Propane dehydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention discloses a propane dehydrogenation catalyst as well as a preparation method and application thereof. The preparation method of the catalyst comprises the following steps: mixing aluminum hydroxide sol with a Pt-containing aqueous solution, dropwise adding the obtained mixture into an oil-ammonia water-oil-water four-layer mixed column, molding, drying and roasting to obtain the catalyst, four layers are sequentially arranged in the oil-ammonia water-oil-water four-layer mixing column 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, the fourth layer is a water layer, and the second oil layer is selected from modified transformer oil. The catalyst disclosed by the invention is applied to propane dehydrogenation reaction and has relatively good stability.

Description

Technical Field

[0001] The present invention relates to a propane dehydrogenation catalyst, a preparation method thereof, and an application thereof, and particularly relates to a propane dehydrogenation catalyst suitable for a fluidized bed, a preparation method thereof, and an application thereof. Background Art

[0002] The shape and size of catalyst particles are generally determined according to the requirements of reactors used in industrial production. At present, 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, cloverleaf, four-leaf, and flake catalysts. Moving bed reactors often use large-particle spherical catalysts. Fluidized bed reactors generally use small-particle spherical or bar-shaped catalysts.

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

[0004] Currently, catalysts for dehydrogenating light alkanes to produce olefins are mainly prepared by loading 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 use time of the catalyst increases, 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 and destroying the pore structure. Furthermore, the active components of the catalyst aggregate, and the activity of the catalyst drops severely. Therefore, it is necessary to further modify the γ-Al 2 O 3 support to make the catalyst have high 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 in an oil-ammonia column for aging, and finally washing, drying, and calcining to obtain a composite small ball with high strength and large specific surface area. This method is to re-colloidize the suspension slurry obtained by ball-milling pseudo-boehmite and molecular sieve and mix it with a dilute sol, 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 3 spheres. The method is to stir and slurrize pseudo-boehmite dry gel powder and deionized water, add dilute nitric acid for acidification, 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 and form spheres in an oil-ammonia column, cure the wet spheres in ammonia water for 2 hours, then filter, wash with deionized water, dry, and calcine to obtain silicon-containing γ-Al 2 O 3 spheres. The method for preparing γ-Al 2 O 3 spheres has a long curing time, difficult washing, and low production efficiency.

[0007] CN104289220A discloses a preparation method and use of a high thermal stability low-carbon alkane dehydrogenation catalyst. 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 spheres, and then dry and calcine to obtain γ-Al 2 O 3 spheres 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 spheres, and then dry and calcine to obtain γ-Al 2 O 3 spheres, and then immerse the γ-Al 2 O 3 spheres 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 spheres containing Si element. The disadvantages of this method are long preparation cycle, complex process, need to regulate the pH value, and unable to ensure product consistency. SUMMARY OF THE INVENTION

[0008] In view of the deficiencies of the prior art, the present invention provides a propane dehydrogenation catalyst, its preparation method and application. The catalyst is used in the reaction of propane dehydrogenation to produce propylene, and has a high propane conversion rate, high propylene selectivity and good stability.

[0009] The first aspect of the present invention provides a preparation method of a propane dehydrogenation catalyst, including:

[0010] An aluminum hydroxide sol is mixed with an aqueous Pt solution, and the resulting mixture is dropped into an oil-ammonia water-oil-water four-layer mixing column to form a shape, followed by drying and calcination to obtain a propane dehydrogenation catalyst; in the oil-ammonia water-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 water layer. Among them, the second oil layer is selected from modified transformer oil, and the modified transformer oil includes transformer oil and a water-soluble surfactant. Preferably, the water-soluble surfactant is one or more of lauroyl diethanolamine, nonylphenol polyoxyethylene ether (the polymerization degree is preferably 9, i.e., n = 9), or octylphenol polyoxyethylene ether (the polymerization degree is preferably 7, i.e., n = 7).

