A carbon dioxide removal and removal of propylene prior to depropanization prior to hydrogenation catalyst and a method for preparing the same

Abstract

The application provides a carbon di-pretreatment depropanization pre-hydrogenation catalyst and a preparation method thereof. The catalyst comprises a carrier and an active component, the carrier is a phosphorus-doped carbon material, the active component comprises a main active component and an auxiliary active component, the main active component comprises Pd, the auxiliary active component comprises Ag, and the main active component and the auxiliary active component are atomically dispersed on the carrier. The preparation method comprises the following steps: mixing a phosphorus-containing compound and a carbohydrate in water, carrying out a hydrothermal reaction, and then drying and calcining to obtain a phosphorus-doped carbon material carrier; loading the active component on the phosphorus-doped carbon material carrier to obtain a catalyst semi-product; and reducing the catalyst semi-product to obtain a reduced catalyst, which is the carbon di-pretreatment depropanization pre-hydrogenation catalyst. The carbon di-pretreatment depropanization pre-hydrogenation catalyst provided by the application has excellent hydrogenation activity, selectivity and anti-coking performance.

Description

Technical Field

[0001] This invention relates to a pre-propane dehydrogenation catalyst for C2 and its preparation method, belonging to the field of hydrogenation catalyst technology. Background Technology

[0002] Ethylene is hailed as the "leading force" in the petrochemical industry, and its production capacity is a standard for measuring the level of a country's chemical industry. Ethylene is mainly used to produce polyethylene plastic products (such as cling film, plastic bags, food bags, baby bottles, buckets, kettles, etc.).

[0003] Currently, the main process for ethylene production is pre-hydrogenation thermal cracking of petroleum fractions. The pre-hydrogenation process is further divided into two types: pre-ethane removal and pre-propane removal, developed by LINDE and S&W respectively. In the pre-ethane removal pre-hydrogenation process, the acetylene removal hydrogenation reactor is located before the demethanizer and after the deethaner, and there are no C3 components in the feed to the reactor. In the pre-propane removal pre-hydrogenation process, the acetylene removal hydrogenation reactor is located before the demethanizer and after the depropanerizer. Therefore, this process needs to remove most of the propyne and propadiene while removing acetylene, and this process has high requirements for catalyst selectivity.

[0004] The reactions involved in the pre-propane dehydrogenation process, specifically the alkyne removal hydrogenation reactor, include:

[0005] Main reaction: C2H2 + H2 → C2H4 + 174.3 kJ / mol (1)

[0006] CH3-C≡CH + H2→C3H6+ 165 kJ / mol (2)

[0007] H2C=C=CH2+H2→C3H6+ 173 kJ / mol (3)

[0008] Side reaction: C2H2 + 2H2 → C2H6 + 311.0 kJ / mol (4)

[0009] C2H4+ H2 → C2H6+136.7kJ / mol (5)

[0010] C3H6+ H2 → C3H8+136.7kJ / mol (6)

[0011] nC2H2→Oligomer (Green Oil) (7)

[0012] Of these reactions, reactions (1), (2), and (3) are the desired main reactions, which remove acetylene, propyne, and propadiene, and increase the production of ethylene and propylene. Reactions (4), (5), (6), and (7) are undesirable side reactions, which will result in the loss of ethylene and propylene. For side reaction (7), the acetylene polymerization reaction produces butadiene, which further undergoes oligomerization with acetylene to form green oil. Therefore, butadiene is an important intermediate in the formation of green oil. Green oil contains aliphatic dienes, alkenes, and C4-C20 unsaturated alkanes, with a boiling point range of 120-140℃. Green oil is divided into oligomers and repolymers. After depressurization during the reaction, the oligomers are analyzed as gases. They contain a large amount of C4 hydrocarbons and trace amounts of C6 hydrocarbons, approximately 200-450 ppm. Some of the repolymers adsorb onto the catalyst pores, causing the catalyst to coke and eventually deactivate. The other part condenses into fine droplets when the gas stream leaves the reactor and cools, leading to scaling in downstream equipment. Green oil is generally considered not only a poison for catalysts but also an uneconomical waste, and there are currently no reports on its development and application both domestically and internationally. Therefore, developing a catalyst with high anti-coking properties and high selectivity based on the pre-propane dehydrogenation process has extremely high industrial value.

[0013] The key to improving the separation process for acetylene removal via pre-propane dehydrogenation lies in enhancing the selectivity and activity of the selective hydrogenation catalyst and reducing its sensitivity to hydrogen and CO concentrations. Furthermore, improving the selectivity and activity of the pre-hydrogenation selective hydrogenation catalyst for acetylene removal hinges on improving the pore structure of the support. To address these issues, increasing the calcination temperature of the support typically yields a macroporous α-Al₂O₃ support; however, this method has limited effectiveness in reducing the surface sensitivity of the catalyst support.

[0014] CN101433845A discloses a selective hydrogenation catalyst for unsaturated hydrocarbons and its preparation method. This catalyst uses alumina as a support and palladium as the active component. Rare earth and alkaline earth metals and fluorine are added to improve the catalyst's resistance to impurities and coking. However, the catalyst selectivity is not ideal.

[0015] Existing technologies also attempt to improve catalyst performance by preparing composite supports. However, for C2 pre-hydrogenation catalysts, only CN1361231A has demonstrated this by preparing a composite support of alumina and titanium oxide, exhibiting a bimodal pore size distribution at 50 nm and 1000 nm. This support, when used to prepare hydrogenation catalysts, effectively improves the anti-coking performance of C2 pre-hydrogenation catalysts. However, the larger pore size at 1000 nm leads to excessively large pores in some catalysts, resulting in reduced catalyst activity. Other supports with bimodal pore size distributions used in C2 pre-hydrogenation catalysts suffer from defects such as specific surface area and pore size distribution that are not suitable for the catalyst requirements, resulting in low dispersion of the active component Pd or high surface acidity.

[0016] CN101433842B discloses a hydrogenation catalyst with Pd and Ag bimetallic components as active components. The catalyst support has two pore structures: micropores with a most probable radius of 2–50 nm and macropores with a most probable radius of 100–500 nm. The support has low surface acidity, which can effectively reduce side reactions in acetylene hydrogenation and extend the catalyst's service life. CN108147938B discloses a method for the selective hydrogenation of acetylene to ethylene. This method uses PdxMy as a precursor and silica as a support, which is calcined at high temperature to obtain a PdxM / SiO2 catalyst, where M is one of Ag, Au, Cu, Ni, or Pd. CN101862653B discloses an acetylene selective hydrogenation catalyst and its preparation method. The catalyst uses Pd as the main metal component and adds Bi, Sb, Pb and other metals as promoters. In the prepared catalyst, Pd exists in the elemental form after ionization radiation treatment. Compared with Pd catalysts prepared by conventional methods, this catalyst has higher activity and selectivity. Summary of the Invention

[0017] To address the aforementioned technical problems, the present invention aims to provide a pre-propane dehydrogenation catalyst for C2 and its preparation method. The pre-propane dehydrogenation catalyst provided by the present invention exhibits excellent hydrogenation activity, selectivity, and anti-coking properties.

