A catalyst for dehydrogenation of propane to propylene and preparation and application thereof

Abstract

The application discloses a catalyst for preparing propylene from propane dehydrogenation and a preparation and application thereof. The catalyst comprises a tin-containing spherical alumina carrier and a noble metal Pt, wherein the preparation method of the tin-containing spherical alumina carrier comprises the following steps: mixing an aluminum hydroxide sol with an acidic silicon sol, dropping the obtained mixture into an oil-ammonia water-oil-water four-layer mixed column to form, drying and calcining, and thus obtaining the tin-containing spherical alumina carrier; 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 tin-containing water layer. The catalyst can significantly improve the catalyst activity when applied to a propane dehydrogenation reaction for preparing propylene.

Description

TECHNICAL FIELD

[0001] The present application relates to a catalyst for dehydrogenation of propane to propylene and its preparation and application. 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 properties and high packing coefficients, uniform fluid distribution, low resistance and small pressure drop, and are widely used in low-carbon alkane dehydrogenation 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 its preparation and application. 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 to the sol, and then adding a sol modification additive to the sol. The mixture is then dropped into an oil-ammonia column for spherification and aging, and finally washed, dried and calcined to obtain a high-strength large-specific-surface-area composite pellet. This method is to mix the suspension slurry of the ball-milled pseudoboehmite and molecular sieve with the dilute sol and then gelatinize 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 Si-containing γ-Al2O3 pellets. The method is to stir and slurry pseudo-boehmite dry glue 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 catalyst for propane dehydrogenation to propylene and a preparation and application thereof. The catalyst can significantly improve the catalyst activity when applied to the reaction of propane dehydrogenation to propylene.

[0009] The first aspect of the present application provides a preparation method of a catalyst for propane dehydrogenation to propylene, wherein the catalyst comprises a tin-containing spherical alumina carrier and a noble metal Pt; and the preparation method of the tin-containing spherical alumina carrier comprises:

[0010] The aluminum hydroxide sol is mixed with the acidic silicon sol, and the obtained mixture is dropped into an oil-ammonia water-oil-water four-layer mixed column for forming, drying, and calcining to obtain the tin-containing spherical alumina carrier; 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 tin-containing water layer.

[0011] Further, the tin-containing water layer comprises a tin salt and hydrochloric acid, wherein the tin salt is at least one of stannous chloride or tin tetrachloride, preferably stannous chloride. Further, in the tin-containing water layer, the concentration of the tin salt is 0.5wt% to 1.1wt%, preferably 0.6wt% to 0.8wt%, and the concentration of the hydrochloric acid is 5wt% to 8wt%.

[0012] Further, the alumina content in the aluminum hydroxide sol is 15wt% to 26wt%.

[0013] 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 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), 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 alumina, preferably 2wt% to 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% to 25wt%. Preferably, the properties of the aluminum hydroxide after calcination are as follows: specific surface area is 110 to 201m 2 / g, pore volume is 0.8 to 2.0mL / g, and average pore size is 15 to 17nm. The calcination conditions are as follows: temperature is 600 to 850℃, time is 2 to 12h, and the atmosphere contains oxygen, such as 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%.

[0014] Further, the concentration of the acid silicon sol is 5 to 45g SiO2 / L in terms of SiO2, the pH value of the silicon sol is controlled to be 3 to 5 by using an acid (such as at least one of nitric acid and acetic acid), and the addition amount of the acid silicon sol is 0.2wt% to 8.0wt% of the mass of the aluminum hydroxide sol in terms of alumina, preferably 2.5wt% to 7.5wt%.

[0015] Further, the oil-ammonia water-oil-water four-layer mixed column is a straight column, preferably a circular column.

[0016] 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, and the kinematic viscosity of the white oil at 40℃ is 20 to 40mm 2 / s, preferably 25 to 35mm 2 / s. The height of the first layer is 30% to 50% of the height of the second layer.

[0017] 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%.

