na, K, Ba, Ca, Mg and Zn.

[0028] After preparing the composite disproportionation catalyst using the above technical solution, it is mixed with an alkaline earth metal oxide as an isomerization catalyst, and a mixed catalyst is prepared at a weight ratio of composite disproportionation catalyst: isomerization catalyst = 1:1-1:20; the alkaline earth metal oxide is one or more of magnesium oxide, calcium oxide, barium oxide, and strontium oxide. The mixed catalyst of this invention is loaded in stages. First, 1-5 parts by weight of the isomerization catalyst are loaded into the upper part of the reactor, and then the mixed catalyst with a disproportionation catalyst: isomerization catalyst ratio of 1:1-1:15 is loaded into the lower part of the reactor.

[0029] This invention uses 1-butene and ethylene as raw materials, with an ethylene / 1-butene molar ratio of 0.2-10. The raw materials and a mixed catalyst react in a fixed-bed reactor to produce a propylene-containing product. The reaction temperature is 250℃-500℃, the reaction pressure is 0.1MPa-5MPa, and the weight hourly space velocity is 1-50 h⁻¹. -1 .

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention prepares a WO3 / SiO2 catalyst and an element-I modified molecular sieve catalyst via impregnation. The two catalysts are then mixed and molded to obtain a composite catalyst. Metal II is used to modify the composite catalyst, resulting in a composite disproportionation catalyst. Compared to disproportionation catalysts for propylene production based on a single support, the molecular sieve in this invention has a unique pore structure. This structure significantly improves carbon holding capacity, and the diffusion coefficient of propylene within the pore structure is much greater than that of aromatics. This promotes the chemical reaction in a direction favorable to propylene formation, suppresses side reactions, and increases the stability and reactivity of the catalyst in the disproportionation reaction. Metal II modification significantly suppresses the acid catalytic activity of the composite disproportionation catalyst, inhibits side reactions, reduces the depth of propylene reaction, and achieves high reactant conversion and propylene selectivity. It also exhibits good reaction stability, enhancing the advantages of disproportionation for propylene production. Detailed Implementation

[0032] To better understand the content of this invention, specific embodiments will be used to further illustrate the invention below. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps; however, the scope of protection of this invention is not limited to the following embodiments.

[0033] Example 1:

[0034] (1) Preparation of WO3 / SiO2 catalyst by impregnation method, wherein the mass fraction of WO3 loading is 8%. The preparation method is as follows: Weigh a certain amount of SiO2 powder (analytical grade, content ≥99%, specific surface area ≥100m²)2 Place the ammonium metatungstate (Hg) in a 150℃ oven and dry for 20 minutes. Weigh out 10g for later use. Calculate the required ammonium metatungstate (Hg) for loading. 28 N6O 41 W 12 Weigh out m = 0.934 g of ammonium metatungstate (analytical grade, purity ≥ 99.5%) and add pure water. Sonicate the mixture for 10 min to obtain an ammonium metatungstate aqueous solution. Remove the dried SiO2, allow it to reach room temperature, add the ammonium metatungstate aqueous solution, and oscillate on an ultrasonic instrument for 2 h. Let it stand for 24 h to obtain tungsten-loaded SiO2. Place the tungsten-loaded SiO2 in a crucible and dry it in a 120℃ drying oven for 12 h. Then, calcine it in a muffle furnace at 450℃ for 5 h. After calcination, cool it to room temperature to obtain a WO3 / SiO2 catalyst with a loading mass fraction of 8%.

[0035] (2) Preparation of element I (lanthanum) modified MCM-22 molecular sieve catalyst by impregnation method: Weigh a certain amount of MCM-22 molecular sieve (silicon-aluminum ratio 17, specific surface area 470m²) 2 / g, pore volume 0.60cm 3 / g) was placed in a 150℃ oven and dried for 20 min. 10g was weighed out for later use. The amount m of lanthanum nitrate hexahydrate (La·3NO3·6H2O, molecular weight 433.1, analytical grade, purity ≥99.9%) required for loading was calculated. m = 0.965g of lanthanum nitrate was weighed and added to pure water and ultrasonically vibrated for 10 min to obtain a lanthanum nitrate solution. The dried MCM-22 molecular sieve was taken out, placed at room temperature, and then the lanthanum nitrate solution was added. The mixture was placed on an ultrasonic instrument and vibrated for 2 h. After standing for 24 h, a lanthanum nitrate loaded mixture was obtained. The lanthanum nitrate loaded mixture was placed in a crucible and dried in a 120℃ drying oven for 12 h. Then it was placed in a muffle furnace at 450℃ and calcined for 5 h. After calcination, it was cooled to room temperature to obtain the elemental lanthanum modified MCM-22 molecular sieve catalyst, in which the mass fraction of lanthanum loading was 3%.