[0018] To achieve the above objectives, the first aspect of the present invention provides a pre-propane dehydrogenation catalyst for C2, the catalyst comprising a support and an active component, the support being a phosphorus-doped carbon material, the active component comprising a main active component and a co-active component, the main active component comprising Pd, the co-active component comprising Ag, the main active component and the co-active component being atomically dispersed on the support.

[0019] According to a specific embodiment of the present invention, preferably, based on 100% of the total mass of the catalyst, the content of the main active component is 0.02-0.30%, the content of the co-active component is 0.04-1.00%, and the balance is the support. More preferably, based on 100% of the total mass of the catalyst, the content of the main active component is 0.02-0.18%, the content of the co-active component is 0.05-0.40%, and the balance is the support.

[0020] According to a specific embodiment of the present invention, preferably, the catalyst comprises a support and an active component, wherein the support is a phosphorus-doped carbon material, and the active component comprises Pd and Ag, wherein Pd and Ag are atomically dispersed on the support, and based on 100% of the total mass of the catalyst, the Pd content is 0.02-0.30%, the Ag content is 0.04-1.00%, and the balance is the support; more preferably, based on 100% of the total mass of the catalyst, the Pd content is 0.02-0.18%, the Ag content is 0.05-0.40%, and the balance is the support.

[0021] In the catalyst described above, preferably, the support has a porous structure with a high specific surface area, and the main active component and the co-active component are atomically dispersed on the surface and within the pores of the support. The specific surface area can be tested using methods conventional in the art, such as GB / T-5816.

[0022] According to a specific embodiment of the present invention, preferably, the pre-propane dehydrogenation catalyst of C2 is prepared by the following steps:

[0023] (1) A phosphorus-containing compound and a carbohydrate are mixed in water, then subjected to a hydrothermal reaction, and then dried and calcined to obtain a phosphorus-doped carbon material carrier.

[0024] (2) The active component is loaded onto the phosphorus-doped carbon material support to obtain a catalyst semi-finished product;

[0025] (3) The catalyst semi-finished product is reduced to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst.

[0026] In the catalyst preparation steps described above, preferably, in step (1), the phosphorus-containing compound includes phosphoric acid and / or phytic acid, etc.

[0027] In the catalyst preparation steps described above, preferably, in step (1), the carbohydrates include glucose and / or sucrose, etc.

[0028] In the catalyst preparation steps described above, preferably, in step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.0001 to 1000, more preferably 0.001 to 10, and even more preferably 0.02 to 0.4.

[0029] In the catalyst preparation step (1) above, the concentrations of the phosphorus-containing compound and the carbohydrate in water can be conventionally adjusted by those skilled in the art, as long as they can be fully dissolved and mixed in water and the reaction can proceed smoothly.

[0030] In the catalyst preparation steps described above, preferably, in step (1), the mixing of the phosphorus-containing compound and the carbohydrate in water is carried out under stirring conditions, and the stirring time is 30 to 120 min.

[0031] In the catalyst preparation steps described above, preferably, in step (1), the hydrothermal reaction is carried out at a temperature of 160–300°C for 4–12 hours. More specifically, the hydrothermal reaction is conducted in a hydrothermal reactor placed in an oven, and the process does not require stirring.

[0032] In the catalyst preparation steps described above, preferably, in step (1), the drying temperature is 120-160°C and the time is 4-12 hours.

[0033] In the catalyst preparation steps described above, preferably, step (1) further includes: ball milling to refine the powder, wherein the ball milling is performed after the drying and before the calcination, and the ball milling time is 3 to 10 minutes.

[0034] In the catalyst preparation steps described above, preferably, in step (1), the calcination is carried out under an inert atmosphere, and the calcination temperature is 600-1000℃ for 1-5 hours.

[0035] In the catalyst preparation steps described above, preferably, step (2) specifically includes:

[0036] (2)-a1 The phosphorus-doped carbon material support is added to the precursor aqueous solution of the main active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the support loaded with the main active component.

[0037] (2)-a2 The support for the main active component is added to the precursor aqueous solution of the auxiliary active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the catalyst semi-finished product.

[0038] Alternatively, step (2) may specifically include:

[0039] (2)-b1 The phosphorus-doped carbon material support is added to the precursor aqueous solution of the active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the support loaded with the active component.

[0040] (2)-b2 The carrier loaded with the auxiliary active component is added to the precursor aqueous solution of the main active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the catalyst semi-finished product.

[0041] In the catalyst preparation step (2) above, the main active component can be loaded onto the support first, and then the auxiliary active component can be loaded; or the auxiliary active component can be loaded onto the support first, and then the main active component can be loaded.

[0042] In the catalyst preparation steps described above, preferably, in step (2), the precursor of the main active component includes a palladium salt compound, specifically including one or a combination of palladium chloride, palladium nitrate, and palladium sulfate.

[0043] In the catalyst preparation steps described above, preferably, in step (2), the precursor of the co-active component includes a silver salt compound, specifically including one or a combination of silver nitrate, silver fluoride, silver chlorate, and silver perchlorate.

[0044] In the catalyst preparation steps described above, preferably, in step (2), the concentration of the main active component in the precursor aqueous solution of the main active component is 0.1 to 5 mg Pd / mL Pd precursor aqueous solution.

[0045] In the catalyst preparation steps described above, preferably, in step (2), the concentration of the co-active component in the precursor aqueous solution of the co-active component is 0.1 to 10 mg Ag / mL Ag precursor aqueous solution.

[0046] In the catalyst preparation step (2) above, the amount of support added to the aqueous solution of the active component precursor can be conventionally adjusted by those skilled in the art, as long as it can be fully mixed and the content of the active component in the prepared catalyst meets the requirements of the present invention.

[0047] In the catalyst preparation steps described above, preferably, in step (2), the irradiation time under an ultraviolet xenon lamp is 0.5 to 5.0 h.

[0048] In the above catalyst preparation steps, preferably, in step (2), the freeze-drying time is 2 to 7 hours and the vacuum degree of the freeze-drying is 15 to 20 Pa.

[0049] In the catalyst preparation steps described above, preferably, in step (2), the calcination is carried out under an inert atmosphere, and the calcination temperature is 300-500°C and the time is 0.5-5h.

