CN116832808A

CN116832808A - Propane dehydrogenation catalyst, preparation method and application

Info

Publication number: CN116832808A
Application number: CN202310670573.4A
Authority: CN
Inventors: 顾彬; 孙承林; 李敬美
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2023-06-07
Filing date: 2023-06-07
Publication date: 2023-10-03

Abstract

The application discloses a propane dehydrogenation catalyst, a preparation method and application thereof, wherein the propane dehydrogenation catalyst comprises a carrier, and a Pt component, a Sn component and an alkali metal component which are loaded on the carrier; the carrier is spherical active carbon; the alkali metal component is selected from potassium and/or sodium. Wherein the carrier is spherical active carbon, the spherical active carbon is spherical particles with the diameter of 0.4-2.0 mm, and the specific surface area of the spherical active carbon is 500-2000 m ² Per g, pore volume of 0.55-1.5 mL/g, micropores with pore diameter of 0.5-1.5 nm, mesopores with pore diameter of 4-10 nm and macropores with pore diameter of 50-200 nm. Prepared by the applicationThe catalyst with spherical active carbon as carrier has relatively high catalytic activity, propylene selectivity and catalytic stability.

Description

Propane dehydrogenation catalyst, preparation method and application

Technical Field

The application relates to a propane dehydrogenation catalyst, a preparation method and application thereof, and belongs to the technical field of catalysts.

Background

Propylene can be used for producing polypropylene, propylene oxide, butanol, phenol, propylene glycol, acetone, acrylic acid, acrylonitrile, octanol, isopropanol and the like, and is an important basic chemical raw material and petrochemical intermediate. With the rapid development of the economy in China, the domestic propylene demand is rapidly increased. However, the conventional propylene production technology such as steam cracking technology and catalytic cracking technology has the problems of light raw materials, slow yield increase and the like in the way of producing propylene as a byproduct. Therefore, propylene produced by the conventional process has failed to meet the demand of propylene.

In recent years, with the mass exploitation of shale gas and natural gas in the middle east, the technology of producing propylene by propane dehydrogenation has been paid more and more attention, and great development is made. The technology has the advantages of short flow, high yield, less byproducts, low investment cost and the like. At present, the most widely used propane dehydrogenation processes are the Oleflex process of UOP and the Catofin process of Lummus, wherein Pt and Cr are respectively adopted as active components of the catalyst, and the carriers are all alumina. Alumina is the most commonly used carrier for propane dehydrogenation catalysts, and has the advantages of large specific surface area, high thermal stability, high mechanical strength, capability of dispersing metal active components and the like. However, because the surface of alumina contains more acidic sites, side reactions such as hydrogenolysis, isomerization, coking and the like are aggravated, and propylene selectivity is lower. The occurrence of side reactions can be suppressed to some extent by adding a certain amount of an alkaline metal promoter to the catalyst. Such as: U.S. Pat. No. 3,3779A 1, U.S. Pat. No. 3, 2013072739A1; chinese patent: CN103990454A, CN104289220a, CN103787810a, etc. Propylene selectivity is often still below 92%.

Compared with alumina, the active carbon has larger specific surface area and weak acid-base property, and can greatly improve the selectivity of propylene products when being used as a carrier of a propane dehydrogenation catalyst. For example, CN109745978A discloses a propane dehydrogenation catalyst with Pt-Sn supported on a mesoporous carbon material as a support. CN112403458A discloses a Cr-supported propane dehydrogenation catalyst with a non-metallic carbon material as a support. CN109926038A directly uses waste tea carbon as a propane dehydrogenation catalyst. However, most of these reported carbon material-supported catalysts use irregularly granular activated carbon such as powdery activated carbon or coconut shell carbon as a raw material, and have problems such as difficulty in molding, low strength, and the like, and are difficult to meet the demands of practical industrial applications.

Disclosure of Invention

In order to overcome the defects in the prior art, the application provides a spherical activated carbon supported platinum propane dehydrogenation catalyst and a preparation method thereof, and the catalyst has high propylene selectivity and good stability.

The application aims at: spherical active carbon carriers are prepared based on spherical high molecular polymers, and propane dehydrogenation catalysts with high propylene selectivity are prepared.

