A propane dehydrogenation catalyst and its preparation method and application

Abstract

The present invention provides a propane dehydrogenation catalyst and a preparation method and application thereof, and relates to the technical field of catalysts. The propane dehydrogenation catalyst comprises a V2O5-CeO2-Al2O3 composite carrier and an active component; the active component is Cr element, K element, Zr element, Ni element and Sn element; the preparation method comprises the following steps: (1) aging treatment with alkaline solution, aluminum nitrate nonahydrate and cerium nitrate hexahydrate, dispersion, dropwise addition of an acidic solution containing ammonium metavanadate, aging treatment again, drying, and gradient temperature roasting to obtain a V2O5-CeO2-Al2O3 composite carrier; (2) vacuum treatment of the V2O5-CeO2-Al2O3 composite carrier and impregnation solution; (3) roasting. The propane dehydrogenation catalyst prepared by the present invention has a high specific surface area and high strength, the active components are evenly dispersed on the carrier surface, and the catalytic performance and service life are significantly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of catalysts, and in particular relates to a propane dehydrogenation catalyst and a preparation method and application thereof. Background Art

[0002] Propylene is an important raw material in the chemical field. In addition to being used to produce polypropylene, it can also be used to produce organic chemical products such as acrylonitrile, isopropanol, phenol, acetone, butanol, octanol, and acrylic acid. In recent years, the rapid development of propylene downstream products has greatly increased the demand for propylene. At present, the production of propylene mostly adopts the cracking method and FCC (catalytic cracking) method. With the increasing depletion of petroleum resources and the enhancement of environmental awareness, it is urgent to develop a propane dehydrogenation catalyst with high performance and long service life.

[0003] In the process of technical research on propane dehydrogenation to propylene, Chinese invention patent CN112403458A discloses a double-active center propane dehydrogenation catalyst and its preparation method and application, including a carrier and an active component loaded on the carrier; the carrier is made of non-metallic carbon material, the active component is made of metal chromium oxide, the chromium loading is 0.3%-5%, the pore size of the mesoporous carbon is 2nm-50nm, and the specific surface area is 2500m 2 / g, pore volume 2.25cm 3 / g, and the specific surface area of ​​the carrier is 500m² / g-1700m² / g. The method adopts an impregnation method, has a simple processing process, high processing efficiency, and can form a dual-active center catalyst system with a low amount of chromium loaded.

[0004] Chinese invention patent CN116764631A discloses a propane dehydrogenation catalyst, preparation method and application, wherein the propane dehydrogenation catalyst comprises a carrier and an active component loaded on the carrier; the carrier is spherical activated carbon; the active component comprises a Pt component, a Cr component and an alkali metal component. The spherical activated carbon is a spherical particle of 0.5mm-1.8mm, with a specific surface area of ​​700m 2 / g-2200m 2 / g, pore volume of 0.5mL / g-1.5mL / g, micropores with pore diameters of 0.5nm-2.0nm and mesopores of 10nm-30nm. The catalyst prepared by the invention with spherical activated carbon as carrier has high catalytic activity, propylene selectivity and catalytic stability.

[0005] Although the catalyst prepared by the above invention has good catalytic activity, a higher reaction temperature is often required in the preparation of propylene, while the metal carbon material is not resistant to high temperature, has low mechanical strength, wears quickly, and has a short service life. The catalytic performance of the catalyst is significantly reduced after repeated use.

[0006] Chinese invention patent CN103301830A adopts a one-step hydrothermal synthesis method to synthesize the catalyst active component chromium oxide by combining a chromium source, an aluminum source, a template and deionized water, and disperses it on a carrier porous alumina to prepare a propane dehydrogenation catalyst. Chinese invention patent CN117643875A discloses a preparation method and application of a chromium-based propane dehydrogenation catalyst, wherein the catalyst is prepared by modifying a composite carrier with multiple active components; wherein the composite carrier is composed of an XY-Al compound prepared by a precipitation-impregnation method and γ-Al2O3, η-Al2O3 or δ-Al2O3, wherein X is from a transition metal and Y is from an alkaline earth metal; the multiple active components are Cr, Ga, alkali metals and rare earth metals; based on the mass of the catalyst itself, the catalyst comprises the following components in percentage by mass: 10%-20% active component Cr2O3, 0.05%-5% Ga2O3, 0.1%-2.0% alkali metals, 0.1%-2.0% rare earth metals, 60%-80% of the composite carrier and the remainder of a binder; the contents of X and Y in the composite carrier are both 0.01%-5.0%.