[0036] (3) Mixing and molding 10g of lanthanum-modified MCM-22 molecular sieve catalyst with WO3 / SiO2 catalyst: Take 10g of lanthanum-modified MCM-22 molecular sieve catalyst, 6g of WO3 / SiO2 catalyst (with a loading mass fraction of 8%) and 4g of binder and dry them in a 180℃ drying oven for 2h for later use; weigh nitric acid with a water-to-powder ratio of 0.4 and a mass concentration of 4% for later use; mix the molecular sieve catalyst, WO3 / SiO2 catalyst and binder in a mortar and mix them evenly, then add nitric acid dropwise while stirring until the nitric acid is completely added to obtain a binder mixture; knead the binder mixture and let it stand for at least 8h; put the binder mixture into a 180℃ drying oven and dry it for 3h, then take it out and calcine it in a 550℃ muffle furnace for 4h to obtain composite catalyst F1 (i.e., disproportionation catalyst).

[0037] Example 2

[0038] (1) WO3 / SiO2 catalyst was prepared by impregnation method, wherein the loading mass fraction of WO3 was 8%: the preparation method was the same as in Example 1.

[0039] (2) Preparation of element I (phosphorus) modified MCM-22 molecular sieve catalyst by impregnation method: Compared with step (2) in Example 1, the loading is element phosphorus. Calculate the amount m of diammonium hydrogen phosphate (H9N2O4P, molecular weight 132.06, analytical grade, purity ≥99%) required for the loading. Weigh m = 1.793 g of diammonium hydrogen phosphate and add pure water for ultrasonic oscillation for 10 min to obtain a diammonium hydrogen phosphate solution. After adding the diammonium hydrogen phosphate solution to the MCM-22 molecular sieve, a diammonium hydrogen phosphate loaded mixture is obtained. After drying in a blast furnace, it is placed in a muffle furnace (drying and calcination conditions are the same as in Example 1) to obtain the element phosphorus modified MCM-22 molecular sieve catalyst, wherein the mass fraction of phosphorus loading is 4%.

[0040] (3) Element I (phosphorus) modified MCM-22 molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded: Compared with step (3) in Example 1, the molecular sieve catalyst is element phosphorus modified MCM-22 molecular sieve catalyst, and the mixing and kneading steps are the same as in Example 1. Finally, composite catalyst F2 (i.e. disproportionation catalyst) is obtained.

[0041] Example 3

[0042] (1) Preparation of WO3 / SiO2 catalyst by impregnation method: wherein the loading mass fraction of WO3 is 8%; the preparation method is the same as in Example 1.

[0043] (2) Preparation of element I (lanthanum) modified MCM-49 molecular sieve catalyst by impregnation method: Compared with step (2) in Example 1, the molecular sieve used is MCM-49 molecular sieve (silicon-aluminum ratio 12, specific surface area 499m²). 2 / g, pore volume 0.59cm 3 / g), the impregnation steps are the same as in Example 1, and finally the elemental lanthanum modified MCM-49 molecular sieve catalyst is obtained, wherein the mass fraction of lanthanum loading is 3%.

[0044] (3) Element I (lanthanum) modified MCM-49 molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded: Compared with step (3) in Example 1, the molecular sieve catalyst is element lanthanum modified MCM-49 molecular sieve catalyst, and the mixing and kneading steps are the same as in Example 1. Finally, composite catalyst F3 (i.e. disproportionation catalyst) is obtained.

[0045] Example 4

[0046] (1) Preparation of WO3 / SiO2 catalyst by impregnation method: wherein the loading mass fraction of WO3 is 8%; the preparation method is the same as in Example 1.

