Catalyst for preparing propylene through propane dehydrogenation as well as preparation and application of catalyst

Abstract

The invention discloses a catalyst for preparing propylene through propane dehydrogenation as well as preparation and application of the catalyst. The catalyst comprises a tin-containing spherical alumina carrier and noble metal Pt, and a preparation method of the tin-containing spherical alumina carrier comprises the following steps: mixing aluminum hydroxide sol with acidic silica sol, dropwise adding the obtained mixture into an oil-ammonia water-oil-water four-layer mixed column, molding, drying and roasting to obtain the tin-containing spherical alumina carrier; the oil-ammonia water-oil-water four-layer mixing column is sequentially 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 tin-containing water layer. When the catalyst is applied to propane dehydrogenation propylene preparation reaction, the activity of the catalyst can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to a catalyst for propane dehydrogenation to propylene, its preparation and application. Background Art

[0002] The shape and size of catalyst particles are generally determined according to the requirements of the reactors used in industrial production. Currently, there are four common types of reactors in industry: fixed bed, fluidized bed (boiling bed), suspension bed and moving bed. Fixed bed reactors commonly use spherical, cylindrical strip, clover, four-leaf and flake catalysts. Moving bed reactors often use large particle spherical catalysts. Fluidized bed reactors generally use smaller spherical or bar-shaped catalysts.

[0003] Spherical catalysts have good fluidity, a higher packing coefficient, uniform fluid distribution, low resistance, small pressure drop and other advantages, and are widely used in the technology of dehydrogenating lower alkanes to produce olefins.

[0004] Currently, the catalysts for dehydrogenating lower alkanes to produce olefins are mainly prepared by loading the active component Pt and other additives on a γ-Al 2 O 3 support, such as EP100222A, CN1185994A, etc. However, since the dehydrogenation reaction is carried out at a high temperature of about 600 °C, the high reaction temperature often causes a large amount of carbon deposition on the catalyst. As the catalyst is used for a longer time, the catalyst needs to be subjected to multiple high-temperature carbon burning regeneration treatments, resulting in the γ-Al 2 O 3 support being prone to sintering and α-phase transformation, greatly reducing the specific surface area of the support, damaging the pore structure, and then aggregating the active components of the catalyst, resulting in a serious decline in the catalyst activity. Therefore, it is necessary to further modify the γ-Al 2 O 3 support to make the catalyst have higher thermal stability.

[0005] CN112973771A discloses a spherical catalyst support containing molecular sieve and alumina, its preparation and application. The catalyst support is obtained by precipitating an inorganic aluminum salt with ammonia water and acidifying to obtain a sol, adding a mixed solution of ball-milled pseudo-boehmite and molecular sieve and a sol modification additive to the sol, then dropping and forming and aging in an oil-ammonia column, and finally washing, drying and calcining to obtain a composite small ball with high strength and large specific surface area. This method is to mix the suspension slurry obtained by ball-milling pseudo-boehmite and molecular sieve with a dilute sol and then peptize again, which will have the disadvantage of uneven dispersion of the molecular sieve. At the same time, the doping of solid molecular sieve will also lead to a decrease in the strength of the support.

[0006] CN105478100A discloses a method for preparing silicon-containing γ-Al 2 O 3Method for preparing small balls. This method involves stirring and slurrying pseudo-boehmite dry gel powder with deionized water, acidifying with dilute nitric acid, adding urea and a predetermined amount of sodium silicate solution, stirring for 5 hours, adding kerosene and fatty alcohol polyoxyethylene ether and stirring for 5 hours, dropping and forming balls in an oil-ammonia column, curing the wet balls in ammonia water for 2 hours, then filtering, rinsing with deionized water, drying, and calcining to obtain silicon-containing γ-Al 2 O 3 small balls. The method for preparing γ-Al 2 O 3 small balls has a long curing time, is difficult to wash, and has low production efficiency.