[0007] The traditional preparation method of chromium oxide / aluminum oxide catalyst is impregnation method, which makes it difficult to evenly disperse the active components on the surface of the carrier alumina, and the different specific surface areas and pore sizes of commercially available alumina carriers will affect the catalytic activity of the catalyst. In addition, the alumina carrier needs to load a higher content of Cr to achieve higher catalytic performance, which is easy to cause waste of resources and environmental pollution.

[0008] In view of this, the present invention adopts a V2O5-CeO2-Al2O3 composite carrier to load a small amount of active components to reduce the occurrence of aggregation; the surface of the V2O5-CeO2-Al2O3 composite carrier has more active groups, which are tightly combined with specific types of active components under vacuum conditions to improve the catalytic performance and service life. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a propane dehydrogenation catalyst and a preparation method and application thereof; the V2O5-CeO2-Al2O3 composite carrier in the catalyst has a large specific surface area, many and uniform surface pores, and high strength, thereby reducing the occurrence of active component aggregation; the catalyst of the present invention, which uniformly loads active components, can withstand high temperatures in the preparation of propylene, thereby extending the life of the catalyst; in addition, the active components Cr, K, Zr, Ni and Sn are mixed in specific proportions, so that the active components can achieve higher catalytic performance of the catalyst with a smaller amount.

[0010] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0011] First, the present invention provides a propane dehydrogenation catalyst, including a V2O5-CeO2-Al2O3 composite carrier and active components; the active components are Cr element, K element, Zr element, Ni element and Sn element; the mass ratio of the Cr element, K element, Zr element, Ni element and Sn element is 10-20:0.5-1.5:1-2:0.5-1.5:0.5-1.5.

[0012] Preferably, the mass ratio of the Cr element, the K element, the Zr element, the Ni element and the Sn element is 15.5:1.0:1.5:1.0:1.0.

[0013] Preferably, the weight of the active component is 10%-22% of the weight of the propane dehydrogenation catalyst.

[0014] Further preferably, the weight of the active component is 15%-21% of the weight of the propane dehydrogenation catalyst.

[0015] More preferably, the weight of the active component is 20% of the weight of the propane dehydrogenation catalyst.

[0016] In the present invention, the source of the active component is not limited to chromium oxide, chromium trioxide, chromium chloride, chromium bromide, chromium nitrate, chromium sulfate, chromium phosphate, potassium hydroxide, potassium nitrate, zirconium nitrate (Zr(NO3)4), nickel nitrate hexahydrate (Ni(NO3)2·6H2O), and tin nitrate (Sn(NO3)4). The present invention does not limit the source of the active component, and all substances containing active components and soluble in water for preparing catalysts can achieve the technical effects of the present invention.

[0017] Then, the present invention provides a method for preparing the above propane dehydrogenation catalyst, comprising the steps of:

[0018] (1) Preparation of V2O5-CeO2-Al2O3 composite carrier:

[0019] (1.1) Add the alkaline solution to the mixed solution of Al(NO3)3·9H2O and Ce(NO3)3·6H2O, stir evenly, and perform the first aging to obtain precipitate A;

[0020] (1.2) Precipitate A is dispersed with a dispersion liquid, and then an acidic solution containing ammonium metavanadate is added dropwise at a rate of 5 mL / min-20 mL / min, and a second aging is performed under stirring conditions, and the solution is removed to obtain a precipitate B; the precipitate B is calcined at a gradient temperature to obtain a V2O5-CeO2-Al2O3 composite carrier;

[0021] (2) Impregnation treatment:

[0022] (2.1) Preparing an impregnation solution: dissolving a substance containing active components of Cr, K, Zr, Ni and Sn in water to obtain an impregnation solution;

[0023] (2.2) Vacuum impregnation: the impregnation solution is added dropwise to the V2O5-CeO2-Al2O3 composite support and vacuum treated to obtain a catalyst pretreatment product;

[0024] (3) The catalyst pretreatment product is calcined to obtain a propane dehydrogenation catalyst.

[0025] Preferably, in step (1.1), the alkaline solution is selected from at least one of aqueous ammonia with a volume concentration of 30%-50% and sodium hydroxide solution with a mass concentration of 2%-5%.

[0026] Further preferably, in step (1.1), the alkaline solution is aqueous ammonia with a volume concentration of 40%.

[0027] Preferably, in step (1.1), the volume ratio of the alkaline solution to the mixed solution is 1:60-120; further preferably, the volume ratio of the alkaline solution to the mixed solution is 1:80.

[0028] Preferably, in step (1.1), the molar ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and ammonium metavanadate is 6-10:2:1; further preferably, the molar ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and ammonium metavanadate is 4:2:1.

[0029] Preferably, in step (1.1), in the mixed solution, the molar concentration of Al(NO3)3·9H2O is 0.2 mol / L-0.6 mol / L, and the molar concentration of Ce(NO3)3·6H2O is 0.1 mol / L-0.3 mol / L.

