A catalyst for dehydrogenation of propane to produce propylene and preparation and use thereof

Abstract

The application discloses a catalyst for propane dehydrogenation to produce propylene and preparation and application thereof. The catalyst comprises a tin-containing alumina carrier and active metal Pt, wherein the pore size distribution of the tin-containing alumina carrier is as follows: the pore volume of pores with a pore size less than 2 nm accounts for 1.5-5.0% of the total pore volume, and the pore volume of pores with a pore size of 2-50 nm accounts for 95.0-98.5% of the total pore volume. The catalyst can significantly improve the catalyst activity when applied to the reaction of propane dehydrogenation to produce propylene.

Description

TECHNICAL FIELD

[0001] The present application relates to a catalyst for producing propylene by dehydrogenation of propane 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 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 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, followed by 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. This method is to mix the suspension slurry of the pseudoboehmite and the molecular sieve after ball milling with the dilute sol again, which will cause uneven dispersion of the molecular sieve. At the same time, the doping of the solid molecular sieve will also cause a decrease in the strength of the carrier.

[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 and 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, 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, 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 produce propylene and a preparation and application thereof. The catalyst is used in the reaction of propane dehydrogenation to produce propylene, and the catalytic activity is significantly improved.

[0009] The first aspect of the present application provides a catalyst for propane dehydrogenation to produce propylene, which comprises a tin-containing alumina carrier and active metal Pt, wherein the pore size distribution of the tin-containing alumina carrier is that the pore volume of pores with a pore size less than 2nm accounts for 1.5%-5.0% of the total pore volume, and the pore volume of pores with a pore size of 2-50nm accounts for 95.0%-98.5%, preferably 95.5%-98.0% of the total pore volume.

[0010] Further, in the catalyst for propane dehydrogenation to produce propylene, the content of Pt is 0.2%-1.6% based on the mass of the catalyst, and the content of the tin-containing alumina carrier is 98.4%-99.8% based on the mass.

[0011] Further, the specific surface area of the tin-containing alumina carrier is 65-120 m 2 / g, and the pore volume is 0.50-0.86 mL / g.

[0012] Further, the tin-containing alumina carrier is a spherical particle, and the average diameter of the particle is 1.8-2.0 mm.

[0013] Further, the average pore diameter of the tin-containing alumina carrier is 14-18 nm.

[0014] Further, the crushing strength of the tin-containing alumina carrier is 62-79 N / particle.

[0015] Further, the roundness of the tin-containing alumina carrier is 97.7%-99.9%.

[0016] Further, in the tin-containing alumina carrier, the content of Sn is 0.08%-0.89%, the content of SiO2 is 3.0%-5.1%, and the content of alumina is 94.01%-96.92%.

[0017] The second aspect of the present application provides a preparation method of the above-mentioned catalyst for producing propylene by dehydrogenation of propane, wherein the preparation method of the tin-containing alumina carrier comprises:

[0018] The aluminum hydroxide sol is mixed with an acidic silica sol, and the obtained mixture is dropped into an oil-ammonia water-oil-water four-layer mixed column to form a shape, and then dried and calcined to obtain a tin-containing spherical alumina carrier; in the oil-ammonia water-oil-water four-layer mixed column, a first oil layer, an ammonia water layer, a second oil layer and a tin-containing water layer are sequentially arranged from top to bottom, wherein the second oil layer is selected from modified transformer oil, and the tin-containing water layer comprises a tin salt and hydrochloric acid.

[0019] Further, in the tin-containing water layer, the tin salt is at least one of stannous chloride or tin tetrachloride, and preferably stannous chloride. Further, in the tin-containing water layer, the concentration of the tin salt is 0.5wt%-1.1wt%, and preferably 0.6wt%-0.8wt%, and the concentration of hydrochloric acid is 5wt%-8wt%.

[0020] Further, the content of alumina in the aluminum hydroxide sol is 15wt%-26wt%.