According to an aspect of the present application, there is provided a propane dehydrogenation catalyst comprising a carrier and a Pt component, a Sn component, an alkali metal component supported on the carrier;

the carrier is spherical active carbon;

the alkali metal component is at least one selected from potassium, sodium, lithium and cesium.

Optionally, the spherical activated carbon is spherical particles with the diameter of 0.4-2.0 mm.

Alternatively, the spherical activated carbon is selected from any value or range of values between any of 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm in diameter.

Optionally, the specific surface area of the spherical active carbon is 500-2000 m ² Per gram, the pore volume is 0.55-1.5 mL/g.

Alternatively, the specific surface area of the spherical activated carbon is selected from 500m ² /g、800m ² /g、1000m ² /g、1500m ² /g、2000m ² Any value in/g or a range of values between any two of the above.

Alternatively, the pore volume is selected from any of 0.55mL/g, 0.7mL/g, 0.8mL/g, 1.0mL/g, 1.2mL/g, 1.5mL/g, or a range of values between any two of the foregoing.

Optionally, the spherical activated carbon has micropores with a pore diameter of 0.5 to 1.5nm, mesopores with a pore diameter of 4 to 10nm, and macropores with a pore diameter of 50 to 200 nm.

Optionally, in the spherical activated carbon, the number proportion of micropores, mesopores and macropores is as follows: 1 to 10:0.1 to 5:1.

alternatively, the carrier is present in an amount of 94.1 to 99.7wt.%, the Pt component is present in an amount of 0.1 to 1.0wt.%, the Sn component is present in an amount of 0.05 to 5.0wt.%, and the alkali metal component is present in an amount of 0.15 to 2.0wt.%, based on the total weight of the propane dehydrogenation catalyst.

Alternatively, when the alkali metal component is potassium, the content is 0.15 to 1.5wt.% in terms of potassium metal element.

Alternatively, when the alkali metal component is sodium, the content is 1.0 to 2.0wt.% in terms of sodium metal element.

According to another aspect of the present application, there is provided a method for preparing the propane dehydrogenation catalyst described above, the method comprising:

and (3) immersing the carrier in a mixture containing a Pt component precursor, a Sn component precursor and an alkali metal component precursor, drying and calcining to obtain the propane dehydrogenation catalyst.

Optionally, the preparation method of the propane dehydrogenation catalyst comprises the following steps: immersing a carrier in a mixed solution containing a Pt component precursor, a Sn component precursor and an alkali metal component precursor for 0.5-12 h, and then drying and calcining under a high-temperature inert atmosphere, wherein the carrier is spherical active carbon which is spherical particles with the diameter of 0.4-2.0 mm and the specific surface area of 500-2000 m ² Per g, pore volume of 0.55-1.5 mL/g, micropores with pore diameter of 0.5-1.5 nm, mesopores with pore diameter of 4-10 nm and macropores with pore diameter of 50-200 nm.

Optionally, the carrier is spherical active carbon, and the preparation method of the spherical active carbon comprises the following steps:

under the inactive atmosphere, the spherical high polymer is carbonized, then is contacted with an activating agent and is activated, thus obtaining the spherical active carbon.

Optionally, the method for forming the carrier comprises the following steps:

(a) Placing the spherical high molecular polymer under an inert condition for high-temperature carbonization treatment to obtain a spherical carrier precursor;

(b) And (3) contacting the spherical carrier precursor obtained in the step (a) with an activating agent at a high temperature, and activating to obtain the spherical active carbon carrier.

Optionally, the method for forming the carrier comprises the following steps:

(b) And (3) contacting the spherical carrier precursor obtained in the step (a) with an activating agent at high temperature, activating, cooling, and sequentially carrying out acid washing, water washing and drying to obtain the spherical active carbon carrier.

Optionally, the spherical high molecular polymer is selected from at least one of phenolic resin, polystyrene resin and polypropylene-based resin.

Optionally, the activator is selected from at least one of water, carbon dioxide, potassium hydroxide, potassium carbonate, phosphoric acid.

Optionally, the inactive atmosphere is selected from at least one of nitrogen, argon and helium.

Optionally, the carbonization temperature is 600-1200 ℃, and the carbonization time is 1-8 h.

Optionally, the charring temperature is selected from any value or range of values between any two of 600 ℃, 700 ℃, 750 ℃, 800 ℃, 900 ℃, 1200 ℃.

Optionally, the carbonization time is selected from any value of 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or a range of values between any two of the above.