[0030] Further preferably, the molar concentration of Al(NO3)3·9H2O is 0.4 mol / L, and the molar concentration of Ce(NO3)3·6H2O is 0.2 mol / L.

[0031] Preferably, in step (1.1), the first aging condition is: aging at 100°C-150°C for 10h-20h.

[0032] Further preferably, the first aging condition is: aging at 120° C. for 16 h.

[0033] Preferably, step (1.1) further comprises a drying step: removing the solution after aging and drying at 80°C-120°C for 4h-6h.

[0034] Preferably, in step (1.2), the dispersion liquid is polyethylene glycol and water in a volume ratio of 10:30-50; further preferably, the dispersion liquid is polyethylene glycol and water in a volume ratio of 10:40.

[0035] Preferably, in step (1.2), the mass volume ratio of the precipitate A to the dispersion is 1:30 g / mL-100 g / mL; further preferably, the mass volume ratio of the precipitate A to the dispersion is 1:50 g / mL.

[0036] Preferably, in step (1.2), the polyethylene glycol is selected from at least one of PEG 400 and PEG 600.

[0037] Preferably, in step (1.2), the dispersion speed is 100 rpm-400 rpm; if necessary, ultrasonic treatment is performed to make the precipitate dispersed evenly.

[0038] Preferably, in step (1.2), the dropping rate is 10 mL / min.

[0039] Preferably, in step (1.2), the acidic solution is selected from at least one of phosphoric acid, ascorbic acid and tartaric acid.

[0040] More preferably, the mass concentration of the acidic solution is 1%-3%; even more preferably, the mass concentration of the acidic solution is 2%.

[0041] Preferably, in step (1.2), the molar concentration of the ammonium metavanadate in the acidic solution is 0.2 mol / L-0.8 mol / L; further preferably, the molar concentration of the ammonium metavanadate in the acidic solution is 0.5 mol / L.

[0042] Preferably, in step (1.2), the second aging conditions are: 80°C-100°C, 100rpm-300rpm, stirring for 6h-12h.

[0043] Further preferably, in step (1.2), the second aging conditions are: stirring at 90° C. and 200 rpm for 8 h.

[0044] Preferably, in step (1.2), the gradient temperature calcination is specifically as follows: first calcine at 300°C-400°C for 1h-3h, then increase the temperature to 700°C-800°C at 5°C / min-8°C / min, and calcine for 1h-3h to obtain a V2O5-CeO2-Al2O3 composite carrier.

[0045] Further preferably, in step (1.2), the gradient temperature rise calcination is specifically as follows: first calcine at 350°C for 2h, then increase the temperature to 750°C at 6°C / min, and calcine for 2h to obtain a V2O5-CeO2-Al2O3 composite carrier.

[0046] Preferably, step (1.2) requires drying at 80°C-120°C for 4h-6h before calcination.

[0047] Preferably, in step (2.1), the mass ratio of the Cr element, the K element, the Zr element, the Ni element and the Sn element is 10-20:0.5-1.5:1-2:0.5-1.5:0.5-1.5.

[0048] Further preferably, in step (2.1), the mass ratio of the Cr element, the K element, the Zr element, the Ni element and the Sn element is 15.5:1.0:1.5:1.0:1.0.

[0049] Preferably, in step (2.1), the total mass concentration of active components in the impregnation solution is 10 g / L-30 g / L.

[0050] Further preferably, in the impregnation solution, the total mass concentration of active components is 20 g / L.

[0051] Preferably, in step (2.2), the vacuum impregnation is performed by uniformly dropping the impregnation solution onto the surface of the V2O5-CeO2-Al2O3 composite carrier according to the mass ratio of the active components to obtain the propane dehydrogenation catalyst.

[0052] Preferably, in step (2.2), the vacuum treatment time is 0.5 h-2 h; further preferably, the vacuum treatment time is 1 h.

[0053] Preferably, in step (3), the calcination is specifically: calcination at 450°C-600°C for 4h-7h; further preferably, in step (3), the calcination is specifically: calcination at 500°C for 5h.

[0054] Preferably, step (3) requires drying at 80°C-120°C for 4h-6h before calcination.

[0055] Preferably, in the propane dehydrogenation catalyst described in step (3), the weight of the active component is 10%-22% of the weight of the propane dehydrogenation catalyst.

[0056] Further preferably, the weight of the active component is 15%-21% of the weight of the propane dehydrogenation catalyst.

[0057] More preferably, the weight of the active component is 20% of the weight of the propane dehydrogenation catalyst.