[0047] (2) Preparation of element I (lanthanum) modified β molecular sieve catalyst by impregnation method: Compared with step (2) in Example 1, the molecular sieve used is β molecular sieve (silicon-aluminum ratio 25, specific surface area 610 m²). 2 / g, pore volume 0.318cm 3 / g), the impregnation steps are the same as in Example 1, and finally the elemental lanthanum modified β molecular sieve catalyst is obtained, wherein the mass fraction of lanthanum loading is 3%.

[0048] (3) Element I (lanthanum) modified β molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded: Compared with step (3) in Example 1, the molecular sieve catalyst is element lanthanum modified β molecular sieve catalyst, and the mixing and kneading steps are the same as in Example 1. Finally, composite catalyst F4 (i.e. disproportionation catalyst) is obtained.

[0049] Example 5

[0050] (1) Preparation of WO3 / SiO2 catalyst by impregnation method: wherein the loading mass fraction of WO3 is 8%; the preparation method is the same as in Example 1.

[0051] (2) Preparation of element I (lanthanum) modified ZSM-5 molecular sieve catalyst by impregnation method: Compared with step (2) in Example 1, the molecular sieve used is ZSM-5 molecular sieve (silicon-aluminum ratio 59.3, specific surface area 409 m²). 2 / g), the impregnation steps are the same as in Example 1, and finally the elemental lanthanum modified ZSM-5 molecular sieve catalyst is obtained, wherein the mass fraction of lanthanum loading is 3%.

[0052] (3) Element I (lanthanum) modified ZSM-5 molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded: Compared with step (3) in Example 1, the molecular sieve catalyst is element lanthanum modified ZSM-5 molecular sieve catalyst, and the mixing and kneading steps are the same as in Example 1. Finally, composite catalyst F5 (i.e. disproportionation catalyst) is obtained.

[0053] Example 6

[0054] (1) Preparation of WO3 / SiO2 catalyst by impregnation method: wherein the loading mass fraction of WO3 is 8%; the preparation method is the same as in Example 1.

[0055] (2) Preparation of element I (phosphorus) modified β molecular sieve catalyst by impregnation method: Compared with step (2) in Example 1, the molecular sieve used is β molecular sieve (silicon-to-aluminum ratio 25, specific surface area 610 m²). 2 / g, pore volume 0.318cm 3 / g), the impregnation steps are the same as in Example 1, and finally the elemental phosphorus modified β molecular sieve catalyst is obtained, wherein the mass fraction of phosphorus loading is 4%.

[0056] (3) Element I (phosphorus) modified β molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded: Compared with step (3) in Example 1, the molecular sieve catalyst is element phosphorus modified β molecular sieve catalyst, and the mixing and kneading steps are the same as in Example 1. Finally, composite catalyst F6 (i.e. disproportionation catalyst) is obtained.

[0057] Example 7

[0058] (1) Preparation of WO3 / SiO2 catalyst by impregnation method: wherein the loading mass fraction of WO3 is 8%; the preparation method is the same as in Example 1.

[0059] (2) Preparation of element I (phosphorus) modified ZSM-5 molecular sieve catalyst by impregnation method: Compared with step (2) in Example 1, the molecular sieve used is ZSM-5 molecular sieve (silicon-to-aluminum ratio 59.3, specific surface area 409 m²). 2 / g), the impregnation steps are the same as in Example 1, and finally the elemental phosphorus modified ZSM-5 molecular sieve catalyst is obtained, wherein the mass fraction of phosphorus loading is 4%.

[0060] (3) Element I (phosphorus) modified ZSM-5 molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded: Compared with step (3) in Example 1, the molecular sieve catalyst is element phosphorus modified ZSM-5 molecular sieve catalyst, and the mixing and kneading steps are the same as in Example 1. Finally, composite catalyst F7 (i.e. disproportionation catalyst) is obtained.

[0061] Example 8

[0062] The preparation methods of steps (1), (2), and (3) are the same as in Example 1. After the element I (lanthanum) modified MCM-22 molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded, composite catalyst F1 is obtained for later use.