[0007] CN104289220A discloses a preparation method and use of a high thermal stability dehydrogenation catalyst for lower alkanes. The method for preparing the carrier is to add an aluminum source to an alkaline aqueous solution, stir, continue to drop 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 and form balls, and then dry and calcine to obtain γ-Al 2 O 3 small balls containing Si element; or add an aluminum source to an alkaline aqueous solution, stir, continue to drop 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 and form balls, and then dry and calcine to obtain γ-Al 2 O 3 small balls, and then impregnate the γ-Al 2 O 3 small balls in an aqueous solution or ethanol solution of a silicon source at 60-120 °C for 2-6 hours, and then dry and calcine to obtain γ-Al 2 O 3 small balls containing Si element. The disadvantages of this method are long preparation cycle, complex process, need to regulate the pH value, and cannot ensure product consistency. SUMMARY OF THE INVENTION

[0008] Aiming at the deficiencies of the prior art, the present invention provides a catalyst for propane dehydrogenation to propylene and its preparation and application. The catalyst can significantly improve the catalyst activity when applied to the propane dehydrogenation to propylene reaction.

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

[0010] The aluminum hydroxide sol is mixed with the acidic silica sol, and the resulting mixture is dropped into an oil-ammonia-oil-water four-layer mixing column for shaping, followed by drying and calcination to obtain a tin-containing spherical alumina support; in the oil-ammonia-oil-water four-layer mixing column, four layers are arranged in sequence from top to bottom, the first layer is the first oil layer, the second layer is the ammonia water layer, the third layer is the second oil layer, and the fourth layer is the tin-containing water layer.

[0011] Further, the tin-containing water layer includes 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 0.5 wt% to 1.1 wt%, preferably 0.6 wt% to 0.8 wt%, and the concentration of hydrochloric acid is 5 wt% to 8 wt%.

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

[0013] Further, the preparation method of the aluminum hydroxide sol includes: mixing aluminum hydroxide and water to make a slurry, adding a peptizing agent, and stirring evenly to obtain the aluminum hydroxide sol. Further, the peptizing agent is selected from one or more of inorganic acids (such as nitric acid), organic acids (such as acetic acid, citric acid), 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 calculated as acid is 1 wt% to 10 wt% of the mass of aluminum hydroxide calculated as alumina, preferably 2 wt% to 8 wt%. Further, the aluminum hydroxide is preferably hydrated aluminum hydroxide, such as wet aluminum hydroxide material. Preferably, in the aluminum hydroxide, the moisture content is 17 wt% to 25 wt%. Preferably, the properties of the aluminum hydroxide after calcination are as follows: specific surface area is 110 - 201 m 2 / g, pore volume is 0.8 - 2.0 mL / g, and average pore diameter is 15 - 17 nm. The calcination conditions are as follows: temperature is 600 - 850 °C, time is 2 - 12 h, and an oxygen-containing atmosphere such as air. The aluminum hydroxide can be commercially purchased or prepared by conventional methods. The aluminum hydroxide is preferably macroporous pseudo-boehmite with water content, and the water content is 19 wt% to 23 wt%.

[0014] Further, the concentration of the acidic silica sol is 5 - 45 g SiO 2 / L calculated as SiO 2 , and the pH value of the silica sol is adjusted to 3 - 5 with an acid (such as at least one of nitric acid and acetic acid). The addition amount of the acidic silica sol calculated as SiO 2 is 0.2 wt% to 8.0 wt% of the mass of the aluminum hydroxide sol calculated as alumina, preferably 2.5 wt% to 7.5 wt%.

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

[0016] Further, in the oil-ammonia water-oil-water four-layer mixing column, the first layer is the first oil layer, selected from one or more of white oil and diesel oil, preferably white oil, and the kinematic viscosity of the white oil at 40 °C is 20-40 mm 2 / s, preferably 25-35 mm 2 / s. The height of the first layer is 30% - 50% of the height of the second layer.

[0017] Further, in the oil-ammonia water-oil-water four-layer mixing column, the second layer is the ammonia water layer, and the concentration of the ammonia water is 20 wt% - 28 wt%, preferably 22 wt% - 26 wt%.