[0058] Finally, the present invention provides an application of a propane dehydrogenation catalyst in the preparation of propylene, wherein the propane dehydrogenation catalyst is the above-mentioned propane dehydrogenation catalyst, or is the propane dehydrogenation catalyst obtained by the above-mentioned preparation method.

[0059] Preferably, the catalytic performance of the propane dehydrogenation catalyst is: specific surface area 250m 2 / g-300m 2 / g, average strength 200N-270N, propane conversion 48%-55%, propylene selectivity 90%-94%, propane conversion after 36h of continuous reaction 40%-50%.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] 1. The present invention uses a V2O5-CeO2-Al2O3 composite carrier to closely combine with the active components, thereby reducing the amount of active components used. The active components Cr element, K element, Zr element, Ni element and Sn element are specifically proportioned, and the catalyst can achieve higher catalytic performance with a smaller amount of active components.

[0062] 2. The present invention improves the traditional Al2O3 monomer catalyst carrier, and prepares a V2O5-CeO2-Al2O3 composite carrier with high strength, large specific surface area, many surface pores and uniform pore size by loading V2O5 and CeO2, thereby reducing the aggregation of active components; the catalyst of the present invention can withstand high temperatures in the preparation and application of propylene, thereby extending the life of the catalyst.

[0063] 3. The surface of the V2O5-CeO2-Al2O3 composite carrier of the present invention has a large number of active groups. The vacuum treatment can closely combine the active components with the composite carrier, improve the catalytic performance and service life, and still have a high propane conversion rate and propylene selectivity after long-term use. DETAILED DESCRIPTION

[0064] The following non-limiting examples can enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. The following content is merely an exemplary description of the scope of the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of the present invention.

[0065] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those generally understood by those of ordinary skill in the art to which the present invention belongs.

[0066] The present invention is further described below by way of specific examples. Unless otherwise specified, the various chemical reagents used in the examples of the present invention are obtained through conventional commercial channels.

[0067] In the following examples, the polyethylene glycol 400 was purchased from Aladdin; the ammonium metavanadate was purchased from Aladdin, with a CAS number of 7803-55-6. The above components, products from different manufacturers, have no significant effect on the effects.

[0068] Example 1

[0069] A propane dehydrogenation catalyst has the following composition by weight percentage: 15.5% Cr element, 1% K element, 1.5% Zr element, 1% Ni element, 1% Sn element, and a V2O5-CeO2-Al2O3 composite carrier supplemented to 100%.

[0070] The preparation method of the above-mentioned propane dehydrogenation catalyst is:

[0071] (1) Preparation of V2O5-CeO2-Al2O3 composite carrier:

[0072] (1.1) Add 40% ammonia water to a mixed solution of 0.4 mol / L Al(NO3)3·9H2O and 0.2 mol / L Ce(NO3)3·6H2O, with the volume ratio of ammonia water to the mixed solution being 1:80; stir evenly and perform the first aging; the first aging temperature is 120°C and the aging time is 16 h. After removing the solution, dry at 100°C for 5 h to obtain precipitate A;

[0073] (1.2) Precipitate A was dispersed with a dispersion solution having a volume ratio of PEG 400:water = 10:40, and then a 2% tartaric acid solution containing ammonium metavanadate (the molar concentration of ammonium metavanadate was 0.5 mol / L) was added dropwise at a rate of 10 mL / min, and a second aging was performed under stirring at 200 rpm; the second aging temperature was 90°C and the aging time was 8 h; the solution was removed, and the precipitate was dried at 100°C for 5 h to obtain precipitate B;

[0074] The precipitate B was first calcined at 350°C for 2 h, and then increased to 750°C at 6°C / min for 2 h to obtain a V2O5-CeO2-Al2O3 composite support.

[0075] (2) Impregnation treatment:

[0076] (2.1) Preparing an impregnation solution: dissolving chromium trioxide, potassium nitrate, zirconium nitrate, nickel nitrate hexahydrate and tin nitrate containing active components in water, and stirring to obtain an impregnation solution, wherein the mass ratio of the Cr element, K element, Zr element, Ni element and Sn element is 15.5:1.0:1.5:1.0:1.0; and the total mass concentration of the active components Cr element, K element, Zr element, Ni element and Sn element in the impregnation solution is 20 g / L;

[0077] (2.2) Vacuum impregnation: the impregnation solution is uniformly added dropwise to the surface of the V2O5-CeO2-Al2O3 composite support in a specific weight ratio, and vacuum treated for 1 h to obtain a catalyst pretreatment product;

[0078] The specific weight ratio is: in the dripped impregnation solution, the weight of the active component is 20% of the weight of the propane dehydrogenation catalyst.

[0079] (3) The catalyst pretreatment product was dried at 100°C for 5 h and then calcined at 500°C for 5 h to obtain a propane dehydrogenation catalyst.