[0063] (4) Modification of the composite catalyst by impregnation with zinc (II): A certain amount of composite catalyst F1 (20-40 mesh) was weighed and dried in an oven at 150℃ for 20 min, and then 10 g was weighed for later use. The amount m of zinc nitrate hydrate (ZnNO3·xH2O, molecular weight 189.4, analytical grade, purity ≥99.999%) required for loading was calculated. 0.896 g of zinc nitrate hydrate was weighed and added to pure water for ultrasonic oscillation for 10 min. The dried composite catalyst F1 was taken out, placed at room temperature, and then zinc nitrate aqueous solution was added. The mixture was then placed on an ultrasonic instrument and oscillated for 2 h. After standing for 24 h, it was placed in a drying oven at 120℃ for 12 h. After drying, it was placed in a muffle furnace at 500℃ for 5 h and cooled to room temperature to obtain zinc-modified composite disproportionation catalyst FG1, in which the zinc loading was 3%.

[0064] Example 9

[0065] The preparation methods of steps (1), (2), and (3) are the same as in Example 8. After the element I (lanthanum) modified MCM-22 molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded, composite catalyst F1 is obtained for later use.

[0066] (4) Modification of the composite catalyst by impregnation with metal II (sodium): Compared with Example 8, anhydrous sodium carbonate (Na2CO3, molecular weight 105.99, analytical grade, purity ≥99.5%) was loaded with m = 0.116 g. Sodium carbonate aqueous solution was added to the dried composite catalyst F1 to finally obtain sodium-modified composite disproportionation catalyst FG2, wherein the sodium loading was 0.5%.

[0067] Example 10

[0068] The preparation methods of steps (1), (2), and (3) are the same as in Example 4. After the element I (lanthanum) modified β molecular sieve catalyst and WO3 / SiO2 catalyst are mixed and kneaded, composite catalyst F4 is obtained for later use.

[0069] (4) Modification of the composite catalyst by impregnation with metal II (sodium): Compared with Example 8, anhydrous sodium carbonate (Na2CO3, molecular weight 105.99, analytical grade, purity ≥99.5%) was loaded with m = 0.070 g. Sodium carbonate aqueous solution was added to the dried composite catalyst F4 to finally obtain sodium-modified composite disproportionation catalyst FG3, in which the sodium loading was 0.3%.

[0070] Example 11

[0071] The preparation methods of steps (1), (2), and (3) are the same as in Example 5. After the lanthanum-modified ZSM-5 molecular sieve catalyst and the WO3 / SiO2 catalyst are mixed and kneaded, the composite catalyst F5 is obtained for later use.

[0072] (4) Modification of the composite catalyst by impregnation with metal II (sodium): Compared with Example 8, anhydrous sodium carbonate (Na2CO3, molecular weight 105.99, analytical grade, purity ≥99.5%) was loaded with m = 0.035 g. Sodium carbonate aqueous solution was added to the dried composite catalyst F5 to finally obtain sodium-modified composite disproportionation catalyst FG4, in which the sodium loading was 0.15%.

[0073] Comparative Example 1

[0074] A single disproportionation catalyst with SiO2 as the support and WO3 as the loading was used as a comparative example: a certain amount of SiO2 powder (analytical grade, content ≥99%, specific surface area ≥100m²) was weighed. 2 After drying the ammonium metatungstate (Hg) in a 150℃ oven for 20 minutes, weigh out 10g for later use; calculate the required load of ammonium metatungstate (Hg). 28 N6O 41 W 12 Weigh out m (analytical grade, purity ≥ 99.5%); weigh m = 0.934 g of ammonium metatungstate and add pure water for ultrasonic oscillation for 10 min; take out the dried SiO2, place it at room temperature, add ammonium metatungstate aqueous solution, place it on an ultrasonic instrument for oscillation for 2 h, and then let it stand for 24 h to obtain tungsten salt-loaded SiO2; put the tungsten salt-loaded SiO2 into a crucible and dry it in a 120℃ drying oven for 12 h; after drying, calcine it in a muffle furnace at 450℃ for 5 h, and cool it to room temperature to obtain WO3 / SiO2 catalyst, in which the mass fraction of WO3 loading is 8%.