[0050] In the above catalyst preparation steps, preferably, in step (3), the catalyst semi-finished product is reduced using a mixture of H2 and He gas with a volume percentage of 10-100% H2 or pure hydrogen gas, at a reduction temperature of 50-300°C, a reduction pressure of 0.1-2.0 MPa, and a reduction time of 0.5-10 h. More preferably, the reduction temperature is 100-200°C, the reduction pressure is 0.5-1.0 MPa, and the reduction time is 2-6 h.

[0051] A second aspect of the present invention provides a method for preparing the above-mentioned pre-propane dehydrogenation catalyst of C2, comprising the following steps:

[0052] (1) A phosphorus-containing compound and a carbohydrate are mixed in water, then subjected to a hydrothermal reaction, and then dried and calcined to obtain a phosphorus-doped carbon material carrier.

[0053] (2) The active component is loaded onto the phosphorus-doped carbon material support to obtain a catalyst semi-finished product;

[0054] (3) The catalyst semi-finished product is reduced to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst.

[0055] In the above preparation method, preferably, in step (1), the phosphorus-containing compound includes phosphoric acid and / or phytic acid, etc.

[0056] In the above preparation method, preferably, in step (1), the carbohydrate includes glucose and / or sucrose, etc.

[0057] In the above preparation method, preferably, in step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.0001 to 1000, more preferably 0.001 to 10, and even more preferably 0.02 to 0.4.

[0058] In step (1) of the preparation method described above, the concentrations of the phosphorus-containing compound and the carbohydrate in water can be conventionally adjusted by those skilled in the art, as long as they can be fully dissolved and mixed in water and the reaction can proceed smoothly.

[0059] In the above preparation method, preferably, in step (1), the mixing of phosphorus-containing compound and carbohydrate in water is carried out under stirring conditions, and the stirring time is 30 to 120 min.

[0060] In the above preparation method, preferably, in step (1), the hydrothermal reaction temperature is 160–300°C and the time is 4–12 h. More specifically, the hydrothermal reaction is carried out in a hydrothermal reactor placed in an oven, and the process does not require stirring.

[0061] In the above preparation method, preferably, in step (1), the drying temperature is 120-160°C and the time is 4-12 hours.

[0062] In the above preparation method, preferably, step (1) further includes: ball milling to refine into powder, wherein the ball milling is performed after the drying and before the calcination, and the ball milling time is 3 to 10 minutes.

[0063] In the above preparation method, preferably, in step (1), the calcination is carried out under an inert atmosphere, the calcination temperature is 600-1000℃, and the time is 1-5h.

[0064] In the above preparation method, preferably, step (2) specifically includes:

[0065] (2)-a1 The phosphorus-doped carbon material support is added to the precursor aqueous solution of the main active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the support loaded with the main active component.

[0066] (2)-a2 The support for the main active component is added to the precursor aqueous solution of the auxiliary active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the catalyst semi-finished product.

[0067] Alternatively, step (2) may specifically include:

[0068] (2)-b1 The phosphorus-doped carbon material support is added to the precursor aqueous solution of the active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the support loaded with the active component.

[0069] (2)-b2 The carrier loaded with the auxiliary active component is added to the precursor aqueous solution of the main active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the catalyst semi-finished product.

[0070] In step (2) of the preparation method described above, the main active component can be loaded onto the support first, and then the auxiliary active component can be loaded; or the auxiliary active component can be loaded onto the support first, and then the main active component can be loaded.

[0071] In the above preparation method, preferably, in step (2), the precursor of the main active component includes a palladium salt compound, specifically including one or a combination of palladium chloride, palladium nitrate and palladium sulfate.

[0072] In the above preparation method, preferably, in step (2), the precursor of the auxiliary active component includes a silver salt compound, specifically including one or a combination of silver nitrate, silver fluoride, silver chlorate and silver perchlorate.

[0073] In the above preparation method, preferably, in step (2), the concentration of the main active component in the precursor aqueous solution of the main active component is 0.1 to 5 mg Pd / mL Pd precursor aqueous solution.

[0074] In the above preparation method, preferably, in step (2), the concentration of the co-active component in the precursor aqueous solution of the co-active component is 0.1 to 10 mg Ag / mL Ag precursor aqueous solution.

[0075] In step (2) of the above preparation method, the amount of support added to the aqueous solution of the active component precursor can be conventionally adjusted by those skilled in the art, as long as it can be fully mixed and the content of the active component in the prepared catalyst meets the requirements of the present invention.

[0076] In the above preparation method, preferably, in step (2), the irradiation time under ultraviolet xenon lamp is 0.5 to 5.0 h.

[0077] In the above preparation method, preferably, in step (2), the freeze-drying time is 2 to 7 hours and the vacuum degree of the freeze-drying is 15 to 20 Pa.

[0078] In the above preparation method, preferably, in step (2), the calcination is carried out under an inert atmosphere, the calcination temperature is 300-500℃, and the time is 0.5-5h.

[0079] In the above preparation method, preferably, in step (3), the catalyst semi-finished product is reduced using a mixture of H2 and He gas with a volume percentage of 10-100% H2 or pure hydrogen gas, at a reduction temperature of 50-300°C, a reduction pressure of 0.1-2.0 MPa, and a reduction time of 0.5-10 h. More preferably, the reduction temperature is 100-200°C, the reduction pressure is 0.5-1.0 MPa, and the reduction time is 2-6 h.

[0080] This invention provides a high-resistance anti-coking alkyne selective hydrogenation catalyst, specifically an anti-coking C2 pre-propane dehydrogenation catalyst and its preparation method. Although Pd-based catalysts are considered the mainstream in current research on acetylene selective hydrogenation catalysts, the process still has many problems: (1) the use of large amounts of promoters makes it difficult to recover and reuse the catalyst; (2) catalyst coking leads to deactivation of Pd-based catalysts. Therefore, developing a novel palladium-based catalyst that is resistant to coking and requires less promoters for the selective hydrogenation of acetylene under conditions of large amounts of ethylene and hydrogen is of great significance.

[0081] Traditional hydrogenation catalysts often contain active components in the form of nanoparticles or sub-nano clusters, which negatively impacts catalyst performance. However, the C2 pre-propane dehydrogenation catalyst provided in this invention uses phosphorus-doped carbon material as a support. This support has a porous structure and a high specific surface area. The active components, palladium and silver, are dispersed in a single-atom state on the support (both on the surface and within the pores) using a photoreduction method, rather than forming nanoparticles or sub-nano clusters. The atomically dispersed Pd and Ag exhibit the following characteristics in the selective hydrogenation of alkynes: increased metal atom utilization due to the atomic dispersion of the active components enhances the catalyst's hydrogenation activity; reduced olefin adsorption capacity improves hydrogenation selectivity; and a decreased probability of simultaneous adsorption of alkynes / dienes at adjacent active sites significantly reduces the likelihood of polymerization and coking, thus improving the catalyst's anti-coking performance. Therefore, the C2 pre-propane dehydrogenation catalyst of this invention exhibits excellent hydrogenation activity, selectivity, and anti-coking properties. Even when the hydrogenation feedstock contains a large amount of heavy fractions and the amount of green oil generated by the catalyst increases significantly, the catalyst activity and selectivity do not show a downward trend when using the catalyst of the present invention. Attached Figure Description

[0082] Figure 1 This is an aberration-corrected transmission electron microscope image of the hydrogenation catalyst provided in Example 2.