Optionally, the activating temperature is 500-1100 ℃, and the activating time is 1-8 h.

Optionally, the temperature of the activation is selected from any value or range of values between any two of 500 ℃, 700 ℃, 750 ℃, 800 ℃, 900 ℃, 1000 ℃, 1100 ℃.

Alternatively, the time of activation is selected from any value of 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or a range of values between any two of the foregoing.

Optionally, the Pt component precursor is selected from chloroplatinic acid and/or platinum acetylacetonate.

Optionally, the Sn component precursor is selected from at least one of stannous chloride and stannic chloride.

Optionally, the alkali metal component precursor is selected from at least one of potassium chloride, sodium chloride, lithium chloride, potassium nitrate, sodium nitrate, cesium chloride.

Optionally, the carrier, the Pt component precursor, the Sn component precursor, and the alkali metal component precursor are used in amounts such that the propane dehydrogenation catalyst is prepared, the carrier is present in an amount of 94.1 to 99.7wt.%, the Pt component is present in an amount of 0.1 to 1.0wt.%, the Sn component is present in an amount of 0.05 to 5.0wt.%, and the alkali metal component is present in an amount of 0.15 to 2.0wt.%, based on the total weight of the propane dehydrogenation catalyst.

Optionally, the time of the impregnation is 0.5 to 12 hours.

Optionally, the drying temperature is 60-130 ℃, and the drying time is 0.5-6 h.

Optionally, the temperature of the drying is selected from any value or range of values between any two of 60 ℃, 70 ℃, 75 ℃, 80 ℃, 90 ℃, 100 ℃, 130 ℃.

Optionally, the drying time is selected from any value of 0.5h, 1h, 2h, 3h, 4h, 5h, 6h or a range of values between any two of the foregoing.

Optionally, the calcination temperature is 200-800 ℃ and the calcination time is 1-8 h.

Alternatively, the temperature of the calcination is selected from any value or range of values between any two of 200 ℃, 300 ℃, 400 ℃, 500 ℃, 600 ℃, 800 ℃.

Optionally, the time of calcination is selected from any value of 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h or a range of values between any two of the foregoing.

According to yet another aspect of the present application, there is provided a process for producing propylene by dehydrogenation of propane, the process comprising: in the presence of a propane dehydrogenation catalyst and hydrogen, carrying out dehydrogenation reaction on propane to prepare propylene;

the propane dehydrogenation catalyst is selected from the propane dehydrogenation catalysts described above.

Optionally, the dehydrogenation reaction conditions include: the reaction temperature is 450-700 ℃, the reaction pressure is 0-0.5 MPa, and the weight hourly space velocity of propane is 1-20 h ^-1 Hydrogen to hydrocarbon molar ratio of 0.25:1 to 10:1.

the catalyst provided by the application is evaluated by the following conditions:

the reaction temperature is 450-700 ℃, the reaction pressure is 0-0.5 MPa, and the weight hourly space velocity of propane is 1-20 h ^-1 Hydrogen to hydrocarbon molar ratio of 0.25:1 to 10:1. the gas phase product of the reaction was purified by gas chromatography Agilent7890 (HP-Al ₂ O ₃ KCl capillary packed column, FID detector) on-line analysis.

The application has the beneficial effects that:

the catalyst obtained by the application takes the spherical active carbon with weak acidity and high strength as a carrier, takes the loaded Pt as a main active component, has better propylene selectivity and catalytic stability, the conversion rate of the propane can reach 43%, and the propylene selectivity can reach 98.8%.

Drawings

FIG. 1 is N of spherical activated carbon carriers prepared in example 1 of the present application ₂ Physical adsorption curve graph.

FIG. 2 is a graph showing pore size distribution of the spherical activated carbon support prepared in example 1 of the present application.

FIG. 3 is a schematic representation of the catalyst Cat-1 prepared in example 7 of the present application.

FIG. 4 is a graph showing the conversion and selectivity of catalyst Cat-1 for the catalytic dehydrogenation of propane to propylene over time, plotted on the ordinate as propane conversion or propylene selectivity, and plotted on the abscissa as time in hours (h), as described in example 20 of the present application.

Detailed Description

The present application is described in detail below with reference to examples, but the present application is not limited to these examples.

Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially.

