A propane dehydrogenation catalyst, a preparation method and application thereof

Abstract

The application discloses a propane dehydrogenation catalyst and a preparation method and application thereof. The preparation method of the catalyst comprises the following steps: mixing an aluminum hydroxide sol with a Pt-containing aqueous solution, dropping the obtained mixture into an oil-ammonia water-oil-water four-layer mixed column for molding, drying and calcining to obtain the catalyst; four layers are sequentially arranged from top to bottom in the oil-ammonia water-oil-water four-layer mixed column, the first layer is a first oil layer, the second layer is an ammonia water layer, the third layer is a second oil layer, and the fourth layer is a water layer, wherein the second oil layer is selected from modified transformer oil. The catalyst is applied to a propane dehydrogenation reaction and has good stability.

Description

TECHNICAL FIELD

[0001] The present application relates to a propane dehydrogenation catalyst and a preparation method and application thereof, in particular to a propane dehydrogenation catalyst suitable for a boiling bed and a preparation method and application thereof. BACKGROUND

[0002] The shape and size of the catalyst particles are generally determined according to the requirements of the reactor used in industrial production. At present, there are four types of commonly used reactors in industry: fixed bed, fluidized bed (boiling bed), suspended bed and moving bed. The fixed bed reactor often uses spherical, cylindrical strip, three-leaf clover, four-leaf clover and sheet-shaped catalysts. The moving bed reactor often uses large particle spherical catalysts. The fluidized bed reactor generally uses small particle spherical or strip-shaped catalysts.

[0003] Spherical catalysts have good flow performance and high packing factor, uniform fluid distribution, low resistance and small pressure drop, and are widely used in the technology of dehydrogenation of low-carbon alkanes to obtain olefins.

[0004] At present, the catalyst for dehydrogenation of low-carbon alkanes to obtain olefins is mainly prepared by loading active components Pt and other additives on a γ-Al2O3 carrier, such as EP100222A, CN1185994A, etc. However, since the dehydrogenation reaction is carried out at a high temperature of about 600℃, the high reaction temperature often causes a large amount of carbon deposition on the catalyst. With the increase of the use time of the catalyst, the catalyst needs to be treated by high-temperature carbon burning and regeneration for multiple times, which causes sintering and α-phase transformation of the γ-Al2O3 carrier, greatly reduces the specific surface area of the carrier, destroys the pore structure, and further causes aggregation of the active components of the catalyst, thereby seriously reducing the activity of the catalyst. Therefore, it is necessary to further modify the γ-Al2O3 carrier to make the catalyst have high thermal stability.

[0005] CN112973771A discloses a spherical catalyst carrier containing molecular sieve and alumina and a preparation and application thereof. The catalyst carrier is prepared by precipitating an inorganic aluminum salt with ammonia water and acidifying to obtain a sol, adding a mixed solution of ball-milled pseudoboehmite and molecular sieve and a sol modification additive to the sol, then drop-sphere forming and aging in an oil ammonia column, and finally washing, drying and calcining to obtain a high-strength large-specific-surface-area composite pellet. The method is to mix the suspension slurry of the ball-milled pseudoboehmite and molecular sieve with the dilute sol again, which will cause uneven dispersion of the molecular sieve. At the same time, the doping of solid molecular sieve will also cause the strength of the carrier to decrease.

[0006] CN105478100A discloses a method for preparing silicon-containing γ-Al2O3 pellets. The method is to stir and slurry pseudo-boehmite dry glue powder and deionized water, add dilute nitric acid for acidification, then add urea and a predetermined amount of sodium silicate solution, stir for 5 hours, add kerosene and fatty alcohol polyoxyethylene ether and stir for 5 hours, drop ball forming in an oil ammonia column, solidify the wet ball in ammonia water for 2 hours, then filter, rinse with deionized water, dry and calcine to obtain silicon-containing γ-Al2O3 pellets. The method has a long solidification time for preparing γ-Al2O3 pellets, is difficult to wash, and has low production efficiency.

