Spherical pt-containing catalyst and preparation and use thereof

Abstract

The application discloses a spherical Pt-containing catalyst and a preparation method and application thereof. The catalyst comprises alumina and Pt, and the preparation method comprises the following steps: 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 mixed column to form a shape, drying and calcining, and obtaining the spherical Pt-containing catalyst. The catalyst is used in a propane dehydrogenation reaction, and has good stability and good reaction performance.

Description

TECHNICAL FIELD

[0001] The present application relates to a spherical Pt-containing catalyst and a preparation method and application thereof, in particular to a spherical Pt-containing catalyst suitable for a boiling bed and a preparation method and application thereof. BACKGROUND

[0002] The shape and size of 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. 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 the 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 the aggregation of the active components of the catalyst and the serious decrease of 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-sphering 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 the uneven dispersion of the molecular sieve. At the same time, the doping of solid molecular sieve will also cause the decrease of the strength of the carrier.

[0006] CN105478100A discloses a method for preparing Si-containing γ-Al2O3 pellets. The method is to stir and slurry pseudo-boehmite dry gel powder and deionized water, acidify 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 solidification in ammonia water for 2 hours, then filter, rinse with deionized water, dry, and calcine to obtain Si-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, 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 long preparation period, complex process, and pH value needs to be adjusted, and cannot guarantee product consistency. SUMMARY

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

[0009] The first aspect of the present application provides a method for preparing a spherical Pt-containing catalyst, wherein the catalyst comprises aluminum oxide and Pt, and the preparation method of the catalyst comprises:

[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 spherical Pt-containing catalyst.

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

[0012] Further, the preparation method of the aluminum hydroxide sol comprises: mixing aluminum hydroxide and 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) 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 1% to 10% by mass of the aluminum hydroxide in terms of acid, and preferably 2% to 8% by mass. Further, the aluminum hydroxide is preferably hydrous aluminum hydroxide, such as aluminum hydroxide wet material. Preferably, the water content in the aluminum hydroxide is 17% to 25% by mass. Preferably, the properties of the aluminum hydroxide after calcination are as follows: the specific surface area is 110 to 201 m 2 / g, the pore volume is 0.8 to 2.0 mL / g, and the average pore diameter is 15 to 17 nm. The calcination conditions are as follows: the temperature is 600 to 850°C, the time is 2 to 12 hours, 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 19% to 23% by mass.

[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 2% to 6% by mass. The addition amount of the Pt-containing aqueous solution is 8% to 40% by mass of the aluminum hydroxide sol in terms of aluminum oxide, and is preferably 15% to 30%.

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

[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 1.0% to 1.9% by mass. The addition amount of the organic Pt salt solution is 9% to 11% by mass of the aluminum hydroxide sol in terms of aluminum oxide.

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

[0018] Further, in the oil-ammonia water-oil-water four-layer mixed column, four layers are arranged in sequence 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.

[0019] 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, the kinematic viscosity of the white oil at 40℃ is 20-40mm 2 / s, preferably 25-35mm 2 / s. The height of the first layer is 30%-50% of the height of the second layer.

[0020] Further, in the oil-ammonia water-oil-water four-layer mixed column, the second layer is an ammonia water layer, the concentration of the ammonia water is 20wt%-28wt%, preferably 22wt%-26wt%.

[0021] 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, which is one or more plant oils with a kinematic viscosity of 60mm 2 / s or less at 40℃, preferably a mixed oil of castor oil and soybean oil with a volume ratio of 1 / 4-1 / 6. The kinematic viscosity of the castor oil at 40℃ is 500-650mm 2 / s, preferably 570-600mm 2 / s; the kinematic viscosity of the soybean oil at 40℃ is 10-25mm 2 / s, preferably 13-17mm 2 / s. The height of the third layer is 30%-50% of the height of the second layer, preferably 35%-45%.

[0022] 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 the height of the second layer, preferably 1.2-1.5 times.

[0023] 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%.

[0024] Further, the preparation method of the oil-ammonia water-oil-water four-layer mixed column comprises:

[0025] (1) Pour the required material of the fourth layer into a columnar container (preferably an organic glass container) and ensure uniform solution;

[0026] (2) slowly add the required material of the third layer to the fourth layer material of step (1) and stabilize for 20-35 min;

[0027] (3) slowly add the required material of the second layer to the third layer material of step (2);

[0028] (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, slow up-and-down circulation is performed above the interface between the first layer and the second layer by a peristaltic pump to weaken 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, so that the aluminum hydroxide sol can quickly pass through the interface between the first layer and the second layer, preventing the generation of tailing due to stagnation and affecting the roundness.