The gas phase product of the reaction was purified by gas chromatography Agilent7890 (HP-Al ₂ O ₃ KCl capillary packed column, FID detector) on-line analysis.

In the examples of the present application, room temperature refers to "25 ℃.

In the following experimental examples and experimental comparative examples,

conversion (%) of propane= (amount of propane-amount of propane in reaction product)/(amount of propane×100%;

selectivity (%) of propylene=actual yield of propylene ∈theoretical yield of propylene x 100%.

Example 1: preparation of spherical active carbon carrier

10g of spherical polystyrene resin is placed in a heating area of a high-temperature furnace, nitrogen (100 mL/min) is introduced, the high-temperature furnace is heated to raise the temperature, the temperature of the heating area is raised to 800 ℃, and the spherical carrier precursor is obtained after constant-temperature carbonization treatment for 2 hours. Then the temperature of the heating zone is increased to 900 ℃, steam is introduced into the heating zone, the constant-temperature activation is carried out for 2 hours, and the temperature is cooled to room temperature, so as to obtain a spherical active carbon carrier, which is marked as SAC-1, the detailed synthesis parameters are shown in table 1, and the specific surface area, pore volume, pore distribution and other properties are shown in table 2. FIG. 1 is N of a spherical activated carbon support prepared ₂ As can be seen from fig. 1, the physical adsorption graph shows that SAC-1 is an IV-type adsorption curve, and has a large adsorption-desorption hysteresis loop in a high relative pressure region, which indicates that the carrier SAC-1 contains micropores, mesopores and macropores.

FIG. 2 is a graph showing pore size distribution of the prepared spherical activated carbon support, and as can be seen from FIG. 2, SAC-1 has microporous channels of 0.8nm and mesoporous channels of 6.3 nm.

Examples 2-3: preparation of spherical active carbon carrier

Substantially the same as in example 1, except that spherical polystyrene resin was replaced with spherical phenol resin and spherical polyacrylonitrile resin, respectively, and the remaining conditions were exactly the same as in example 1, spherical activated carbon carriers, respectively designated SAC-2 and SAC-3, were obtained, the detailed synthesis parameters of which are shown in Table 1, and the properties of specific surface area, pore volume, pore distribution, etc., are shown in Table 2.

Example 4: preparation of spherical active carbon carrier

10g of spherical polystyrene resin is placed in a heating area of a high-temperature furnace, nitrogen (100 mL/min) is introduced, the high-temperature furnace is heated to raise the temperature, the temperature of the heating area is raised to 600 ℃, and the spherical carrier precursor is obtained after constant-temperature carbonization treatment for 8 hours. Then the temperature of the heating zone is increased to 1100 ℃, carbon dioxide is introduced into the heating zone, the constant-temperature activation is carried out for 2 hours, and the spherical active carbon carrier is obtained after cooling to room temperature, and is marked as SAC-4, the detailed synthesis parameters are shown in table 1, and the properties of specific surface area, pore volume, pore distribution and the like are shown in table 2.

Example 5: preparation of spherical active carbon carrier

Placing 10g of spherical phenolic resin in a heating area of a high-temperature furnace, introducing nitrogen (100 mL/min), heating the high-temperature furnace to raise the temperature of the heating area to 1200 ℃, carbonizing at constant temperature for 1h, and cooling to room temperature to obtain spherical carrier precursors. The precursor is uniformly mixed with 10mL of solution containing 2g of potassium hydroxide, then the mixture is dried at 110 ℃ to remove redundant solvent, the obtained solid is placed in a heating area of a high-temperature furnace, nitrogen (100 mL/min) is introduced, the high-temperature furnace is heated to raise the temperature of the heating area to 600 ℃, the constant-temperature activation is carried out for 1h, the mixture is cooled to room temperature, the obtained solid is washed by dilute hydrochloric acid and deionized water in sequence until filtrate is neutral, the spherical active carbon carrier is obtained after drying at 110 ℃, the spherical active carbon carrier is marked as SAC-5, the detailed synthesis parameters are listed in Table 1, and the specific surface area, pore volume, pore distribution and other properties are listed in Table 2.

Example 6: preparation of spherical active carbon carrier

Substantially the same as in example 5, except that the activation temperature was changed to 500℃and the activation time was adjusted to 8 hours, the other conditions were exactly the same as in example 5, to obtain a spherical activated carbon support, designated SAC-6, whose detailed synthesis parameters are shown in Table 1, and the properties of specific surface area, pore volume, pore distribution, etc. are shown in Table 2.