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

[0012] Further, the preparation method of the aluminum hydroxide sol includes: mixing aluminum hydroxide and water to form 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), 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 in terms of acid is 1 wt% to 10 wt% of the mass of aluminum hydroxide in terms of 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 water content is 17 wt% to 25 wt%. Preferably, the properties of the aluminum hydroxide after calcination are as follows: the specific surface area is 110 to 201 m 2 / g, the pore volume is 0.8 to 2.0 mL / g, and the average pore diameter is 15 to 17 nm. The calcination conditions are as follows: the temperature is 600 to 850 °C, the time is 2 to 12 h, and the oxygen-containing atmosphere is such as air. The aluminum hydroxide can be commercially purchased or prepared by a conventional method. The aluminum hydroxide is preferably macroporous pseudo-boehmite containing water, and the water content is 19 wt% to 23 wt%.

[0013] Further, the platinum-containing compound in the aqueous Pt solution is one or more of platinum chloride (PtCl 4 ), chloroplatinic acid (H 2 PtCl 6 ), and is preferably chloroplatinic acid. Further, the aqueous Pt solution contains stannous chloride (SnCl 2 ) and hydrochloric acid.

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

[0015] Further, the aqueous Pt solution contains stannous chloride (SnCl 2 ) and hydrochloric acid. Further, in the aqueous Pt solution, the concentration of stannous chloride (SnCl 2 ) is 0.5 wt% to 3.5 wt%, and the concentration of hydrochloric acid is 5 wt% to 12 wt%.

[0016] Further, the oil-ammonia water-oil-water four-layer mixing column is a straight column, preferably a cylinder.

[0017] 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. The kinematic viscosity of the white oil at 40 °C is 20 to 40 mm 2 / s, preferably 25 to 35 mm 2 / s. The height of the first layer is 30% to 50% of the height of the second layer.

[0018] 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% to 28 wt%, preferably 22 wt% to 26 wt%.

[0019] Further, in the oil-ammonia water-oil-water four-layer mixing column, the third layer is the second oil layer, i.e., the liquid seal oil layer. The height of the third layer is 30% to 50% of the height of the second layer, preferably 35% to 45%. The density of the modified transformer oil used in the second oil layer is between that of ammonia water and water. Preferably, the density of the modified transformer oil at 20 °C is above 0.90 g / mL, preferably 0.93 to 0.96 g / mL, and further preferably 0.94 to 0.96 g / mL.

[0020] Further, the mass of the water-soluble surfactant is 6% to 25%, preferably 10% to 18%, of the mass of the transformer oil.

[0021] Further, the density (at 20 °C) of the transformer oil is 0.86 to 0.89 g / mL, and the kinematic viscosity at 40 °C is 9 to 15 mm 2 / s.

[0022] Further, the preparation process of the modified transformer oil is as follows:

[0023] Mix a water-soluble surfactant with transformer oil, and subject the resulting mixture to heat treatment, i.e., successively to sealed heating treatment and open heating treatment, and repeat the above heat treatment 3 to 6 times to obtain the modified transformer oil.

[0024] Further, the conditions for the sealed heating treatment are as follows: the heating temperature is 80 to 120 °C, and the heating time is 6 to 20 h. Further, the conditions for the open heating treatment are as follows: the heating temperature is 80 to 120 °C, and the heating time is 6 to 20 h.

[0025] Further, in the oil-ammonia water-oil-water four-layer mixing column, the fourth layer is a water layer, preferably deionized water or a dilute acid solution. The height of the fourth layer is 1.0 to 2.0 times, preferably 1.2 to 1.5 times, the height of the second layer.

[0026] Further, the fourth layer preferably uses a dilute acid solution. In the dilute acid solution, the acid is selected from at least one of acetic acid and citric acid. The mass concentration of the dilute acid solution is 3% to 8%.