[0029] Further, the spherical Pt-containing catalyst is formed in the oil-ammonia water-oil-water four-layer mixed column, and the mixture of the aluminum hydroxide sol and the Pt-containing aqueous solution and the organic Pt salt solution is dropped into the oil-ammonia water-oil-water four-layer mixed column, wherein the inner diameter of the dropping head used is 1.0 mm-1.6 mm.

[0030] Further, the residence time of the mixture of the aluminum hydroxide sol and the Pt-containing aqueous solution and the organic Pt salt solution in the oil-ammonia water-oil-water four-layer mixed column is 5-18 s, preferably 7-11 s.

[0031] 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.

[0032] The second aspect of the present application provides a spherical Pt-containing catalyst prepared by the above preparation method.

[0033] Further, the specific surface area of the spherical Pt-containing catalyst is 65-115 m 2 / g, and the pore volume is 0.55-0.75 mL / g.

[0034] Further, the spherical Pt-containing catalyst particles are spherical, and the average diameter of the particles is 1.6-1.9 mm.

[0035] Further, the pore size distribution of the spherical Pt-containing catalyst is that the pore volume of the pores with a pore size less than 2 nm accounts for 0.5%-5.5% of the total pore volume, and the pore volume of the pores with a pore size of 2-50 nm accounts for 93.0%-99.0%, preferably 95.0%-98.0%, of the total pore volume.

[0036] Further, the average pore size of the spherical Pt-containing catalyst is 13-16 nm.

[0037] Further, the crush strength of the spherical Pt-containing catalyst is 60-80 N / particle.

[0038] Further, the sphericity of the spherical Pt-containing catalyst is 94.9%-99.9%.

[0039] Further, in the spherical Pt-containing catalyst, the content of total Pt in the catalyst is 0.25%-1.3% by mass, the content of Sn is 0.02%-0.8% by mass, and the content of alumina is 97.9%-99.7% by mass, based on the mass of the catalyst. Further, the content of Pt on the surface of the catalyst is 0.005%-0.03%, preferably 0.01%-0.03%.

[0040] The third aspect of the present application provides the use of the above catalyst in a propane dehydrogenation reaction.

[0041] Further, the use comprises: contacting a propane raw material with the catalyst to perform a dehydrogenation reaction, to obtain a product propylene.

[0042] 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.

[0043] Further, the propane dehydrogenation reaction conditions are preferably as follows: the reaction temperature is 500-600°C, the reaction pressure is 0-1 MPa, the volume space velocity is 50-200 h-1, and the catalyst bed height is 1-10 cm. -1 .

[0044] Compared with the prior art, the present application has the following advantages:

[0045] (1) The present application uses a one-step method to synthesize a spherical Pt-containing catalyst. Pt-containing aqueous solution and organic Pt salt solution are added to the aluminum hydroxide sol, so that the metal Pt is uniformly dispersed in the alumina carrier, and also plays a pore expansion role. The four-layer oil-ammonia water-oil-water mixed column is different from the two-layer oil-ammonia column or hot oil column. The third layer of oil layer serves as a liquid seal oil layer and the fourth layer of water layer. The sol can quickly enter the third layer and the fourth layer after passing through the second layer of ammonia water layer, the pH value quickly decreases to neutral, so that the small balls are not easy to break or shrink during the drying process due to the volatilization of surface ammonia water, the catalyst particle size and mechanical strength are significantly increased, and at the same time, the metal and the carrier are in full contact, and the metal is not easy to agglomerate. In addition, the rapid decrease of the pH value of the sol small ball surface also causes the rapid decrease of the hydrophobicity of the colloidal particle surface, 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 to the fourth layer of water layer, the pore structure can be further optimized.

[0046] (2) In the preparation process of the catalyst, the organic Pt salt solution is added, because the solubility of the organic Pt is small, and the molecular weight is large, and the space steric hindrance of the organic molecules connected with the Pt atoms is large, so that the monatomic Pt catalyst is easily formed in the synthesis process, the four-layer oil-ammonia water-oil-water mixed column makes the organic Pt not easy to precipitate, and the contact with the pseudo-boehmite is more sufficient, and the interaction force is stronger, and after calcination, the monatomic Pt and the nanoparticle Pt exist in the catalyst at the same time, which can play a synergistic effect, and improve the catalyst activity.