Comparative example 1: preparation of spherical active carbon carrier

Substantially the same as in example 4, except that the activation temperature was increased to 1250℃and the other conditions were exactly the same as in example 4, a spherical activated carbon support, designated DSAC-1, was obtained, the detailed synthesis parameters of which are shown in Table 1, and the properties of specific surface area, pore volume, pore distribution, etc. are shown in Table 2.

Comparative example 2: preparation of spherical active carbon carrier

The procedure was substantially as in example 4, except that the spherical resin was carbonized at a high temperature and then cooled to room temperature without high temperature activation treatment, and the remaining conditions were exactly the same as those in example 4, to give a spherical activated carbon support, designated as DSAC-2, whose detailed synthesis parameters are shown in Table 1 and whose specific surface area, pore volume, pore distribution and the like are shown in Table 2.

Table 1 summary of the example conditions above.

Table 2 the properties of the spherical activated carbon supports obtained in the above examples are summarized.

As can be seen from the data of tables 1 and 2, the specific surface area of the spherical activated carbon is 500 to 2000m ² The ratio of the number of micropores, mesopores and macropores is (1-10): 0.1-5): 1.

Example 7: preparation of the catalyst

The spherical activated carbon carrier SAC-1 obtained in example 1 was sieved to obtain spherical activated carbon having a particle size of 0.4 to 2.0 mm. 1g of the sieved spherical activated carbon was weighed and immersed in 1.7mL of an aqueous solution containing 0.013g of chloroplatinic acid, 0.024g of stannous chloride and 0.01g of potassium chloride, immersed for 1 hour, dried in a water bath at 60-70 ℃ for 30 minutes, dried in an oven at 120 ℃ for 4 hours, and calcined at 350 ℃ for 4 hours under nitrogen protection. The composition of the obtained catalyst is as follows: platinum: 0.5%, tin: 1.5%, potassium: 0.5% and the remaining 97.5% are carriers, designated Cat-1. FIG. 3 is a physical diagram of the prepared Cat-1 catalyst, and as can be seen from FIG. 3, the catalyst Cat-1 is black pellets with smooth surfaces, and the diameters of the pellets are 0.7-1.6 mm.

Example 8: preparation of the catalyst

The spherical activated carbon carrier SAC-1 obtained in example 1 was sieved to obtain spherical activated carbon having a particle size of 0.4 to 2.0 mm. 1g of the sieved spherical activated carbon was weighed and immersed in 1.7mL of an aqueous solution containing 0.026g of chloroplatinic acid, 0.024g of stannous chloride and 0.03g of potassium chloride for 0.5 hour, dried in a water bath at 60 to 70℃for 30 minutes, dried in an oven at 120℃for 4 hours, and calcined at 350℃for 4 hours under nitrogen. The composition of the obtained catalyst is as follows: platinum: 1.0%, tin: 1.5%, potassium: 1.5% and the remaining 96% are carriers, designated Cat-2.

Example 9: preparation of the catalyst

The spherical activated carbon carrier SAC-1 obtained in example 1 was sieved to obtain spherical activated carbon having a particle size of 0.4 to 2.0 mm. 1g of the sieved spherical activated carbon was weighed and immersed in 1.7mL of an aqueous solution containing 0.0026g of chloroplatinic acid, 0.0008g of stannous chloride and 0.003g of potassium chloride for 0.5 hour, dried in a water bath at 60 to 70℃for 30 minutes, dried in an oven at 120℃for 4 hours, and calcined at 350℃for 4 hours under nitrogen. The composition of the obtained catalyst is as follows: platinum: 0.1%, tin: 0.05%, potassium: 0.15% and the remaining 99.7% are carriers, designated Cat-3.

Example 10: preparation of the catalyst

The spherical activated carbon carrier SAC-1 obtained in example 1 was sieved to obtain spherical activated carbon having a particle size of 0.4 to 2.0 mm. 1g of the sieved spherical activated carbon was weighed and immersed in 1.7mL of an aqueous solution containing 0.013g of chloroplatinic acid, 0.024g of stannous chloride and 0.025g of sodium chloride, immersed for 12 hours, dried in a water bath at 60-70 ℃ for 30 minutes, dried in an oven at 120 ℃ for 4 hours, and baked at 350 ℃ for 4 hours under the protection of nitrogen. The composition of the obtained catalyst is as follows: platinum: 0.5%, tin: 1.5%, sodium: 1.0% and the remaining 97% are carriers, designated Cat-4.