[0075] The disproportionation catalysts prepared in Examples 1-11 and Comparative Example 1 were loaded and pretreated according to the following procedure:

[0076] Catalyst loading: The catalyst is loaded in stages. A mixed catalyst (disproportionation catalyst: isomerization catalyst = 1:1-1:15) is loaded in the lower middle part of the isothermal zone of the reactor. 1-5 parts of the isomerization catalyst are loaded in the upper middle part of the isothermal zone. The space between the two catalyst sections and the rest of the reactor are filled with inert alumina ceramic balls. The isomerization catalyst is prepared as follows: magnesium oxide (analytical grade, purity ≥99.95%, molecular weight 40.30) and deionized water are mixed at a mass ratio of 1:10 and subjected to hydrothermal treatment under boiling conditions for 24 hours. After filtration, washing, and drying in a 120℃ oven for 2 hours, it is calcined in a 450℃ muffle furnace for 5 hours. After cooling, it is pressed into tablets and crushed to 20-40 mesh for later use.

[0077] Catalyst pretreatment: After the catalyst is loaded, nitrogen gas is introduced to make the reaction pressure reach 1 MPa, and then the temperature is raised to 400℃ under nitrogen atmosphere and held for 2 hours; then it is reduced for 30 minutes at 400℃ in an atmosphere of hydrogen:nitrogen = 1:10 (volume ratio) with a hydrogen flow rate of 30 ml / min; then the temperature is switched to nitrogen and raised to 550℃ and held for 2 hours to complete the pretreatment.

[0078] Reaction conditions: Reaction temperature is 250℃-500℃ (preferably 300℃-450℃); the reactant gases are ethylene (≥99.9%) and 1-butene (≥99.9%), with a molar ratio of 0.2:1-10:1 (preferably 1:1-5:1); the reaction pressure is 0.1MPa-5MPa (preferably 0.1MPa-3MPa); the total mass hourly space velocity (MHV) is 1-50 h⁻¹. -1 (preferably 1-10h) -1 The disproportionation reaction was carried out under the above reaction conditions, and the reaction products were analyzed online by gas chromatography. The time from the start of the reaction until the 1-butene conversion decreased to 80% of the initial conversion is defined as the catalyst stability factor t. The reaction results are shown in the table below:

[0079] Table 1 Results of the 1-butene disproportionation reaction using the composite disproportionation catalyst

[0080]

[0081] In summary, compared to the single inert support disproportionation catalyst WO3 / SiO2, the molecular sieve inert support composite disproportionation catalyst of this invention significantly improves the overall selectivity and stability of propylene, with the highest overall propylene selectivity reaching 96.41% and the highest catalyst stability factor reaching 521 h. This is due to the unique pore structure of the molecular sieve in the composite disproportionation catalyst. On the one hand, it greatly enhances the carbon-holding capacity; on the other hand, the diffusion coefficient of propylene in the pore structure is much greater than that of aromatics, thus promoting the chemical reaction in a direction favorable to propylene formation and suppressing side reactions. Metal II modification significantly suppresses the acid catalytic activity of the composite disproportionation catalyst, inhibits side reactions, reduces the deep reaction of propylene, improves propylene selectivity, and also improves catalyst stability.

[0082] This invention can have other embodiments based on the above preparation method, which will not be listed one by one. Therefore, any simple modifications, equivalent changes and alterations made by any person skilled in the art to the above embodiments without departing from the scope of the technical solution of this invention shall still fall within the scope of the technical solution of this invention.

Claims

1. A composite disproportionation catalyst for the production of propylene by the disproportionation of ethylene and 1-butene, characterized in that, The following components and mass fractions are included: WO3 / SiO2 catalyst: 1%-49%; Element I modified molecular sieve catalyst: 50%-98%; The balance is a binder; The mass fraction of element I loaded in the element I modified molecular sieve catalyst is 0.01%-10%; element I is one or more of rare earth metals and P, Ga, Sn, Bi, and the molecular sieve is one or more of MCM-22 group molecular sieves, Y type molecular sieves, β molecular sieves, HMS series molecular sieves, and SBA series molecular sieves.

2. A composite disproportionation catalyst for the preparation of propylene by the disproportionation of ethylene and 1-butene according to claim 1, characterized in that, The mass fraction of WO3 loaded in the WO3 / SiO2 catalyst is 1%-20%.

3. A composite disproportionation catalyst for the preparation of propylene by the disproportionation of ethylene and 1-butene according to claim 1, characterized in that, The binder is one or more of SB powder, white carbon black, water glass, and sesbania powder.