[0021] Further, the preparation method of the aluminum hydroxide sol comprises: mixing aluminum hydroxide with water to obtain a slurry, and adding a peptizing agent to obtain the aluminum hydroxide sol after uniform stirring. Further, the peptizing agent is selected from one or more of inorganic acids (such as nitric acid) 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 is 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 aluminum hydroxide after calcination has the following properties: a specific surface area of 110 to 201 m 2 / g, a pore volume of 0.8 to 2.0 mL / g, and an average pore diameter of 15 to 17 nm. The calcination conditions are as follows: a temperature of 600 to 850°C, a time of 2 to 12 hours, and an oxygen-containing atmosphere such as air. The aluminum hydroxide can be commercially available or prepared by a conventional method. The aluminum hydroxide is preferably hydrous macroporous pseudoboehmite with a water content of 19% to 23% by mass.

[0022] Further, the concentration of the acidic silica sol is 5 to 45 g SiO2 / L in terms of SiO2, the pH value of the silica sol is adjusted to 3 to 5 by using an acid (such as at least one of nitric acid and acetic acid), and the addition amount of the acidic silica sol is 0.2% to 8.0% by mass of the aluminum hydroxide sol in terms of SiO2, and is preferably 2.5% to 7.5% by mass.

[0023] Further, the oil-ammonia water-oil-water four-layer mixed column is a straight column, and is preferably a circular column.

[0024] Further, in the oil-ammonia water-oil-water four-layer mixed column, the first oil layer is selected from one or more of white oil or diesel oil, and is preferably white oil. The kinematic viscosity of the white oil at 40°C is 20 to 40 mm 2 / s, and is preferably 25 to 35 mm 2 / s. The height of the first oil layer is 30% to 50% of the height of the ammonia water layer.

[0025] Further, in the oil-ammonia water-oil-water four-layer mixed column, the concentration of the ammonia water in the ammonia water layer is 20% to 28% by mass, and is preferably 22% to 26% by mass.

[0026] Further, in the oil-ammonia water-oil-water four-layer mixed column, the density of the modified transformer oil in the second oil layer, i.e. the liquid seal oil layer, is between that of the ammonia water and the water, preferably, the density of the modified transformer oil at 20℃ is 0.90 g / mL or more, preferably 0.93-0.96 g / mL, and further preferably 0.94-0.96 g / mL. Further, the height of the second oil layer is 30%-50% of the height of the ammonia water layer, preferably 35%-45%.

[0027] Further, the modified transformer oil comprises a transformer oil and a water-soluble surfactant.

[0028] Further, the mass of the water-soluble surfactant is 6%-25% of the mass of the transformer oil, preferably 10%-18%.

[0029] Further, the water-soluble surfactant is one or more of lauryl diethanolamide, nonylphenol polyoxyethylene ether (preferably with a polymerization degree of 9, i.e. n=9) or octylphenol polyoxyethylene ether (preferably with a polymerization degree of 7, i.e. n=7).

[0030] Further, the density of the transformer oil (at 20℃) is 0.86-0.89 g / mL, and the kinematic viscosity at 40℃ is 9-15 mm 2 / s.

[0031] Further, the modified transformer oil is prepared as follows:

[0032] The water-soluble surfactant is mixed with the transformer oil, and the obtained mixture is subjected to heat treatment, i.e. sealed heat treatment and open heat treatment, and the heat treatment is repeated 3-6 times to obtain the modified transformer oil.

[0033] Further, the sealed heat treatment is performed at a temperature of 80-120℃ for 6-20 h.

[0034] Further, the open heat treatment is performed at a temperature of 80-120℃ for 6-20 h.

[0035] 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 1.0-2.0 times, preferably 1.2-1.5 times, the height of the second layer. In the preparation of the tin-containing spherical alumina carrier, when the concentration of the tin salt is less than 0.5 wt%, the concentration is increased to the above-mentioned requirement by adding the tin salt through an external circulating pump.