Example 11: preparation of the catalyst

The spherical activated carbon carrier SAC-1 obtained in example 1 was sieved to obtain spherical activated carbon having a particle size of 0.4 to 2.0 mm. 1g of the sieved spherical activated carbon was weighed and immersed in 1.7mL of an aqueous solution containing 0.026g of chloroplatinic acid, 0.024g of stannous chloride and 0.05g of sodium chloride for 0.5 hour, dried in a water bath at 60 to 70℃for 30 minutes, dried in an oven at 120℃for 4 hours, and calcined at 350℃for 4 hours under nitrogen. The composition of the obtained catalyst is as follows: platinum: 1.0%, tin: 1.5%, sodium: 2.0% and the rest 95.5% are carriers, which are marked as Cat-5.

Examples 12 to 16: preparation of the catalyst

Substantially the same as in example 7, except that the spherical activated carbon in example 7 was replaced with spherical activated carbon carriers SAC-2 to SAC-6 obtained in examples 2 to 6, respectively, and the rest of the operations were completely identical to those in example 7, the obtained catalysts were designated Cat-6 to Cat-10, respectively.

Examples 17 to 18: preparation of the catalyst

Substantially the same as in example 7, except that the calcination temperatures in example 7 were adjusted to 200℃and 800℃respectively, and the remaining operations were completely identical to those in example 7, the resultant catalysts were designated Cat-11 to Cat-12, respectively.

Comparative examples 3 to 4: preparation of the catalyst

Substantially the same as in example 7, except that the spherical activated carbon in example 7 was replaced with the spherical activated carbon supports DSAC-1 to DSAC-2 obtained in comparative examples 1 to 2, respectively, and the rest of the operations were exactly the same as in example 7, and the obtained catalysts were designated DCat-1 to DCat-2, respectively.

Comparative example 5: preparation of the catalyst

To further investigate the propane dehydrogenation performance of the catalyst prepared with the spherical activated carbon support, the catalyst was prepared with conventional spherical alumina (particle size 1.0 to 1.6 mm) as a support in comparative example 5. The preparation method of the catalyst comprises the following steps: 1g of a spherical alumina carrier was weighed and immersed in 1.7mL of an aqueous solution containing 0.013g of chloroplatinic acid, 0.024g of stannous chloride and 0.01g of potassium chloride, immersed for 0.5h, dried in a water bath at 60 to 70 ℃ for 30 minutes, dried in an oven at 120 ℃ for 4 hours, and calcined at 350 ℃ for 4 hours under nitrogen protection. The composition of the obtained catalyst is as follows: platinum: 0.5%, tin: 1.5%, potassium: 0.5% and the remaining 97.5% are carriers, designated DCat-3.

Comparative example 6:

to further investigate the propane dehydrogenation performance of the catalyst prepared with the spherical activated carbon support, a catalyst was prepared with conventional coconut shell carbon (10-30 mesh) as a support in comparative example 6. The preparation method of the catalyst comprises the following steps: 1g of coconut shell carbon carrier is weighed and immersed in 1.7mL of aqueous solution containing 0.013g of chloroplatinic acid, 0.024g of stannous chloride and 0.01g of potassium chloride, immersed for 0.5h, dried in a water bath at 60-70 ℃ for 30 minutes, dried in an oven at 120 ℃ for 4 hours, and baked at 350 ℃ for 4 hours under the protection of nitrogen. The composition of the obtained catalyst is as follows: platinum: 0.5%, tin: 1.5%, potassium: 0.5% and the remaining 97.5% are carriers, designated DCat-4.

Comparative example 7: catalyst preparation

Substantially the same as in example 7, except that chloroplatinic acid in example 7 was adjusted to 0.039g, and the remaining operation was conducted in exactly the same manner as in example 7, the composition of the resulting catalyst was: platinum: 1.5%, tin: 1.5%, potassium: 0.5% and the rest 96.5% are carriers, which are marked as DCat-5.

