A catalyst with modified silicon carbide as carrier, a preparation method thereof and application of the catalyst in preparation of propylene from propane dehydrogenation

Abstract

The application belongs to the field of catalyst preparation, and discloses a catalyst with modified silicon carbide as a carrier, a preparation method thereof and application of the catalyst in propane dehydrogenation to prepare propylene. The application prepares a supported Pt-based catalyst with modified silicon carbide as a carrier, and the surface of the carrier has no acid sites, which eliminates the negative effect of acid catalysis, inhibits the occurrence of side reactions, is conducive to improving the selectivity of propylene and reducing the amount of carbon deposition; the metal-carrier interaction is enhanced, the dispersion of active components is promoted, more active sites are exposed, and the catalytic activity of propane dehydrogenation is improved. The catalyst adopts a simple impregnation method, and has simple process, low operation cost and easy scale-up production. The catalyst has high propane conversion rate, high propylene selectivity and strong anti-carbon deposition capacity when applied in the reaction of propane catalytic dehydrogenation to prepare propylene, and has good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation, specifically relating to a catalyst supported on modified silicon carbide, its preparation method, and its application in the dehydrogenation of propane to propylene. Background Technology

[0002] Propylene and other low-carbon olefins are the cornerstone of organic chemicals, widely used in the production of polypropylene, acrylonitrile, propylene oxide, and other high-value-added chemicals. Currently, propylene is mainly derived from the catalytic cracking and steam cracking of naphtha, as well as the coal-based methanol-to-olefins route. However, this route suffers from problems such as the co-production of multiple olefins, high energy consumption, and large carbon emissions. With the increasing demand for propylene in the chemical market, propylene consumption is gradually increasing, and traditional production processes can no longer meet market demands. In recent years, propane dehydrogenation to propylene has become an important route for increasing propylene production. This process uses alumina-supported Pt as a catalyst. However, the presence of acidic sites on the alumina support easily leads to side reactions such as cracking, polymerization, and cyclization, resulting in increased carbon deposition and rapid catalyst deactivation. Therefore, there is an urgent need to develop non-acidic or weakly acidic supports to improve the propane dehydrogenation performance of Pt-based catalysts.

[0003] Silicon carbide (SiC) has a non-acidic surface and excellent thermal and chemical stability, making it a common support in catalysis for strongly exothermic reactions, such as catalytic combustion. However, the inert surface of the SiC support makes it difficult to effectively disperse the active component, resulting in the presence of large-sized Pt particles. This leads to low utilization of the active component. For example, literature reports on SiC-supported Pt-based catalysts applied to reactions such as nitrogen oxide combustion and hydrogen combustion (Appl. Catal., A, 2004, 266, 21-27; Appl. Catal., B, 2017, 201, 391-399) show that the support surface contains significant large-sized Pt particles. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned technical challenges by providing a catalyst supported on modified silicon carbide, its preparation method, and its application in the dehydrogenation of propane to propylene. The catalyst exhibits excellent catalytic activity and anti-carbon deposition properties in the propane dehydrogenation process, and its preparation process is simple, with low production costs and environmental friendliness, resulting in significant social and economic benefits. Compared with traditional catalysts, the silicon carbide catalyst prepared by this invention possesses catalytic characteristics such as high propane conversion rate, high propylene selectivity, and strong anti-carbon deposition ability, showing promising prospects for industrial application. The catalyst provided by this invention uses modified silicon carbide as a support and a low content of the precious metal platinum as the active component.

[0005] The technical solution of the present invention:

[0006] The present invention provides a catalyst supported on modified silicon carbide, the catalyst comprising a platinum active component and a silicon carbide support.

[0007] This invention provides a method for preparing modified silicon carbide.

[0008] This invention provides a method for preparing a catalyst using modified silicon carbide as a support.

[0009] This invention provides the application of a catalyst supported on modified silicon carbide in the propane dehydrogenation to propylene reaction.

[0010] A catalyst supported on modified silicon carbide comprises a support and an active component, wherein the support is silicon carbide and the active component is the noble metal Pt. The loading of the active component is 0.1-1.0 wt.% by weight of the support.

[0011] A method for preparing modified silicon carbide includes the following steps:

[0012] (a) Place silicon carbide in a tube furnace, introduce inert gas, and purge the gas path;

[0013] (b) Introduce the processing gas, heat it up according to the predetermined heating rate program, heat it up to the predetermined processing temperature, and keep it at the predetermined temperature for the predetermined processing time.

