Spherical Pt-containing catalyst as well as preparation and application thereof

Abstract

The invention discloses a spherical Pt-containing catalyst as well as preparation and application thereof. The catalyst comprises aluminum oxide and Pt, and the preparation method of the catalyst comprises the following steps: mixing aluminum hydroxide sol with a Pt-containing aqueous solution and an organic Pt salt solution, and dropwise adding the obtained mixture into an oil-ammonia water-oil-water four-layer mixed column for molding, drying and roasting to obtain the spherical Pt-containing catalyst. The catalyst provided by the invention is used in propane dehydrogenation reaction, and has good stability and good reaction performance.

Description

Technical Field

[0001] The present invention relates to a spherical Pt-containing catalyst, a preparation method thereof, and an application thereof, and particularly to a spherical Pt-containing 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 bar, clover, 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 factor, 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, the 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 easily sintered and undergoing 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 seriously decreases. 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 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 cause 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 slurry pseudoboehmite 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 period, complex process, need to regulate the pH value, and cannot ensure product consistency. Summary of the Invention

[0008] In view of the deficiencies of the prior art, the present invention provides a spherical Pt-containing catalyst and its preparation and application. The catalyst has the characteristics of good roundness, high crushing strength, large pore volume and pore diameter, Pt is not easy to agglomerate, and the product is environmentally friendly and odorless. It has good stability and good reaction performance when used in propane dehydrogenation reaction.

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

[0010] The aluminum hydroxide sol is mixed with an aqueous Pt solution and an organic Pt salt solution, and the resulting mixture is dropped into an oil-ammonia-oil-water four-layer mixing column to form a shape, followed by drying and calcination to obtain a spherical Pt-containing catalyst.

[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), 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: specific surface area is 110 to 201 m 2 / g, pore volume is 0.8 to 2.0 mL / g, and average pore diameter is 15 to 17 nm. The calcination conditions are as follows: temperature is 600 to 850 °C, time is 2 to 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 containing water, and the water content is 19 wt% to 23 wt%.

[0013] Further, the platinum-containing compound in the aqueous Pt solution is platinum chloride (PtCl 4 ), chloroplatinic acid (H 2 PtCl 6 ), or one or more of them, 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% of the mass of the aluminum hydroxide sol in terms of alumina, preferably 15% to 30%.

[0015] 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 organic Pt salt in the organic Pt salt solution is one or more of platinum acetylacetonate or platinum tetrakis(triphenylphosphine), preferably platinum acetylacetonate, and the solvent used is preferably acetone. The concentration of the organic Pt salt in the organic Pt salt solution is 1.0 wt% to 1.9 wt%. The addition amount of the organic Pt salt solution is 9% to 11% of the mass of the aluminum hydroxide sol calculated as alumina.

[0017] Further, the oil-ammonia water-oil-water four-layer mixing column is a straight column, preferably a cylinder.

[0018] Further, 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.

[0019] Further, 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 or 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.

[0020] 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%.

[0021] 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, which is one or more vegetable oils with a density between the second ammonia water layer and the fourth water layer and a kinematic viscosity at 40 °C of 60 mm 2 / s or less, preferably a mixed oil of castor oil and soybean oil, where the volume ratio of castor oil to soybean oil is 1 / 4 to 1 / 6. 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. The height of the third layer is 30% to 50% of the height of the second layer, preferably 35% to 45%.

[0022] Further, in the oil-ammonia water-oil-water four-layer mixing column, the fourth layer is the water layer, preferably deionized water or a dilute acid solution. 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.

[0023] Further, the fourth layer preferably uses a dilute acid solution. In the dilute acid solution, the acid is selected from at least one of acetic acid and citric acid. The mass concentration of the dilute acid solution is 3% - 8%.

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

[0025] (1) Pour the materials required for the fourth layer into a columnar container (preferably a plexiglass container) and ensure the solution is uniform;

[0026] (2) Slowly add the materials required for the third layer on top of the fourth - layer materials in step (1), and stabilize for 20 - 35 min;

[0027] (3) Slowly add the materials required for the second layer on top of the third - layer materials in step (2);

[0028] (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 - 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.