[0047] (3) The preparation process of the application belongs to the environment-friendly type, in the traditional oil-ammonia column balling process, the ammonia water volatilization brings environmental pollution problems and subsequent pollutant emission problems are more serious, the second oil layer separates the second layer of ammonia water layer and the fourth layer of water layer, so that the ammonia water layer is sealed on the fourth layer of water layer, the use time can be prolonged, the environmental pollution caused by the product taking out the ammonia water can be avoided, after long-term use, the deionized water can be replaced to ensure the liquid sealing effect, the operation is simple in industry, and the cost is saved.

[0048] (4) The spherical Pt-containing catalyst prepared by the preparation method has high propane conversion rate and propylene selectivity, 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

[0049] The following examples further illustrate the spherical Pt-containing catalyst and the preparation method and application effect thereof. The examples are implemented on the premise of the technical scheme 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.

[0050] In the following examples, the experimental methods are conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are purchased from conventional biochemical reagent stores unless otherwise specified.

[0051] In the application, the nitrogen adsorption-desorption curve of the sample is tested at-196 DEG C 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.

[0052] In the application, the crushing strength is tested by using the ZQJ-III intelligent particle strength tester manufactured by the Dalian Zhiqu Testing Machine Factory, and the average value of ten spherical catalysts is tested.

[0053] In the application, the true circularity is tested by using the electronic microscope of the Olympus Company, and the average value is calculated after testing 20 samples.

[0054] In the present application, the content of metal Pt on the surface of the catalyst is measured by XPS (instrument: Kratos Axis Ultra DLD model).

[0055] Example 1

[0056] Take 250g of the macroporous pseudoboehmite filter cake with a moisture content of 22wt% (calcined at 600°C for 3h in air atmosphere, properties as follows: pore volume 0.87ml / g, specific surface area 175m 2 / g, average pore diameter 16nm), after stirring and uniformly slurry with deionized water, add 26g of 45% mass concentration nitric acid solution for peptization, finally prepare the pseudoboehmite sol with 20% mass content of alumina; take 300g of the above sol (alumina content of 20wt%), add 12g of chloroplatinic acid solution with 3% concentration of chloroplatinic acid, which contains 0.8% concentration of stannous chloride and 7% concentration of hydrochloric acid at the same time, stir uniformly, then continue to add 6g of acetylacetone platinum solution with 1.2% concentration of acetylacetone platinum, stir uniformly, to obtain the sol mixture;

[0057] Use the nozzle with inner diameter of 1.2mm to drop the above sol into the four-layer mixed column (cylinder) of white oil (40°C kinematic viscosity of 32mm 2 / s) - ammonia water (concentration of 25wt%) - mixed oil - deionized water, the residence time in the four-layer mixed column is 8s. Among them, the addition amount of white oil is 35% of the volume of ammonia water, the addition amount of mixed oil is 38% of the volume of ammonia water, and the addition amount of deionized water is 1.3 times of the volume of ammonia water; the mixed oil is mixed by castor oil with 40°C kinematic viscosity of 580mm 2 / s and soybean oil with kinematic viscosity of 15mm 2 / s, the volume ratio of the two is 1:5. Then dry at 130°C for 8 hours, calcine at 800°C for 3 hours, to obtain the spherical Pt-containing catalyst A of the present application, the analysis results of which are shown in Table 1.

[0058] Example 2

[0059] Compared with Example 1, the difference is that the material in the fourth layer of the four-layer mixed column is changed from deionized water to 5wt% dilute acetic acid solution, to obtain the spherical Pt-containing catalyst B of the present application, the analysis results of which are shown in Table 1.

[0060] Example 3

[0061] Compared with Example 1, the difference is that 15.6g of chloroplatinic acid solution with 6% concentration of chloroplatinic acid is added, which contains 1.0% concentration of stannous chloride and 9% concentration of hydrochloric acid at the same time, stir uniformly, then continue to add 6.4g of acetylacetone platinum solution with 1.8% concentration of acetylacetone platinum, to obtain the spherical Pt-containing catalyst C of the present application, the analysis results of which are shown in Table 1.

[0062] Example 4

[0063] Comparing with Example 1, the difference is that the white oil in the four-layer mixing column is replaced by white oil with 23 mm 2 / s kinematic viscosity at 40°C, the ammonia water concentration is changed to 21 wt%, and the volume ratio of castor oil to soybean oil is changed to 1:4, to obtain the spherical Pt-containing catalyst D of the application, the analysis results of which are shown in Table 1.

[0064] Example 5

[0065] Comparing with Example 1, the difference is that the white oil in the four-layer mixing column is replaced by a mixture of diesel oil and white oil with a mixing mass ratio of 1:1, and the ammonia water concentration is changed to 28 wt%, to obtain the spherical Pt-containing catalyst E of the application, the analysis results of which are shown in Table 1.