[0007] CN104289220A discloses a method for preparing and use of a high-thermal-stability low-carbon alkane dehydrogenation catalyst. The carrier preparation method is to add an aluminum source to an alkaline aqueous solution, stir, continue to add the alkaline aqueous solution to adjust the pH of the mixed solution to 7-14, filter, wash with deionized water, then add dilute nitric acid to form a sol, add a silicon source, stir, filter, age for 10-48 hours, drop ball forming, then dry and calcine to obtain Si-containing γ-Al2O3 pellets; or add an aluminum source to an alkaline aqueous solution, stir, continue to add the alkaline aqueous solution to adjust the pH of the mixed solution to 7-14, filter, wash with deionized water, then add dilute nitric acid to form a sol, stir, filter, age for 10-48 hours, drop ball forming, then dry and calcine to obtain γ-Al2O3 pellets, then immerse the γ-Al2O3 pellets in a silicon source aqueous solution or ethanol solution at 60-120℃ for 2-6 hours, then dry and calcine to obtain Si-containing γ-Al2O3 pellets. The method has the disadvantages of long preparation period, complex process, pH value adjustment, and inability to guarantee product consistency. SUMMARY

[0008] In view of the deficiencies of the prior art, the present application provides a propane dehydrogenation catalyst, a preparation method and application thereof. The catalyst is used in a propane dehydrogenation reaction for preparing propylene, has high propane conversion rate and propylene selectivity, and good stability.

[0009] The first aspect of the present application provides a preparation method of a propane dehydrogenation catalyst, comprising:

[0010] The aluminum hydroxide sol is mixed with a Pt-containing aqueous solution, and the obtained mixture is dropped into an oil-ammonia water-oil-water four-layer mixed column to form a shape, dried, and calcined to obtain a propane dehydrogenation catalyst. In the oil-ammonia water-oil-water four-layer mixed column, four layers are sequentially arranged from top to bottom, the first layer is a first oil layer, the second layer is an ammonia water layer, the third layer is a second oil layer, and the fourth layer is a water layer. The second oil layer is selected from modified transformer oil, and the modified transformer oil comprises transformer oil and a water-soluble surfactant. Preferably, the water-soluble surfactant is one or more of lauryl diethanolamine, nonylphenol polyoxyethylene ether (the degree of polymerization is preferably 9, i.e. n = 9), or octylphenol polyoxyethylene ether (the degree of polymerization is preferably 7, i.e. n = 7).

[0011] Further, the content of aluminum oxide in the aluminum hydroxide sol is 15wt%-26wt%.

[0012] Further, the preparation method of the aluminum hydroxide sol comprises: mixing aluminum hydroxide with water to obtain a slurry, and adding a peptizing agent to obtain the aluminum hydroxide sol after uniform stirring. Further, the peptizing agent is selected from one or more of inorganic acids (such as nitric acid), organic acids (such as acetic acid, citric acid), and is preferably nitric acid. When the peptizing agent contains an inorganic acid, the mass concentration of the inorganic acid is 30%-50%. When the peptizing agent contains an organic acid, the mass concentration of the organic acid is 30%-50%. Further, the addition amount of the peptizing agent is 1wt%-10wt% of the mass of the aluminum hydroxide in terms of acid, and is preferably 2wt%-8wt%. Further, the aluminum hydroxide is preferably hydrous aluminum hydroxide, such as hydrous aluminum hydroxide material. Preferably, the water content in the aluminum hydroxide is 17wt%-25wt%. Preferably, the properties of the aluminum hydroxide after calcination are as follows: the specific surface area is 110-201m 2 / g, the pore volume is 0.8-2.0mL / g, and the average pore size is 15-17nm. The calcination conditions are as follows: the temperature is 600-850℃, the time is 2-12h, and the oxygen-containing atmosphere is air. The aluminum hydroxide can be commercially available or prepared by a conventional method. The aluminum hydroxide is preferably hydrous large-pore pseudoboehmite, and the water content is 19wt%-23wt%.

[0013] Further, the platinum-containing compound in the Pt-containing aqueous solution is one or more of platinum chloride (PtCl4) and chloroplatinic acid (H2PtCl6), and is preferably chloroplatinic acid. Further, the Pt-containing aqueous solution contains stannous chloride (SnCl2) and hydrochloric acid.