[0080] Example 2

[0081] The difference from Example 1 is that step (1.1) is different, specifically:

[0082] Ammonia water with a volume concentration of 50% was added to a mixed solution of 0.6 mol / L Al(NO3)3·9H2O and 0.2 mol / L Ce(NO3)3·6H2O, and the volume ratio of ammonia water to the mixed solution was 1:60; the mixture was stirred evenly and the first aging was performed; the first aging temperature was 100°C and the aging time was 20 h. After removing the solution, the mixture was dried at 100°C for 5 h to obtain precipitate A.

[0083] The remaining steps are the same as those in Example 1.

[0084] Example 3

[0085] The difference from Example 1 is that step (1.1) is different, specifically:

[0086] Step (1.1): adding a sodium hydroxide solution with a volume concentration of 5% to a mixed solution of 1 mol / L Al(NO3)3·9H2O and 0.2 mol / L Ce(NO3)3·6H2O, wherein the volume ratio of the sodium hydroxide solution to the mixed solution is 1:120; stirring evenly, and performing the first aging; the first aging temperature is 150°C and the aging time is 10 h. After removing the solution, drying at 100°C for 5 h to obtain a precipitate A.

[0087] The remaining steps are the same as those in Example 1.

[0088] Example 4

[0089] The difference from Example 1 is that step (1.2) is different, specifically:

[0090] Step (1.2): Precipitate A is dispersed with a dispersion having a volume ratio of PEG 400:water = 10:30, and then a 2% phosphoric acid solution containing ammonium metavanadate (the molar concentration of ammonium metavanadate is 0.2 mol / L) is added dropwise at a rate of 20 mL / min, and a second aging is performed under stirring at 100 rpm; the second aging temperature is 80°C and the aging time is 12 h; the solution is removed, and the precipitate is dried at 100°C for 5 h to obtain precipitate B;

[0091] The precipitate B was first calcined at 300°C for 1 h, and then increased to 700°C at a rate of 5°C / min and calcined for 3 h to obtain a V2O5-CeO2-Al2O3 composite support.

[0092] The remaining steps are the same as those in Example 1.

[0093] Example 5

[0094] The difference from Example 1 is that step (1.2) is different, specifically:

[0095] Step (1.2): Precipitate A is dispersed with a dispersion having a volume ratio of PEG 400:water = 10:50, and then a 3% tartaric acid solution containing ammonium metavanadate (the molar concentration of ammonium metavanadate is 0.8 mol / L) is added dropwise at a rate of 5 mL / min, and a second aging is performed under stirring at 300 rpm; the second aging temperature is 100°C and the aging time is 6 h; the solution is removed, and the precipitate is dried at 100°C for 5 h to obtain a precipitate B;

[0096] The precipitate B was first calcined at 400°C for 3 h, and then increased to 800°C at 8°C / min for 1 h to obtain a V2O5-CeO2-Al2O3 composite support.

[0097] The remaining steps are the same as those in Example 1.

[0098] Example 6

[0099] A propane dehydrogenation catalyst has the following composition by weight percentage: 10% Cr element, 1.5% K element, 2% Zr element, 1.5% Ni element, 1.5% Sn element, and a V2O5-CeO2-Al2O3 composite carrier making up to 100%.

[0100] The preparation method of the above-mentioned propane dehydrogenation catalyst is:

[0101] Step (1) is the same as in Example 1.

[0102] Step (2) impregnation treatment:

[0103] Step (2.1): preparing an impregnation solution: dissolving chromium trioxide, potassium nitrate, zirconium nitrate, nickel nitrate hexahydrate and tin nitrate containing active components in water, and stirring to obtain an impregnation solution, wherein the mass ratio of the Cr element, the K element, the Zr element, the Ni element and the Sn element is 10:1.5:2:1.5:1.5; the total mass concentration of the active components Cr element, K element, Zr element, Ni element and Sn element in the impregnation solution is 20 g / L;

[0104] (2.2) Vacuum impregnation: the impregnation solution is uniformly added dropwise to the surface of the V2O5-CeO2-Al2O3 composite support in a specific weight ratio, and vacuum treated for 1 h to obtain a catalyst pretreatment product;

[0105] The specific weight ratio is: in the dripped impregnation solution, the weight of the active component is 20% of the weight of the propane dehydrogenation catalyst.

[0106] (3) The catalyst pretreatment product was dried at 100°C for 5 h and then calcined at 500°C for 5 h to obtain a propane dehydrogenation catalyst.

[0107] Example 7

[0108] A propane dehydrogenation catalyst has the following composition by weight percentage: 20% Cr element, 0.5% K element, 1% Zr element, 0.5% Ni element, 0.5% Sn element, and a V2O5-CeO2-Al2O3 composite carrier making up to 100%.