[0027] Further, the method for preparing the oil-ammonia water-oil-water four-layer mixing column includes:

[0028] (1) Pour the materials required for the fourth layer into a columnar container (preferably an organic glass container) and ensure the solution is uniform;

[0029] (2) Slowly add the materials required for the third layer on top of the fourth layer materials in step (1) and stabilize for 20 to 35 min;

[0030] (3) Slowly add the materials required for the second layer on top of the third layer materials in step (2);

[0031] (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-water four-layer mixing column. Preferably, during the addition of the materials required for the first layer, slowly circulate up and down above the interface between the first layer and the second layer through a peristaltic pump to weaken the surface tension at the interface between the first layer and the second layer, and then let it stand for 30 to 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, preventing pauses from causing trailing and affecting the true roundness.

[0032] Further, the shaping of the propane dehydrogenation catalyst is carried out in an oil-ammonia water-oil-water four-layer mixing column, and a mixture of aluminum hydroxide sol and an aqueous Pt solution is dropped into the oil-ammonia water-oil-water four-layer mixing column, wherein the inner diameter of the dropping head used is 1.0 mm to 1.6 mm.

[0033] Further, the residence time of the mixture of the aluminum hydroxide sol and the Pt-containing aqueous solution in the oil-ammonia-oil-water four-layer mixing column is 5-18 s, preferably 7-11 s.

[0034] Further, the drying temperature is 100°C to 150°C, and the drying time is 6 to 10 hours; the calcination temperature is 750°C to 950°C, and the calcination time is 1 to 4 hours.

[0035] The second aspect of the present invention provides a propane dehydrogenation catalyst prepared by the above preparation method.

[0036] Further, the specific surface area of the propane dehydrogenation catalyst is 60-125 m 2 / g, and the pore volume is 0.62-0.82 mL / g.

[0037] Further, the propane dehydrogenation catalyst is spherical particles, and the average diameter of the particles is 1.7-1.9 mm.

[0038] Further, the pore size distribution of the propane dehydrogenation catalyst is as follows: the pore volume of pores with a pore size less than 2 nm accounts for 1.5%-4.6% of the total pore volume, and the pore volume of pores with a pore size of 2-50 nm accounts for 95.4%-98.5% of the total pore volume, preferably 96.0%-98.0%.

[0039] Further, the average pore size of the propane dehydrogenation catalyst is 14.5-18.6 nm.

[0040] Further, the crushing strength of the propane dehydrogenation catalyst is 68-89 N / grain.

[0041] Further, the true roundness of the propane dehydrogenation catalyst is 97.8%-99.9%.

[0042] Further, in the propane dehydrogenation catalyst, based on the mass of the catalyst, by mass fraction, the content of Pt is 0.25%-1.20%, the content of Sn is 0.04%-0.87%, and the content of alumina is 97.93%-99.71%.

[0043] The third aspect of the present invention provides the application of the above catalyst in the propane dehydrogenation reaction.

[0044] Further, the application includes: contacting the propane raw material with the catalyst for dehydrogenation reaction to obtain the product propylene.

[0045] 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 450-600°C, and the reduction time is 1-3 h.

[0046] Further, the propane dehydrogenation reaction conditions are preferably as follows: the reaction temperature is 500 - 600 °C, the reaction pressure is 0 - 1 MPa, and the volume space velocity is 50 - 200 h -1 .

[0047] Compared with the prior art, the advantages of the present invention are as follows:

[0048] (1) The present invention adopts a one-step method to synthesize a propane dehydrogenation catalyst. An aqueous solution containing Pt is added to the aluminum hydroxide sol, so that the metal is uniformly dispersed in the alumina support, and at the same time, it also plays a role in pore expansion. During the forming process, the four-layer oil-ammonia-water-oil mixed column is different from the two-layer oil-ammonia column or the hot oil column. The third oil layer is added as a liquid seal oil layer and the fourth water layer, which can enable the sol to quickly enter the third and fourth water layers after passing through the second ammonia water layer, and the pH value quickly drops to neutral. During the drying process of the pellets, they are not easily broken or shrunk with the volatilization of the surface ammonia water, resulting in a significant increase in the alumina particle size and mechanical strength. At the same time, it enables full contact between the metal and the support, and the loading is more uniform. In addition, the rapid decrease in the pH value on the surface of the sol pellets also causes a rapid decrease in the hydrophobicity of the colloidal particle surface, a significant increase in the intermolecular force between the colloidal particles, a shortening of the distance between the colloidal particles, and partial collapse of the original structure, resulting in an increase in the mesoporous structure of the support within the range of 2 - 50 nm. By adding an appropriate amount of acidic solution to the fourth water layer, the pore structure can be further optimized.

[0049] (2) In the four-layer mixed column used for catalyst forming in the present invention, since the density difference between the ammonia water in the ammonia water layer and the pure water in the water layer is small, the density of the liquid seal oil (modified transformer oil) in the second oil layer selected 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, otherwise it will affect the roundness of the sol. By adding a surfactant to the transformer oil in the present invention, the density can be increased without changing its viscosity to meet the requirements. The water-soluble surfactant slowly penetrates into the oil under heating conditions, and the intermolecular force is enhanced. During the process of evaporating the water, the intermolecular distance is shortened. After repeated operations, the stability of the modified oil can be ensured. At the same time, due to the addition of the surfactant, the surface tension at the oil-water interface is significantly reduced, the pause of the sol pellets when passing through the oil-water interface is reduced, and they can quickly pass through the interface, reducing pulling, effectively improving the roundness of the spherical support.

[0050] (3) The preparation process of the present invention is environmentally friendly. In the traditional oil-ammonia column pelletizing process, the problems of environmental pollution caused by ammonia water volatilization and subsequent pollutant emissions are relatively serious. In the present invention, the second oil layer separates the second ammonia water layer and the fourth water layer, so that the ammonia water layer is sealed above the fourth water layer, which can extend the service time and avoid environmental pollution caused by the product carrying out ammonia water. After long-term use, deionized water can be replaced to ensure the liquid seal effect, which is simple to operate and cost-saving in industry.

[0051] (4) The catalyst of the present invention is used in the propane-to-propylene reaction, having a high propane conversion rate and propylene selectivity. The catalyst with large pore diameter and pore volume can avoid carbon deposition after long-term operation, and has good stability and reaction performance. Detailed implementation mode

[0052] The propane dehydrogenation catalyst in the present invention, its preparation method and application effect will be further described below through examples. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following examples.

[0053] In the following examples, the experimental methods are all conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0054] In the present invention, the nitrogen adsorption and desorption curves of the samples are tested at -196 °C using an ASAP2020 full-automatic physical adsorption instrument from Micromeritics, USA, and the specific surface area, pore volume, and pore size distribution are measured.

[0055] In the present invention, the crushing strength is 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 is measured.

[0056] In the present invention, the true roundness is tested using an electron microscope from Olympus, and the average value is calculated after testing 20 samples.

[0057] Example 1

[0058] Take 250 g of macroporous pseudo-boehmite filter cake with a moisture 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). After adding deionized water and stirring to make a uniform slurry, 26 g of nitric acid solution with a mass concentration of 45% is added for peptization, and finally a pseudo-boehmite sol with an alumina mass content of 20% is prepared; take 300 g of the above sol (alumina content of 20 wt%), add 12 g of chloroplatinic acid solution with a chloroplatinic acid concentration of 3%, which also contains stannous chloride with a concentration of 0.8% and hydrochloric acid with a concentration of 7%, and stir evenly to obtain a sol mixture;