[0018] Further, in the oil-ammonia water-oil-water four-layer mixing column, the third layer is the second oil layer, namely the liquid seal oil layer, with a density between the second ammonia water layer and the fourth tin-containing water layer, and the kinematic viscosity at 40 °C is 60 mm 2 / s or less of one or more vegetable oils, preferably a mixed oil of castor oil and soybean oil, and the volume ratio of castor oil to soybean oil is 1 / 4 - 1 / 6. The kinematic viscosity of the castor oil at 40 °C is 500 - 650 mm 2 / s, preferably 570 - 600 mm 2 / s; the kinematic viscosity of the soybean oil at 40 °C is 10 - 25 mm 2 / s, preferably 13 - 17 mm 2 / s. The height of the third layer is 30% - 50% of the height of the second layer, preferably 35% - 45%.

[0019] Further, in the oil-ammonia water-oil-water four-layer mixing 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 the height of the second layer, preferably 1.2 - 1.5 times. During the preparation of the tin-containing spherical alumina support, when the concentration of the tin salt is less than 0.5 wt%, a tin salt is added by an external circulating pump to make the concentration meet the above requirements.

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

[0021] (1) Pour the materials required for the fourth layer into a columnar container (preferably a plexiglass container) and ensure the solution is uniform;

[0022] (2) Slowly add the materials required for the third layer onto the fourth layer materials in step (1) and stabilize for 20 - 35 min;

[0023] (3) Slowly add the materials required for the second layer on top of the third - layer materials in step (2);

[0024] (4) Slowly add the materials required for the first layer on top of the second - layer materials in step (3) to obtain an oil - ammonia - water - oil four - layer mixing column. Preferably, during the addition of the materials required for the first layer, slowly circulate up and down through a peristaltic pump above the interface between the first layer and the second layer to weaken the surface tension at the interface between the first layer and the second layer, and then let it stand for 30 - 60 min until it stabilizes. This can ensure that the aluminum hydroxide sol can quickly pass through the contact interface between the first layer and the second layer, prevent pauses from causing trailing, and affect the true roundness.

[0025] Further, the shaping of the tin - containing spherical alumina support is carried out in the oil - ammonia - water - oil four - layer mixing column. A mixture of aluminum hydroxide sol and acidic silica sol is dropped into the oil - ammonia - water - oil four - layer mixing column, wherein the inner diameter of the dropping head used is 1.0 mm - 1.6 mm.

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

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

[0028] Further, in the catalyst for propane dehydrogenation to propylene, the noble metal Pt can be loaded by an impregnation method, preferably the saturated impregnation method. Among them, the Pt precursor used in the impregnation solution is preferably at least one of PtCl 4 、H 2 PtCl 6 . The drying conditions after impregnation are preferably as follows: the drying temperature is 80 - 120°C and the drying time is 8 - 12 h. The calcination conditions after impregnation are preferably as follows: the calcination temperature is 500 - 700°C and the calcination time is 2 - 6 h.

[0029] The second aspect of the present invention provides a catalyst for propane dehydrogenation to propylene prepared by the above - mentioned preparation method, and the catalyst comprises a tin - containing alumina support and a noble metal Pt.

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

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

[0032] Further, the average diameter of the tin-containing spherical alumina carrier particles is 1.7 to 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% to 6.0% of the total pore volume, and the pore volume of pores with a pore size of 2 - 50 nm accounts for 93.8% to 98.2% of the total pore volume, preferably 95.0% to 98.0%.

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

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

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

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

[0038] Further, the application includes: contacting the propane raw material with the catalyst for dehydrogenation reaction to obtain the product propylene.

[0039] Further, before the propane dehydrogenation catalyst is used, it needs to be reduced. The catalyst precursor is reduced in a reducing atmosphere. The reducing atmosphere is preferably H 2 , the reduction temperature is 450 to 600 °C, and the reduction time is 1 to 3 h.

[0040] Further, the propane dehydrogenation reaction conditions are preferably as follows: the reaction temperature is 500 to 600 °C, the reaction pressure is 0 to 1 MPa, and the volume space velocity is 50 to 200 h -1 .

