A dehydrogenation catalyst, its preparation method and application

Abstract

This invention discloses a dehydrogenation catalyst, its preparation method, and its application. The preparation method of the catalyst includes: mixing aluminum hydroxide sol with a Pt-containing aqueous solution and an organic Pt salt solution; dropping the resulting mixture into a four-layer oil-ammonia-oil-water mixing column to form a solid, then drying and calcining to obtain the dehydrogenation catalyst; the mixing column has four layers arranged sequentially from top to bottom: a first oil layer, a second ammonia layer, a third second oil layer, and a fourth water layer; the second oil layer is selected from modified transformer oil, which includes transformer oil and a water-soluble surfactant. This catalyst, when used in propane dehydrogenation reactions, exhibits high propane conversion, propylene selectivity, and good stability.

Description

TECHNICAL FIELD

[0001] The present application relates to a dehydrogenation catalyst and a preparation method and application thereof, in particular to a 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. Currently, there are four types of reactors commonly used 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 produce olefins.

[0004] Currently, the catalyst for dehydrogenation of low-carbon alkanes to produce 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. As the use time of the catalyst increases, the catalyst needs to be treated by high-temperature carbon burning and regeneration multiple times, which causes the γ-Al2O3 carrier to easily sinter and α-phase change, greatly reduces the specific surface area of the carrier, destroys the pore structure, and further causes the active components of the catalyst to aggregate, resulting in a serious decrease in 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, acidize by adding dilute nitric acid, 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, wet ball is solidified in ammonia water for 2 hours, then filtered, washed with deionized water, dried, calcined to obtain silicon-containing γ-Al2O3 pellets. The method has long solidification time, difficult washing and 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, then add a silicon source, stir, filter, age for 10-48 hours, drop ball forming, then dry and calcine to obtain γ-Al2O3 pellets containing Si element; 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 γ-Al2O3 pellets containing Si element. The method has long preparation period, complex process, pH value needs to be adjusted, and product consistency cannot be guaranteed. SUMMARY

[0008] In view of the deficiencies of the prior art, the present application provides a dehydrogenation catalyst, a preparation method and application thereof. The catalyst has good roundness, high crushing strength, large pore volume and pore size, Pt is not easy to agglomerate, the product is environmentally friendly and has no peculiar smell, and has high propane conversion rate and propylene selectivity and good stability in the propane dehydrogenation reaction.

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

[0010] The aluminum hydroxide sol is mixed with a Pt-containing aqueous solution and an organic Pt salt solution, the obtained mixture is dropped into an oil-ammonia water-oil-water four-layer mixed column for forming, drying and calcining to prepare the dehydrogenation catalyst; the four layers are sequentially arranged from top to bottom in the 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; the second oil layer is selected from modified transformer oil, and the modified transformer oil comprises transformer oil and a water-soluble surfactant.

[0011] Further, the alumina content of the aluminum hydroxide sol is 15wt% to 26wt%.

[0012] Further, the method for preparing 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 stirring. Further, the peptizing agent is selected from one or more of inorganic acids (such as nitric acid) and 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% to 50%. When the peptizing agent contains an organic acid, the mass concentration of the organic acid is 30% to 50%. Further, the addition amount of the peptizing agent is 1wt% to 10wt% of the mass of the aluminum hydroxide in terms of acid, and is preferably 2wt% to 8wt%. Further, the aluminum hydroxide is preferably hydrous aluminum hydroxide, such as hydrous aluminum hydroxide wet material. Preferably, the water content of the aluminum hydroxide is 17wt% to 25wt%. Preferably, the properties of the aluminum hydroxide after calcination are as follows: the specific surface area is 110 to 201m 2 / g, the pore volume is 0.8 to 2.0mL / g, and the average pore size is 15 to 17nm. The calcination conditions are as follows: the temperature is 600 to 850℃, the time is 2 to 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% to 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.