[0014] (c) After the treatment is completed, the mixture is allowed to cool naturally to room temperature to obtain modified silicon carbide.

[0015] In step (a), the inert gas includes one or a mixture of two or more of nitrogen, argon, and helium.

[0016] In step (b), the processing gas includes two or more of nitrogen, argon, helium, and oxygen; the processing temperature is 600-1100℃; and the processing time is 0.5-6 hours.

[0017] A method for preparing a catalyst supported on modified silicon carbide includes the following steps:

[0018] (a) Dissolve a platinum-containing compound in water or an alcohol solvent to obtain a platinum precursor salt solution;

[0019] (b) The platinum precursor salt solution obtained in step (a) is impregnated onto the modified silicon carbide support, dried, calcined, and reduced to obtain a catalyst with modified silicon carbide as the support.

[0020] In step (a), the platinum-containing compound includes one or more of platinum chloride, chloroplatinic acid, ammonium chloroplatinate, aminoplatinum nitrate, and ethylenediamine platinum chloride.

[0021] In step (b), the drying temperature is 30-100℃ and the drying time is 8-12 hours; the calcination temperature is 400-700℃ and the calcination time is 0.5-6 hours; the reduction time is 400-600℃ and the reduction time is 0.5-4 hours.

[0022] Application of a catalyst supported on modified silicon carbide in the dehydrogenation of propane to propylene.

[0023] The hydrogen partial pressure of the feed gas is 0-40 kPa, and the volume hourly space velocity of the feed gas is 5000-50000 mL g. cat -1 h -1 The reaction temperature is 500-600℃. The mixed gas undergoes a catalytic reaction in the reactor under normal pressure.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention utilizes modified silicon carbide as a support to prepare a supported Pt-based catalyst. The support surface is free of acidic sites, eliminating the negative effects of acid catalysis, suppressing side reactions, and thus improving propylene selectivity and reducing carbon deposition. Enhanced metal-support interactions promote the dispersion of active components, exposing more active sites and improving the catalytic activity for propane dehydrogenation. The catalyst is prepared using a simple impregnation method, resulting in a simple process, low operating costs, and easy scale-up for production. When applied to the catalytic dehydrogenation of propane to propylene, the catalyst exhibits high propane conversion, high propylene selectivity, and strong resistance to carbon deposition, demonstrating promising industrial application prospects. Attached Figure Description

[0026] Figure 1 This is a TEM image of the modified silicon carbide prepared in Example 2.

[0027] Figure 2 This refers to the propane dehydrogenation activity of the catalyst prepared in Example 10.

[0028] Figure 3 These are the weight loss curves of catalysts B2 and D3 after the reaction in Example 10 and Comparative Example 3. Detailed Implementation

[0029] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0030] The reaction was carried out in a fixed-bed reactor. The products were analyzed using gas chromatography. The contents of alkanes, alkenes, hydrogen, and inert gases in the products were analyzed online, and the conversion rate, selectivity, and yield of the reaction were calculated. The product yield was calculated using the normalization method.

[0031] Example

[0032] Examples 1-8 below describe the preparation of modified silicon carbide; Examples 9-26 describe the preparation of catalysts and the performance data of the corresponding catalysts in the propane dehydrogenation to propylene reaction.

[0033] The fixed-bed reactor used was built in-house, consisting of an open-tube resistance furnace, a YUDIAN intelligent temperature controller, and a Qixing flow controller. The tubular resistance furnace was manufactured by Yuanbang Circuit Manufacturing Co., Ltd. The intelligent temperature controller was manufactured by Yudian Automation Technology Co., Ltd. (KY-20A). The flow controller was manufactured by Qixing Huachuang Flowmeter Co., Ltd. (D07-7C).

[0034] Product analysis was performed using a GC7900 gas chromatograph. The content of alkanes and alkenes in the dehydrogenation products was analyzed online, and the conversion rate and selectivity of the reaction were calculated. The product was calculated using the area normalization method.

[0035] The gas chromatograph used was a GC7900 from Tianmei (China) Scientific Instruments Co., Ltd., and the specific operation was as follows:

[0036] (1) Column type: Al2O3 packed column and TDX-01 molecular sieve;

[0037] (2) Detector temperature: 200℃;

[0038] (3) Column oven program: Initial temperature 70℃, hold for 3 min, increase temperature to 170℃ at 10℃ / min, hold for 6 min.