[0036] Further, the preparation method of the oil-ammonia water-oil-water four-layer mixed column comprises:

[0037] (1) Pour the material required for tin-containing water layer into a columnar container (preferably an organic glass container) and ensure the solution is uniform;

[0038] (2) Slowly add the material required for the second oil layer to the tin-containing water layer material of step (1) and stabilize for 20-35 min;

[0039] (3) Slowly add the material required for the ammonia water layer to the second oil layer material of step (2);

[0040] (4) Slowly add the material required for the first oil layer to the ammonia water layer material of step (3) to obtain an oil-ammonia water-oil-water four-layer mixed column. Preferably, during the addition of the material required for the first oil layer, slow up-and-down circulation is performed above the interface between the first oil layer and the ammonia water layer by a peristaltic pump to weaken the surface tension at the interface between the first oil layer and the ammonia water layer, and then stand for 30-60 min until it is stable, which can ensure that the aluminum hydroxide sol can quickly pass through the contact interface between the first oil layer and the ammonia water layer, prevent the generation of tailing due to stagnation, and affect the roundness.

[0041] Further, the tin-containing 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 mm-1.6 mm.

[0042] 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.

[0043] Further, the drying temperature is 100-150℃, and the drying time is 6-10 hours; the calcination temperature is 550-950℃, and the calcination time is 1-4 hours.

[0044] Further, in the catalyst for producing propylene by dehydrogenation of propane, the active 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.

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

[0046] The third aspect of the present application provides the use of the above-mentioned catalyst in the dehydrogenation reaction of propane.

[0047] Further, the application comprises: propane raw material is contacted with the catalyst to carry out dehydrogenation reaction, and product propylene is obtained.

[0048] Further, the dehydrogenation reaction conditions of propane are preferably as follows: the reaction temperature is 500-600 DEG C, the reaction pressure is 0-1 MPa, the volume space velocity is 50-200 h -1 .

[0049] Compared with the prior art, the application has the advantages that:

[0050] (1) The four-layer oil-ammonia water-oil-water mixed column used in the preparation process of the tin-containing alumina carrier of the application is different from the two-layer oil-ammonia column or hot oil column, the second oil layer is added as a liquid seal oil layer and the tin-containing water layer, so that the sol can quickly enter the second oil layer and the tin-containing water layer after passing through the ammonia water layer, 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, 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 the increase of the mesoporous structure of the carrier in the range of 2-50 nm. By adjusting the concentration of hydrochloric acid in the fourth layer tin-containing water layer, the pore structure can be further optimized.

[0051] (2) In the four-layer oil-ammonia water-oil-water mixed column used in the application, the density difference between the ammonia water in the ammonia water layer and the pure water in the water layer is small, so the density of the liquid seal oil (modified transformer oil) in the second oil layer needs to be greater than that of the ammonia water and less than that of the pure water, and the viscosity cannot be too large. In the application, the density of the modified transformer oil can be increased without changing the viscosity by adding a surfactant to the transformer oil, so that it meets the requirements. The water-soluble surfactant slowly penetrates into the oil under heating conditions, the intermolecular interaction force is enhanced, the intermolecular distance is shortened during the water evaporation process, and the stability of the modified transformer oil can be ensured after repeated use. The use of modified transformer oil liquid seal can significantly reduce the surface tension at the oil-water interface due to the addition of surfactant, reduce the stop of sol small balls when passing through the oil-water interface, quickly pass through the interface, reduce the pulling, and effectively improve the roundness of the spherical carrier.

[0052] (3) In the four-layer oil-ammonia water-oil-water mixed column used in the application, tin is introduced into the fourth layer water layer. Since the surface potential of the spherical sol is negative, Sn 2+The ion is introduced into the metal element in a one-step method in a carrier synthesis process, and the Sn-doped spherical alumina carrier is prepared through subsequent calcination, which is not only simple in operation, but also beneficial to improve the stability and dispersion of the noble metal after loading, and then improve the catalyst activity, since the adsorption mainly occurs on the outer surface and does not block the pore channel, and the interaction between Sn and alumina is enhanced during the solidification process.