[0109] The preparation method of the above-mentioned propane dehydrogenation catalyst is:

[0110] Step (1) is the same as in Example 1.

[0111] Step (2) impregnation treatment:

[0112] Step (2.1): preparing an impregnation solution: dissolving chromium trioxide, potassium nitrate, zirconium nitrate, nickel nitrate hexahydrate and tin nitrate containing active components in water, and stirring to obtain an impregnation solution, wherein the mass ratio of the Cr element, the K element, the Zr element, the Ni element and the Sn element is 20:0.5:1:0.5:0.5; and the total mass concentration of the active components Cr element, K element, Zr element, Ni element and Sn element in the impregnation solution is 20 g / L;

[0113] (2.2) Vacuum impregnation: the impregnation solution is uniformly added dropwise to the surface of the V2O5-CeO2-Al2O3 composite support in a specific weight ratio, and vacuum treated for 1 h to obtain a catalyst pretreatment product;

[0114] The specific weight ratio is: in the dripped impregnation solution, the weight of the active component is 20% of the weight of the propane dehydrogenation catalyst.

[0115] (3) The catalyst pretreatment product was dried at 100°C for 5 h and then calcined at 500°C for 5 h to obtain a propane dehydrogenation catalyst.

[0116] Comparative Example 1

[0117] The difference from Example 1 is that the composite carrier in step (1) is different. In this comparative example, the modification of CeO2 in step (1.1) was not performed, and a V2O5-Al2O3 composite carrier was obtained:

[0118] Step (1.1): adding ammonia water with a volume concentration of 40% to a 0.4 mol / L Al(NO3)3·9H2O solution, wherein the volume ratio of ammonia water to Al(NO3)3·9H2O solution is 1:80; after stirring evenly, performing the first aging; the first aging temperature is 120°C and the aging time is 16 hours. After removing the solution, drying at 100°C for 5 hours obtains a precipitate A;

[0119] Step (1.2) Precipitate A is dispersed with a dispersion having a volume ratio of PEG 400:water = 10:40, and then a 2% tartaric acid solution containing ammonium metavanadate (the molar concentration of ammonium metavanadate is 0.5 mol / L) is added dropwise at a rate of 10 mL / min, and a second aging is performed under stirring at 200 rpm; the second aging temperature is 90° C. and the aging time is 8 h; the solution is removed, and the mixture is dried at 100° C. for 5 h to obtain a precipitate B;

[0120] The precipitate B was first calcined at 350°C for 2 h, and then increased to 750°C at 6°C / min for 2 h to obtain a V2O5-Al2O3 composite support.

[0121] Step (2) and step (3) are the same as in Example 1.

[0122] Comparative Example 2

[0123] The difference from Example 1 is that the composite carrier of step (1) is different. In this comparative example, the V2O5 modification of step (1.2) is not performed, and the carrier is a CeO2-Al2O3 composite carrier:

[0124] Step (1): Preparation of CeO2-Al2O3 composite carrier:

[0125] Ammonia water with a volume concentration of 40% is added to a mixed solution of 0.4 mol / L Al(NO3)3·9H2O and 0.2 mol / L Ce(NO3)3·6H2O, and the volume ratio of ammonia water to the mixed solution is 1:80; after stirring evenly, the first aging is carried out; the first aging temperature is 120°C, the aging time is 16h, and after removing the solution, it is dried at 100°C for 5h; the obtained precipitate is first calcined at 350°C for 2h, and then increased to 750°C at 6°C / min for 2h to obtain a CeO2-Al2O3 composite carrier.

[0126] Step (2) and step (3) are the same as in Example 1.

[0127] Comparative Example 3

[0128] The difference from Example 1 is that the calcination step in step (1.2) is different, and the temperature increase calcination is not performed.

[0129] Step (1.1): same as in Example 1;

[0130] Step (1.2): Precipitate A is dispersed with a dispersion solution having a volume ratio of PEG 400:water = 10:40, and then a 2% tartaric acid solution containing ammonium metavanadate (the molar concentration of ammonium metavanadate is 0.5 mol / L) is added dropwise at a rate of 10 mL / min, and a second aging is performed under stirring at 200 rpm; the second aging temperature is 90°C and the aging time is 8 h; the solution is removed, and the precipitate is dried at 100°C for 5 h to obtain a precipitate B;

[0131] The precipitate B was directly calcined at 750°C at a rate of 6°C / min for 2h to obtain a V2O5-CeO2-Al2O3 composite support.

[0132] Step (2) and step (3) are the same as in Example 1.

[0133] Comparative Example 4

[0134] The difference from Example 1 is that the acid solution in step (1.2) is added by pouring directly, and the carrier is not prepared by dropwise addition. The rest is the same as Example 1.