4. A process for the preparation of a composite disproportionation catalyst for the disproportionation of ethylene and 1-butene to propylene, characterized in that, The following steps are included: (1) Preparation of WO3 / SiO2 catalyst: dry SiO2 and weigh it for later use; calculate the amount of soluble tungsten salt required for loading, add pure water to the weighed soluble tungsten salt and perform ultrasonic oscillation to obtain a soluble tungsten salt aqueous solution; place the dried SiO2 to room temperature and add the soluble tungsten salt aqueous solution, place it on an ultrasonic instrument for oscillation, and after standing, obtain SiO2 loaded with tungsten salt; dry the SiO2 loaded with tungsten salt and place it in a muffle furnace for calcination, cool to room temperature, and obtain the WO3 / SiO2 catalyst; (2) Preparation of element I modified molecular sieve catalyst: dry the molecular sieve to obtain molecular sieve raw powder and weigh it for later use; calculate the amount of element I soluble salt required for loading, add pure water to the weighed element I soluble salt and perform ultrasonic oscillation to obtain an element I soluble salt aqueous solution; place the molecular sieve raw powder to room temperature and add the element I soluble salt aqueous solution, place it on an ultrasonic instrument for oscillation, and after standing, obtain an element I loading mixture; dry the element I loading mixture and place it in a muffle furnace for calcination, cool to room temperature, and obtain the element I modified molecular sieve catalyst; (3) Kneading the element I modified molecular sieve catalyst and the WO3 / SiO2 catalyst into shape: dry the element I modified molecular sieve catalyst, the WO3 / SiO2 catalyst, and the binder and weigh them according to the weight fraction of each component in the composite disproportionation catalyst for later use; weigh nitric acid with a water powder ratio of 0.4 and a mass concentration of 4% for later use; mix the weighed element I modified molecular sieve catalyst, the WO3 / SiO2 catalyst, and the binder evenly in a mortar, add nitric acid while stirring, obtain a binding mixture after the completion of nitric acid addition, knead the binding mixture into shape, dry after standing, and then place it in a muffle furnace for calcination to obtain a composite catalyst; (4) Modification of the composite catalyst with a metal II soluble salt solution: dry the composite catalyst and weigh it for later use; calculate the amount of metal II soluble salt required for loading, add pure water to the weighed metal II soluble salt and perform ultrasonic oscillation to obtain a metal II soluble salt aqueous solution; place the dried composite catalyst to room temperature and add the metal II soluble salt aqueous solution, and place it on an ultrasonic instrument for oscillation, and after standing, obtain a metal II loading mixture, dry the metal II loading mixture, place it in a muffle furnace for calcination, cool to room temperature, and obtain a composite disproportionation catalyst; The element I in step (2) is one or more of rare earth metal and P, Ga, Sn, Bi, and the molecular sieve is one or more of MCM-22 family molecular sieve, Y molecular sieve, beta molecular sieve, HMS series molecular sieve, and SBA series molecular sieve; The metal II in step (4) is one or more of alkali metal, alkaline earth metal and Group ⅡB metal; the ratio of the composite disproportionation catalyst to the metal II is 85:15-99.9999:0.0001.

5. A process for the preparation of a composite dismutation catalyst for the dismutation of ethylene and 1-butene to propylene according to claim 4, characterized in that, The soluble tungsten salt is selected from alkali metal salt or ammonium salt thereof; the soluble element I salt is selected from nitrate, sulfate or ammonium salt thereof; and the soluble metal II salt is selected from nitrate, sulfate or ammonium salt thereof.

6. A process for the preparation of a composite dismutation catalyst for the dismutation of ethylene and 1-butene to propylene according to claim 4, characterized in that, The calculation method of the soluble tungsten salt and the soluble salt in steps (1), (2) and (4) is m=(f×z) / ((1-z)×x×y); wherein x is the purity of the soluble salt, y is the mass fraction of tungsten trioxide, element I or metal II contained in the soluble salt, z is the mass fraction of the supported catalyst, f is the mass of SiO2 or molecular sieve or composite catalyst, and m is the mass of the soluble salt.

7. A process for the preparation of a composite dismutation catalyst for the dismutation of ethylene and 1-butene to propylene according to claim 4, characterized in that, The calcination temperature of the supported mixture in steps (1), (2) and (4) is 400-600℃, and the calcination time is 4-6h; the calcination temperature of the binding mixture in step (3) is 400-700℃, and the calcination time is 2-6h.

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