[0041] Compared with the prior art, the advantages of the present invention are as follows:

[0042] (1) In the preparation process of the tin-containing spherical alumina support of the catalyst of the present invention, the four-layer oil-ammonia water-oil-water mixing column is different from the two-layer oil-ammonia column or the hot oil column. The third layer of oil layer is added as a liquid seal oil layer and the fourth layer of tin-containing water layer, which can enable the sol to quickly enter the third layer of oil layer and the fourth layer of tin-containing water layer after passing through the second layer of ammonia water layer. The pH value quickly drops to neutral or acidic, so that during the drying process of the small balls, it is not easy to break or shrink with the volatilization of the surface ammonia water, and the alumina particle size and mechanical strength are significantly increased. In addition, the rapid decrease in the pH value on the surface of the sol small balls also makes the hydrophobicity of the colloidal particle surface decrease rapidly, the interaction force between the colloidal particles increases significantly, the distance between the colloidal particles becomes shorter, and part of the original structure collapses, resulting in an increase in the mesoporous structure within the range of 2-50 nm of the support. By adjusting the hydrochloric acid concentration in the tin-containing water layer, the pore structure can be further optimized.

[0043] (2) During the preparation process of the tin-containing spherical alumina support of the present invention, by introducing tin elements into the fourth layer of water layer, since the surface potential of the spherical sol is negative, it can quickly adsorb Sn 2+ ions when passing through the tin-containing water layer, introducing metal elements in one step during the carrier synthesis process, and obtaining Sn-doped spherical alumina through subsequent calcination. It is not only simple in operation, but also because the adsorption mainly occurs on the outer surface, it will not block the pores, and the interaction between Sn and alumina is enhanced during the solidification process, which is beneficial to improving the stability and dispersion degree after loading precious metals, and thus improving the catalyst activity.

[0044] (3) The preparation process of the tin-containing spherical alumina support of the present invention is environmentally friendly. In the traditional oil-ammonia column spheroidization process, the environmental pollution problem caused by the volatilization of ammonia water and the subsequent pollutant emission problem are relatively serious. In the present invention, the second oil layer separates the second layer of ammonia water layer and the fourth layer of tin-containing water layer, so that the ammonia water layer is sealed above the fourth layer of tin-containing water layer, which can extend the service time and avoid environmental pollution caused by the product carrying out ammonia water. After long-term use, the tin-containing water layer can be replaced to ensure the liquid seal effect, which is simple in operation and saves costs in industry. Specific embodiments

[0045] The catalyst for propane dehydrogenation to propylene, its preparation method and application effect in the present invention will be further described below through examples. The examples are implemented on the premise of the technical solution of the present invention, and the detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0046] The experimental methods in the following examples are all conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0047] In the present invention, a nitrogen adsorption-desorption curve of a sample was tested at -196 °C using a Micromeritics ASAP2020 fully automatic physical adsorption analyzer in the United States to determine the specific surface area, pore volume, and pore size distribution.

[0048] In the present invention, the crushing strength was tested using a ZQJ-Ⅲ intelligent particle strength testing machine manufactured by Dalian Zhiqu Testing Machine Factory, and the average value of crushing ten spherical carriers was tested.

[0049] In the present invention, the roundness was tested using an electron microscope of Olympus Corporation, and the average value was calculated after testing 20 samples.

[0050] Example 1

[0051] Take 250 g of macroporous pseudo-boehmite filter cake with a water content of 22 wt% (calcined at 600 °C for 3 h in an air atmosphere, with the following properties: pore volume 0.87 mL / g, specific surface area 175 m 2 / g, average pore diameter of 16 nm), add deionized water and stir to make a uniform slurry, then add 26 g of nitric acid solution with a mass concentration of 45% for peptization, and finally make a pseudo-boehmite sol with an alumina mass content of 20%; take 300 g of the above sol (alumina content of 20 wt%), add 100 mL of acidic silica sol with a pH value of 4, and the concentration of the silica sol is 30 g SiO 2 calculated as 30 g SiO 2 / L, stir evenly to obtain a sol mixture;