[0029] Further, the forming of the spherical Pt - containing catalyst is carried out in an oil - ammonia water - oil - water four - layer mixing column. A mixture of aluminum hydroxide sol, Pt - containing aqueous solution, and organic Pt salt solution is dropped into the oil - ammonia water - oil - water four - layer mixing column. Among them, the inner diameter of the dropping head used is 1.0 mm - 1.6 mm.

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

[0031] Further, the drying temperature is 100°C - 150°C, and the drying time is 6 - 10 hours; the calcination temperature is 750°C - 950°C, and the calcination time is 1 - 4 hours.

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

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

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

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

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

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

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

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

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

[0041] Further, the application includes: contacting the propane raw material with the catalyst for dehydrogenation reaction to obtain the product propylene.

[0042] 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.

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

[0044] Compared with the prior art, the advantages of the present invention are:

[0045] (1) The present invention uses a one-step method to synthesize spherical Pt-containing catalysts. An aqueous Pt solution and an organic Pt salt solution are added to an aluminum hydroxide sol, so that metallic Pt is uniformly dispersed in the alumina support, and at the same time, it also plays a role in pore expansion. 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 water layer, which can enable the sol to quickly enter the third and fourth layers after passing through the second layer of ammonia water layer, and the pH value is quickly reduced to neutral. During the drying process of the small balls, they are not easily broken or shrunk with the volatilization of the surface ammonia water, so that the particle size and mechanical strength of the catalyst are significantly increased. At the same time, the metal and the support are in full contact, and the metal is not easily agglomerated. In addition, the rapid decrease in the pH value on the surface of the sol small balls also makes the hydrophobicity of the colloidal particles 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 of the support in the range of 2-50 nm. By adding an appropriate amount of acidic solution to the fourth layer of water layer, the pore structure can be further optimized.

[0046] (2) During the preparation process of the catalyst of the present invention, an organic Pt salt solution is added. Since the organic Pt has low solubility and a large molecular weight, the organic molecules connected to the Pt atoms have a large steric hindrance and are easy to form single-atom Pt catalysts during the synthesis process. The four-layer oil-ammonia water-oil-water mixing column makes the organic Pt not easily precipitate, has more sufficient contact with pseudo-boehmite, and stronger interaction force. After calcination, both single-atom Pt and nano-particle Pt exist in the catalyst, which can play a synergistic role and improve the catalyst activity.

[0047] (3) The preparation process of the present invention is environmentally friendly. In the traditional oil-ammonia column pelletizing process, the volatilization of ammonia water brings serious environmental pollution problems and subsequent pollutant emission problems. The present invention uses the second oil layer to separate the second layer of ammonia water layer from the fourth layer of water layer, so that the ammonia water layer is sealed above the fourth layer of water layer, which can extend the service time and avoid environmental pollution caused by the product bringing out ammonia water. After long-term use, deionized water can be replaced to ensure the liquid seal effect, and the operation is simple and the cost is saved in industry.

[0048] (4) The spherical Pt-containing catalyst obtained by the preparation method of the present invention is used in the propane-to-propylene reaction, and has 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 good reaction performance. Specific Embodiments

[0049] The following further illustrates the spherical Pt-containing catalyst, its preparation method and application effect in the present invention through examples. The examples are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

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

[0051] In the present invention, a Micromeritics ASAP2020 full-automatic physical sorption analyzer in the United States was used to test the nitrogen adsorption / desorption curve of the sample at -196 °C to determine the specific surface area, pore volume, and pore size distribution.

[0052] 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 catalysts was measured.

[0053] In the present invention, the true roundness was tested using an Olympus electron microscope, and the average value was calculated after testing 20 samples.

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

[0055] Example 1

[0056] 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, stir and beat into a slurry evenly, then add 26 g of nitric acid solution with a mass concentration of 45% for peptization, and finally prepare a pseudo-boehmite sol with an alumina mass content of 20%; 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%, stir evenly, and then continue to add 6 g of platinum acetylacetonate solution with a platinum acetylacetonate concentration of 1.2%, stir evenly to obtain a sol mixture;

[0057] Use a dropper with an inner diameter of 1.2 mm 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% - mixed oil - deionized water) 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 deionized water 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 castor oil with a kinematic viscosity of 15 mm 2It is mixed with soybean oil at a volume ratio of 1:5, and then dried at 130 °C for 8 hours and calcined at 800 °C for 3 hours to obtain the spherical Pt-containing catalyst A of the present invention, and its analysis results are shown in Table 1.