[0039] (4) Gas flow rate: 20 ml / min.

[0040] Examples 1-8 illustrate the preparation of modified silicon carbide.

[0041] Example 1

[0042] 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and purged with inert gas for 30min. Then, an oxygen-nitrogen mixture was introduced with an oxygen partial pressure of 10kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 1000℃, and a treatment time of 2h. After treatment, the mixture was allowed to cool naturally to room temperature. The resulting carrier was denoted as A1.

[0043] Example 2

[0044] 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and purged with inert gas for 30min. Then, an oxygen-nitrogen mixture was introduced with an oxygen partial pressure of 20kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 1000℃, and a treatment time of 2h. After treatment, the mixture was allowed to cool naturally to room temperature. The resulting carrier was denoted as A2.

[0045] Example 3

[0046] 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and purged with inert gas for 30min. Then, an oxygen-nitrogen mixture was introduced with an oxygen partial pressure of 40kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 1000℃, and a treatment time of 2h. After treatment, the mixture was allowed to cool naturally to room temperature. The resulting carrier was denoted as A3.

[0047] Example 4

[0048] 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and purged with inert gas for 30min. Then, an oxygen-nitrogen mixture was introduced with an oxygen partial pressure of 20kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 600℃, and a treatment time of 2h. After treatment, the mixture was allowed to cool naturally to room temperature. The resulting carrier was denoted as A4.

[0049] Example 5

[0050] 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and purged with inert gas for 30min. Then, an oxygen-nitrogen mixture was introduced with an oxygen partial pressure of 20kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 900℃, and a treatment time of 2h. After treatment, the mixture was allowed to cool naturally to room temperature. The resulting carrier was denoted as A5.

[0051] Example 6

[0052] 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and purged with inert gas for 30min. Then, an oxygen-nitrogen mixture was introduced with an oxygen partial pressure of 20kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 1100℃, and a treatment time of 2h. After treatment, the mixture was allowed to cool naturally to room temperature. The resulting carrier was denoted as A6.

[0053] Example 7

[0054] 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and purged with inert gas for 30min. Then, an oxygen-nitrogen mixture was introduced with an oxygen partial pressure of 20kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 1000℃, and a treatment time of 0.5h. After treatment, the mixture was allowed to cool naturally to room temperature. The resulting carrier was designated as A7.

[0055] Example 8

[0056] 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and purged with inert gas for 30min. Then, an oxygen-nitrogen mixture was introduced with an oxygen partial pressure of 20kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 1000℃, and a treatment time of 6h. After treatment, the mixture was allowed to cool naturally to room temperature. The resulting carrier was denoted as A8.

[0057] The processing conditions and sample naming statistics of the modified silicon carbide prepared in Examples 1-8 above are shown in the following table:

[0058] Table 1. Processing conditions and sample naming for Examples 1-8

[0059]

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

[0061] Examples 9-26 present performance data for catalyst preparation and propane dehydrogenation to propylene reaction.

[0062] Example 9

[0063] (1) Take 318 mg of chloroplatinic acid in a small bottle, add 10 mL of deionized water and stir to dissolve, and prepare chloroplatinic acid solution.

[0064] (2) Take 250 μL of chloroplatinic acid solution and impregnate 1 g of the A1 sample obtained in Example 1. Dry at 50 °C, calcine at 500 °C for 4 h, and reduce at 550 °C for 2 h to obtain a fresh catalyst. The obtained catalyst is referred to as B1. The Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0065] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B1 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550 °C. Catalyst B1 exhibited the following catalytic performance: propane conversion rate of 26.6% and propylene selectivity of 98.1%.

[0066] Example 10

[0067] (1) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Example 9 and impregnate it into 1 g of the A2 sample obtained in Example 2. After drying at 50°C, calcining at 500°C for 4 h, and reducing at 550°C for 2 h, a fresh catalyst is obtained. The obtained catalyst is designated as B2, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0068] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B6 exhibited the following catalytic performance: propane conversion rate of 29.1%, propylene selectivity of 99.0%, and thermogravimetric analysis (TGA) carbon deposition of 2.0% after 6 hours of reaction.