Comparative example 8: catalyst preparation

Substantially the same as in example 7, except that the addition amount of stannous chloride in example 7 was adjusted to 0g, that is, stannous chloride was not added, the rest of the operations were exactly the same as in example 7, and the composition of the obtained catalyst was: platinum: 0.5%, potassium: 0.5% and the rest 99% are carriers, which are marked as DCat-6.

Table 3 summary of the catalyst parameters prepared in examples 7-18.

Example 19: investigation of the reactivity of propane dehydrogenation catalyst

The catalysts prepared in examples 7 to 18 and comparative examples 3 to 8 were evaluated for propane dehydrogenation reaction performance on a quartz tube type fixed bed reactor. Catalyst loading 0.15g (0.3 mL) in H ₂ Under the condition of heating to 600 ℃ at the heating rate of 5 ℃/min, reducing for 2 hoursThen, propane was introduced, and the evaluation period was 24 hours. The reaction conditions are as follows: 600 ℃ and 0.01MPa, WHSV=6h ^-1 ，H ₂ And C ₃ H ₈ The molar ratio of (2) was 0.5. The reaction product was analyzed on line by gas chromatography Agilent 7890A, chromatographic conditions were: sample injection temperature 180 ℃, column box temperature 105 ℃, FID detector temperature 200 ℃, chromatographic column HP-Al ₂ O ₃ KCl. The propane dehydrogenation reaction results of the catalyst are shown in Table 4.

The results of the catalytic propane dehydrogenation reactions for the catalysts of Table 4 are summarized.

Catalyst name	Initial conversion%	Initial propylene Selectivity%	24h conversion%	Propylene selectivity for 24 h%
					Cat-1	41.2	97.1	38.7	98.5
Cat-2	42.6	98.1	39.3	98.6
					Cat-3	39.6	96.0	37.1	96.9
Cat-4	40.9	98.3	38.5	98.8
					Cat-5	43.0	97.7	38.8	98.1
Cat-6	41.7	96.3	38.2	97.6
					Cat-7	41.1	96.6	38.0	97.7
Cat-8	41.8	96.3	36.9	96.9
					Cat-9	42.0	97.2	38.1	98.3
Cat-10	40.2	96.1	37.3	96.4
					Cat-11	40.0	96.0	37.1	96.2
Cat-12	39.6	96.1	36.9	96.5
					DCat-1	38.1	94.2	34.4	94.8
DCat-2	37.3	93.8	33.2	94.1
					DCat-3	40.6	90.6	30.1	91.0
DCat-4	36.9	92.5	32.8	92.6
					DCat-5	43.9	93.2	36.1	92.7
DCat-6	44.1	84.5	31.8	83.9

As can be seen from the data in Table 4, the catalyst prepared by the application and taking the spherical activated carbon as the carrier has higher catalytic activity, propylene selectivity and catalytic stability, the initial propane conversion rate can reach 43%, and the propylene selectivity can reach 98.3%; after 24 hours of reaction, the conversion rate of propane can reach 39.3%, and the selectivity of propylene can reach 98.8%.

Example 20: investigation of the reactivity of propane dehydrogenation catalyst

The catalyst Cat-1 prepared in example 7 was subjected to long life performance evaluation of propane dehydrogenation reaction on a quartz tube type fixed bed reactor. Catalyst loading 0.15g (0.3 mL) in H ₂ Under the condition, the temperature is increased to 600 ℃ at the heating rate of 5 ℃/min, the reaction is reduced for 2 hours, and then propane is introduced, and the evaluation time is 160 hours. The reaction conditions are as follows: 600 ℃ and 0.01MPa, WHSV=6h ^-1 ，H ₂ And C ₃ H ₈ The molar ratio of (2) was 0.5. Reaction product passing through gasThe chromatographic conditions of the online analysis of the Agilent 7890A are as follows: sample injection temperature 180 ℃, column box temperature 105 ℃, FID detector temperature 200 ℃, chromatographic column HP-Al ₂ O ₃ KCl. The reaction results are shown in FIG. 4 as a function of time.

As can be seen from fig. 4, the propane conversion of the catalyst Cat-1 was only reduced from 41.2% to 36.0% during the 160h long life averaging process, and the propylene selectivity was always maintained between 98% and 99%, showing excellent catalytic stability and high propylene selectivity.

While the application has been described in terms of preferred embodiments, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the application, and it is intended that the application is not limited to the specific embodiments disclosed.