[0083] Figure 2 Transmission electron microscopy (TEM) image of the hydrogenation catalyst provided in Comparative Example 5.

[0084] Figure 3 The process flow diagram for pre-propane removal and pre-hydrogenation of alkyne in C2 is provided for a specific embodiment of the present invention.

[0085] Explanation of symbols for main components: 1. Cracking furnace, 2. Quenching system, 3. Oil washing tower, 4. Water washing tower, 5. First heat exchanger, 6. Alkali washing tower, 7. Dryer, 8. Pre-propane removal tower, 9. Second heat exchanger, 10. C2 hydrogenation reactor, 11. Demethanizer. Detailed Implementation

[0086] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0087] According to a specific embodiment of the present invention, preferably, the pre-propane dehydrogenation catalyst of the present invention is prepared by the following steps:

[0088] (1) A phosphorus-containing compound and a carbohydrate are thoroughly mixed in water for 30-120 min to obtain a mixed solution; the mixed solution is hydrothermally heated in a hydrothermal reactor in an oven at 160-300℃ for 4-12 h, then dried at 120-160℃ for 4-12 h, and then ball-milled for 3-10 min to obtain a powder; the powder is calcined at 600-1000℃ for 1-5 h under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0089] Wherein, the phosphorus-containing compound includes phosphoric acid and / or phytic acid, etc.; the carbohydrate includes glucose and / or sucrose, etc.; the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.0001 to 1000, preferably 0.001 to 10, and more preferably 0.02 to 0.4;

[0090] (2) a1 The phosphorus-doped carbon material support is added to the palladium precursor aqueous solution, stirred evenly, and then placed in liquid nitrogen for rapid freezing. Then it is irradiated under ultraviolet xenon lamp for 0.5 to 5.0 h; then it is freeze-dried under vacuum of 15 to 20 Pa for 2 to 7 h, and then calcined at 300 to 500 °C for 0.5 to 5 h under an inert atmosphere to obtain the palladium-loaded support.

[0091] (2) a2 The palladium-supported support is added to the silver precursor aqueous solution, stirred evenly, and then placed in liquid nitrogen for rapid freezing. Then it is irradiated under ultraviolet xenon lamp for 0.5 to 5.0 h; then it is freeze-dried under vacuum of 15 to 20 Pa for 2 to 7 h, and then calcined at 300 to 500 °C for 0.5 to 5 h under inert atmosphere to obtain catalyst semi-finished product;

[0092] or,

[0093] (2)-b1 The phosphorus-doped carbon material support is added to the silver precursor aqueous solution, stirred evenly, and then placed in liquid nitrogen for rapid freezing. Then it is irradiated under ultraviolet xenon lamp for 0.5-5.0h; then it is freeze-dried under vacuum of 15-20Pa for 2-7h, and then calcined at 300-500℃ for 0.5-5h under inert atmosphere to obtain the silver-loaded support.

[0094] (2)-b2 The silver-supported carrier is added to the palladium precursor aqueous solution, stirred evenly, and then placed in liquid nitrogen for rapid freezing. Then it is irradiated under ultraviolet xenon lamp for 0.5-5.0h; then it is freeze-dried under vacuum of 15-20Pa for 2-7h, and then calcined at 300-500℃ for 0.5-5h under inert atmosphere to obtain catalyst semi-finished product;

[0095] The palladium precursor includes palladium salt compounds, specifically including one or a combination of palladium chloride, palladium nitrate, and palladium sulfate; the concentration of palladium in the aqueous solution of the palladium precursor is 0.1–5 mg Pd / mL Pd precursor aqueous solution;

[0096] The silver precursor includes silver salt compounds, specifically including one or a combination of silver nitrate, silver fluoride, silver chlorate, and silver perchlorate; the concentration of silver in the aqueous solution of the silver precursor is 0.1–10 mg Ag / mL Ag precursor aqueous solution;

[0097] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He or pure hydrogen with a volume percentage of H2 of 10-100%, at a reduction temperature of 50-300℃ (preferably 100-200℃), a reduction pressure of 0.1-2.0MPa (preferably 0.5-1.0MPa), and a reduction time of 0.5-10h (preferably 2-6h) to obtain the reduced catalyst, which is the pre-propane dehydrogenation catalyst of C2.

[0098] The technical solution of the present invention will be further described below through specific embodiments.

[0099] In the following specific embodiments and comparative examples, the analytical testing methods used include:

[0100] Content of active component in catalyst: atomic absorption spectrometry;

[0101] Single-atom morphology characterization: aberration-corrected transmission electron microscopy;

[0102] Conversion rate and selectivity are calculated using the following formula:

[0103] Acetylene conversion rate (%) = 100 × (inlet acetylene content - outlet acetylene content) / inlet acetylene content,

[0104] Ethylene selectivity (%) = 100 × (exit ethylene content - inlet ethylene content) / (inlet acetylene content - outlet acetylene content).

[0105] Example 1

[0106] This embodiment provides a pre-propane dehydrogenation catalyst for C2, which is prepared through the following steps:

[0107] (1) 10g of phosphoric acid and 120g of glucose were thoroughly mixed in water for 30 minutes to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 160℃ for 4 hours, then dried at 120℃ for 4 hours, and then ball-milled for 3 minutes to obtain powder; the powder was calcined at 600℃ for 1 hour under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0108] (2) Take 10 mL of 0.2 mg Pd / mL Pd(NO3)2 aqueous solution, add 10 g of the phosphorus-doped carbon material support, stir evenly at room temperature, place in liquid nitrogen for rapid freezing, and then irradiate under ultraviolet xenon lamp for 0.5 h; then freeze dry under 15 Pa vacuum for 2 h, and then calcine at 300 °C for 0.5 h under inert atmosphere to obtain palladium-loaded support;

[0109] The palladium-supported support was added to an aqueous solution of silver nitrate containing 6.3 mg of silver nitrate. After stirring evenly at room temperature, the solution was rapidly frozen in liquid nitrogen and then irradiated under a xenon lamp for 0.5 h. After that, it was freeze-dried under a vacuum of 15 Pa for 2 h and then calcined at 300 °C for 0.5 h under an inert atmosphere to obtain a catalyst semi-finished product.