[0059] Add 7 g each of lauroyl diethanolamine and nonylphenol polyoxyethylene ether (n = 9) to 100 g of transformer oil (density at 20 °C is 0.89 g / mL, kinematic viscosity at 40 °C is 12 mm 2In ( / )s, after stirring evenly, it is sealed and placed in an oven at 100 °C for heating for 8 hours, then the sealing cover is removed and heating is continued for 4 hours. The above steps are repeated 3 times to obtain modified transformer oil (with a density of 0.94 g / mL at 20 °C). Using a dropper with an inner diameter of 1.2 mm, the above sol is dropped into a four-layer mixing column (cylindrical) of (white oil with a kinematic viscosity of 32 mm 2 / s - ammonia water with a concentration of 25 wt% - modified transformer oil - deionized water) for forming, 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 modified transformer oil is 38% of the volume of ammonia water, and the addition amount of deionized water is 1.3 times the volume of ammonia water. Then it is dried at 130 °C for 8 hours and calcined at 800 °C for 3 hours to obtain the catalyst A of the present invention, and its analysis results are shown in Table 1.

[0060] Example 2

[0061] Compared with Example 1, the difference is that the deionized water in the fourth layer of the four-layer mixing column is changed to a 5 wt% dilute acetic acid solution to obtain the catalyst B of the present invention, and its analysis results are shown in Table 1.

[0062] Example 3

[0063] Compared with Example 1, the difference is that in the preparation process of the sol mixture, 15.6 g of chloroplatinic acid solution with a concentration of 6% of chloroplatinic acid is added, which simultaneously contains stannous chloride with a concentration of 1.0% and hydrochloric acid with a concentration of 9% to obtain the catalyst C of the present invention, and its analysis results are shown in Table 1.

[0064] Example 4

[0065] Compared with Example 1, the difference is that in the preparation of the modified transformer oil, the surfactant used is changed to lauroyl diethanolamine, the addition amount is changed to 12 g, and the number of repetitions is changed to 4 times. The density of the obtained modified transformer oil at 20 °C is 0.95 g / mL) to obtain the catalyst D of the present invention, and its analysis results are shown in Table 1.

[0066] Example 5

[0067] Compared with Example 1, the difference is that in the preparation of the modified transformer oil, the addition amounts of lauroyl diethanolamine and nonylphenol polyoxyethylene ether (n = 9) are changed to 4 g each. The density of the obtained modified transformer oil at 20 °C is 0.93 g / mL) to obtain the catalyst E of the present invention, and its analysis results are shown in Table 1.

[0068] Example 6

[0069] Compared with Example 1, the differences are as follows: the addition amount of white oil is 42% of the volume of ammonia water, the addition amount of modified transformer oil is 32% of the volume of ammonia water, and the addition amount of deionized water is 1.6 times the volume of ammonia water, obtaining the catalyst F of the present invention, and its analysis results are shown in Table 1.

[0070] Comparative Example 1

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

[0072] Compared with Example 1, the difference is 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, 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, and the remaining forming steps remain unchanged, obtaining the comparative catalyst G of the present invention, and its analysis results are shown in Table 2.

[0073] Comparative Example 2

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

[0075] Compared with Example 1, the difference is that: only the first-layer white oil column in the four-layer mixing column is removed, and a spherical shape is formed with a three-layer column, obtaining the comparative catalyst H of the present invention, and its analysis results are shown in Table 2.

[0076] Comparative Example 3

[0077] The synthesis step of the sol mixture is the same as that in Example 1.

[0078] Compared with Example 1, the difference is that: only the fourth-layer water column is removed, obtaining the comparative catalyst I of the present invention, and its analysis results are shown in Table 2.

[0079] Comparative Example 4

[0080] The synthesis step of the sol mixture is the same as that in Example 1.

[0081] Compared with Example 1, the difference is that: only the modified transformer oil is replaced with transformer oil, and the remaining forming steps remain unchanged, that is, a dropper with an inner diameter of 1.2 mm is used to drip 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% - transformer oil - deionized water) for forming, 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 transformer oil is 38% of the volume of ammonia water, and the addition amount of deionized water is 1.3 times the volume of ammonia water. Then it is dried at 130 °C for 8 hours and calcined at 800 °C for 3 hours, obtaining the comparative catalyst J of the present invention, and its analysis results are shown in Table 2.