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

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

[0016] Further, the organic Pt salt in the organic Pt salt solution is one or more of platinum acetylacetonate and tetrakis(triphenylphosphine) platinum, and is preferably platinum acetylacetonate. The solvent used is preferably acetone. The concentration of the organic Pt salt in the organic Pt salt solution is 1.0wt% to 1.9wt%. The addition amount of the organic Pt salt solution is 9% to 11% of the mass of the aluminum hydroxide sol in terms of alumina.

[0017] Further, the oil-ammonia water-oil-water four-layer mixed column is a straight column, preferably a cylindrical column.

[0018] Further, in the oil-ammonia water-oil-water four-layer mixed column, the first layer is a first oil layer selected from one or more of white oil or diesel oil, preferably white oil, the white oil having a kinematic viscosity of 20-40 mm 2 / s at 40℃, preferably 25-35 mm 2 / s. The height of the first layer is 30-50% of the height of the second layer.

[0019] Further, in the oil-ammonia water-oil-water four-layer mixed column, the second layer is an ammonia water layer, the ammonia water having a concentration of 20-28 wt%, preferably 22-26 wt%.

[0020] 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, the second oil layer using a modified transformer oil having a density between that of ammonia water and water, preferably the modified transformer oil having a density of 0.90 g / mL or more at 20℃, preferably 0.93-0.96 g / mL, further preferably 0.94-0.96 g / mL. The height of the third layer is 30-50% of the height of the second layer, preferably 35-45%.

[0021] Further, the water-soluble surfactant has a mass of 6-25% of the mass of the transformer oil, preferably 10-18%.

[0022] Further, the water-soluble surfactant is one or more of lauric diethanolamide, nonylphenol polyoxyethylene ether (preferably having a degree of polymerization of 9, i.e., n=9) or octylphenol polyoxyethylene ether (preferably having a degree of polymerization of 7, i.e., n=7).

[0023] Further, the transformer oil has a density of 0.86-0.89 g / mL at 20℃ and a kinematic viscosity of 9-15 mm 2 / s at 40℃.

[0024] Further, the modified transformer oil is prepared as follows:

[0025] The water-soluble surfactant is mixed with the transformer oil, and the resulting mixture is heat treated, i.e., sequentially subjected to sealed heat treatment and open heat treatment, and the heat treatment is repeated 3-6 times to obtain the modified transformer oil.

[0026] Further, the sealed heat treatment is performed at a temperature of 80-120℃ for 6-20 h. Further, the open heat treatment is performed at a temperature of 80-120℃ for 6-20 h.

[0027] Further, the oil-ammonia water-oil-water four-layer mixed column is a straight column, preferably a cylindrical column.

[0028] 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 1-2 times, preferably 1.2-1.5 times, the height of the second layer.

[0029] 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%.

[0030] Further, the preparation method of the oil-ammonia water-oil-water four-layer mixed column comprises:

[0031] (1) Pour the required material of the fourth layer into a columnar container (preferably an organic glass container) and ensure uniform solution;

[0032] (2) Slowly add the required material of the third layer to the fourth layer material of step (1), and stabilize for 20-35 min;

[0033] (3) Slowly add the required material of the second layer to the third layer material of step (2);

[0034] (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 30-60 min until it is stable. This can ensure that the aluminum hydroxide sol can quickly pass through the contact interface between the first layer and the second layer, prevent the generation of tailing due to stagnation, and affect the true circularity.

[0035] Further, the dehydrogenation catalyst is formed in the oil-ammonia water-oil-water four-layer mixed column. The mixture of aluminum hydroxide sol, Pt-containing aqueous solution, and organic Pt salt solution is dropped into the oil-ammonia water-oil-water four-layer mixed column, wherein the inner diameter of the drop head used is 1.0 mm-1.6 mm.

[0036] Further, the residence time of the mixture of aluminum hydroxide sol, Pt-containing aqueous solution, and organic Pt salt solution in the oil-ammonia water-oil-water four-layer mixed column is 5-18 s, preferably 7-11 s.

[0037] Further, the drying temperature is 100°C-150°C, and the drying time is 6-10 hours; the calcination temperature is 750°C-950°C, and the calcination time is 1-4 hours.