[0053] (4) The preparation process of the application is environmentally friendly. In the traditional oil-ammonia column balling process, the volatilization of ammonia water causes serious environmental pollution problems and subsequent pollutant emission problems. The second oil layer separates the ammonia water layer and the tin-containing water layer, so that the ammonia water layer is sealed above the tin-containing water layer, which can prolong the use time and avoid environmental pollution caused by the product taking out ammonia water. After long-term use, the tin-containing water layer can be replaced to ensure the liquid sealing effect. The industrial operation is simple and cost-saving. DETAILED DESCRIPTION

[0054] The catalyst for producing propylene by dehydrogenation of propane, the preparation method and application effect thereof in the application will be further illustrated by examples. 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.

[0055] 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.

[0056] 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.

[0057] 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 carriers is tested.

[0058] 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.

[0059] Example 1

[0060] Take 250g of the macroporous pseudo-boehmite filter cake with a water content of 22wt% (calcined at 600 DEG C for 3h in an 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 pseudo-boehmite sol with an alumina content of 20% was prepared; 300 g of the sol (alumina content of 20 wt%) was taken, and 100 mL of an acidic silica sol with a SiO2 concentration of 30 g SiO2 / L and a pH value of 4 was added, and then the mixture was stirred to obtain a sol mixture;

[0061] 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 the mixture was stirred and then sealed and heated in an oven at 100°C for 8 hours, and then the sealed cover was removed and the mixture was heated for another 4 hours, and the above steps were repeated three times to obtain modified transformer oil (density of 0.94 g / mL at 20°C). 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), 25 wt% ammonia water, modified transformer oil, and tin-containing aqueous solution) 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 the ammonia water, the amount of modified transformer oil added was 38% of the volume of the ammonia water, and the amount of tin-containing aqueous solution added was 1.3 times the volume of the ammonia water. The concentration of stannous chloride in the tin-containing aqueous solution was 0.7%, and the concentration of hydrochloric acid was 6 wt%. During the preparation of the tin-containing spherical alumina carrier, when the concentration of stannous chloride was less than 0.5 wt%, stannous chloride was added to the tin-containing aqueous solution to make the concentration of stannous chloride in the tin-containing aqueous solution equal to the initial concentration by means of an external circulating pump. Then the mixture was dried at 130°C for 8 hours, and then calcined at 800°C for 3 hours to obtain the tin-containing alumina carrier A of the present application, and the analysis results are shown in Table 1.

[0062] Example 2

[0063] Compared with Example 1, the difference lies in that the concentration of hydrochloric acid in the fourth layer of tin-containing water is changed to 8 wt%, and the concentration of tin salt is changed to 0.8%, and the tin-containing alumina carrier B of the present application is obtained, and the analysis results are shown in Table 1.

[0064] Example 3

[0065] Compared with Example 1, the difference lies in that the concentration of the acidic silica sol is changed to 15 g 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, and the tin-containing alumina carrier C of the present application is obtained, and the analysis results are shown in Table 1.

[0066] Example 4

[0067] Comparative Example 1

[0068] Example 5

[0069] Comparative Example 1

[0070] Example 6

[0071] Comparative Example 1

[0072] Comparative Example 1

[0073] The sol mixture synthesis step is the same as Example 1.

[0074] Comparative Example 1 2 Comparative Example 1

[0075] Comparative Example 1

[0076] The sol mixture synthesis step is the same as Example 1.

[0077] Comparative Example 1

[0078] Comparative Example 1

[0079] The sol mixture synthesis step is the same as Example 1.

[0080] Comparative Example 1

[0081] Comparative Example 1

[0082] The sol mixture synthesis step is the same as that of Example 1.

[0083] Compared with Example 1, the difference is that only the second oil layer of modified transformer oil layer is removed to obtain the comparative tin-containing alumina carrier J of the present application, and the analysis results are shown in Table 2.