[0014] Further, the concentration of the platinum-containing compound in the Pt-containing aqueous solution is 2wt%-6wt%. The addition amount of the Pt-containing aqueous solution is 8%-40% of the mass of the aluminum hydroxide sol in terms of aluminum oxide, and is preferably 15%-30%.

[0015] Further, the Pt-containing aqueous solution contains stannous chloride (SnCl2) and hydrochloric acid. Further, in the Pt-containing aqueous solution, the concentration of stannous chloride (SnCl2) is 0.5wt% to 3.5wt%, and the concentration of hydrochloric acid is 5wt% to 12wt%.

[0016] Further, the oil-ammonia water-oil-water four-layer mixed column is a straight column, preferably a cylindrical column.

[0017] Further, in the oil-ammonia water-oil-water four-layer mixed column, the first layer is a first oil layer, which is selected from one or more of white oil or diesel oil, preferably white oil, and the white oil has a kinematic viscosity of 20 to 40mm 2 / s at 40℃, preferably 25 to 35mm 2 / s. The height of the first layer is 30% to 50% of the height of the second layer.

[0018] Further, in the oil-ammonia water-oil-water four-layer mixed column, the second layer is an ammonia water layer, and the concentration of the ammonia water is 20wt% to 28wt%, preferably 22wt% to 26wt%.

[0019] Further, in the oil-ammonia water-oil-water four-layer mixed column, the third layer is a second oil layer, i.e., a liquid seal oil layer, and the height of the third layer is 30% to 50% of the height of the second layer, preferably 35% to 45%. The modified transformer oil used in the second oil layer has a density between that of ammonia water and water, and preferably, the modified transformer oil has a density of 0.90g / mL or more at 20℃, preferably 0.93 to 0.96g / mL, and further preferably 0.94 to 0.96g / mL.

[0020] Further, the mass of the water-soluble surfactant is 6% to 25% of the mass of the transformer oil, preferably 10% to 18%.

[0021] Further, the transformer oil has a density of 0.86 to 0.89g / mL at 20℃, and a kinematic viscosity of 9 to 15mm 2 / s at 40℃.

[0022] Further, the preparation process of the modified transformer oil is as follows:

[0023] The water-soluble surfactant is mixed with the transformer oil, and the obtained mixture is subjected to heat treatment, i.e., sealed heating treatment and open heating treatment in sequence, and the above heat treatment is repeated 3 to 6 times to obtain the modified transformer oil.

[0024] Further, the conditions of the sealed heating treatment are as follows: heating temperature is 80-120℃, and heating time is 6-20h. Further, the conditions of the open heating treatment are as follows: heating temperature is 80-120℃, and heating time is 6-20h.

[0025] Further, in the oil-ammonia water-oil-water four-layer mixed column, the fourth layer is a water layer, preferably deionized water or a dilute acid solution. The height of the fourth layer is 1.0-2.0 times, preferably 1.2-1.5 times, the height of the second layer.

[0026] Further, the fourth layer preferably uses a dilute acid solution. In the dilute acid solution, the acid is selected from at least one of acetic acid and citric acid. The mass concentration of the dilute acid solution is 3%-8%.

[0027] Further, the preparation method of the oil-ammonia water-oil-water four-layer mixed column comprises:

[0028] (1) Pour the required material of the fourth layer into a columnar container (preferably an organic glass container) and ensure uniform solution;

[0029] (2) Slowly add the required material of the third layer to the fourth layer material of step (1), and stabilize for 20-35min;

[0030] (3) Slowly add the required material of the second layer to the third layer material of step (2);

[0031] (4) Slowly add the required material of the first layer to the second layer material of step (3) to obtain an oil-ammonia water-oil-water four-layer mixed column. Preferably, during the addition of the required material of the first layer, a peristaltic pump is used to slowly circulate up and down above the interface between the first layer and the second layer to reduce the surface tension at the interface between the first layer and the second layer, and then stand for 30-60min until it is stable. In this way, it can be ensured that the aluminum hydroxide sol can quickly pass through the contact interface between the first layer and the second layer, preventing the generation of tailing due to stagnation and affecting the true circularity.