[0038] The second aspect of the present application provides a dehydrogenation catalyst prepared by the above preparation method.

[0039] Further, the specific surface area of the dehydrogenation catalyst is 80-110 m 2 / g, and the pore volume is 0.55-0.80 mL / g.

[0040] Further, the dehydrogenation catalyst is a spherical particle, and the average diameter of the particle is 1.6-1.9 mm.

[0041] Further, the pore size distribution of the dehydrogenation catalyst is as follows: the pore volume of the pores with a pore size less than 2 nm accounts for 0.9%-4.3% of the total pore volume, the pore volume of the pores with a pore size of 2-50 nm accounts for 95.7%-99.1% of the total pore volume, and preferably 96.0%-98.0%.

[0042] Further, the average pore size of the dehydrogenation catalyst is 14-18 nm.

[0043] Further, the crushing strength of the dehydrogenation catalyst is 66-88 N / particle.

[0044] Further, the roundness of the dehydrogenation catalyst is 97.5%-99.9%.

[0045] Further, in the dehydrogenation catalyst, the total content of Pt is 0.16%-1.20% by mass fraction, the content of Sn is 0.03%-0.90% by mass fraction, and the content of alumina is 97.90%-99.81% by mass fraction.

[0046] Further, in the dehydrogenation catalyst, the content of Pt on the surface of the catalyst is 0.001%-0.025%.

[0047] The third aspect of the present application provides the use of the above catalyst in a propane dehydrogenation reaction.

[0048] Further, the use includes: contacting a propane raw material with the catalyst to perform a dehydrogenation reaction, and obtaining a product propylene.

[0049] 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°C, and the reduction time is 1-3 h.

[0050] Further, the propane dehydrogenation reaction conditions are preferably as follows: the reaction temperature is 500-600°C, the reaction pressure is 0-1 MPa, and the volume space velocity is 50-200 h -1 .

[0051] Compared with the prior art, the present application has the following advantages:

[0052] (1) The present application adopts one-step synthesis of dehydrogenation catalyst, adding Pt-containing aqueous solution and organic Pt salt solution into 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 and fourth layers of water layer after passing through the second layer of ammonia water layer, and the pH value quickly decreases 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 decrease of the pH value of the sol pellet surface, at the same time, 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.

[0053] (2) The catalyst preparation process of the present application adds organic Pt salt solution. Due to the small solubility and large molecular weight of organic Pt, the organic molecules connected to Pt atoms occupy a large steric hindrance, and a single-atom Pt catalyst is easily formed during synthesis. The four-layer oil-water mixed column makes the organic Pt less likely to precipitate, and the contact with pseudo-boehmite is more sufficient, and the interaction force is stronger. After calcination, single-atom Pt and nanoparticle Pt exist in the catalyst at the same time, which can play a synergistic effect and improve the catalyst activity. In the four-layer mixed column of the present application, on the one hand, due to the small density difference between ammonia water and pure water, the selected liquid seal oil density 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. By adding a surfactant to transformer oil, the density can be increased without changing the viscosity, so that it meets the requirements. The water-soluble surfactant slowly penetrates into the oil under heating conditions, the intermolecular interaction force is enhanced, and the intermolecular distance is shortened during the evaporation of water. After repeated several times, the stability of the modified oil can be ensured. On the other hand, the modified transformer oil liquid seal is used. Due to the addition of surfactant, the surface tension at the oil-water interface is significantly reduced, the sol pellets stop at the oil-water interface, and can quickly pass through the interface, reducing the pulling force and effectively improving the roundness of the spherical carrier.

[0054] (3) The preparation process of the present application belongs to the environment-friendly type. In the traditional oil-ammonia column balling process, the volatilization of ammonia water brings serious environmental pollution problems and subsequent pollutant emission problems. The present application separates the second layer of ammonia water layer from the fourth layer of water layer by the second oil layer, so that the ammonia water layer is sealed on the fourth layer of water layer, which can prolong the use time, avoid environmental pollution caused by the product taking out ammonia water, and replace the deionized water after long-term use to ensure the liquid sealing effect. It is simple to operate and cost-saving in industry.