[0058] Example 2

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

[0060] Example 3

[0061] Compared with Example 1, the difference is that 15.6 g of a chloroplatinic acid solution with a chloroplatinic acid concentration of 6% is added, which simultaneously contains 1.0% stannous chloride and 9% hydrochloric acid. After stirring evenly, 6.4 g of an acetylacetone platinum solution with an acetylacetone platinum concentration of 1.8% is added continuously to obtain the spherical Pt-containing catalyst C of the present invention, and its analysis results are shown in Table 1.

[0062] Example 4

[0063] 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 to obtain the spherical Pt-containing catalyst D of the present invention, and its analysis results are shown in Table 1.

[0064] Example 5

[0065] 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% to obtain the spherical Pt-containing catalyst E of the present invention, and its analysis results are shown in Table 1.

[0066] Example 6

[0067] Compared with Example 1, the difference is that the chloroplatinic acid concentration is changed to 6% and the acetylacetone platinum concentration is changed to 1.8%. 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 to obtain the spherical Pt-containing catalyst F of the present invention, and its analysis results are shown in Table 1.

[0068] Example 7

[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 mixed 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 spherical Pt-containing catalyst G 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, 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, and the remaining forming steps remain unchanged, obtaining the comparative spherical Pt-containing catalyst H 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 mixture is removed, and the sphere is formed with a three-layer column, obtaining the comparative spherical Pt-containing catalyst I 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 spherical Pt-containing catalyst J 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 third-layer castor oil and soybean oil mixing layer in the four-layer mixing column is removed, obtaining the comparative spherical Pt-containing catalyst K 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 mixed 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 spherical Pt-containing catalyst L of the present invention, and its analysis results are shown in Table 2.

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

[0086] Catalyst Number A B C D E F G Average Particle Diameter, mm 1.84 1.83 1.80 1.79 1.81 1.83 1.82 <![CDATA[Specific surface area, m 2 / g]]> 78 82 83 80 79 81 80 Pore Volume, mL / g 0.715 0.729 0.712 0.699 0.701 0.711 0.698 Pore Size Distribution, % < 2nm 3.9 4.0 4.1 3.8 4.2 4.2 4.1 2 - 50nm 96.0 95.9 95.4 95.6 95.4 95.6 95.8 > 50nm 0.1 0.1 0.5 0.6 0.4 0.2 0.1 Average Pore Size, nm 15.9 15.8 15.4 14.5 14.8 15.6 14.5 Crushing Strength, N / particle 75 73 70 69 71 72 71 Roundness, % 96.9 96.5 96.3 96.4 96.2 96.0 96.3

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

[0088] Catalyst Number H I J K L Average Particle Diameter, mm 1.75 1.76 1.55 1.70 1.72 <![CDATA[Specific surface area, m 2 / g]]> 85 89 86 87 88 Pore Volume, mL / g 0.586 0.584 0.498 0.506 0.512 Pore Size Distribution, % < 2nm 6.9 7.5 6.3 5.0 5.2 2 - 50nm 92.4 92.1 93.1 94.5 94.6 > 50nm 0.7 0.4 0.6 0.5 0.2 Average Pore Size, nm 14.2 14.6 13.0 12.1 13.1 Crushing Strength, N / particle 53 60 59 43 45 Roundness, % 89.2 85.2 84.1 79.6 82.9

[0089] Table 3 Compositions of the catalysts in each example

[0090]

[0091]

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

[0093] Catalyst Number H I J K L Alumina (wt%) 99.7 99.6 99.7 99.6 99.6 Total Pt (wt%) 0.2 0.3 0.2 0.3 0.3 Surface Pt (wt%) 0.01 0.01 0.01 0.01 0.01 Sn (wt%) 0.1 0.1 0.1 0.1 0.1

[0094] Catalyst evaluation

[0095] Take 5 g of each 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 the activity evaluation of propane dehydrogenation: the reaction temperature is 550 °C, the pressure is 0.5 MPa, and the volume space velocity is 100 h -1 . The results of propane dehydrogenation 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 Evaluation results of the stability of the catalysts in each example for propane dehydrogenation

[0101]

[0102] Table 8 Evaluation results of the stability 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 method for preparing a spherical Pt-containing catalyst, wherein the catalyst comprises alumina and Pt, and the preparation method of the catalyst comprises: Mixing aluminum hydroxide sol with a Pt-containing aqueous solution and an organic Pt salt solution, dropping the resulting mixture into an oil-ammonia-oil-water four-layer mixing column for shaping, drying, and calcining to obtain a spherical Pt-containing catalyst.