[0032] Further, the propane dehydrogenation catalyst is formed in the oil-ammonia water-oil-water four-layer mixed column, and the mixture of aluminum hydroxide sol and Pt-containing aqueous solution is dropped into the oil-ammonia water-oil-water four-layer mixed column, wherein the inner diameter of the drop head used is 1.0mm-1.6mm.

[0033] Further, the residence time of the mixture of aluminum hydroxide sol and Pt-containing aqueous solution in the oil-ammonia water-oil-water four-layer mixed column is 5-18s, preferably 7-11s.

[0034] Further, the drying temperature is 100-150℃, and the drying time is 6-10 hours; the calcination temperature is 750-950℃, and the calcination time is 1-4 hours.

[0035] The second aspect of the present application provides a propane dehydrogenation catalyst prepared by the above preparation method.

[0036] Further, the specific surface area of the propane dehydrogenation catalyst is 60-125m 2 / g, and the pore volume is 0.62-0.82mL / g.

[0037] Further, the propane dehydrogenation catalyst is a spherical particle, and the average diameter of the particle is 1.7-1.9mm.

[0038] Further, the pore size distribution of the propane dehydrogenation catalyst is as follows: the pore volume of the pores with a pore size less than 2nm accounts for 1.5%-4.6% of the total pore volume, the pore volume of the pores with a pore size of 2-50nm accounts for 95.4%-98.5% of the total pore volume, and preferably 96.0%-98.0%.

[0039] Further, the average pore size of the propane dehydrogenation catalyst is 14.5-18.6nm.

[0040] Further, the crushing strength of the propane dehydrogenation catalyst is 68-89N / particle.

[0041] Further, the true circularity of the propane dehydrogenation catalyst is 97.8%-99.9%.

[0042] Further, in the propane dehydrogenation catalyst, the content of Pt is 0.25%-1.20%, the content of Sn is 0.04%-0.87%, and the content of alumina is 97.93%-99.71%, all based on the mass of the catalyst.

[0043] The third aspect of the present application provides the use of the above catalyst in a propane dehydrogenation reaction.

[0044] Further, the use includes: contacting a propane raw material with the catalyst to perform a dehydrogenation reaction, so as to obtain a product propylene.

[0045] Further, the propane dehydrogenation catalyst needs to be reduced before use. The catalyst precursor is reduced under a reducing atmosphere. The reducing atmosphere is preferably H2, the reduction temperature is 450-600℃, and the reduction time is 1-3h.

[0046] Further, the propane dehydrogenation reaction conditions are preferably as follows: the reaction temperature is 500-600℃, the reaction pressure is 0-1MPa, and the volume space velocity is 50-200h -1 .

[0047] Compared with the prior art, the present application has the advantages of:

[0048] (1) The present application adopts one-step synthesis of propane dehydrogenation catalyst, and Pt-containing aqueous solution is added in aluminum hydroxide sol, so that the metal is uniformly dispersed in the alumina carrier, and also plays a pore expanding role. In the molding process, the four-layer oil-ammonia water-oil-water mixed column is different from the two-layer oil-ammonia column or hot oil column, and the third layer of oil layer is added as a liquid seal oil layer and the fourth layer of water layer, which can make the sol quickly enter the third layer and the fourth layer of water layer after passing through the second layer of ammonia water layer, and the pH value is quickly reduced to neutral, so that the pellets are not easy to break or shrink during the drying process with the volatilization of surface ammonia water, so that the alumina particle size and mechanical strength are significantly increased, and at the same time, the metal and the carrier are in full contact, and the loading is more uniform. In addition, the rapid decline of the pH value of the sol pellet surface also makes the hydrophobicity of the colloidal particle surface decrease rapidly, the interaction force between the colloidal particles increases significantly, the distance between the colloidal particles becomes shorter, and the original structure collapses partially, resulting in an increase in the mesoporous structure of the carrier in the range of 2-50 nm. By adding an appropriate amount of acidic solution into the fourth layer of water layer, the pore structure can be further optimized.