[0052] Use a dropper with an inner diameter of 1.2 mm to drop the above sol into a four-layer mixing column (cylindrical) of (white oil with a kinematic viscosity of 32 mm 2 / s at 40 °C - ammonia water with a concentration of 25 wt% - mixed oil - stannous chloride-containing aqueous solution) for shaping, and the residence time in the four-layer mixing column is 8 s. 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 the stannous chloride-containing water layer is 1.3 times the volume of ammonia water; the mixed oil is composed of castor oil with a kinematic viscosity of 580 mm 2 / s at 40 °C and soybean oil with a kinematic viscosity of 15 mm 2 / s, and the volume ratio of the two is 1:5. The concentration of stannous chloride in the stannous chloride-containing aqueous solution is 0.7%, and the concentration of hydrochloric acid is 6 wt%. During the preparation of the stannous chloride-containing spherical alumina carrier, when the concentration of stannous chloride is less than 0.5 wt%, stannous chloride is added by an external circulation pump to make the concentration of stannous chloride in the stannous chloride-containing aqueous solution the initial concentration. Then dry at 130 °C for 8 hours and calcine at 800 °C for 3 hours to obtain the stannous chloride-containing spherical alumina carrier A of the present invention, and its analysis results are shown in Table 1.

[0053] Example 2

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

[0055] Example 3

[0056] Compared with Example 1, the difference is that the concentration of the acidic silica sol used is changed to 15 g SiO 2 / 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, obtaining the stannous-containing spherical alumina support C of the present invention, and its analysis results 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 23 mm 2 / s at 40 °C. At the same time, the ammonia water concentration is changed to 21 wt%, and the volume ratio of castor oil to soybean oil added is changed to 1:4, obtaining the stannous-containing spherical alumina support D of the present invention, and its analysis results 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. At the same time, the ammonia water concentration is changed to 28 wt%, obtaining the stannous-containing spherical alumina support E of the present invention, and its analysis results 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 25 g SiO 2 / L; the white oil in the four-layer mixing column is changed to white oil with a kinematic viscosity of 28 mm 2 / s at 40 °C, the ammonia water concentration is changed to 23 wt%, and at the same time, the volume ratio of castor oil to soybean oil is changed to 1:4, obtaining the stannous-containing spherical alumina support F of the present invention, and its analysis results are shown in Table 1.

[0063] Example 7

[0064] Compared with Example 1, the difference is that the addition amount of white oil is 42% of the volume of ammonia water, the addition amount of the mixed oil is 32% of the volume of ammonia water, and the addition amount of the stannous-containing water layer is 1.6 times the volume of ammonia water, obtaining the stannous-containing spherical alumina support G of the present invention, and its analysis results are shown in Table 1.

[0065] Comparative Example 1

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

[0067] Compared with Example 1, the difference lies in that the four-layer oil-ammonia water-oil-water mixing column is changed to a two-layer oil-ammonia column. The upper layer is white oil with a kinematic viscosity of 32 mm 2 / s at 40 °C, and the lower layer is ammonia water with a concentration of 25 wt%. The addition amount of white oil is 25% of the volume of ammonia water. The remaining forming steps remain unchanged, and the comparative spherical alumina support H of the present invention is obtained. The analysis results are shown in Table 2.

[0068] Comparative Example 2

[0069] The synthesis step of the sol mixture is the same as that of Example 1.

[0070] Compared with Example 1, the difference lies in that only the first layer of white oil column is removed, and the spheres are formed with a three-layer column, and the comparative tin-containing spherical alumina support I of the present invention is obtained. The analysis results are shown in Table 2.

[0071] Comparative Example 3

[0072] The synthesis step of the sol mixture is the same as that of Example 1.

[0073] Compared with Example 1, the difference lies in that only the third layer of the mixed layer of castor oil and soybean oil is removed, and the comparative tin-containing spherical alumina support J of the present invention is obtained. The analysis results are shown in Table 2.

[0074] Comparative Example 4

[0075] The synthesis method of the sol mixture is the same as that of Example 1.