[0069] Example 11

[0070] (1) Take 250 μL of the chloroplatinic acid solution prepared in Example 9 and impregnate it into 1 g of the A3 sample obtained in Example 3. After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is designated as B3, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0071] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B3 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B3 exhibited the following catalytic performance: propane conversion rate of 25.0% and propylene selectivity of 98.8%.

[0072] Example 12

[0073] (1) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Example 9 and impregnate it into 1 g of the A4 sample obtained in Example 4. After drying at 50°C, calcining at 500°C for 4 h, and reducing at 550°C for 2 h, a fresh catalyst is obtained. The obtained catalyst is designated as B4, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0074] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B4 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B4 exhibited the following catalytic performance: propane conversion rate of 22.3% and propylene selectivity of 99.8%.

[0075] Example 13

[0076] (1) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Example 9 and impregnate it into 1 g of the A5 sample obtained in Example 5. After drying at 50°C, calcining at 500°C for 4 h, and reducing at 550°C for 2 h, a fresh catalyst is obtained. The obtained catalyst is designated as B5, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0077] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B5 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹.-1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B5 exhibited the following catalytic performance: propane conversion rate of 27.8% and propylene selectivity of 99.4%.

[0078] Example 14

[0079] (1) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Example 9 and impregnate it into 1 g of the A6 sample obtained in Example 6. After drying at 50°C, calcining at 500°C for 4 h, and reducing at 550°C for 2 h, a fresh catalyst is obtained. The obtained catalyst is designated as B6, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0080] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B6 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B6 exhibited the following catalytic performance: propane conversion of 16.8% and propylene selectivity of 99.8%.

[0081] Example 15

[0082] (1) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Example 9 and impregnate it into 1 g of the A7 sample obtained in Example 7. After drying at 50°C, calcining at 500°C for 4 h, and reducing at 550°C for 2 h, a fresh catalyst is obtained. The obtained catalyst is designated as B7, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0083] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B7 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa. The reaction temperature was 550℃. The catalytic performance of catalyst B7 was: propane conversion rate of 26.5% and propylene selectivity of 99.4%.

[0084] Example 16

[0085] (1) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Example 9 and impregnate it into 1 g of the A8 sample obtained in Example 8. After drying at 50°C, calcining at 500°C for 4 h, and reducing at 550°C for 2 h, a fresh catalyst is obtained. The obtained catalyst is designated as B8, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0086] The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B8 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B8 exhibited the following catalytic performance: propane conversion rate of 18.4% and propylene selectivity of 99.7%.

[0087] Example 17

[0088] The reactant gas was introduced into a reactor containing catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 1.2 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B2 exhibited the following catalytic performance: propane conversion rate of 32.4% and propylene selectivity of 97.1%.

[0089] Example 18

[0090] The reactant gas was introduced into a reactor carrying catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 4.8 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B2 exhibited the following catalytic performance: propane conversion rate of 21.5% and propylene selectivity of 99.5%.

[0091] Example 19

[0092] The reactant gas was introduced into a reactor carrying catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 9.6 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B2 exhibited the following catalytic performance: propane conversion rate of 16.3% and propylene selectivity of 99.6%.

[0093] Example 20

[0094] The reactant gas was introduced into a reactor carrying catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 0 kPa, and the reaction temperature was 550℃. Catalyst B2 exhibited the following catalytic performance: propane conversion rate of 17.1% and propylene selectivity of 99.6%.

[0095] Example 21

[0096] The reactant gas was introduced into a reactor carrying catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 20 kPa, and the reaction temperature was 550 °C. Catalyst B2 exhibited the following catalytic performance: propane conversion rate of 24.1% and propylene selectivity of 98.6%.

[0097] Example 22

[0098] The reactant gas was introduced into a reactor carrying catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 40 kPa, and the reaction temperature was 550 °C. Catalyst B2 exhibited the following catalytic performance: propane conversion rate of 17.9% and propylene selectivity of 94.7%.

[0099] Example 23

[0100] The reactant gas was introduced into a reactor carrying catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 500℃. Catalyst B2 exhibited the following catalytic performance: propane conversion rate of 14.3% and propylene selectivity of 99.6%.

[0101] Example 24

[0102] The reactant gas was introduced into a reactor carrying catalyst B2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 600℃. Catalyst B2 exhibited the following catalytic performance: propane conversion rate of 18.1% and propylene selectivity of 95.5%.