[0049] (2) In the four-layer mixed column used in the catalyst molding of the present application, due to the small difference between the density of ammonia water in the ammonia water layer and the density of pure water in the water layer, the density of the liquid seal oil (modified transformer oil) in the second oil layer needs to be greater than that of ammonia water and less than that of pure water, and at the same time, the viscosity cannot be too large, otherwise it will affect the roundness of the sol. The present application can improve the density without changing the viscosity by adding a surfactant to the transformer oil, so that it meets the requirements. The water-soluble surfactant slowly penetrates into the oil under heating conditions, the intermolecular interaction force is enhanced, the intermolecular distance is shortened during the evaporation of water, and the stability of the modified oil can be ensured after repeated multiple times. At the same time, due to the addition of the surfactant, the surface tension at the oil-water interface is significantly reduced, the sol pellets stop at the oil-water interface, and the roundness of the spherical carrier is effectively improved.

[0050] (3) The preparation process of the present application is environmentally friendly. In the traditional oil-ammonia column balling process, the volatilization of ammonia water causes serious environmental pollution and subsequent pollutant emission problems. The present application separates the second layer of ammonia water layer and the fourth layer of water layer by the second oil layer, so that the ammonia water layer is sealed above the fourth layer of water layer, which can prolong the use time and avoid environmental pollution caused by the product taking out ammonia water. After long-term use, the deionized water can be replaced to ensure the liquid sealing effect, which is simple to operate and cost-saving in industry.

[0051] (4) The catalyst of the present application has high propane conversion rate and propylene selectivity in the reaction of propane to propylene, and the catalyst with large pore size and pore volume can avoid carbon deposition after long-term operation, and has good stability and good reaction performance. DETAILED DESCRIPTION

[0052] The application is further illustrated by the following examples. The examples are implemented on the premise of the technical solutions of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following examples.

[0053] In the following examples, the experimental methods are all conventional methods in the art unless otherwise specified. In the following examples, the experimental materials are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0054] In the application, the nitrogen adsorption-desorption curve of the sample is tested at-196 ℃ by using the ASAP2020 full-automatic physical adsorption instrument of the American Micromeritics company, and the specific surface area, pore volume and pore size distribution are determined.

[0055] In the application, the crushing strength is tested by using the ZQJ-III intelligent particle strength tester manufactured by the Dalian Zhiqu tester factory, and the average value of crushing ten spherical carriers is tested.

[0056] In the application, the true circularity is tested by using the electronic microscope of the Olympus company, and the average value is calculated after 20 samples are tested.

[0057] Example 1

[0058] Take 250g of macroporous pseudo-boehmite filter cake with a water content of 22wt% (calcined at 600℃ for 3h in an air atmosphere, and the properties are as follows: pore volume 0.87mL / g, specific surface area 175m 2 / g, and average pore diameter 16nm), add deionized water to stir and uniformly pulp, then add 26g of a 45% mass concentration nitric acid solution for peptization, and finally prepare a pseudo-boehmite sol with an alumina mass content of 20%; take 300g of the above sol (alumina content of 20wt%), add 12g of a chloroplatinic acid solution with a chloroplatinic acid concentration of 3%, which contains 0.8% stannous chloride and 7% hydrochloric acid at the same time, and stir uniformly to obtain a sol mixture;

[0059] Add 7g of lauryl diethanolamine and 7g of nonylphenol polyoxyethylene ether (n=9) to 100g of transformer oil (20℃ density of 0.89g / mL, 40℃ kinematic viscosity of 12mm 2 / s), stir uniformly, seal and place in a 100℃ oven for heating for 8h, remove the sealing cover and continue heating for 4h, repeat the above steps for 3 times, and obtain modified transformer oil (20℃ density of 0.94g / mL). Use a nozzle with an inner diameter of 1.2mm to drop the modified transformer oil into a 40℃ water bath, and the kinematic viscosity of the modified transformer oil is 32mm 2The sol was dropped into a four-layer mixed column (cylinder) with a residence time of 8 s, wherein the white oil was added in an amount of 35% of the volume of the ammonia water, the modified transformer oil was added in an amount of 38% of the volume of the ammonia water, and the deionized water was added in an amount of 1.3 times the volume of the ammonia water. Then, drying was performed at 130°C for 8 hours, and calcination was performed at 800°C for 3 hours to obtain the catalyst A of the present application, and the analysis results are shown in Table 1.