[0018] 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 has a kinematic viscosity of 60mm 2 / s or more of one or more plant oils, preferably a mixed oil of castor oil and soybean oil, wherein the volume ratio of castor oil to soybean oil is 1 / 4 to 1 / 6. The castor oil has a kinematic viscosity of 500 to 650mm 2 / s, preferably 570 to 600mm 2 / s; the soybean oil has a kinematic viscosity of 10 to 25mm 2 / s, preferably 13 to 17mm 2 / s. The height of the third layer is 30% to 50% of the height of the second layer, preferably 35% to 45%.

[0019] Further, in the oil-ammonia water-oil-water four-layer mixed column, the tin-containing water layer is prepared by dissolving a tin salt in hydrochloric acid. The height of the fourth layer is 1.0 to 2.0 times the height of the second layer, preferably 1.2 to 1.5 times. In the preparation of the tin-containing spherical alumina carrier, when the concentration of the tin salt is less than 0.5wt%, the concentration is increased to the above-mentioned requirement by adding the tin salt through an external circulating pump.

[0020] Further, the preparation method of the oil-ammonia water-oil-water four-layer mixed column comprises:

[0021] (1) Pour the required material of the fourth layer into a columnar container (preferably an organic glass container) and ensure uniform solution;

[0022] (2) Slowly add the required material of the third layer to the fourth layer material of step (1) and stabilize for 20 to 35 minutes;

[0023] (3) Slowly add the required material of the second layer to the third layer material of step (2);

[0024] (4) slowly add the first layer of required material on the second layer of material of step (3) to obtain an oil-ammonia water-oil-water four-layer mixed column. Preferably, during the addition of the first layer of required material, slowly circulate up and down above the interface between the first layer and the second layer by peristaltic pump to weaken the surface tension on the interface between the first layer and the second layer, and then stand for 30-60 min until it is stable, so as to ensure that the aluminum hydroxide sol can quickly pass through the interface between the first layer and the second layer, prevent the generation of tailing due to stagnation, and affect the roundness.

[0025] Further, the tin-containing spherical alumina carrier is formed in the oil-ammonia water-oil-water four-layer mixed column, and the mixture of the aluminum hydroxide sol and the acidic silica sol is dropped into the oil-ammonia water-oil-water four-layer mixed column, wherein the inner diameter of the drop head used is 1.0-1.6 mm.

[0026] Further, the residence time of the mixture of the aluminum hydroxide sol and the acidic silica sol in the oil-ammonia water-oil-water four-layer mixed column is 5-18 s, preferably 7-11 s.

[0027] Further, the drying temperature is 100-150 ℃, and the drying time is 6-10 h; the calcination temperature is 550-950 ℃, and the calcination time is 1-4 h.

[0028] Further, in the catalyst for preparing propylene by dehydrogenation of propane, the noble metal Pt can be loaded by impregnation, preferably saturated impregnation. The Pt precursor used in the impregnating solution is preferably at least one of PtCl4 and H2PtCl6, and the drying conditions after impregnation are preferably as follows: the drying temperature is 80-120 ℃, and the drying time is 8-12 h. The calcination conditions after impregnation are preferably as follows: the calcination temperature is 500-700 ℃, and the calcination time is 2-6 h.

[0029] The second aspect of the present application provides a catalyst for preparing propylene by dehydrogenation of propane, which is prepared by the above preparation method, and the catalyst comprises a tin-containing alumina carrier and a noble metal Pt.

[0030] Further, in the catalyst, the content of Pt in terms of Pt is 0.2%-1.5% by mass fraction based on the mass of the catalyst, and the content of the carrier is 98.5%-99.8%. Further, in the tin-containing spherical alumina carrier, the mass fraction of silicon oxide in the mass of the alumina is 0.2wt%-7.0wt%, preferably 3.3wt%-5.1wt%, and the mass fraction of Sn in the mass of the alumina is 0.09wt%-0.89wt%, preferably 0.15wt%-0.55wt%.

[0031] Further, the specific surface area of the tin-containing spherical alumina carrier is 75-188 m 2The pore volume is 0.45-0.80 mL / g.