[0110] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 10% H2, at a reduction temperature of 60°C, a reduction pressure of 0.5 MPa, and a reduction time of 1 h to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst.

[0111] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.02%, the Ag content is 0.04%, and the balance is a phosphorus-doped carbon material support.

[0112] Example 2

[0113] This embodiment provides a pre-propane dehydrogenation catalyst for C2, which is prepared through the following steps:

[0114] (1) 10g of phytic acid and 120g of sucrose were thoroughly mixed in water for 100min to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 200℃ for 6h, then dried at 130℃ for 6h, and then ball-milled for 5min to obtain powder; the powder was calcined at 800℃ for 2h under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0115] (2) Measure 10 mL of 1 mg Pd / mL PdCl2 aqueous solution, add 10 g of the phosphorus-doped carbon material support, stir evenly at room temperature, place in liquid nitrogen for rapid freezing, and then irradiate under ultraviolet xenon lamp for 1 h; then freeze dry under 16 Pa vacuum for 2 h, and then calcine at 300 °C for 2 h under inert atmosphere to obtain palladium-loaded support.

[0116] The palladium-supported support was added to an aqueous solution of silver nitrate containing 31.5 mg of silver nitrate. After stirring at room temperature, the solution was rapidly frozen in liquid nitrogen and then irradiated under a xenon lamp for 1 hour. After that, it was freeze-dried under a vacuum of 16 Pa for 2 hours and then calcined at 300 °C for 2 hours under an inert atmosphere to obtain a catalyst semi-finished product.

[0117] (3) The catalyst semi-finished product is reduced by a mixture of H2 and He with a volume percentage of 15% H2, at a reduction temperature of 80°C, a reduction pressure of 1 MPa, and a reduction time of 2 h to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst.

[0118] According to atomic absorption spectrometry, the catalyst contains 0.1% Pd and 0.2% Ag by mass, with the remainder being a phosphorus-doped carbon material support.

[0119] The aberration-corrected transmission electron microscope image of the catalyst is shown below. Figure 1 As shown, by Figure 1 It can be seen that Pd and Ag are atomically dispersed on the support.

[0120] Example 3

[0121] This embodiment provides a pre-propane dehydrogenation catalyst for C2, which is prepared through the following steps:

[0122] (1) 10g of phytic acid and 120g of sucrose were thoroughly mixed in water for 120min to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 200℃ for 8h, then dried at 140℃ for 8h, and then ball-milled for 7min to obtain powder; the powder was calcined at 900℃ for 3h under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0123] (2) 10g of the phosphorus-doped carbon material carrier was added to a silver nitrate aqueous solution containing 63mg of silver nitrate. After stirring evenly at room temperature, the carrier was placed in liquid nitrogen for rapid freezing and then irradiated under a xenon lamp for 1h. After that, it was freeze-dried under a vacuum of 17Pa for 3h and then calcined at 300℃ for 3h under an inert atmosphere to obtain a silver-loaded carrier.

[0124] Measure 18 mL of 1 mg Pd / mL palladium sulfate aqueous solution, add it to the silver-supported carrier, stir evenly at room temperature, place it in liquid nitrogen for rapid freezing, and then irradiate it under ultraviolet xenon lamp for 1 h; then freeze-dry it under vacuum of 17 Pa for 3 h, and then calcine it at 300 °C for 3 h under an inert atmosphere to obtain the catalyst semi-finished product.

[0125] (3) The catalyst semi-finished product is reduced by a mixture of H2 and He with a volume percentage of 20% H2, at a reduction temperature of 150°C, a reduction pressure of 1 MPa, and a reduction time of 2 h to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst.

[0126] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.18%, the Ag content is 0.4%, and the balance is a phosphorus-doped carbon material support.

[0127] Example 4

[0128] This embodiment provides a pre-propane dehydrogenation catalyst for C2, which is prepared through the following steps:

[0129] (1) 10g of phytic acid and 120g of glucose were thoroughly mixed in water for 60 minutes to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 250°C for 10 hours, then dried at 150°C for 10 hours, and then ball-milled for 8 minutes to obtain powder; the powder was calcined at 700°C for 4 hours under an inert atmosphere to obtain a phosphorus-doped carbon material carrier.

[0130] (2) 10g of the phosphorus-doped carbon material carrier was added to a silver nitrate aqueous solution containing 110mg of silver nitrate. After stirring evenly at room temperature, the carrier was placed in liquid nitrogen for rapid freezing and then irradiated under a xenon lamp for 3h. After that, it was freeze-dried under a vacuum of 18Pa for 5h and then calcined at 400℃ for 4h under an inert atmosphere to obtain a silver-loaded carrier.

[0131] Measure 20 mL of 1 mg Pd / mL Pd(NO3)2 aqueous solution, add the silver-supported carrier, stir evenly at room temperature, place in liquid nitrogen for rapid freezing, then irradiate under ultraviolet xenon lamp for 3 h; then freeze-dry under 18 Pa vacuum for 5 h, and then calcine at 400 °C for 4 h under inert atmosphere to obtain catalyst semi-finished product.

[0132] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 50% H2, at a reduction temperature of 200℃, a reduction pressure of 1.5MPa, and a reduction time of 4h to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst.

[0133] According to atomic absorption spectrometry, the catalyst contains 0.2% Pd and 0.7% Ag by mass, with the remainder being a phosphorus-doped carbon material support.

[0134] Example 5

[0135] This embodiment provides a pre-propane dehydrogenation catalyst for C2, which is prepared through the following steps:

[0136] (1) 10g of phosphoric acid and 120g of sucrose were thoroughly mixed in water for 90 minutes to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 300℃ for 12 hours, then dried at 160℃ for 12 hours, and then ball-milled for 10 minutes to obtain powder; the powder was calcined at 1000℃ for 5 hours under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0137] (2) Take 30 mL of 1 mg Pd / mL PdCl2 aqueous solution, add 10 g of the phosphorus-doped carbon material support, stir evenly at room temperature, place in liquid nitrogen for rapid freezing, and then irradiate under ultraviolet xenon lamp for 5 h; then freeze dry under 20 Pa vacuum for 7 h, and then calcine at 500 °C for 5 h under inert atmosphere to obtain palladium-loaded support.

[0138] The palladium-supported support was added to an aqueous solution of silver nitrate containing 158 mg of silver nitrate. After stirring at room temperature, the solution was rapidly frozen in liquid nitrogen and then irradiated under a xenon lamp for 5 hours. After that, it was freeze-dried under a vacuum of 20 Pa for 7 hours and then calcined at 500 °C for 5 hours under an inert atmosphere to obtain a catalyst semi-finished product.