[0055] (4) The dehydrogenation catalyst prepared by the preparation method is used in the reaction of propane to propylene, has high propane conversion rate and propylene selectivity, the catalyst with large pore size and pore volume can avoid carbon deposition after long-term operation, Pt is mainly loaded in the interior of the catalyst and is not easy to be precipitated, and the catalyst has good stability and good reaction performance. DETAILED DESCRIPTION

[0056] The dehydrogenation catalyst, the preparation method and the application effect thereof are further illustrated by the following examples. The examples are implemented on the premise of the technical scheme of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0057] In the following examples, the experimental methods are all conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0058] In the present 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.

[0059] In the present application, the crushing strength is tested by using the ZQJ-III intelligent particle strength tester manufactured by the Dalian Ziqushen tester factory, and the average value of ten spherical carriers is tested.

[0060] In the present 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.

[0061] In the present application, the content of Pt on the surface of the catalyst is measured by using XPS (the instrument is Kratos Axis Ultra DLD model).

[0062] Example 1

[0063] Take 250g of the large-pore pseudo-boehmite filter cake with a water content of 22wt% (calcined at 600℃ for 3h in air atmosphere, and the properties are as follows: pore volume 0.87ml / g, specific surface area 175m 2 / g, and the average pore size is 16 nm), and then 26 g of a 45% nitric acid solution was added to gel the sol, and finally a boehmite sol with an alumina mass content of 20% was prepared; 300 g of the sol (alumina content of 20 wt%) was taken, 12 g of a chloroplatinic acid solution with a chloroplatinic acid concentration of 3% was added, and the solution simultaneously contained stannous chloride with a concentration of 0.8% and hydrochloric acid with a concentration of 7%, and then 6 g of an acetylacetone platinum solution with a concentration of 1.2% was added after uniform stirring, and the sol mixture was obtained after continuous stirring;

[0064] Lauryl diethanolamide and nonylphenol polyoxyethylene ether (n=9) were each added to 100 g of transformer oil (density of 0.89 g / mL at 20°C and kinematic viscosity of 12 mm 2 / s at 40°C) in an amount of 7 g, and after uniform stirring, the mixture was sealed and heated in an oven at 100°C for 8 hours, the sealing cover was removed and the mixture was continuously heated for 4 hours, and the above steps were repeated three times, and the final density of the modified transformer oil was 0.94 g / mL; the sol was added dropwise to a four-layer mixed column (cylinder) of white oil (kinematic viscosity of 32 mm 2 / s at 40°C) - ammonia water with a concentration of 25 wt% - modified transformer oil - deionized water) through a nozzle with an inner diameter of 1.2 mm, and the residence time in the four-layer mixed column was 8 s. The amount of white oil added was 35% of the volume of ammonia water, the amount of modified transformer oil added was 38% of the volume of ammonia water, and the amount of deionized water added was 1.3 times the volume of ammonia water. Then, the mixture was dried at 130°C for 8 hours, and calcined at 800°C for 3 hours to obtain the catalyst A of the present application, and the analysis results are shown in Table 1.

[0065] Example 2

[0066] 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 5 wt% dilute acetic acid solution, and the catalyst B of the present application is obtained, and the analysis results are shown in Table 1.

[0067] Example 3

[0068] Compared with Example 1, the difference is that 15.6 g of a chloroplatinic acid solution with a chloroplatinic acid concentration of 6% was added, and the solution simultaneously contained stannous chloride with a concentration of 1.0% and hydrochloric acid with a concentration of 9%, and then 6.4 g of an acetylacetone platinum solution with an acetylacetone platinum concentration of 1.8% was added after uniform stirring, and the catalyst C of the present application was obtained, and the analysis results are shown in Table 1.

[0069] Example 4

[0070] Compared with Example 1, the difference is that in the preparation of modified transformer oil, the surfactant used was changed to lauroyl diethanolamine, the amount added was changed to 12g, the number of repetitions was changed to 4, and the density of the modified transformer oil at 20℃ was 0.95g / mL, thus obtaining the catalyst D of the present invention. The analysis results are shown in Table 1.