[0060] Example 2

[0061] Compared with Example 1, the difference is that the deionized water in the fourth layer of the four-layer mixed column is replaced with a 5wt% dilute acetic acid solution to obtain the catalyst B of the present application, and the analysis results are shown in Table 1.

[0062] Example 3

[0063] Compared with Example 1, the difference is that in the preparation of the sol mixture, 15.6g of chloroplatinic acid solution with a concentration of 6% chloroplatinic acid, 1.0% stannous chloride, and 9% hydrochloric acid is added to obtain the catalyst C of the present application, and the analysis results are shown in Table 1.

[0064] Example 4

[0065] Compared with Example 1, the difference is that in the preparation of the modified transformer oil, the surfactant is replaced with lauryl diethanolamide, the amount is changed to 12g, and the number of repetitions is changed to 4 times, and the 20°C density of the obtained modified transformer oil is 0.95g / mL to obtain the catalyst D of the present application, and the analysis results are shown in Table 1.

[0066] Example 5

[0067] Compared with Example 1, the difference is that in the preparation of the modified transformer oil, the amounts of lauryl diethanolamide and nonylphenol polyoxyethylene ether (n=9) are changed to 4g each, and the 20°C density of the obtained modified transformer oil is 0.93g / mL to obtain the catalyst E of the present application, and the analysis results are shown in Table 1.

[0068] Example 6

[0069] Compared with Example 1, the difference is that the amount of white oil is 42% of the volume of the ammonia water, the amount of modified transformer oil is 32% of the volume of the ammonia water, and the amount of deionized water is 1.6 times the volume of the ammonia water to obtain the catalyst F of the present application, and the analysis results are shown in Table 1.

[0070] Comparative Example 1

[0071] The sol mixture synthesis step is the same as Example 1.

[0072] Comparative Example 1 2 / s, the lower layer was ammonia water with a concentration of 25wt%, the amount of white oil added was 25% of the volume of ammonia water, and the remaining forming steps were unchanged, to obtain Comparative Catalyst G of the present application, the analysis results of which are shown in Table 2.

[0073] Comparative Example 2

[0074] The sol mixture synthesis step was the same as in Example 1.

[0075] Comparative Example 1

[0076] Comparative Example 3

[0077] The sol mixture synthesis step was the same as in Example 1.

[0078] Comparative Example 1

[0079] Comparative Example 4

[0080] The sol mixture synthesis step was the same as in Example 1.

[0081] Comparative Example 1 2 / s, the lower layer was ammonia water with a concentration of 25wt%, the amount of white oil added was 25% of the volume of ammonia water, and the remaining forming steps were unchanged, to obtain Comparative Catalyst G of the present application, the analysis results of which are shown in Table 2.

[0082] Comparative Example 5

[0083] The sol mixture synthesis step was the same as in Example 1.

[0084] Comparative Example 1

[0085] Table 1: Physicochemical properties of catalysts obtained in each example

[0086] Catalyst No. A B C D E F Particle average diameter, mm 1.82 1.82 1.81 1.81 1.80 1.80 Specific surface area, m 2 / g]] 92 91 93 92 93 92 Pore volume, mL / g 0.635 0.637 0.632 0.632 0.620 0.621 Pore size distribution, % < 2 nm 1.9 1.8 2.0 2.1 2.2 2.1 2-50 nm 97.9 97.7 97.8 97.8 97.6 97.4 > 50 nm 0.2 0.5 0.2 0.1 0.2 0.5 Average pore diameter, nm 16.9 17.1 16.8 16.7 15.7 15.4 Crushing strength, N / particle 70 70 68 69 69 70 True circularity, % 98.8 98.7 98.5 98.4 98.6 98.7

[0087] Physical and chemical properties of catalysts obtained in each of the comparative examples of Table 2

[0088]

[0089]