[0139] (3) The catalyst semi-finished product is reduced with pure hydrogen at a reduction temperature of 250°C, a reduction pressure of 2MPa, and a reduction time of 6h to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst.

[0140] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.3%, the Ag content is 1%, and the balance is a phosphorus-doped carbon material support.

[0141] Comparative Example 1

[0142] This comparative example provides a hydrogenation catalyst, which is prepared by the following steps:

[0143] (1) 120g of glucose was thoroughly stirred in water for 30 minutes to obtain a glucose aqueous solution; the glucose aqueous solution was reacted in a hydrothermal reactor in an oven at 160℃ for 4 hours, then dried at 120℃ for 4 hours, and then ball-milled for 3 minutes to obtain powder; the powder was calcined at 600℃ for 1 hour under an inert atmosphere to obtain a carbon material carrier.

[0144] (2) Take 10 mL of 0.2 mg Pd / mL Pd(NO3)2 aqueous solution, add 10 g of the carbon material support, stir evenly at room temperature, place in liquid nitrogen for rapid freezing, and then irradiate under ultraviolet xenon lamp for 0.5 h; then freeze dry under 15 Pa vacuum for 2 h, and then calcine at 300 °C for 0.5 h under inert atmosphere to obtain palladium-loaded support;

[0145] The palladium-supported support was added to an aqueous solution of silver nitrate containing 6.3 mg of silver nitrate. After stirring evenly at room temperature, the solution was rapidly frozen in liquid nitrogen and then irradiated under a xenon lamp for 0.5 h. After that, it was freeze-dried under a vacuum of 15 Pa for 2 h and then calcined at 300 °C for 0.5 h under an inert atmosphere to obtain a catalyst semi-finished product.

[0146] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 10% H2, at a reduction temperature of 60°C, a reduction pressure of 0.5 MPa, and a reduction time of 1 h to obtain the reduced catalyst, which is the hydrogenation catalyst.

[0147] Atomic absorption spectrometry analysis revealed that, based on the total mass of the catalyst (100%), the Pd content was 0.02%, the Ag content was 0.04%, and the remainder was a carbon material support. The active components in the catalyst provided in this comparative example are not entirely dispersed as single atoms; nanoparticles are present.

[0148] Comparative Example 2

[0149] This comparative example provides a hydrogenation catalyst, which is prepared by the following steps:

[0150] (1) The carrier is a commercially available bimodal spherical alumina carrier with a diameter of 4 mm; the bimodal spherical alumina carrier is calcined at 1250℃ for 4 h to obtain the catalyst carrier.

[0151] (2) Measure 10 mL of 1 mg Pd / mL PdCl2 aqueous solution, add 10 g of the catalyst support, stir evenly at room temperature, place in liquid nitrogen for rapid freezing, and then irradiate under ultraviolet xenon lamp for 1 h; then freeze dry under 16 Pa vacuum for 2 h, and then calcine at 300 °C for 2 h under inert atmosphere to obtain palladium-loaded support.

[0152] The palladium-supported support was added to an aqueous solution of silver nitrate containing 31.5 mg of silver nitrate. After stirring at room temperature, the solution was rapidly frozen in liquid nitrogen and then irradiated under a xenon lamp for 1 hour. After that, it was freeze-dried under a vacuum of 16 Pa for 2 hours and then calcined at 300 °C for 2 hours under an inert atmosphere to obtain a catalyst semi-finished product.

[0153] (3) The catalyst semi-finished product is reduced by a mixture of H2 and He with a volume percentage of 15% H2, at a reduction temperature of 80°C, a reduction pressure of 1 MPa, and a reduction time of 2 h to obtain the reduced catalyst, which is the hydrogenation catalyst.

[0154] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.1%, the Ag content is 0.2%, and the balance is the catalyst support.

[0155] Comparative Example 3

[0156] This comparative example provides a hydrogenation catalyst, which is prepared by the following steps:

[0157] (1) 10g of phytic acid and 120g of sucrose were thoroughly mixed in water for 120min to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 200℃ for 8h, then dried at 140℃ for 8h, and then ball-milled for 7min to obtain powder; the powder was calcined at 900℃ for 3h under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0158] (2) 10g of the phosphorus-doped carbon material carrier was added to a silver nitrate aqueous solution containing 63mg of silver nitrate. After stirring evenly at room temperature, the carrier was placed in liquid nitrogen for rapid freezing and then irradiated under a xenon lamp for 1h. After that, it was freeze-dried under a vacuum of 17Pa for 3h and then calcined at 300℃ for 3h under an inert atmosphere to obtain a silver-loaded carrier.

[0159] 50 mL of 1 mg Pd / mL palladium sulfate aqueous solution was taken and added to the silver-supported carrier. After stirring evenly at room temperature, the mixture was rapidly frozen in liquid nitrogen and then irradiated under a xenon lamp for 1 h. After that, it was freeze-dried under a vacuum of 17 Pa for 3 h and then calcined at 300 °C for 3 h under an inert atmosphere to obtain a catalyst semi-finished product.

[0160] (3) The catalyst semi-finished product is reduced by a mixture of H2 and He with a volume percentage of 20% H2, at a reduction temperature of 150°C, a reduction pressure of 1 MPa, and a reduction time of 2 h to obtain the reduced catalyst, which is the hydrogenation catalyst.

[0161] According to atomic absorption spectrometry, the catalyst contains 0.5% Pd and 0.4% Ag, with the remainder being a phosphorus-doped carbon material carrier, based on a total mass of 100%.

[0162] Comparative Example 4

[0163] This comparative example provides a hydrogenation catalyst, which is prepared by the following steps:

[0164] (1) 10g of phytic acid and 120g of glucose were thoroughly mixed in water for 60 minutes to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 250°C for 10 hours, then dried at 150°C for 10 hours, and then ball-milled for 8 minutes to obtain powder; the powder was calcined at 700°C for 4 hours under an inert atmosphere to obtain a phosphorus-doped carbon material carrier.

[0165] (2) 10g of the phosphorus-doped carbon material carrier was added to a silver nitrate aqueous solution containing 787mg of silver nitrate. After stirring evenly at room temperature, the carrier was placed in liquid nitrogen for rapid freezing and then irradiated under a xenon lamp for 3h. After that, it was freeze-dried under a vacuum of 18Pa for 5h and then calcined at 400℃ for 4h under an inert atmosphere to obtain a silver-loaded carrier.