[0076] Compared with Example 1, the difference lies in that the addition amount of white oil is 16% of the volume of ammonia water, the addition amount of the mixed oil is 20% of the volume of ammonia water, and the addition amount of the tin-containing water layer is 0.4 times the volume of ammonia water, and the comparative tin-containing spherical alumina support K of the present invention is obtained. The analysis results are shown in Table 2.

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

[0078]

[0079]

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

[0081] Carrier number H I J K Average particle diameter, mm 1.83 1.79 1.64 1.65 <![CDATA[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, % < 2nm 7.1 7.4 6.9 6.3 2 - 50nm 92.5 92.4 92.6 93.5 > 50nm 0.4 0.2 0.5 0.2 Average pore size, nm 12.9 12.3 14.5 12.4 Crushing strength, N / particle 43 49 32 36 Roundness, % 95.4 91.9 89.5 90.8

[0082] Catalyst evaluation

[0083] 100 g of the tin-containing spherical alumina supports prepared in Examples 1-7 and Comparative Examples 2-4 were respectively taken and saturatedly impregnated into an aqueous solution containing 0.8 g of chloroplatinic acid. After impregnation for 30 min, they were dried in an oven at 90 °C for 10 h, calcined in a muffle furnace at 600 °C for 4 h, and reduced in a hydrogen atmosphere at 520 °C for 1.5 h. 100 g of the spherical alumina support prepared in Comparative Example 1 was taken and saturatedly impregnated into an aqueous solution containing 0.8 g of chloroplatinic acid and 0.4 g of stannic chloride. After impregnation for 30 min, it was dried in an oven at 90 °C for 10 h, calcined in a muffle furnace at 600 °C for 4 h, and reduced in a hydrogen atmosphere at 520 °C for 1.5 h. The compositions of the obtained catalysts are listed in Table 3-4.

[0084] 5 g of each of the above catalysts were respectively taken and loaded into a fixed-bed reactor for the evaluation of propane dehydrogenation activity: the reaction temperature was 580 °C, the pressure was atmospheric, and the volume space velocity was 50 h -1 . The results of propane dehydrogenation are listed in Table 5-6.

[0085] Table 3 Compositions of the catalysts obtained in each example

[0086]

[0087]

[0088] Table 4 Compositions of the catalysts obtained in each comparative example

[0089] Carrier number H I J K <![CDATA[Al 2 O 3 (wt%)]]> 97.1 97.7 97.3 96.45 Sn (wt%) 0.2 0.1 0.1 0.15 <![CDATA[SiO 2 (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 in each example for propane dehydrogenation

[0091]

[0092] Table 6 Evaluation results of the catalysts in each comparative example for propane dehydrogenation

[0093]

[0094] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A preparation method of a catalyst for propane dehydrogenation to propylene, the catalyst comprising a tin-containing spherical alumina support and a noble metal Pt; the preparation method of the tin-containing spherical alumina support, comprising: Mixing an aluminum hydroxide sol and an acidic silica sol, dropping the obtained mixture into an oil-ammonia water-oil-water four-layer mixing column for shaping, drying and calcining to obtain a tin-containing spherical alumina support; in the oil-ammonia water-oil-water four-layer mixing 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.

2. The preparation method according to claim 1, characterized in that: the alumina content in the aluminum hydroxide sol is 15 wt% to 26 wt%; and / or, the concentration of the acidic silica sol is 5 to 45 g SiO 2 calculated as / L; 2 / L; and / or, the pH value of the acidic silica sol is 3 to 5; And / or, the addition amount of the acidic silica sol is 0.2 wt% to 8.0 wt%, preferably 2.5 wt% to 7.5 wt% of the mass of the aluminum hydroxide sol calculated as alumina in terms of SiO 2 count.

3. The preparation method according to claim 1, characterized in that: In the oil-ammonia water-oil-water four-layer mixing column, the first layer is the first oil layer, which is selected from one or more of white oil and diesel oil, preferably white oil. The kinematic viscosity of the white oil at 40 °C is 20-40 mm 2 / s, preferably 25-35 mm 2 / s.