[0032] Further, the average diameter of the tin-containing spherical alumina carrier particles is 1.7-1.9 mm.

[0033] Further, the pore size distribution of the tin-containing spherical alumina carrier is as follows: the pore volume of pores with a pore size less than 2 nm accounts for 1.5%-6.0% of the total pore volume, the pore volume of pores with a pore size of 2-50 nm accounts for 93.8%-98.2%, preferably 95.0%-98.0%, of the total pore volume.

[0034] Further, the average pore size of the tin-containing spherical alumina carrier is 15-18 nm.

[0035] Further, the crush strength of the tin-containing spherical alumina carrier is 60-85 N / particle.

[0036] Further, the roundness of the tin-containing spherical alumina carrier is 95.5%-99.9%.

[0037] The third aspect of the present application provides the use of the above catalyst in a propane dehydrogenation reaction.

[0038] Further, the use comprises: contacting a propane raw material with the catalyst to perform a dehydrogenation reaction to obtain a product propylene.

[0039] 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.

[0040] 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 .

[0041] Compared with the prior art, the present application has the following advantages:

[0042] (1) The four-layer oil-ammonia water-oil-water mixed column used in the preparation process of the tin-containing spherical alumina carrier of the catalyst of the present application is different from the two-layer oil-ammonia column or the hot oil column, a third oil layer is added as a liquid seal oil layer and a fourth tin-containing water layer, which can make the sol quickly enter the third oil layer and the fourth tin-containing water layer after passing through the second ammonia water layer, and the pH value is quickly reduced to neutral or acidic, so that the small balls are not easy to break or shrink during the drying process due to the volatilization of the surface ammonia water, and the alumina particle size and mechanical strength are obviously increased. 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 is obviously increased, the distance between the colloidal particles is shortened, and the original structure is partially collapsed, resulting in an increase in the mesoporous structure of the carrier in the range of 2-50 nm. By adjusting the concentration of hydrochloric acid in the tin-containing water layer, the pore structure can be further optimized.

[0043] (2) In the preparation process of the tin-containing spherical alumina carrier of the present application, tin is introduced into the fourth water layer. Since the surface potential of the spherical sol is negative, Sn 2+ ions can be quickly adsorbed when passing through the tin-containing water layer. The metal element is introduced in one step during the synthesis of the carrier, and Sn-doped spherical alumina is prepared by subsequent calcination. The operation is simple, the adsorption mainly occurs on the outer surface, and the pore channel is not blocked. In addition, the interaction between Sn and alumina is enhanced during the solidification process, which is beneficial to improve the stability and dispersion of noble metal after loading, and thus improve the catalyst activity.

[0044] (3) The preparation process of the tin-containing spherical alumina carrier 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. In the present application, the second oil layer separates the second ammonia water layer and the fourth tin-containing water layer, so that the ammonia water layer is sealed above the fourth tin-containing water layer, which can prolong the service time and avoid environmental pollution caused by the product taking out ammonia water. After long-term use, the tin-containing water layer can be replaced to ensure the liquid sealing effect. The operation is simple and cost-saving in industry. DETAILED DESCRIPTION

[0045] The following examples further illustrate the catalyst for preparing propylene by dehydrogenation of propane and the preparation method and application effect thereof. The examples are implemented on the premise of the technical solutions 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.

[0046] 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.

[0047] 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 to determine the specific surface area, pore volume and pore size distribution.

[0048] In the present application, the crushing strength is tested by using the ZQJ-III intelligent particle strength tester manufactured by the Dalian Zixie Test Machine Factory, and the average value of crushing ten spherical carriers is tested.

[0049] 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 testing 20 samples.