[0166] Measure 20 mL of 1 mg Pd / mL Pd(NO3)2 aqueous solution, add the silver-supported carrier, stir evenly at room temperature, place in liquid nitrogen for rapid freezing, then irradiate under ultraviolet xenon lamp for 3 h; then freeze-dry under 18 Pa vacuum for 5 h, and then calcine at 400 °C for 4 h under inert atmosphere to obtain catalyst semi-finished product.

[0167] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 50% H2, at a reduction temperature of 200°C, a reduction pressure of 1.5 MPa, and a reduction time of 4 h to obtain the reduced catalyst, which is the hydrogenation catalyst.

[0168] According to atomic absorption spectrometry, the catalyst contains 0.2% Pd and 5.0% Ag, with the remainder being a phosphorus-doped carbon material carrier, based on a total mass of 100%.

[0169] Comparative Example 5

[0170] This comparative example provides a hydrogenation catalyst, which is prepared by the following steps:

[0171] (1) 10g of phosphoric acid and 120g of sucrose were thoroughly mixed in water for 90 minutes to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 300℃ for 12 hours, then dried at 160℃ for 12 hours, and then ball-milled for 10 minutes to obtain powder; the powder was calcined at 1000℃ for 5 hours under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0172] (2) Take 30 mL of 1 mg Pd / mL PdCl2 aqueous solution, adjust the pH of the PdCl2 aqueous solution to 2 with hydrochloric acid, add 10 g of the phosphorus-doped carbon material support, impregnate and adsorb at room temperature for 1 h, dry at 110 °C for 2 h, and then calcine at 480 °C for 6 h to obtain the palladium-loaded support.

[0173] The palladium-supported support was added to an aqueous solution of silver nitrate containing 158 mg of silver nitrate. After stirring evenly at room temperature, it was impregnated and adsorbed at room temperature for 1 hour, then dried at 100°C for 3 hours, and then calcined at 500°C for 4 hours to obtain a catalyst semi-finished product.

[0174] (3) The catalyst semi-finished product is reduced with pure hydrogen at a reduction temperature of 250°C, a reduction pressure of 2MPa, and a reduction time of 6h to obtain the reduced catalyst, which is the hydrogenation catalyst.

[0175] Atomic absorption spectrometry analysis revealed that, based on the total mass of the catalyst (100%), the Pd content was 0.3%, the Ag content was 1%, and the remainder was a phosphorus-doped carbon support. The transmission electron microscopy (TEM) image of the hydrogenation catalyst in this comparative example is shown below. Figure 2 As shown, by Figure 2 It can be seen that Pd and Ag are almost dispersed at the nanoparticle level.

[0176] Comparative Example 6

[0177] This comparative example provides a hydrogenation catalyst, which is prepared by the following steps:

[0178] (1) Weigh 12.5g of melamine into a beaker and add 30mL of water, then add 27.8mL of phytic acid solution (the mass ratio of phytic acid to melamine is 2:1). After sonicating for 30min, put the beaker into a microwave oven and heat it with 1000W power for 120s. After washing and drying, nitrogen and phosphorus co-doped carbon support is obtained.

[0179] (2) Take 10 mL of 0.2 mg Pd / mL Pd(NO3)2 aqueous solution, add 10 g of the nitrogen-phosphorus co-doped carbon support, stir evenly at room temperature, place in liquid nitrogen for rapid freezing, and then irradiate under ultraviolet xenon lamp for 0.5 h; then freeze dry under 15 Pa vacuum for 2 h, and then calcine at 300 °C for 0.5 h under inert atmosphere to obtain palladium-loaded support;

[0180] The palladium-supported support was added to an aqueous solution of silver nitrate containing 6.3 mg of silver nitrate. After stirring evenly at room temperature, the solution was rapidly frozen in liquid nitrogen and then irradiated under a xenon lamp for 0.5 h. After that, it was freeze-dried under a vacuum of 15 Pa for 2 h and then calcined at 300 °C for 0.5 h under an inert atmosphere to obtain a catalyst semi-finished product.

[0181] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 10% H2, at a reduction temperature of 60°C, a reduction pressure of 0.5 MPa, and a reduction time of 1 h to obtain the reduced catalyst, which is the hydrogenation catalyst.

[0182] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.02%, the Ag content is 0.04%, and the balance is a nitrogen-phosphorus co-doped carbon support.

[0183] The catalysts provided in the above examples and comparative examples were evaluated for performance in a single-stage fixed-bed reactor. The inlet material composition of the single-stage fixed-bed reactor is shown in Table 1. The reaction conditions were: space velocity 14000 h⁻¹. -1 The pressure was 2.5 MPa, and the reactor inlet temperature was 80℃. The evaluation results are shown in Table 2.

[0184] Table 1 Composition of reactants

[0185]

[0186] Table 2 Catalyst Evaluation Results

[0187]

[0188]

[0189] Note: Coking amount = (Loss on ignition at 600℃ ÷ Initial catalyst charge) × 100%

[0190] The catalyst provided in the embodiments of the present invention can be applied to the process of hydrogenation and alkyne removal before propane removal from C2, and its process flow diagram is shown below. Figure 3As shown in the figure. The process flow mainly includes: feeding the raw material of the ethylene unit into the cracking furnace 1 for high-temperature cracking; cooling the product through the quench system 2; then processing it sequentially through the oil washing tower 3, water washing tower 4, first heat exchanger 5, alkali washing tower 6, and dryer 7; and then feeding it into the pre-propane stripper 8. The top material of the pre-propane stripper 8 is processed through the second heat exchanger 9 and then enters the C2 hydrogenation reactor 10 for selective hydrogenation and alkyne removal. The C2 hydrogenation reactor 10 is filled with the catalyst provided in the embodiments of the present invention, and the C2 hydrogenation reactor 10 can be a single-stage fixed-bed reactor. The material after hydrogenation and alkyne removal enters the demethanizer 11. Methane and hydrogen are separated from the top of the demethanizer 11, and the bottom material goes to the subsequent separation system.

[0191] The above evaluation results show that the C2 pre-propane dehydrogenation catalyst provided by this invention uses phosphorus-doped carbon material as a support. This support has a porous structure and a high specific surface area. The active components palladium and silver are dispersed on the support in a single-atom state (on the surface and within the pores) using a photoreduction method, rather than forming nanoparticles or sub-nano clusters. The atomically dispersed Pd and Ag exhibit the following characteristics in the selective hydrogenation reaction of alkynes: due to the atomic dispersion of the active components, the utilization rate of metal atoms is increased, thereby improving the catalyst's hydrogenation activity; the adsorption capacity for olefins is reduced, thereby improving the catalyst's hydrogenation selectivity; the probability of simultaneous adsorption of alkynes / dienes at adjacent active sites decreases, thus significantly reducing the probability of polymerization and coking, thereby improving the catalyst's anti-coking performance. Therefore, the C2 pre-propane dehydrogenation catalyst of this invention exhibits excellent hydrogenation activity, selectivity, and anti-coking performance.