[0071] Example 5

[0072] Compared with Example 1, the difference is that 5.4g of a 1.8% platinum acetylacetonate solution was added to obtain the catalyst E of the present invention, and the analytical results are shown in Table 1.

[0073] Example 6

[0074] Compared with Example 1, the difference is that the amount of white oil added is 42% of the volume of ammonia water, the amount of modified transformer oil added is 32% of the volume of ammonia water, and the amount of deionized water added is 1.6 times the volume of ammonia water, thus obtaining the catalyst F of the present invention. The analysis results are shown in Table 1.

[0075] Comparative Example 1

[0076] The synthesis steps for the sol mixture are the same as in Example 1.

[0077] Compared with Example 1, the difference is that the four-layer oil-ammonia-oil-water mixed column is replaced with a two-layer oil-ammonia column, and the upper layer has a kinematic viscosity of 32 mmHg at 40°C. 2 / s of white oil, the lower layer of which is 25wt% ammonia water, the amount of white oil added is 25% of the volume of ammonia water, and the remaining molding steps remain unchanged, to obtain the comparative catalyst G of this invention, and its analysis results are shown in Table 2.

[0078] Comparative Example 2

[0079] The synthesis steps for the sol mixture are the same as in Example 1.

[0080] Compared with Example 1, the difference is that only the first white oil column in the four-layer mixing column was removed, and a three-layer column was used to form a ball to obtain the comparative catalyst H of the present invention. The analysis results are shown in Table 2.

[0081] Comparative Example 3

[0082] The synthesis steps for the sol mixture are the same as in Example 1.

[0083] Compared with Example 1, the difference is that only the fourth water column was removed to obtain the comparative catalyst I of the present invention, and its analysis results are shown in Table 2.

[0084] Comparative Example 4

[0085] The synthesis steps for the sol mixture are the same as in Example 1.

[0086] Compared with Example 1, the difference is that only the modified transformer oil layer in the four-layer mixed column was removed to obtain the comparative catalyst J of the present invention, and its analysis results are shown in Table 2.

[0087] Comparative Example 5

[0088] The synthesis steps for the sol mixture are the same as in Example 1.

[0089] Compared to Example 1, the difference lies in that the modified transformer oil in the four-layer mixture is replaced with transformer oil, while the remaining molding steps remain unchanged. Specifically, the molding step involves using a dropper with an inner diameter of 1.2 mm to... (the text abruptly ends here, likely due to an incomplete sentence or missing information). 2 The above sol was added dropwise to a four-layer mixed column (cylinder) consisting of white oil, 25wt% ammonia, transformer oil, and deionized water, and the residence time in the four-layer mixed column was 8 s. The amount of white oil added was 35% of the volume of ammonia, the amount of transformer oil added was 38% of the volume of ammonia, and the amount of deionized water added was 1.3 times the volume of ammonia. After drying at 130℃ for 8 hours and calcining at 800℃ for 3 hours, the comparative catalyst K of this invention was obtained, and its analytical results are shown in Table 2.

[0090] Comparative Example 6

[0091] The method for synthesizing the sol mixture is the same as in Example 1.

[0092] Compared with Example 1, the difference is that the amount of white oil added is 16% of the volume of ammonia water, the amount of modified transformer oil added is 20% of the volume of ammonia water, and the amount of deionized water added is 0.4 times the volume of ammonia water, thus obtaining the comparative catalyst L of the present invention. The analysis results are shown in Table 2.

[0093] Table 1. Physicochemical properties of the catalysts obtained in each example.

[0094]

[0095]

[0096] Table 2. Physicochemical properties of the catalysts obtained in each comparative example.