[0050] Example 1

[0051] Take 250g of the 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, average pore diameter 16nm), add deionized water to stir and uniformly pulp, then add 26g of a 45wt% 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 20wt%), add 100mL of an acidic silica sol with a pH value of 4, and the silica sol concentration is 30g SiO2 / L, and after stirring uniformly, a sol mixture is obtained;

[0052] Use a nozzle with an inner diameter of 1.2mm to add the above sol to a four-layer mixed column (cylinder) of (white oil with a kinematic viscosity of 32mm 2 / s at 40℃-25wt% ammonia water-mixed oil-tin-containing aqueous solution) to form, and 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 tin-containing water layer is 1.3 times the volume of ammonia water; the mixed oil is mixed with castor oil with a kinematic viscosity of 580mm 2 / s at 40℃ and soybean oil with a kinematic viscosity of 15mm 2 / s at a volume ratio of 1:5. The stannous chloride concentration in the tin-containing aqueous solution is 0.7%, and the hydrochloric acid concentration is 6wt%. In the preparation process of the tin-containing spherical alumina carrier, when the stannous chloride concentration is less than 0.5wt%, the stannous chloride concentration in the tin-containing aqueous solution is supplemented by connecting a circulating pump to make the stannous chloride concentration equal to the initial concentration. Then dry at 130℃ for 8 hours, and calcine at 800℃ for 3 hours to obtain the tin-containing spherical alumina carrier A of the present application, and the analysis results are shown in Table 1.

[0053] Example 2

[0054] Compared with Example 1, the difference is that the concentration of hydrochloric acid in the fourth layer of the four-layer mixing column is changed to 8wt%, and the concentration of stannous chloride is changed to 0.8wt%, to obtain the tin-containing spherical alumina carrier B of the present application, the analysis results of which are shown in Table 1.

[0055] Example 3

[0056] Compared with Example 1, the difference is that the concentration of the acidic silica sol is changed to 15g SiO2 / L, the pH value of the acidic silica sol is adjusted to 5, the drying temperature is changed to 140°C, and the calcination temperature is changed to 850°C, to obtain the tin-containing spherical alumina carrier C of the present application, the analysis results of which are shown in Table 1.

[0057] Example 4

[0058] Compared with Example 1, the difference is that the white oil in the four-layer mixing column is changed to white oil with a kinematic viscosity of 23mm 2 / s at 40°C, the concentration of ammonia water is changed to 21wt%, and the volume ratio of castor oil to soybean oil is changed to 1:4, to obtain the tin-containing spherical alumina carrier D of the present application, the analysis results of which are shown in Table 1.

[0059] Example 5

[0060] Compared with Example 1, the difference is that the white oil in the four-layer mixing column is changed to a mixture of diesel oil and white oil with a mixing mass ratio of 1:1, and the concentration of ammonia water is changed to 28wt%, to obtain the tin-containing spherical alumina carrier E of the present application, the analysis results of which are shown in Table 1.

[0061] Example 6

[0062] Compared with Example 1, the difference is that the concentration of the acidic silica sol is changed to 25g SiO2 / L, the white oil in the four-layer mixing column is changed to white oil with a kinematic viscosity of 28mm 2 / s at 40°C, the concentration of ammonia water is changed to 23wt%, and the volume ratio of castor oil to soybean oil is changed to 1:4, to obtain the tin-containing spherical alumina carrier F of the present application, the analysis results of which are shown in Table 1.

[0063] Example 7

[0064] 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 mixed oil added is 32% of the volume of ammonia water, and the amount of tin-containing water layer added is 1.6 times the volume of ammonia water, to obtain the tin-containing spherical alumina carrier G of the present application, the analysis results of which are shown in Table 1.

[0065] Comparative Example 1

[0066] The sol mixture synthesis step is the same as that of Example 1.

[0067] Comparative Example 1 except that the four-layer oil-ammonia water-oil-water mixed column was changed to a two-layer oil-ammonia column, the upper layer was white oil with a kinematic viscosity of 32 mm 2 / s at 40°C, and the lower layer was ammonia water with a concentration of 25 wt%, the amount of white oil added was 25% of the volume of ammonia water, and the remaining molding steps were unchanged, to obtain a comparative spherical alumina carrier H of the present application, the analysis results of which are shown in Table 2.

[0068] Comparative Example 2

[0069] The sol mixture synthesis step was the same as in Example 1.