Claims

1. A pre-propane dehydrogenation catalyst for C2, the catalyst comprising a support and an active component, wherein the support is a phosphorus-doped carbon material, the active component comprises a main active component and a co-active component, the main active component comprises Pd, the co-active component comprises Ag, and the main active component and the co-active component are atomically dispersed on the support; based on the total mass of the catalyst as 100%, the content of the main active component is 0.02~0.30%, the content of the co-active component is 0.04~1.00%, and the balance is the support; The catalyst is prepared by the following steps: (1) A phosphorus-containing compound and a carbohydrate are mixed in water, and then subjected to a hydrothermal reaction. After drying and calcination, a phosphorus-doped carbon material carrier is obtained. (2) The active component is loaded onto the phosphorus-doped carbon material support to obtain a catalyst semi-finished product; (3) The catalyst semi-finished product is reduced to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst; in, Step (2) specifically includes: (2) -a1 The phosphorus-doped carbon material support is added to the precursor aqueous solution of the main active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the support loaded with the main active component; (2) -a2 The support carrying the main active component is added to the precursor aqueous solution of the auxiliary active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the catalyst semi-finished product. Alternatively, step (2) may specifically include: (2) -b1 The phosphorus-doped carbon material support is added to the precursor aqueous solution of the active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the support loaded with the active component; (2)-b2 The carrier loaded with the auxiliary active component is added to the precursor aqueous solution of the main active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the catalyst semi-finished product.

2. The pre-propane dehydrogenation catalyst according to claim 1, wherein, Based on the total mass of the catalyst (100%), the content of the main active component is 0.02~0.18%, the content of the co-active component is 0.05~0.40%, and the balance is the support.

3. The pre-propane dehydrogenation catalyst according to claim 1, wherein, The catalyst comprises a support and an active component. The support is a phosphorus-doped carbon material, and the active component comprises Pd and Ag, which are atomically dispersed on the support. Based on the total mass of the catalyst (100%), the Pd content is 0.02-0.30%, the Ag content is 0.04-1.00%, and the balance is the support.

4. The pre-propane dehydrogenation catalyst according to claim 3, wherein, Based on the total mass of the catalyst (100%), the Pd content is 0.02-0.18%, the Ag content is 0.05-0.40%, and the balance is the support.

5. A method for preparing a pre-propane dehydrogenation catalyst according to any one of claims 1-4, comprising the following steps: (1) A phosphorus-containing compound and a carbohydrate are mixed in water, and then subjected to a hydrothermal reaction. After drying and calcination, a phosphorus-doped carbon material carrier is obtained. (2) The active component is loaded onto the phosphorus-doped carbon material support to obtain a catalyst semi-finished product; (3) The catalyst semi-finished product is reduced to obtain the reduced catalyst, which is the C2 pre-propane dehydrogenation catalyst; Step (2) specifically includes: (2) -a1 The phosphorus-doped carbon material support is added to the precursor aqueous solution of the main active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the support loaded with the main active component; (2) -a2 The support carrying the main active component is added to the precursor aqueous solution of the auxiliary active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the catalyst semi-finished product. Alternatively, step (2) may specifically include: (2) -b1 The phosphorus-doped carbon material support is added to the precursor aqueous solution of the active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the support loaded with the active component; (2)-b2 The carrier loaded with the auxiliary active component is added to the precursor aqueous solution of the main active component, mixed evenly, frozen in liquid nitrogen, then irradiated under ultraviolet xenon lamp, then freeze-dried, and then calcined to obtain the catalyst semi-finished product.

6. The preparation method according to claim 5, wherein, In step (1), the phosphorus-containing compound includes phosphoric acid and / or phytic acid.

7. The preparation method according to claim 5, wherein, In step (1), the carbohydrates include glucose and / or sucrose.

8. The preparation method according to claim 5, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.0001 to 1000.

9. The preparation method according to claim 8, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.001 to 10.

10. The preparation method according to claim 9, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.02 to 0.

4.

11. The preparation method according to claim 5, wherein, In step (1), the phosphorus-containing compound and carbohydrates are mixed in water under stirring conditions for a duration of 30 to 120 minutes.

12. The preparation method according to claim 5, wherein, In step (1), the temperature of the hydrothermal reaction is 160~300℃ and the time is 4~12h.

13. The preparation method according to claim 5, wherein, In step (1), the drying temperature is 120~160℃ and the time is 4~12h.

14. The preparation method according to claim 5, wherein, Step (1) further includes ball milling, which is performed after drying and before calcination, and the ball milling time is 3 to 10 minutes.

15. The preparation method according to claim 5, wherein, In step (1), the calcination is carried out under an inert atmosphere at a temperature of 600-1000°C for 1-5 hours.

16. The preparation method according to claim 5, wherein, In step (2), the precursor of the main active component includes a palladium salt compound.

17. The preparation method according to claim 16, wherein, In step (2), the precursor of the main active component includes one or a combination of palladium chloride, palladium nitrate and palladium sulfate.

18. The preparation method according to claim 5, wherein, In step (2), the precursor of the co-active component includes a silver salt compound.

19. The preparation method according to claim 18, wherein, In step (2), the precursor of the co-active component includes one or a combination of silver nitrate, silver fluoride, silver chlorate and silver perchlorate.

20. The preparation method according to claim 5, wherein, In step (2), the concentration of the main active component in the precursor aqueous solution of the main active component is 0.1~5 mgPd / mL Pd precursor aqueous solution.

21. The preparation method according to claim 5, wherein, In step (2), the concentration of the co-active component in the precursor aqueous solution of the co-active component is 0.1~10 mgAg / mL Ag precursor aqueous solution.

22. The preparation method according to claim 5, wherein, In step (2), the illumination time under the ultraviolet xenon lamp is 0.5~5.0h.

23. The preparation method according to claim 5, wherein, In step (2), the freeze-drying time is 2-7 hours and the vacuum degree of the freeze-drying is 15-20 Pa.

24. The preparation method according to claim 5, wherein, In step (2), the calcination is carried out under an inert atmosphere at a temperature of 300-500°C for a time of 0.5-5 hours.

25. The preparation method according to claim 5, wherein, In step (3), the catalyst semi-finished product is reduced by using a mixture of H2 and He gas with a volume percentage of 10-100% or pure hydrogen gas, at a reduction temperature of 50-300℃, a reduction pressure of 0.1-2.0MPa, and a reduction time of 0.5-10h.

26. The preparation method according to claim 25, wherein, In step (3), the reduction temperature is 100~200℃, the reduction pressure is 0.5~1.0MPa, and the reduction time is 2~6h.

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