[0097] Catalyst No. G H I J K L Particle average diameter, mm 1.79 1.77 1.75 1.75 1.76 1.76 Specific surface area, m 2 / g]] 98 107 99 101 105 99 Pore volume, mL / g 0.454 0.401 0.423 0.421 0.397 0.402 Pore size distribution, % < 2 nm 4.9 4.5 4.7 5.3 6.0 5.1 2-50 nm 95.0 95.3 95.3 94.5 94.0 94.6 > 50 nm 0.1 0.2 - 0.2 - 0.3 Average pore diameter, nm 13.1 13.0 13.6 11.2 10.5 11.4 Crushing strength, N / particle 37 22 39 41 37 38 True circularity, % 95.1 95.3 94.2 95.8 93.9 95.2

[0098] Table 3 Composition of catalysts in each embodiment

[0099] Catalyst No. A B C D E F Alumina (wt%) 99.6 99.6 99.0 99.6 99.6 99.6 Total Pt (wt%) 0.3 0.3 0.8 0.3 0.3 0.3 Sn (wt%) 0.1 0.1 0.2 0.1 0.1 0.1 Surface Pt (wt%) 0.01 0.01 0.02 0.01 0.01 0.01

[0100] Table 4. Composition of catalysts in each comparative example

[0101] Catalyst No. G H I J K L Alumina (wt%) 99.6 99.7 99.6 99.6 99.6 99.6 Total Pt (wt%) 0.3 0.2 0.3 0.3 0.3 0.3 Sn (wt%) 0.1 0.1 0.1 0.1 0.1 0.1 Surface Pt (wt%) Catalyst No. Alumina (wt%) Total Pt (wt%) Sn (wt%) Surface Pt (wt%) Catalyst No. Alumina (wt%) Total Pt (wt%) Sn (wt%) Surface Pt (wt%) Catalyst No. Alumina (wt%) Total Pt (wt%) Sn (wt%) Surface Pt (wt%) Catalyst No. Alumina (wt%) Total Pt (wt%) Sn (wt%) Surface Pt (wt%) Catalyst No. Alumina (wt%) Total Pt (wt%) Sn (wt%) Surface Pt (wt%) Catalyst No. Alumina (wt%) Total Pt (wt 0.01 0.01 0.01 0.01 0.01 0.01

[0102] Catalyst evaluation

[0103] Take 5g of the above catalyst and reduce it at 520℃ for 1.5h under a hydrogen atmosphere. Then, load it into a fixed-bed reactor for propane dehydrogenation activity evaluation: reaction temperature 600℃, pressure 0.5MPa, volume hourly space velocity 140h⁻¹. -1 The results of propane dehydrogenation are listed in Table 5-8.

[0104] Table 5 Evaluation results of the catalysts in each example for propane dehydrogenation

[0105]

[0106] Table 6 Evaluation results of the comparative catalysts for propane dehydrogenation

[0107]

[0108] Table 7. Stability evaluation results of the catalysts in each example for propane dehydrogenation.

[0109]

[0110] Table 8. Stability evaluation results of each comparative catalyst for propane dehydrogenation.

[0111]

[0112] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a dehydrogenation catalyst, comprising mixing an aluminum hydroxide sol with a Pt-containing aqueous solution and an organic Pt salt solution, dropping the obtained mixture into an oil-ammonia water-oil-water four-layer mixing column to form a shape, drying and calcining to obtain the dehydrogenation catalyst; In the mixing 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; The first oil layer is selected from one or more of white oil or diesel oil, 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 modified transformer oil used in the second oil layer has a density between that of ammonia water and water; The fourth layer of water layer 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; The Pt-containing aqueous solution contains stannous chloride and hydrochloric acid.

2. The method of claim 1, wherein: The Pt-containing compound in the Pt-containing aqueous solution is one or more of platinum chloride and chloroplatinic acid; And / or, the concentration of the Pt-containing compound in the Pt-containing aqueous solution is 2wt%-6wt%; And / or, the amount of the Pt-containing aqueous solution added is 8%-40% of the mass of the aluminum hydroxide sol calculated as aluminum oxide.

3. The method of claim 2, wherein: The Pt-containing compound in the Pt-containing aqueous solution is chloroplatinic acid; And / or, the amount of the Pt-containing aqueous solution added is 15%-30% of the mass of the aluminum hydroxide sol calculated as aluminum oxide.