[0090] Composition of catalysts of each of the examples of Table 3

[0091] Catalyst No. A B C D E F Alumina (wt%) 99.6 99.6 99.1 99.6 99.6 99.6 Pt (wt%) 0.3 0.3 0.7 0.3 0.3 0.3 Sn (wt%) 0.1 0.1 0.2 0.1 0.1 0.1

[0092] Composition of catalysts of each of the comparative examples of Table 4

[0093] Catalyst No. G H I J K Alumina (wt%) 99.6 99.6 99.6 99.6 99.6 Pt (wt%) 0.3 0.3 0.3 0.3 0.3 Sn (wt%) Catalyst No. Alumina (wt%) Pt (wt%) Sn (wt%) Catalyst No. Alumina (wt%) Pt (wt%) Sn (wt%) Catalyst No. Alumina (wt%) Pt (wt%) Sn (wt%) Catalyst No. Alumina (wt%) Pt (wt%) Sn (wt%) Catalyst No. Alumina (wt%) Pt (wt%) Sn (wt%) Catalyst No. Alumina (wt%) Pt (wt%) Sn (wt%) Catalyst No. Al 0.1 0.1 0.1 0.1 0.1

[0094] Evaluation of catalysts

[0095] 5 g of each of the above catalysts were reduced under a hydrogen atmosphere at 520°C for 1.5 h, and then were respectively charged into a fixed bed reactor for evaluation of the dehydrogenation activity of propane: reaction temperature 520°C, pressure 0.7 MPa, volumetric space velocity 80 h -1 The results of the dehydrogenation of propane are shown in Tables 5-8.

[0096] Evaluation results of the dehydrogenation of propane using the catalysts of each of the examples of Table 5

[0097]

[0098] Evaluation results of the dehydrogenation of propane using the catalysts of each of the comparative examples of Table 6

[0099]

[0100] Stability evaluation results of the dehydrogenation of propane using the catalysts of each of the examples of Table 7

[0101]

[0102] Stability evaluation results of the dehydrogenation of propane using the catalysts of each of the comparative examples of Table 8

[0103]

[0104] The specific embodiments of the present application have been described in detail above, but the present application is not limited thereto. Various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, including the combination of each technical feature in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for preparing a propane dehydrogenation catalyst, comprising: mixing an aluminum hydroxide sol with a Pt-containing aqueous solution, and dropping the obtained mixture into an oil-ammonia water-oil-water four-layer mixed column to form a shape, and drying and calcining to obtain a propane dehydrogenation catalyst; In the oil-ammonia water-oil-water four-layer mixed column, four layers are arranged from top to bottom, the first layer is a first oil layer, the second layer is an ammonia water layer, the third layer is a second oil layer, and the fourth layer is a water layer, wherein the second oil layer is selected from modified transformer oil, the modified transformer oil comprises transformer oil and a water-soluble surfactant, the water-soluble surfactant is one or more of lauryl diethanolamine, nonylphenol polyoxyethylene ether or octylphenol polyoxyethylene ether; The Pt-containing aqueous solution contains chloroplatinic acid, stannous chloride and hydrochloric acid; The first oil layer is selected from one or more of white oil or diesel oil; The density of the second oil layer is between the second layer of ammonia water and the fourth layer of water; The fourth layer of water is deionized water or a dilute acid solution; The height of the first layer is 30%-50% of the height of the second layer; The height of the third layer is 30%-50% of the height of the second layer; The height of the fourth layer is 1.0-2.0 times the height of the second layer.

2. The method of claim 1, wherein: The concentration of chloroplatinic acid in the Pt-containing aqueous solution is 2wt%-6wt%; And / or, the concentration of stannous chloride in the Pt-containing aqueous solution is 0.5wt%-3.5wt%, and the concentration of hydrochloric acid is 5wt%-12wt%.

3. The method of claim 1, wherein: The content of aluminum oxide in the aluminum hydroxide sol is 15wt%-30wt%; And / or, the amount of the Pt-containing aqueous solution added is 8%-40% of the mass of the aluminum hydroxide sol in terms of aluminum oxide.

4. The method of claim 3, wherein: The amount of the Pt-containing aqueous solution added is 15%-30% of the mass of the aluminum hydroxide sol in terms of aluminum oxide.