[0070] Comparative Example 1 except that only the first layer of white oil column was removed, and a three-layer column was used to form the spheres, to obtain a comparative tin-containing spherical alumina carrier I of the present application, the analysis results of which are shown in Table 2.

[0071] Comparative Example 3

[0072] The sol mixture synthesis step was the same as in Example 1.

[0073] Comparative Example 1 except that only the third layer of castor oil and soybean oil mixed layer was removed, to obtain a comparative tin-containing spherical alumina carrier J of the present application, the analysis results of which are shown in Table 2.

[0074] Comparative Example 4

[0075] The sol mixture synthesis method was the same as in Example 1.

[0076] Comparative Example 1 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 tin-containing water layer added was 0.4 times the volume of ammonia water, to obtain a comparative tin-containing spherical alumina carrier K of the present application, the analysis results of which are shown in Table 2.

[0077] Table 1 Physical and chemical properties of the tin-containing spherical alumina carriers obtained in each of the examples

[0078]

[0079]

[0080] Table 2 Physical and chemical properties of the tin-containing spherical alumina carriers obtained in each of the comparative examples

[0081] Support No. H I J K Particle average diameter, mm 1.83 1.79 1.64 1.65 Specific surface area, m 2 / g]] 99 104 95 96 Pore volume, mL / g 0.571 0.440 0.403 0.412 Pore size distribution, % < 2 nm 7.1 7.4 6.9 6.3 2-50 nm 92.5 92.4 92.6 93.5 > 50 nm 0.4 0.2 0.5 0.2 Average pore diameter, nm 12.9 12.3 14.5 12.4 Crushing strength, N / particle 43 49 32 36 True sphericity, % 95.4 91.9 89.5 90.8

[0082] Catalyst evaluation

[0083] Take 100 g of the spherical alumina support containing tin prepared in the above Examples 1-7 and Comparative Examples 2-4, respectively, and saturate-impregnate in an aqueous solution containing 0.8 g of chloroplatinic acid, dry in a drying oven at 90°C for 10 h after impregnation for 30 min, calcine in a muffle furnace at 600°C for 4 h, and reduce at 520°C for 1.5 h under a hydrogen atmosphere. Take 100 g of the spherical alumina support prepared in the above Comparative Example 1, saturate-impregnate in an aqueous solution containing 0.8 g of chloroplatinic acid and 0.4 g of tin tetrachloride, dry in a drying oven at 90°C for 10 h after impregnation for 30 min, calcine in a muffle furnace at 600°C for 4 h, and reduce at 520°C for 1.5 h under a hydrogen atmosphere. The compositions of the resulting catalysts are shown in Tables 3-4.

[0084] Take 5 g of each of the above catalysts, and load into a fixed bed reactor for evaluation of the activity for dehydrogenation of propane: reaction temperature 580°C, atmospheric pressure, volume space velocity 50 h -1 The results of the dehydrogenation of propane are shown in Tables 5-6.

[0085] Table 3 Compositions of the catalysts obtained in the Examples

[0086]

[0087]

[0088] Table 4 Compositions of the catalysts obtained in the Comparative Examples

[0089] Support No. H I J K Al2O3 (wt%) 97.1 97.7 97.3 96.45 Sn (wt%) 0.2 0.1 0.1 0.15 SiO2 (wt%) 2.3 1.9 2.2 3.0 Pt (wt%) 0.4 0.3 0.4 0.4

[0090] Table 5 Evaluation results of the catalysts obtained in the Examples for dehydrogenation of propane

[0091]

[0092] Table 6 Evaluation results of the catalysts obtained in the Comparative Examples for dehydrogenation of propane

[0093]

[0094] The above detailed description of the specific embodiments of the present application, however, is not intended to limit the present application. 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, 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 catalyst for dehydrogenation of propane to propylene, said catalyst comprising a tin-containing spherical alumina support and a noble metal Pt; said method for preparing the tin-containing spherical alumina support comprising: The tin-containing spherical alumina carrier is prepared by mixing aluminum hydroxide sol with acidic silica sol, dropping the obtained mixture into an oil-ammonia water-oil-water four-layer mixed column to shape, drying and calcining.