[0103] Example 25

[0104] (1) Take 106 mg of chloroplatinic acid in a small bottle, add 10 mL of deionized water and stir to dissolve, and prepare chloroplatinic acid solution.

[0105] (2) Take 250 μL of the sample A2 obtained in Example 2 and impregnate it with 1 g. Dry it at 50 °C, calcine it at 500 °C for 4 h, and reduce it at 550 °C for 2 h to obtain a fresh catalyst. The obtained catalyst is designated as B9. The Pt loading is 0.1 wt.% based on the weight of silicon carbide.

[0106] (3) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B9 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. Catalyst B9 exhibited the following catalytic performance: propane conversion of 25.8% and propylene selectivity of 98.6%.

[0107] Example 26

[0108] (1) Take 530 mg of chloroplatinic acid in a small bottle, add 10 mL of deionized water and stir to dissolve, and prepare chloroplatinic acid solution.

[0109] (2) Take 250 μL of the sample A2 obtained in Example 2 and impregnate it with 1 g. Dry it at 50 °C, calcine it at 500 °C for 4 h, and reduce it at 550 °C for 2 h to obtain a fresh catalyst. The obtained catalyst is designated as B10. The Pt loading is 0.5 wt.% based on the weight of silicon carbide.

[0110] (3) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst B10. The reaction pressure was 0.1 MPa, the catalyst loading was 100 mg, and the propane weight hourly space velocity was 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. The catalytic performance of catalyst B10 was: propane conversion of 32.6% and propylene selectivity of 97.7%.

[0111] The statistical data of propane dehydrogenation catalytic performance of the modified silicon carbide-supported Pt-based catalysts prepared in Examples 9-26 above are shown in the following table:

[0112] Table 2. Catalytic performance of propane dehydrogenation in Examples 9-26

[0113] Example Carrier number Catalyst number Propane conversion rate (%) Propylene selectivity (%) 9 A1 B1 26.6 98.1 10 A2 B2 29.1 99.0 11 A3 B3 25.0 98.8 12 A4 B4 22.3 99.8 13 A5 B5 27.8 99.4 14 A6 B6 16.8 99.8 15 A7 B7 26.5 99.4 16 A8 B8 18.4 99.7 17 A2 B2 32.4 97.1 18 A2 B2 21.5 99.5 19 A2 B2 16.3 99.6 20 A2 B2 17.1 99.6 21 A2 B2 24.1 98.6 22 A2 B2 17.9 94.7 23 A2 B2 14.3 99.6 24 A2 B2 18.1 95.5 25 A2 B9 25.8 98.6 26 A2 B10 32.6 97.7

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

[0115] Comparative Examples 1-8 present the catalyst preparation and performance data of the corresponding catalysts in the propane dehydrogenation to propylene reaction. Comparative Example 1

[0116] (1) Take 318 mg of chloroplatinic acid in a small bottle, add 10 mL of deionized water and stir to dissolve, and prepare chloroplatinic acid solution.

[0117] (2) Take 250 μL of the chloroplatinic acid solution prepared in step (1) and impregnate it onto 1 g of raw untreated silicon carbide C1 support. After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is denoted as D1. The Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0118] (3) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst D1 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550 °C. Catalyst D1 exhibited the following catalytic performance: propane conversion of 8.6% and propylene selectivity of 99.4%.

[0119] Comparative Example 2

[0120] (1) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Comparative Example 1 and impregnate it onto 1 g of commercial silica C2 support. After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is denoted as D2, in which the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0121] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst D2 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550 °C. The catalytic performance of catalyst D2 was: propane conversion of 17.1% and propylene selectivity of 79.8%.

[0122] Comparative Example 3

[0123] (1) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Comparative Example 1 and impregnate it onto 1 g of commercial alumina C3 support. After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is denoted as D3, in which the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0124] (2) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst D3 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. The catalytic performance of catalyst D3 was as follows: propane conversion rate was 35.4%, propylene selectivity was 69.9%, and after 6 hours of reaction, the thermogravimetric analysis showed a carbon deposition of 4.4%.

[0125] Comparative Example 4

[0126] (1) 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and inert gas was introduced and purged for 30min; high-purity nitrogen was introduced, the temperature program was 10℃ / min, the treatment temperature was 1000℃, and the treatment time was 2h; after the treatment was completed, it was naturally cooled to room temperature, and the resulting carrier was recorded as C4.