[0135] Comparative Example 5

[0136] The difference from Example 1 is that the ammonium metavanadate in step (1.2) is replaced by ammonium niobium oxalate (CAS No.: 168547-43-1). The rest is the same as Example 1.

[0137] Comparative Example 6

[0138] The difference from Example 1 is that the active components are only Cr, K and Ni.

[0139] A propane dehydrogenation catalyst, the composition by weight percentage is as follows: 17.7% Cr element, 1.15% K element, 1.15% Ni element, V2O5-CeO2-Al2O3 composite carrier is supplemented to 100%. The rest is the same as Example 1.

[0140] Comparative Example 7

[0141] The difference from Example 1 is that the active components are only Zr and Sn elements.

[0142] A propane dehydrogenation catalyst has the following composition by weight percentage: 10% Zr element, 10% Sn element, and V2O5-CeO2-Al2O3 composite carrier to make up to 100%. The rest is the same as Example 1.

[0143] Test 1: Catalyst physical property testing

[0144] The specific surface area and strength of the propane dehydrogenation catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 4 were tested respectively.

[0145] The specific surface areas of the propane dehydrogenation catalysts prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were measured using an ASAP 2460 fully automatic specific surface and pore size analyzer produced by American Minionomeritics Instruments. The process was repeated 5 times, and the specific surface area results are shown in Table 1.

[0146] The crushing strength of the propane dehydrogenation catalyst particles prepared in Examples 1 to 5 and Comparative Examples 1 to 4 was measured using a ZQJ-II intelligent particle strength testing machine. The number of samples was 50, and the results were averaged. The average strength of the propane dehydrogenation catalyst is shown in Table 1.

[0147] Table 1

[0148]

[0149] In Table 1, each comparative example is compared with Example 1. # P≤0.05, ## P≤0.01.

[0150] It can be seen from Table 1 that the propane dehydrogenation catalyst of the present invention has a higher specific surface area than the propane dehydrogenation catalyst of the comparative example; and the present invention prepares the V2O5-CeO2-Al2O3 composite carrier by dropwise addition and gradient temperature calcination, so that the pores of the propane dehydrogenation catalyst are increased and the pore size is uniform, which increases the specific surface area of ​​the catalyst and is more conducive to the loading of the active components, thereby efficiently exerting the catalytic effect of the catalyst.

[0151] In addition, the present invention adopts a gradient temperature rise calcination method to prepare the composite carrier, which improves the strength of the catalyst, prevents the catalyst carrier from cracking under high temperature conditions, and prolongs the service life of the catalyst.

[0152] Test 2 Catalytic performance test

[0153] The propane dehydrogenation reaction to produce propylene was carried out in a fixed bed reactor at a reaction temperature of 600°C, a reaction pressure of atmospheric pressure, and a reaction gas composition of propane: nitrogen = 9:1; the space velocity was 800 h -1 , propane dehydrogenation catalyst loading amount 5g. The reaction gas was introduced into the reactor loaded with the above catalyst for 5h to obtain the product, and the product was analyzed by GC 7900 gas chromatograph. The propane conversion rate, propylene selectivity, and propane conversion rate after continuous reaction for 36h are shown in Table 2.

[0154] Table 2

[0155]

[0156] In Table 2, each comparative example is compared with Example 1. # P≤0.05, ## P≤0.01.

[0157] It can be seen from Table 2 that the propane dehydrogenation catalyst of the embodiment of the present invention has a higher catalytic effect than the propane dehydrogenation catalyst of the comparative example, and the propane conversion rate and propylene selectivity are significantly improved; the catalyst of the present invention still has a relatively high propane conversion rate after working continuously for 36 hours in the propylene production reaction.

[0158] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A propane dehydrogenation catalyst, characterized in that: The propane dehydrogenation catalyst comprises a V2O5-CeO2-Al2O3 composite carrier and an active component; The active components are Cr, K, Zr, Ni and Sn; the mass ratio of Cr, K, Zr, Ni and Sn is 10-20:0.5-1.5:1-2:0.5-1.5:0.5-1.5; The preparation method of the propane dehydrogenation catalyst comprises the steps of: (1) Preparation of V2O5-CeO2-Al2O3 composite carrier: (1.1) Add the alkaline solution to the mixed solution of Al(NO3)3·9H2O and Ce(NO3)3·6H2O, stir evenly, and perform the first aging to obtain precipitate A; (1.2) Precipitate A is dispersed with a dispersion liquid, and then an acidic solution containing ammonium metavanadate is added dropwise at a rate of 5 mL / min-20 mL / min, and a second aging is performed under stirring conditions, and the solution is removed to obtain a precipitate B; Precipitate B is subjected to gradient temperature calcination, first at 300°C-400°C for 1h-3h, and then increased to 700°C-800°C at a rate of 5°C / min-8°C / min, and calcined for 1h-3h to obtain a V2O5-CeO2-Al2O3 composite carrier; (2) Impregnation treatment: (2.1) Preparing an impregnation solution: dissolving a substance containing active components of Cr, K, Zr, Ni and Sn in water to obtain an impregnation solution; (2.2) Vacuum impregnation: the impregnation solution is added dropwise to the V2O5-CeO2-Al2O3 composite support and vacuum treated to obtain a catalyst pretreatment product; (3) The catalyst pretreatment product is calcined to obtain a propane dehydrogenation catalyst.