[0084] Comparative Example 5

[0085] The sol mixture synthesis step is the same as that of Example 1.

[0086] Compared with Example 1, the difference is that only the second oil layer of modified transformer oil layer is replaced by transformer oil, and the remaining molding steps remain unchanged, i.e., the molding step is to add the above sol into the four-layer mixed column (cylinder) of (40 ℃ kinematic viscosity of 32 mm 2 / s white oil-ammonia water with a concentration of 25 wt% -transformer oil-tin-containing aqueous solution) through a nozzle with an inner diameter of 1.2 mm, and the residence time in the four-layer mixed column is 8 s. Among them, the amount of white oil added is 35% of the volume of ammonia water, the amount of transformer oil added is 38% of the volume of ammonia water, and the amount of tin-containing aqueous solution added is 1.3 times the volume of ammonia water. The concentration of stannous chloride in the tin-containing aqueous solution is 0.7%, and the concentration of hydrochloric acid is 6 wt%. During the preparation of the tin-containing spherical alumina carrier, when the concentration of stannous chloride is less than 0.5 wt%, the stannous chloride in the tin-containing aqueous solution is supplemented by an external circulating pump to make the concentration of stannous chloride in the tin-containing aqueous solution be the initial concentration. Then dried at 130 ℃ for 8 hours, and calcined at 800 ℃ for 3 hours to obtain the comparative alumina carrier K of the present application, and the analysis results are shown in Table 2.

[0087] Comparative Example 6

[0088] The sol mixture synthesis method is the same as that of Example 1.

[0089] 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 tin-containing aqueous solution added is 0.4 times the volume of ammonia water, to obtain the comparative tin-containing alumina carrier L of the present application, and the analysis results are shown in Table 2.

[0090] Table 1 Physical and chemical properties of tin-containing alumina carriers obtained in each example

[0091]

[0092]

[0093] Table 2 Physical and chemical properties of tin-containing alumina carriers obtained in each comparative example

[0094] Support No. G H I J K L Particle average diameter, mm 1.76 1.76 1.77 1.64 1.72 1.73 Specific surface area, m 2 / g]] 89 91 96 87 89 92 Pore volume, mL / g 0.431 0.435 0.492 0.395 0.401 0.411 Pore size distribution, % < 2 nm 6.2 3.6 7.7 7.1 6.3 6.1 2-50 nm 93.6 96.2 92.2 92.8 93.6 93.8 > 50 nm 0.2 0.1 0.1 0.1 0.1 0.1 Average pore diameter, nm 13.7 12.9 12.3 12.5 10.4 11.2 Crushing strength, N / particle 35 41 37 44 23 30 True sphericity, % 93.2 95.7 91.4 90.4 90.2 91.4

[0095] Catalyst evaluation

[0096] Example 1-6 and Comparative Examples 2, 4, 5 were taken respectively to prepare 100 g of tin-containing alumina support, saturated impregnation into an aqueous solution containing 0.8 g of chloroplatinic acid, impregnated for 30 min, dried in a drying oven at 90°C for 10 h, calcined in a muffle furnace at 600°C for 4 h, and reduced at 520°C under hydrogen atmosphere for 1.5 h. Comparative Examples 1, 3 were taken respectively to prepare 100 g of spherical alumina support, saturated impregnation into an aqueous solution containing 0.8 g of chloroplatinic acid, 0.4 g of tin tetrachloride, impregnated for 30 min, dried in a drying oven at 90°C for 10 h, calcined in a muffle furnace at 600°C for 4 h, and reduced at 520°C under hydrogen atmosphere for 1.5 h. The compositions of the obtained catalysts are listed in Tables 3-4.

[0097] 5 g of the above catalysts were taken respectively and loaded into a fixed bed reactor for evaluation of the propane dehydrogenation activity: reaction temperature 590°C, atmospheric pressure, volume space velocity 110 h -1 The results of propane dehydrogenation are listed in Tables 5-6.