4. The production method according to claim 1 or 2, characterized by: In the Pt-containing aqueous solution, the concentration of stannous chloride is 0.5wt%-3.5wt%, and the concentration of hydrochloric acid is 5wt%-12wt%.

5. The method of claim 1, wherein: The organic Pt salt in the organic Pt salt solution is one or more of platinum acetylacetonate or tetraphenylphosphonium platinum, and the solvent used is acetone; And / or, the concentration of the organic Pt salt in the organic Pt salt solution is 1.0wt%-1.9wt%; And / or, the amount of the organic Pt salt solution added is 9%-11% of the mass of the aluminum hydroxide sol calculated as aluminum oxide.

6. The method of claim 1, wherein: The organic Pt salt in the organic Pt salt solution is platinum acetylacetonate.

7. The method of claim 1, wherein: The content of aluminum oxide in the aluminum hydroxide sol is 15wt%-26wt%.

8. The method of claim 1, wherein: And / or, the oil-ammonia water-oil-water four-layer mixing column is a straight column.

9. The method of claim 8, wherein: And / or, the oil-ammonia water-oil-water four-layer mixing column is a cylindrical column.

10. 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.

11. The method of claim 1, wherein: The white oil has a kinematic viscosity at 40°C of 25-35 mm 2 / s.

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

13. The method of claim 12, wherein: The concentration of ammonia water in the ammonia water layer is 22wt%-26wt%.

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

15. The method of claim 14, wherein: The density of the modified transformer oil at 20℃ is 0.93-0.96 g / mL.

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

17. The method of claim 16, wherein: The mass of the water-soluble surfactant is 10%-18% of the mass of the transformer oil.

18. 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.

19. The method of claim 1, wherein: The preparation process of the modified transformer oil is as follows: The water-soluble surfactant is mixed with transformer oil, and the obtained mixture is subjected to heat treatment, i.e., sealed heat treatment and open heat treatment, repeatedly for 3-6 times, to obtain the modified transformer oil.

20. The method of claim 19, wherein: The sealed heat treatment is performed at a temperature of 80-120 DEG C for 6-20 hours.

21. The method of claim 19, wherein: The open heat treatment is performed at a temperature of 80-120 DEG C for 6-20 hours.

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

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

24. The dehydrogenation catalyst prepared by the preparation method of any one of claims 1-23.

25. The catalyst of claim 24, wherein: The specific surface area of the dehydrogenation catalyst is 80-110 m 2 / g, and the pore volume is 0.55-0.80 mL / g. And / or, the dehydrogenation catalyst is a spherical particle, and the average diameter of the particle is 1.6-1.9 mm. And / or, the average pore size of the dehydrogenation catalyst is 14-18 nm. And / or, the crushing strength of the dehydrogenation catalyst is 66-88 N / particle. And / or, the roundness of the dehydrogenation catalyst is 97.5%-99.9%. And / or, the pore size distribution of the dehydrogenation catalyst is as follows: the pore volume of pores with a pore size less than 2 nm accounts for 0.9%-4.3% of the total pore volume, and the pore volume of pores with a pore size of 2-50 nm accounts for 95.7%-99.1% of the total pore volume.

26. The catalyst of claim 25, wherein: The pore volume of pores with a pore size of 2-50 nm accounts for 96.0%-98.0% of the total pore volume.

27. The catalyst of claim 24, wherein: In the catalyst, the content of total Pt is 0.16%-1.20%, the content of Sn is 0.03%-0.90%, and the content of alumina is 97.90%-99.81%, all based on the mass of the catalyst.

28. The catalyst of claim 27, wherein: The content of Pt on the surface of the catalyst is 0.001%-0.025%.

29. The use of the catalyst of any one of claims 24-28 in a propane dehydrogenation reaction.

30. The use according to claim 29, characterized in that: Before use, the catalyst needs to be reduced.

31. The use according to claim 30, characterized in that: The reduction atmosphere is H2, the reduction temperature is 450-600 DEG C, and the reduction time is 1-3 hours.

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