4. The preparation method according to claim 1, characterized in that: in the oil-ammonia water-oil-water four-layer mixing column, the second layer is an ammonia water layer, and the ammonia water concentration is 20 wt% to 28 wt%, preferably 22 wt% to 26 wt%.

5. The preparation method according to claim 1, characterized in that: In the oil-ammonia water-oil-water four-layer mixing column, the third layer is the second oil layer, namely the liquid-sealing oil layer, which is one or more vegetable oils with a density between the second ammonia water layer and the fourth tin-containing water layer and a kinematic viscosity of 60 mm 2 / s or less at 40°C, preferably a mixed oil of castor oil and soybean oil; the volume ratio of castor oil to soybean oil is 1 / 4 to 1 / 6; Preferably, the kinematic viscosity of the castor oil at 40 °C is 500 to 650 mm 2 / s, preferably 570 to 600 mm 2 / s; the kinematic viscosity of the soybean oil at 40 °C is 10 to 25 mm 2 / s, preferably 13 to 17 mm 2 / s.

6. The preparation method according to claim 1, characterized in that: in the oil-ammonia water-oil-water four-layer mixing column, 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; and / or, in the tin-containing water layer, the concentration of the tin salt is 0.5 wt% to 1.1 wt%, preferably 0.6 wt% to 0.8 wt%, and the concentration of hydrochloric acid is 5 wt% to 8 wt%.

7. The preparation method according to claim 1, characterized in that: the oil-ammonia water-oil-water four-layer mixing column is a straight column, preferably a cylinder; and / or, the height of the first layer is 30% to 50% of the height of the second layer; and / or, the height of the third layer is 30% to 50% of the height of the second layer, preferably 35% to 45%; and / or, 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.

8. The preparation method according to claim 1, characterized in that: in the catalyst for propane dehydrogenation to propylene, the noble metal Pt can be loaded by an impregnation method, preferably a saturated impregnation method.

9. A catalyst for propane dehydrogenation to propylene prepared by the preparation method according to any one of claims 1-8, the catalyst comprising a tin-containing alumina support and a noble metal Pt.

10. The catalyst according to claim 9, characterized in that: in the catalyst, based on the mass of the catalyst and in terms of mass fraction, the content of Pt in terms of Pt is 0.2% to 1.5%, and the content of the tin-containing alumina support is 98.5% to 99.8%.

11. The catalyst according to claim 9, characterized in that: In the tin-containing spherical alumina support, silica accounts for 0.2 wt% to 7.0 wt% of the mass of alumina, preferably 3.3 wt% to 5.1 wt%; Sn accounts for 0.09 wt% to 0.89 wt% of the mass of alumina in terms of Sn, preferably 0.15 wt% to 0.55 wt%.

12. The catalyst according to any one of claims 9-11, characterized in that: The specific surface area of the tin-containing spherical alumina carrier is 75 to 188 m 2 / g; and / or, the pore volume of the tin-containing spherical alumina support is 0.45 to 0.80 mL / g; and / or, the average diameter of the particles of the tin-containing spherical alumina support is 1.7 to 1.9 mm; and / or, the average pore diameter of the tin-containing spherical alumina support is 15 to 18 nm; and / or, the crushing strength of the tin-containing spherical alumina support is 60 to 85 N / grain; and / or, the true roundness of the tin-containing spherical alumina support is 95.5% to 99.9%; and / or, the pore size distribution of the tin-containing spherical alumina support is: the pore volume of pores with a pore size less than 2 nm accounts for 1.5% to 6.0% of the total pore volume, and the pore volume of pores with a pore size of 2-50 nm accounts for 93.8% to 98.2% of the total pore volume, preferably 95.0% to 98.0%.

13. Use of the catalyst according to any one of claims 9-12 in the propane dehydrogenation reaction 14. The use according to claim 13, characterized in that: Before use, the propane dehydrogenation catalyst needs to be reduced; Preferably, the reducing atmosphere is preferably H 2 , the reduction temperature is 450-600 °C, and the reduction time is 1-3 h.

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