[0066] Example 6

[0067] Comparing with Example 1, the difference is that the chloroplatinic acid concentration is changed to 6%, the acetylacetone platinum concentration is changed to 1.8%, the white oil in the four-layer mixing column is replaced by white oil with 28 mm 2 / s kinematic viscosity at 40°C, the ammonia water concentration is changed to 23 wt%, and the volume ratio of castor oil to soybean oil is changed to 1:4, to obtain the spherical Pt-containing catalyst F of the application, the analysis results of which are shown in Table 1.

[0068] Example 7

[0069] Comparing with Example 1, the difference is that the amount of white oil added is 42% of the volume of ammonia water, the amount of mixed 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, to obtain the spherical Pt-containing catalyst G of the application, the analysis results of which are shown in Table 1.

[0070] Comparative Example 1

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

[0072] Comparing with Example 1, the difference is that the four-layer oil-ammonia water-oil-water mixing column is replaced by a two-layer oil-ammonia column, the upper layer is white oil with 32 mm 2 / s kinematic viscosity at 40°C, and the lower layer is ammonia water with a concentration of 25 wt%, 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 spherical Pt-containing catalyst H of the application, the analysis results of which are shown in Table 2.

[0073] Comparative Example 2

[0074] The sol mixture synthesis step is the same as that of Example 1.

[0075] Comparative Example 1 was repeated except that only the first layer of white oil column was removed and the three-layer column was used to form the spherical catalyst, to obtain Comparative Spherical Pt-containing Catalyst I of the present application. The analysis results are shown in Table 2.

[0076] Comparative Example 3

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

[0078] Comparative Example 1 was repeated except that only the fourth layer of water column was removed, to obtain Comparative Spherical Pt-containing Catalyst J of the present application. The analysis results are shown in Table 2.

[0079] Comparative Example 4

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

[0081] Comparative Example 1 was repeated except that only the third layer of castor oil and soybean oil mixed layer in the four-layer mixed column was removed, to obtain Comparative Spherical Pt-containing Catalyst K of the present application. The analysis results 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 was repeated except that the amount of white oil added was 16% of the volume of ammonia water, the amount of mixed oil added was 20% of the volume of ammonia water, and the amount of deionized water added was 0.4 times the volume of ammonia water, to obtain Comparative Spherical Pt-containing Catalyst L of the present application. The analysis results are shown in Table 2.

[0085] Table 1 Physical and chemical properties of the spherical catalysts obtained in the examples

[0086] Catalyst No. A B C D E F G Particle average diameter, mm 1.84 1.83 1.80 1.79 1.81 1.83 1.82 Specific surface area, m 2 / g]] 78 82 83 80 79 81 80 Pore volume, mL / g 0.715 0.729 0.712 0.699 0.701 0.711 0.698 Pore size distribution, % < 2 nm 3.9 4.0 4.1 3.8 4.2 4.2 4.1 2-50 nm 96.0 95.9 95.4 95.6 95.4 95.6 95.8 > 50 nm 0.1 0.1 0.5 0.6 0.4 0.2 0.1 Average pore diameter, nm 15.9 15.8 15.4 14.5 14.8 15.6 14.5 Crushing strength, N / particle 75 73 70 69 71 72 71 True circularity, % 96.9 96.5 96.3 96.4 96.2 96.0 96.3

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

[0088] Catalyst No. H I J K L Particle average diameter, mm 1.75 1.76 1.55 1.70 1.72 Specific surface area, m 2 / g]] 85 89 86 87 88 Pore volume, mL / g 0.586 0.584 0.498 0.506 0.512 Pore size distribution, % < 2 nm 6.9 7.5 6.3 5.0 5.2 2-50 nm 92.4 92.1 93.1 94.5 94.6 > 50 nm 0.7 0.4 0.6 0.5 0.2 Average pore diameter, nm 14.2 14.6 13.0 12.1 13.1 Crushing strength, N / particle 53 60 59 43 45 True circularity, % 89.2 85.2 84.1 79.6 82.9

[0089] Table 3 Composition of the catalysts in the examples

[0090]

[0091]

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

[0093] Catalyst No. H I J K L Alumina (wt%) 99.7 99.6 99.7 99.6 99.6 Total Pt (wt%) 0.2 0.3 0.2 0.3 0.3 Surface Pt (wt%) 0.01 0.01 0.01 0.01 0.01 Sn (wt%) 0.1 0.1 0.1 0.1 0.1

[0094] Catalyst evaluation

[0095] Each of the 5 g catalysts was reduced under hydrogen atmosphere at 520°C for 1.5 h, and then was charged into a fixed bed reactor for evaluation of propane dehydrogenation activity: reaction temperature 550°C, pressure 0.5 MPa, volume space velocity 100 h -1 The results of propane dehydrogenation are listed in Tables 5-8.