2. The propane dehydrogenation catalyst according to claim 1, characterized in that The weight of the active component is 10%-22% of the weight of the propane dehydrogenation catalyst.

3. The propane dehydrogenation catalyst according to claim 2, characterized in that The weight of the active component is 15%-21% of the weight of the propane dehydrogenation catalyst.

4. The method for preparing the propane dehydrogenation catalyst according to any one of claims 1 to 3, characterized in that: Includes steps: (1) Preparation of V2O5-CeO2-Al2O3 composite carrier: (1.1) Add the alkaline solution to the mixed solution of Al(NO3)3·9H2O and Ce(NO3)3·6H2O, stir evenly, and perform the first aging to obtain precipitate A; (1.2) Precipitate A is dispersed with a dispersion liquid, and then an acidic solution containing ammonium metavanadate is added dropwise at a rate of 5 mL / min-20 mL / min, and a second aging is performed under stirring conditions, and the solution is removed to obtain a precipitate B; Precipitate B is subjected to gradient temperature calcination, first at 300°C-400°C for 1h-3h, and then increased to 700°C-800°C at a rate of 5°C / min-8°C / min, and calcined for 1h-3h to obtain a V2O5-CeO2-Al2O3 composite carrier; (2) Impregnation treatment: (2.1) Preparing an impregnation solution: dissolving a substance containing active components of Cr, K, Zr, Ni and Sn in water to obtain an impregnation solution; (2.2) Vacuum impregnation: the impregnation solution is added dropwise to the V2O5-CeO2-Al2O3 composite support and vacuum treated to obtain a catalyst pretreatment product; (3) The catalyst pretreatment product is calcined to obtain a propane dehydrogenation catalyst.

5. The preparation method according to claim 4, characterized in that: In step (1.1), the alkaline solution is selected from at least one of ammonia solution with a volume concentration of 30%-50% and sodium hydroxide solution with a mass concentration of 2%-5%; the volume ratio of the alkaline solution to the mixed solution is 1:60-120; the molar ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and ammonium metavanadate is 6-10:2:1; In the mixed solution of step (1.1), the molar concentration of Al(NO3)3·9H2O is 0.2mol / L-0.6mol / L, and the molar concentration of Ce(NO3)3·6H2O is 0.1mol / L-0.3mol / L; In step (1.1), the first aging condition is: aging at 100°C-150°C for 10h-20h.

6. The preparation method according to claim 4, characterized in that: In step (1.2), the dispersion liquid is polyethylene glycol and water in a volume ratio of 10:30-50; the mass volume ratio of precipitate A to the dispersion liquid is 1:30 g / mL-100 g / mL; In step (1.2), the dripping speed is 10 mL / min; the acidic solution is selected from at least one of phosphoric acid, ascorbic acid, and tartaric acid, and the mass concentration of the acidic solution is 1%-3%; In step (1.2), the molar concentration of the ammonium metavanadate in the acidic solution is 0.2 mol / L-0.8 mol / L.

7. The preparation method according to claim 4, characterized in that: In step (1.2), the second aging conditions are: 80°C-100°C, 100rpm-300rpm, stirring for 6h-12h.

8. The preparation method according to claim 4, characterized in that: In step (2.1), the mass ratio of the Cr element, the K element, the Zr element, the Ni element and the Sn element is 10-20:0.5-1.5:1-2:0.5-1.5:0.5-1.5; the total mass concentration of the active components in the impregnation solution is 10-30 g / L; In step (2.2), the vacuum treatment time is 0.5h-2h.

9. The preparation method according to claim 4, characterized in that: In step (3), the calcination is specifically: calcination at 450°C-600°C for 4h-7h.

10. Use of a propane dehydrogenation catalyst in the preparation of propylene, characterized in that: The propane dehydrogenation catalyst is the propane dehydrogenation catalyst according to any one of claims 1 to 3, or is the propane dehydrogenation catalyst obtained by the preparation method according to any one of claims 4 to 9.

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