[0127] (2) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Comparative Example 1 and impregnate it onto 1 g of the C4 support obtained in step (1). After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is denoted as D4, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0128] (3) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst D4 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550 °C. Catalyst D4 exhibited the following catalytic performance: propane conversion of 6.4% and propylene selectivity of 98.0%.

[0129] Comparative Example 5

[0130] (1) 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and inert gas was introduced and purged for 30min; high-purity hydrogen was introduced, the programmed heating rate was 10℃ / min, the treatment temperature was 1000℃, and the treatment time was 2h; after the treatment was completed, it was naturally cooled to room temperature, and the resulting carrier was recorded as C5.

[0131] (2) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Comparative Example 1 and impregnate it onto 1 g of the C5 support obtained in step (1). After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is denoted as D5, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0132] (3) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst D5 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. The catalytic performance of catalyst D5 was: propane conversion of 5.2% and propylene selectivity of 99.3%.

[0133] Comparative Example 6

[0134] (1) 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and inert gas was introduced and purged for 30min; high-purity oxygen was introduced, the temperature program was 10℃ / min, the treatment temperature was 1000℃, and the treatment time was 2h; after the treatment was completed, it was naturally cooled to room temperature, and the resulting carrier was recorded as C6.

[0135] (2) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Comparative Example 1 and impregnate it onto 1 g of the C6 support obtained in step (1). After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is denoted as D6, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0136] (3) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst D6 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹.-1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. The catalytic performance of catalyst D6 was: propane conversion of 3.9% and propylene selectivity of 98.6%.

[0137] Comparative Example 7

[0138] (1) 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and inert gas was introduced and purged for 30min; an oxygen-nitrogen mixture was introduced, with an oxygen partial pressure of 60kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 1000℃, and a treatment time of 2h; after treatment, the mixture was naturally cooled to room temperature, and the resulting carrier was denoted as C7.

[0139] (2) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Comparative Example 1 and impregnate it onto 1 g of the C5 support obtained in step (1). After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is denoted as D7, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0140] (3) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst D7 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1 The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. The catalytic performance of catalyst D7 was: propane conversion of 8.3% and propylene selectivity of 99.3%.

[0141] Comparative Example 8

[0142] (1) 1g of silicon carbide was loaded into a quartz tube, placed in a tube furnace, connected to a gas line, and inert gas was introduced and purged for 30min; an oxygen-nitrogen mixture was introduced, with an oxygen partial pressure of 20kPa, a programmed heating rate of 10℃ / min, a treatment temperature of 1200℃, and a treatment time of 2h; after treatment, the mixture was naturally cooled to room temperature, and the resulting carrier was denoted as C8.

[0143] (2) Take 250 μL of the chloroplatinic acid solution prepared in step (1) of Comparative Example 1 and impregnate it onto 1 g of the C8 support obtained in step (1). After drying at 50 °C, calcining at 500 °C for 4 h, and reducing at 550 °C for 2 h, a fresh catalyst is obtained. The obtained catalyst is denoted as D8, wherein the Pt loading is 0.3 wt.% based on the weight of silicon carbide.

[0144] (3) The reaction was carried out in a fixed-bed reactor. The reactant gas was introduced into the reactor carrying catalyst D8 at a reaction pressure of 0.1 MPa, a catalyst loading of 100 mg, and a propane weight hourly space velocity of 2.4 h⁻¹. -1The hydrogen partial pressure was 10 kPa, and the reaction temperature was 550℃. The catalytic performance of catalyst D8 was: propane conversion of 3.5% and propylene selectivity of 99.5%.

[0145] The statistical data of propane dehydrogenation catalytic performance of the Pt-based catalysts prepared in Comparative Examples 1-8 are shown in the table below:

[0146] Table 3. Catalytic performance of propane dehydrogenation in comparative examples 1-8

[0147] Comparative Example Carrier number Catalyst number Propane conversion rate (%) Propylene selectivity (%) 1 C1 D1 8.6 99.4 2 C2 D2 17.1 79.8 3 C3 D3 35.4 69.9 4 C4 D4 6.4 98.0 5 C5 D5 5.2 99.3 6 C6 D6 3.9 98.6 7 C7 D7 8.3 99.3 8 C8 D8 3.5 99.5

[0148] The results of the propane dehydrogenation catalytic performance of Comparative Example 1 showed that the propane conversion rate of catalyst D1 prepared using the original untreated silicon carbide support was only 8.6%. The results of the propane dehydrogenation catalytic performance of Examples 9-26 showed that the modified silicon carbide support prepared in this invention can significantly improve the catalytic activity of the catalyst, and the propane conversion rate is increased by 2-4 times.