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

[0097]

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

[0099]

[0100] Table 7 Evaluation results of each of the catalysts of the examples for propane dehydrogenation stability

[0101]

[0102] Table 8 Evaluation results of each of the catalysts of the comparative examples for propane dehydrogenation stability

[0103]

[0104] The above detailed description of the specific embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. 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 spherical Pt-containing catalyst, wherein the catalyst comprises alumina and Pt, the method 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 mixed column to form a shape, drying and calcining to obtain the spherical Pt-containing catalyst; the Pt-containing aqueous solution contains stannous chloride and hydrochloric acid; the oil-ammonia water-oil-water four-layer mixed column is provided with four layers 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 a mixed oil of castor oil and soybean oil; the volume ratio of castor oil to soybean oil is 1 / 4 to 1 / 6; the density of the second oil layer is between the second ammonia water layer and the fourth water layer; the fourth water layer is deionized water or a dilute acid solution; the height of the first layer is 30% to 50% of the height of the second layer; the height of the third layer is 30% to 50% of the height of the second layer; and the height of the fourth layer is 1.0 to 2.0 times the height of the second layer.

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% to 6wt%; and / or, the amount of the Pt-containing aqueous solution added is 8% to 40% of the mass of the aluminum hydroxide sol in terms of alumina.

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

4. The method of claim 1, wherein: in the Pt-containing aqueous solution, the concentration of stannous chloride is 0.5wt% to 3.5wt%, and the concentration of hydrochloric acid is 5wt% to 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 tetrakis(triphenylphosphine) 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% to 1.9wt%; and / or, the amount of the organic Pt salt solution added is 9% to 11% of the mass of the aluminum hydroxide sol in terms of alumina.

6. The method of claim 5, wherein: the organic Pt salt is platinum acetylacetonate.

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

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

9. The method of claim 1, wherein: the oil-ammonia water-oil-water four-layer mixed 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 10, 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 mixed column, the concentration of the ammonia water is 20wt% to 28wt%.

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

14. The method of claim 1, wherein: The oil-ammonia water-oil-water four-layer mixed column, the kinematic viscosity of castor oil at 40℃ is 500~650mm 2 / s; the kinematic viscosity of soybean oil at 40℃ is 10~25mm 2 / s.

15. The method of claim 14, wherein: The castor oil has a kinematic viscosity at 40°C of 570-600 mm 2 / s; and the soybean oil has a kinematic viscosity at 40°C of 13-17 mm 2 / s.

16. 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; the acid in the dilute acid solution is selected from at least one of acetic acid and citric acid; and the mass concentration of the dilute acid solution is 3% to 8%. 17.The method according to claim 1, characterized in that: and / or, 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 the height of the second layer. 18.A spherical Pt-containing catalyst prepared by the method of any one of claims 1 to 17.

19. The catalyst of claim 18, wherein: The specific surface area of the spherical Pt-containing catalyst is 65-115 m 2 / g; and / or, the pore volume of the spherical Pt-containing catalyst is 0.55-0.75 mL / g; and / or, the average diameter of the spherical Pt-containing catalyst particle is 1.6-1.9 mm; and / or, the average pore diameter of the spherical Pt-containing catalyst is 13-16 nm; and / or, the crush strength of the spherical Pt-containing catalyst is 60-80 N / particle; and / or, the sphericity of the spherical Pt-containing catalyst is 94.9%-99.9%.

20. The catalyst of claim 18, wherein: The pore size distribution of the catalyst is: the pore volume of the pores with a pore diameter less than 2 nm accounts for 0.5%-5.5% of the total pore volume, and the pore volume of the pores with a pore diameter of 2-50 nm accounts for 93.0%-99.0% of the total pore volume.

21. The catalyst of claim 20, wherein: The pore volume of the pores with a pore diameter of 2-50 nm accounts for 95.0%-98.0% of the total pore volume.

22. The catalyst of claim 18, wherein: In the catalyst, the content of total Pt is 0.25%-1.3%, the content of Sn is 0.02%-0.8%, and the content of alumina is 97.9%-99.7% by mass based on the mass of the catalyst.

23. The catalyst of claim 22, wherein: The content of Pt on the surface of the catalyst is 0.005%-0.03%.

24. The catalyst of claim 23, wherein: The content of Pt on the surface of the catalyst is 0.01%-0.03%.

25. The catalyst of any one of claims 18-24 is used in the dehydrogenation reaction of propane.

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

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

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