Claims

1. A propane dehydrogenation catalyst, characterized in that the propane dehydrogenation catalyst comprises a carrier and a Pt component, a Sn component, an alkali metal component supported on the carrier;

the carrier is spherical active carbon;

2. The propane dehydrogenation catalyst according to claim 1, characterized in that the spherical activated carbon is spherical particles having a diameter of 0.4 to 2.0 mm;

preferably, the specific surface area of the spherical activated carbon is 500-2000 m ² Per gram, the pore volume is 0.55-1.5 mL/g;

preferably, the spherical activated carbon has micropores with a pore diameter of 0.5 to 1.5nm, mesopores with a pore diameter of 4 to 10nm and macropores with a pore diameter of 50 to 200 nm;

preferably, in the spherical activated carbon, the number proportion of micropores, mesopores and macropores is as follows: 1 to 10:0.1 to 5:1.

3. the propane dehydrogenation catalyst according to claim 1, characterized in that the carrier is present in an amount of 94.1 to 99.7wt.%, the Pt component is present in an amount of 0.1 to 1.0wt.%, the Sn component is present in an amount of 0.05 to 5.0wt.%, and the alkali metal component is present in an amount of 0.15 to 2.0wt.%, based on the total weight of the propane dehydrogenation catalyst;

preferably, when the alkali metal component is potassium, the content is 0.15 to 1.5wt.% in terms of potassium metal element;

preferably, when the alkali metal component is sodium, the content is 1.0 to 2.0wt.% in terms of sodium metal element.

4. A process for the preparation of a propane dehydrogenation catalyst according to any of claims 1 to 3, characterized in that the preparation process comprises:

5. The method of preparing the spherical activated carbon according to claim 4, wherein the carrier is spherical activated carbon, and the method of preparing the spherical activated carbon comprises:

under the inactive atmosphere, carbonizing the spherical high polymer, contacting with an activating agent, and activating to obtain spherical active carbon;

preferably, the spherical high molecular polymer is selected from at least one of phenolic resin, polystyrene resin and polypropylene-based resin;

preferably, the activator is selected from at least one of water, carbon dioxide, potassium hydroxide, potassium carbonate, phosphoric acid;

preferably, the inactive atmosphere is selected from at least one of nitrogen, argon and helium.

6. The method according to claim 5, wherein the carbonization temperature is 600 to 1200 ℃ and the carbonization time is 1 to 8 hours;

preferably, the activation temperature is 500-1100 ℃ and the activation time is 1-8 h.

7. The method of claim 4, wherein the Pt component precursor is selected from chloroplatinic acid and/or platinum acetylacetonate;

preferably, the Sn component precursor is selected from at least one of stannous chloride and stannic chloride;

preferably, the alkali metal component precursor is selected from at least one of potassium chloride, sodium chloride, lithium chloride, potassium nitrate, sodium nitrate, cesium chloride;

preferably, the carrier, the Pt component precursor, the Sn component precursor, and the alkali metal component precursor are used in such an amount that the propane dehydrogenation catalyst is prepared, the carrier is present in an amount of 94.1 to 99.7wt.%, the Pt component is present in an amount of 0.1 to 1.0wt.%, the Sn component is present in an amount of 0.05 to 5.0wt.%, and the alkali metal component is present in an amount of 0.15 to 2.0wt.%, based on the total weight of the propane dehydrogenation catalyst.

8. The method according to claim 4, wherein the time of the impregnation is 0.5 to 12 hours;

preferably, the drying temperature is 60-130 ℃, and the drying time is 0.5-6 h;

preferably, the calcination temperature is 200-800 ℃ and the calcination time is 1-8 h.

9. A process for the dehydrogenation of propane to propylene, said process comprising: in the presence of a propane dehydrogenation catalyst and hydrogen, carrying out dehydrogenation reaction on propane to prepare propylene;

the propane dehydrogenation catalyst is selected from the propane dehydrogenation catalysts of any one of claims 1-3.

10. The method according to claim 9, which comprisesCharacterized in that the dehydrogenation reaction conditions include: the reaction temperature is 450-700 ℃, the reaction pressure is 0-0.5 MPa, and the weight hourly space velocity of propane is 1-20 h ^-1 Hydrogen to hydrocarbon molar ratio of 0.25:1 to 10:1.