[0082] Comparative Example 5

[0083] The synthesis method of the sol mixture is the same as that in Example 1.

[0084] Compared with Example 1, the differences are as follows: the addition amount of white oil is 16% of the volume of ammonia water, the addition amount of modified transformer oil is 20% of the volume of ammonia water, and the addition amount of deionized water is 0.4 times the volume of ammonia water, obtaining the comparative catalyst K of the present invention, and the analysis results are shown in Table 2.

[0085] Table 1 Physicochemical properties of the catalysts obtained in each example

[0086] Catalyst number A B C D E F Average particle diameter, mm 1.82 1.82 1.81 1.81 1.80 1.80 <![CDATA[Specific surface area, m 2 / g]]> 92 91 93 92 93 92 Pore volume, mL / g 0.635 0.637 0.632 0.632 0.620 0.621 Pore size distribution, % < 2nm 1.9 1.8 2.0 2.1 2.2 2.1 2 - 50nm 97.9 97.7 97.8 97.8 97.6 97.4 > 50nm 0.2 0.5 0.2 0.1 0.2 0.5 Average pore diameter, nm 16.9 17.1 16.8 16.7 15.7 15.4 Crushing strength, N / grain 70 70 68 69 69 70 Roundness, % 98.8 98.7 98.5 98.4 98.6 98.7

[0087] Table 2 Physicochemical properties of the catalysts obtained in each comparative example

[0088]

[0089]

[0090] Table 3 Compositions of the catalysts in each example

[0091] Catalyst number A B C D E F Aluminum oxide (wt%) 99.6 99.6 99.1 99.6 99.6 99.6 Pt (wt%) 0.3 0.3 0.7 0.3 0.3 0.3 Sn (wt%) 0.1 0.1 0.2 0.1 0.1 0.1

[0092] Table 4 Compositions of the catalysts in each comparative example

[0093] Catalyst number G H I J K Aluminum oxide (wt%) 99.6 99.6 99.6 99.6 99.6 Pt (wt%) 0.3 0.3 0.3 0.3 0.3 Sn (wt%) 0.1 0.1 0.1 0.1 0.1

[0094] Catalyst evaluation

[0095] Respectively take 5 g of the above catalysts, first reduce them at 520 °C for 1.5 h in a hydrogen atmosphere, and then load them into a fixed-bed reactor for propane dehydrogenation activity evaluation: the reaction temperature is 520 °C, the pressure is 0.7 MPa, and the volume space velocity is 80 h -1 . The propane dehydrogenation results are listed in Tables 5 - 8.

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

[0097]

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

[0099]

[0100] Table 7 Stability evaluation results of the catalysts in each example for propane dehydrogenation

[0101]

[0102] Table 8 Stability evaluation results of the catalysts in each comparative example for propane dehydrogenation

[0103]

[0104] 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 propane dehydrogenation catalyst, comprising: mixing an aluminum hydroxide sol with an aqueous Pt-containing solution, dropping the obtained mixture into an oil-ammonia water-oil-water four-layer mixing column for shaping, drying and calcining to obtain a propane dehydrogenation catalyst; 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 water layer, wherein the second oil layer is selected from modified transformer oil, and the modified transformer oil comprises transformer oil and a water-soluble surfactant. Preferably, the water-soluble surfactant is one or more of lauroyl diethanolamine, nonylphenol polyoxyethylene ether or octylphenol polyoxyethylene ether.

2. The preparation method according to claim 1, characterized in that: the platinum-containing compound in the aqueous Pt-containing solution is one or more of platinum chloride and chloroplatinic acid, preferably chloroplatinic acid; and / or, the aqueous Pt-containing solution contains stannous chloride and hydrochloric acid.