[0098] Composition of the catalysts of each example in Table 3

[0099]

[0100]

[0101] Composition of the catalysts of each comparative example in Table 4

[0102] Support No. G H I J K L Alumina (wt%) 95.3 95.5 96.2 96.5 95.5 95.5 Pt (wt%) 0.4 0.4 0.4 0.4 0.4 0.4 Sn (wt%) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 0.2 0.2 0.2 0.1 0.1 0.1 SiO2(wt%) 4.1 3.9 3.2 3.0 4.0 4.0

[0103] Evaluation results of the catalysts of each example in Table 5 for propane dehydrogenation

[0104]

[0105] Evaluation results of the catalysts of each comparative example in Table 6 for propane dehydrogenation

[0106]

[0107] The specific embodiments of the present application are described in detail above, 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, 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 catalyst for the dehydrogenation of propane to propylene, said catalyst comprising a tin-containing alumina support and an active metal Pt, wherein, The pore size distribution of the tin-containing alumina support is as follows: pores with a pore size less than 2 nm account for 1.5% to 5.0% of the total pore volume, and pores with a pore size of 2-50 nm account for 95.0% to 98.5% of the total pore volume; in the catalyst, based on the mass of the catalyst, the content of Pt (calculated as Pt) is 0.2% to 1.6% by mass fraction, and the content of the tin-containing alumina support is 98.4% to 99.8%; in the tin-containing alumina support, the content of Sn is 0.08% to 0.89%, the content of SiO2 is 3.0% to 5.1%, and the content of alumina is 94.01% to 96.92%; The preparation method of the tin-containing alumina carrier includes: mixing aluminum hydroxide sol and acidic silica sol, dripping the resulting mixture into a four-layer oil-ammonia-oil-water mixing column to form a solid, drying, and calcining solution to obtain a tin-containing spherical alumina carrier; the four-layer oil-ammonia-oil-water mixing column is provided with a first oil layer, an ammonia layer, a second oil layer, and a tin-containing water layer from top to bottom, wherein the second oil layer is selected from modified transformer oil, and the tin-containing water layer includes tin salt and hydrochloric acid; the first oil layer is selected from one or more of white oil or diesel oil; the height of the first oil layer is 30% to 50% of the height of the ammonia layer; the height of the second oil layer is 30% to 50% of the height of the ammonia layer; and the height of the tin-containing water layer is 1.0 to 2.0 times the height of the ammonia layer.

2. The catalyst according to claim 1, characterized in that: The tin-containing alumina carrier has pores with a diameter of 2-50 nm accounting for 95.5% to 98.0% of the total pore volume.

3. The catalyst according to claim 1, characterized in that: The specific surface area of ​​the tin-containing alumina carrier is 65~120m². 2 / g; And / or, the pore volume of the tin-containing alumina support is 0.50~0.86 mL / g; And / or, the average diameter of the tin-containing alumina carrier is 1.8~2.0 mm; And / or, the average pore size of the tin-containing alumina support is 14~18 nm; And / or, the crushing strength of the tin-containing alumina carrier is 62~79 N / particle; And / or, the sphericity of the tin-containing alumina carrier is 97.7%~99.9%.

4. The method for preparing the catalyst according to any one of claims 1-3, characterized in that: The preparation method of the tin-containing alumina carrier includes: mixing aluminum hydroxide sol and acidic silica sol, dropping the resulting mixture into a four-layer oil-ammonia-oil-water mixing column to form a solid, drying, and calcining to obtain a tin-containing spherical alumina carrier; the four-layer oil-ammonia-oil-water mixing column is provided with a first oil layer, an ammonia layer, a second oil layer, and a tin-containing water layer from top to bottom, wherein the second oil layer is selected from modified transformer oil, and the tin-containing water layer includes tin salt and hydrochloric acid.

5. The preparation method according to claim 4, characterized in that: In the tin-containing aqueous layer, the tin salt is at least one of stannous chloride or stannous tetrachloride; And / or, in the tin-containing aqueous layer, the concentration of tin salt is 0.5wt%~1.1wt%, and the concentration of hydrochloric acid is 5wt%~8wt%.