2. The method of claim 1, wherein: The aluminum oxide content in the aluminum hydroxide sol is 15wt%-26wt%. And / or, the concentration of the acidic silica sol is 5-45g SiO2 / L in terms of SiO2. And / or, the pH value of the acidic silica sol is 3-5. And / or, the addition amount of the acidic silica sol in terms of SiO2 is 0.2wt%-8.0wt% of the mass of the aluminum hydroxide sol in terms of aluminum oxide.

3. The method of claim 2, wherein: The addition amount of the acidic silica sol in terms of SiO2 is 2.5wt%-7.5wt% of the mass of the aluminum hydroxide sol in terms of aluminum oxide.

4. 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.

5. The method of claim 4, wherein: The white oil has a kinematic viscosity at 40°C of 25-35 mm 2 / s.

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

7. The method of claim 6, wherein: The concentration of the ammonia water is 22wt%-26wt%.

8. 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.

9. The method of claim 8, 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.

10. The method of claim 1, wherein: In the oil-ammonia water-oil-water four-layer mixed column, in the tin-containing water layer, the tin salt is at least one of stannous chloride or tin tetrachloride. And / or, in the tin-containing water layer, the concentration of the tin salt is 0.5wt%-1.1wt%, and the concentration of hydrochloric acid is 5wt%-8wt%.

11. The method of claim 10, wherein: The tin salt is stannous chloride. And / or, the concentration of the tin salt is 0.6wt%-0.8wt%.

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

13. The method of claim 12, wherein: The oil-ammonia water-oil-water four-layer mixed column is a cylindrical column.

14. The method of claim 1, wherein: In the catalyst for preparing propylene by dehydrogenation of propane, the noble metal Pt is loaded by impregnation method.

15. The method of claim 14, wherein: The impregnation method is saturation impregnation method.

16. The catalyst for preparing propylene by dehydrogenation of propane prepared by the preparation method of any one of claims 1-15, wherein the catalyst comprises a tin-containing alumina carrier and a noble metal Pt.

17. The catalyst of claim 16, wherein: In the catalyst, in terms of mass fraction, the content of Pt in terms of Pt is 0.2%-1.5%, and the content of the tin-containing alumina carrier is 98.5%-99.8%.

18. The catalyst of claim 16, wherein: In the tin-containing spherical alumina carrier, the content of silicon oxide is 0.2wt%-7.0wt% of the mass of aluminum oxide, and the content of Sn in terms of Sn is 0.09wt%-0.89wt% of the mass of aluminum oxide.

19. The catalyst of claim 18, wherein: The tin-containing spherical alumina carrier has 3.3wt%-5.1wt% of silicon oxide in terms of the mass of alumina; and 0.15wt%-0.55wt% of Sn in terms of the mass of alumina.

20. The catalyst of any one of claims 16-19, wherein: The tin-containing spherical alumina support has a specific surface area of 75 to 188 m 2 / g; And / or, the tin-containing spherical alumina carrier has a pore volume of 0.45-0.80 mL / g; And / or, the tin-containing spherical alumina carrier has an average diameter of 1.7-1.9 mm; And / or, the tin-containing spherical alumina carrier has an average pore diameter of 15-18 nm; And / or, the tin-containing spherical alumina carrier has a crushing strength of 60-85 N / particle; And / or, the tin-containing spherical alumina carrier has a roundness of 95.5%-99.9%; And / or, the tin-containing spherical alumina carrier has a pore size distribution of: 1.5%-6.0% of the pore volume of pores with a pore size less than 2 nm, and 93.8%-98.2% of the pore volume of pores with a pore size of 2-50 nm, in terms of the total pore volume.

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

22. Use of the catalyst of any one of claims 16-21 in a propane dehydrogenation reaction.

23. The use according to claim 22, characterized in that: The propane dehydrogenation catalyst needs to be reduced before use.

24. The use according to claim 23, 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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