3. The preparation method according to claim 2, characterized in that: the concentration of the platinum-containing compound in the aqueous Pt-containing solution is 2 wt% to 6 wt%; and / or, in the aqueous Pt-containing solution, the concentration of stannous chloride is 0.5 wt% to 3.5 wt%, and the concentration of hydrochloric acid is 5 wt% to 12 wt%.

4. The preparation method according to claim 1, characterized in that: the alumina content in the aluminum hydroxide sol is 15 wt% to 30 wt%; and / or, the addition amount of the aqueous Pt-containing solution is 8% to 40% of the mass of the aluminum hydroxide sol calculated as alumina, preferably 15% to 30%.

5. 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.

6. 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%.

7. 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, i.e., the liquid seal oil layer, and its density is between that of the second ammonia water layer and the fourth water layer. Preferably, the density of the modified transformer oil at 20 °C is 0.90 g / mL or more, further 0.93 to 0.96 g / mL; preferably, the mass of the water-soluble surfactant is 6% to 25% of the mass of the transformer oil, preferably 10% to 18%; Preferably, the density of the transformer oil at 20 °C is 0.86 to 0.89 g / mL, and the kinematic viscosity at 40 °C is 9 to 15 mm 2 / s.

8. The preparation method according to claim 7, characterized in that: the preparation process of the modified transformer oil is as follows: mixing the water-soluble surfactant with the transformer oil, and heat-treating the obtained mixture, i.e., sequentially performing sealed heating treatment and open heating treatment, and repeating the above heat treatment 3 to 6 times to obtain the modified transformer oil; preferably, the conditions of the sealed heating treatment are as follows: the heating temperature is 80 to 120 °C, and the heating time is 6 to 20 h; preferably, the conditions of the open heating treatment are as follows: the heating temperature is 80 to 120 °C, and the heating time is 6 to 20 h.

9. The preparation method according to claim 1, characterized in that: In the oil-ammonia water-oil-water four-layer mixing column, the fourth layer is a water layer, preferably deionized water or a dilute acid solution, more preferably a dilute acid solution; in the dilute acid solution, the acid is selected from at least one of acetic acid and citric acid; the mass concentration of the dilute acid solution is 3% to 8%.

10. According to the preparation method described in claim 1, it is characterized in that: 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.

11. The propane dehydrogenation catalyst prepared by the preparation method described in any one of claims 1-10.

12. According to the catalyst described in claim 11, it is characterized in that: The specific surface area of the propane dehydrogenation catalyst is 60 to 125 m 2 / g, and the pore volume is 0.62 to 0.82 mL / g; and / or, the average diameter of the propane dehydrogenation catalyst particles is 1.7 to 1.9 mm; and / or, the average pore diameter of the propane dehydrogenation catalyst is 14.5 to 18.6 nm; and / or, the crushing strength of the propane dehydrogenation catalyst is 68 to 89 N / grain; and / or, the true roundness of the propane dehydrogenation catalyst is 97.8% to 99.9%.

13. According to the catalyst described in claim 11, it is characterized in that: The pore size distribution of the propane dehydrogenation catalyst is as follows: the pore volume of pores with a pore size less than 2 nm accounts for 1.5% to 4.6% of the total pore volume, and the pore volume of pores with a pore size of 2-50 nm accounts for 95.4% to 98.5% of the total pore volume, preferably 96.0% to 98.0%.

14. According to the catalyst described in claim 11, it is characterized in that: In the catalyst, based on the mass of the catalyst, by mass fraction, the content of Pt is 0.25% to 1.20%, the content of Sn is 0.04% to 0.87%, and the content of alumina is 97.93% to 99.71%.

15. The application of the catalyst described in any one of claims 11-14 in the propane dehydrogenation reaction.

16. According to the application described in claim 15, it is characterized in that: Before use, the 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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