6. The preparation method according to claim 5, characterized in that: The tin salt is stannous chloride; the tin salt concentration is 0.6wt%~0.8wt%.

7. The preparation method according to claim 4, characterized in that: The aluminum hydroxide sol contains 15wt%~26wt% aluminum oxide. And / or, the concentration of the acidic silica sol is 5~45 g SiO2 / L, calculated as SiO2; And / or, the pH value of the acidic silica sol is 3 to 5; And / or, the amount of acidic silica sol added is 0.2wt% to 8.0wt% of the mass of aluminum hydroxide sol (calculated as aluminum oxide), based on SiO2.

8. The preparation method according to claim 7, characterized in that: The amount of acidic silica sol added is 2.5wt% to 7.5wt% of the mass of aluminum hydroxide sol (calculated as aluminum oxide), based on SiO2.

9. The preparation method according to claim 4, characterized in that: In the oil-ammonia-oil-water four-layer mixed column, the first oil layer is white oil, and the kinematic viscosity of the white oil at 40°C is 20~40 mmHg. 2 / s.

10. The preparation method according to claim 9, characterized in that: The kinematic viscosity of the white oil at 40°C is 25~35 mm. 2 / s.

11. The preparation method according to claim 4, characterized in that: In the oil-ammonia-oil-water four-layer mixed column, the ammonia concentration in the ammonia layer is 20wt%~28wt%.

12. The preparation method according to claim 11, characterized in that: The ammonia concentration is 22wt%~26wt%.

13. The preparation method according to claim 4, characterized in that: The density of the modified transformer oil is between that of ammonia and water.

14. The preparation method according to claim 13, characterized in that: The modified transformer oil has a density of 0.90 g / mL or higher at 20°C.

15. The preparation method according to claim 14, characterized in that: The modified transformer oil has a density of 0.93~0.96 g / mL at 20°C.

16. The preparation method according to claim 4, characterized in that: In the oil-ammonia-oil-water four-layer mixed column, the modified transformer oil includes transformer oil and water-soluble surfactant.

17. The preparation method according to claim 16, characterized in that: The mass of the water-soluble surfactant is 6% to 25% of the transformer oil mass.

18. The preparation method according to claim 17, characterized in that: The mass of the water-soluble surfactant is 10% to 18% of the mass of the transformer oil.

19. The preparation method according to claim 16, characterized in that: The water-soluble surfactant is one or more of lauroyl diethanolamine, nonylphenol polyoxyethylene ether, or octylphenol polyoxyethylene ether.

20. The preparation method according to claim 16, characterized in that: The transformer oil has a density of 0.86~0.89 g / mL at 20℃ and a kinematic viscosity of 9~15 mm at 40℃. 2 / s.

21. The preparation method according to claim 4, characterized in that: The modified transformer oil is prepared as follows: a water-soluble surfactant is mixed with transformer oil, and the resulting mixture is subjected to heat treatment, namely, sealed heating treatment and open heating treatment in sequence, and the above heat treatment is repeated 3 to 6 times to obtain the modified transformer oil.

22. The preparation method according to claim 21, characterized in that: The conditions for the sealing heat treatment are as follows: heating temperature is 80~120℃, and heating time is 6~20 h.

23. The preparation method according to claim 21, characterized in that: The conditions for the open-type heat treatment are as follows: the heating temperature is 80~120℃, and the heating time is 6~20 h.

24. The preparation method according to claim 4, characterized in that: The height of the second oil layer is 35% to 45% of the height of the ammonia water layer; And / or, the height of the tin-containing water layer is 1.2 to 1.5 times the height of the ammonia water layer.

25. The use of the catalyst according to any one of claims 1-3 in the propane dehydrogenation reaction.

26. The application according to claim 25, characterized in that: The catalyst needs to be reduced before it can be used.

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

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