2. The preparation method according to claim 1, characterized in that: The platinum compound in the Pt-containing aqueous solution is one or more of platinum chloride and chloroplatinic acid, preferably chloroplatinic acid; and / or, the concentration of the platinum compound in the Pt-containing aqueous solution is 2 wt% to 6 wt%; and / or, the addition amount of the Pt-containing aqueous solution is 8% to 40% of the mass of the aluminum hydroxide sol calculated as alumina, preferably 15% to 30%.

3. The preparation method according to claim 1 or 2, characterized in that: The Pt-containing aqueous solution contains stannous chloride and hydrochloric acid; and / or, in the Pt-containing aqueous 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 organic Pt salt in the organic Pt salt solution is one or more of platinum acetylacetonate and tetrakis(triphenylphosphine)platinum, preferably platinum acetylacetonate, and the solvent used is preferably acetone; and / or, in the organic Pt salt solution, the concentration of the organic Pt salt is 1.0 wt% to 1.9 wt%; and / or, the addition amount of the organic Pt salt solution is 9% to 11% of the mass of the aluminum hydroxide sol calculated as alumina.

5. The preparation method according to claim 1, characterized in that: The alumina content in the aluminum hydroxide sol is 15 wt% to 26 wt%.

6. The preparation method according to claim 1, characterized in that: 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 water layer; and / or, the oil-ammonia-oil-water four-layer mixing column is a straight column, preferably a cylinder.

7. The preparation method according to claim 6, 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, and the kinematic viscosity of the white oil at 40 °C is 20 to 40 mm 2 / s, preferably 25 to 35 mm 2 / s.

8. The preparation method according to claim 6, characterized in that: In the oil-ammonia-oil-water four-layer mixing column, the second layer is the ammonia water layer, and the ammonia water concentration is 20 wt% to 28 wt%, preferably 22 wt% to 26 wt%.

9. The preparation method according to claim 6, 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 seal oil layer, which is one or more vegetable oils with a density between the second ammonia water layer and the fourth 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.

10. The preparation method according to claim 6, characterized in that: In the oil-ammonia-oil-water four-layer mixing column, the fourth layer is the 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%.

11. The preparation method according to claim 6, 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% - 50% of the height of the second layer, preferably 35% - 45%; And / or, the height of the fourth layer is 1.0 - 2.0 times the height of the second layer, preferably 1.2 - 1.5 times.

12. The spherical Pt-containing catalyst prepared by the preparation method according to any one of claims 1 - 11.

13. The catalyst according to claim 11, wherein: The specific surface area of the spherical Pt-containing catalyst is 65 to 115 m 2 / g; And / or, the pore volume of the spherical Pt-containing catalyst is 0.55 - 0.75 mL / g; And / or, the average diameter of the spherical Pt-containing catalyst particles is 1.6 - 1.9 mm; And / or, the average pore diameter of the spherical Pt-containing catalyst is 13 - 16 nm; And / or, the crushing strength of the spherical Pt-containing catalyst is 60 - 80 N / grain; And / or, the roundness of the spherical Pt-containing catalyst is 94.9% - 99.9%.

14. The catalyst according to claim 12, wherein: The pore size distribution of the catalyst is: the pore volume of pores with a pore size less than 2 nm accounts for 0.5% - 5.5% of the total pore volume, and the pore volume of pores with a pore size of 2 - 50 nm accounts for 93.0% - 99.0% of the total pore volume, preferably 95.0% - 98.0%.

15. The catalyst according to claim 12, wherein: In the catalyst, based on the mass of the catalyst, by mass fraction, the total Pt content in the catalyst is 0.25% - 1.3%, the Sn content is 0.02% - 0.8%, and the alumina content is 97.9% - 99.7%; Preferably, the Pt content on the catalyst surface is 0.005% - 0.03%, preferably 0.01% - 0.03%.

16. The application of the catalyst according to any one of claims 12 - 15 in the propane dehydrogenation reaction.

17. The application according to claim 16, wherein: 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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