5. The method of claim 1, wherein: The oil-ammonia water-oil-water four-layer mixed column, the first oil layer is white oil, the white oil has a kinematic viscosity of 20-40 mm 2 / s at 40°C.

6. The method of claim 5, wherein: The white oil has a kinematic viscosity at 40°C of 25-35 mm 2 / s.

7. The method of claim 1, wherein: In the oil-ammonia water-oil-water four-layer mixed column, the concentration of ammonia water is 20wt%-28wt%.

8. The method of claim 7, wherein: The concentration of ammonia water is 22wt%-26wt%.

9. The method of claim 1, wherein: In the oil-ammonia water-oil-water four-layer mixed column, the density of the modified transformer oil at 20℃ is 0.90 g / mL or more.

10. The method of claim 9, wherein: In the oil-ammonia water-oil-water four-layer mixed column, the density of the modified transformer oil at 20℃ is 0.93-0.96 g / mL.

11. The method of claim 1, wherein: The mass of the water-soluble surfactant is 6%-25% of the mass of the transformer oil.

12. The method of claim 11, wherein: The mass of the water-soluble surfactant is 10%-18% of the mass of the transformer oil.

13. The method of claim 1, wherein: The transformer oil has a density of 0.86-0.89 g / mL at 20°C and a kinematic viscosity of 9-15 mm 2 / s at 40°C.

14. The method of claim 1, wherein: The preparation process of the modified transformer oil is as follows: mixing the water-soluble surfactant with the transformer oil, and heat treating the obtained mixture, i.e. sequentially carrying out sealed heating treatment and open heating treatment, and repeating the above heat treatment for 3-6 times to obtain the modified transformer oil.

15. The method of claim 14, wherein: The conditions of the sealed heating treatment are as follows: the heating temperature is 80-120℃, and the heating time is 6-20 h.

16. The method of claim 14, wherein: The conditions of the open heating treatment are as follows: the heating temperature is 80-120℃, and the heating time is 6-20 h.

17. The method of claim 1, wherein: In the oil-ammonia water-oil-water four-layer mixed column, the fourth layer of water is a dilute acid solution; In the dilute acid solution, the dilute acid is at least one of acetic acid and citric acid; The mass concentration of the dilute acid solution is 3%-8%.

18. The method of claim 1, wherein: The height of the third layer is 35% to 45% of the height of the second layer. And / or, the height of the fourth layer is 1.2 to 1.5 times of the height of the second layer.

19. The propane dehydrogenation catalyst prepared by the method of any one of claims 1-18.

20. The catalyst of claim 19, wherein: The specific surface area of the propane dehydrogenation catalyst is 60-125 m 2 / g, and the pore volume is 0.62-0.82 mL / g; And / or, the average diameter of the propane dehydrogenation catalyst particles is 1.7 to 1.9 mm. And / or, the average pore size of the propane dehydrogenation catalyst is 14.5 to 18.6 nm. And / or, the crushing strength of the propane dehydrogenation catalyst is 68 to 89 N / particle. And / or, the roundness of the propane dehydrogenation catalyst is 97.8% to 99.9%.

21. The catalyst of claim 19, wherein: The pore size distribution of the propane dehydrogenation catalyst is that the pore volume of pores with a pore size less than 2 nm accounts for 1.5% to 4.6% of the total pore volume, and the pore volume of pores with a pore size of 2-50 nm accounts for 95.4% to 98.5% of the total pore volume.

22. The catalyst of claim 21, wherein: The pore volume of pores with a pore size of 2-50 nm accounts for 96.0% to 98.0% of the total pore volume.

23. The catalyst of claim 19, wherein: In the catalyst, the content of Pt is 0.25% to 1.20%, the content of Sn is 0.04% to 0.87%, and the content of alumina is 97.93% to 99.71%, all based on the mass of the catalyst.

24. The use of the catalyst of any one of claims 19-23 in a propane dehydrogenation reaction.

25. The use according to claim 24, characterized in that: The catalyst needs to be reduced before use.

26. The use according to claim 25, characterized in that: The reducing atmosphere is H2, the reducing temperature is 450-600°C, and the reducing time is 1-3 h.

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