[0149] The results of the propane dehydrogenation catalytic performance of Comparative Examples 2 and 3 showed that catalyst D2, prepared using a commercial silica support, had a propylene selectivity of 79.8%, while catalyst D3, prepared using a commercial alumina support, had a propylene selectivity of 69.9%. The results of the propane dehydrogenation catalytic performance of Examples 9-16 showed that the modified silicon carbide support prepared in this invention can significantly improve the target product selectivity of the catalyst, with propylene selectivity exceeding 98.0% under the same test conditions.

[0150] In Comparative Example 3, the catalyst prepared using a commercial alumina support showed a carbon deposition of 4.4% after the reaction. In Example 10, the modified silicon carbide support prepared according to this invention significantly improved the catalyst's resistance to carbon deposition; the carbon deposition of the B2 catalyst after the reaction was 2.0%. The carbon deposition test results are shown below. Figure 3 .

[0151] The results of propane dehydrogenation catalytic performance in Comparative Examples 4 and 5 show that high-temperature heat treatment cannot improve the catalytic performance of the catalyst when the silicon carbide support is in a pure inert or reducing atmosphere.

[0152] The results of propane dehydrogenation catalytic performance in Comparative Examples 6 and 7 show that when the oxygen partial pressure in the treatment atmosphere of the silicon carbide support is too high, the high-temperature heat treatment method cannot improve the catalytic performance of the catalyst.

[0153] The results of the propane dehydrogenation catalytic performance of Comparative Example 8 show that when the processing temperature of the silicon carbide support is too high, the high-temperature heat treatment method cannot improve the catalytic performance of the catalyst.

Claims

1. A method for preparing a catalyst using modified silicon carbide as a support, characterized in that, The catalyst supported on modified silicon carbide comprises a support and an active component, wherein the support is modified silicon carbide and the active component is the noble metal Pt; the loading of the active component is 0.1-1.0 wt.% based on the weight of the support. The preparation method of modified silicon carbide includes the following steps: (a) Place silicon carbide in a tube furnace, introduce inert gas, and purge the gas path; (b) Introduce a treatment gas, heat it according to a predetermined heating rate program until it reaches a predetermined treatment temperature, and maintain the temperature for a predetermined treatment time; the treatment gas is a mixture of nitrogen and oxygen, and the partial pressure of oxygen is 20 kPa; the treatment temperature is 600-1100 °C; the treatment time is 0.5-6 hours. (c) After the treatment is completed, the mixture is allowed to cool naturally to room temperature to obtain modified silicon carbide; The method for preparing the catalyst supported on modified silicon carbide includes the following steps: (1) Dissolve the platinum-containing compound in water or alcohol solvent to obtain a platinum precursor salt solution; (2) The platinum precursor salt solution obtained in step (1) is impregnated onto the modified silicon carbide support, dried, calcined and reduced to obtain a catalyst with modified silicon carbide as the support.

2. The preparation method according to claim 1, characterized in that, In step (a), the inert gas includes one or a mixture of two or more of nitrogen, argon, and helium.

3. The preparation method according to claim 1, characterized in that, In step (1), the platinum-containing compound includes one or more of platinum chloride, chloroplatinic acid, ammonium chloroplatinate, aminoplatinum nitrate, and ethylenediamine platinum chloride.

4. The preparation method according to claim 3, characterized in that, In step (2), the drying temperature is 30-100℃ and the drying time is 8-12 hours; the calcination temperature is 400-700℃ and the calcination time is 0.5-6 hours; the reduction time is 400-600℃ and the reduction time is 0.5-4 hours.

5. The application of a catalyst prepared by the method according to any one of claims 1 to 4, using modified silicon carbide as a support, in the propane dehydrogenation to propylene reaction.

6. The application according to claim 5, characterized in that, The reaction conditions are as follows: hydrogen partial pressure of the feed gas is 0-40 kPa, and volume hourly space velocity of the feed gas is 5000-50000 mL g. cat -1 h -1 The reaction temperature is 500-600 ℃; the mixed gas undergoes a catalytic reaction in the reactor under normal pressure.

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