A c3 fraction selective hydrogenation catalyst and a method for preparing the same

Abstract

The application provides a C3 fraction selective 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 Pb, 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 C3 fraction selective hydrogenation catalyst. The C3 fraction selective hydrogenation catalyst provided by the application has excellent hydrogenation activity, selectivity and anti-coking performance.

Description

A C3 fraction selective hydrogenation catalyst and its preparation method Technical Field

[0001] This invention relates to a selective hydrogenation catalyst for C3 fractions and its preparation method, belonging to the field of hydrogenation catalyst technology. Background Technology

[0002] Propylene is one of the most important basic raw materials in the petrochemical industry and a crucial monomer for the synthesis of various polymers. It is mostly produced by steam cracking of petroleum hydrocarbons (such as ethane, propane, butane, naphtha, and light diesel oil). The C3 fraction obtained by this method, which is mainly composed of propylene, typically contains 1.5–8.0% propyne (MA) + propadiene (PD). The presence of MAPD affects the quality of polymer products, and currently, the petrochemical industry generally uses selective hydrogenation to remove MAPD.

[0003] Traditional C3 hydrogenation catalysts typically use Al2O3 as a support, Pd as the active component, and Ag as a co-active component. These catalysts have a specific surface area of ​​15–100 m². 2 / g. The catalyst is prepared by impregnation. During the impregnation and drying processes, the surface tension and solvation effects of the impregnation solution are particularly significant, causing the metal active component precursor to deposit as aggregates on the support surface. Furthermore, the distribution of Pd and Ag is not ideal, making it difficult to control the catalyst activity. The selectivity of the catalyst mainly depends on the catalyst pore size and the dispersion state of the active components. Because the dispersion of the active components is affected by the number of surface groups on the support and solvation during catalyst preparation, the dispersion of the active components is highly random, resulting in poor reproducibility and ultimately unsatisfactory catalytic reaction performance.

[0004] CN1275157A discloses a catalytic distillation method for removing MAPD from C3 fractions. This method combines catalytic hydrogenation and distillation separation processes into one. Due to sufficient heat exchange during this process, temperature runaway is less likely, and the small amount of oligomers generated are easily carried away, significantly reducing coking on the catalyst surface. However, this method places high demands on the packing of the catalytic distillation column, and the fluid distribution significantly affects the separation effect. This method also increases the operational complexity.

[0005] CN102206132A discloses a method for selective hydrogenation of C3 fractions. This method uses a catalyst with Pd as the main active component, alumina as the support, and added Ag as a co-active component. Specific polymeric compounds are adsorbed onto the support, forming a polymeric compound coating of a certain thickness on the support surface. The reaction of compounds with functional groups with the polymeric compounds imparts functional groups capable of complexing with the active component. The active component undergoes a complexation reaction on the functional groups on the support surface, ensuring the ordered and highly dispersed nature of the active component. However, this method has the following drawbacks: the adsorption of specific polymeric compounds on the support is achieved through chemisorption between the hydroxyl groups of alumina and the polymer, and the amount of polymeric compounds adsorbed on the support is limited by the number of hydroxyl groups in the alumina; the complexation effect between the functionalized polymer and Pd is not strong, sometimes resulting in insufficient loading of the active component, leaving some active component residue in the impregnation solution, increasing catalyst costs; the preparation of C3 hydrogenation catalysts using this method also suffers from a complex process flow.

[0006] CN1972885A discloses a selective hydrogenation catalyst for acetylene and dienes in light olefin feedstocks. The catalyst comprises a first component selected from copper, gold, and silver, and a second component selected from nickel, platinum, palladium, iron, cobalt, ruthenium, and rhodium. It also includes at least one inorganic salt and oxide selected from zirconium, lanthanides, and a mixture of alkaline earth metals, as well as an inorganic support. After calcination, use, or regeneration, the catalyst forms a fluorite structure. Adding a third oxide, using modified alumina or silica as a support, helps increase the catalyst's selectivity and its activity and selectivity after regeneration. However, the catalyst still uses copper, gold, silver, palladium, etc., as active components, and nickel, platinum, palladium, iron, cobalt, ruthenium, rhodium, etc., as co-active components. The regeneration performance of the catalyst is improved by modifying the oxide of the support.

[0007] CN102218323A discloses a hydrogenation catalyst for unsaturated hydrocarbons. The active component of this catalyst is a mixture of 5-15% nickel oxide and 1-10% other metal oxides, which can be one or more of molybdenum oxide, cobalt oxide, and iron oxide. It also includes 1-10% additives. This catalyst is mainly used for the hydrogenation of ethylene, propylene, butene, etc., in coal-to-oil industrial tail gases into saturated hydrocarbons, exhibiting good deep hydrogenation capabilities. However, this catalyst is primarily used for the complete hydrogenation of ethylene, propylene, butene, etc., in various industrial tail gases rich in CO and hydrogen, and is not suitable for the selective hydrogenation of alkynes and dienes.

[0008] CN101433845A discloses a selective hydrogenation catalyst and its preparation method. This catalyst uses alumina as a support and palladium as the active component. The addition of rare earth metals, alkaline earth metals, and fluorine improves the catalyst's resistance to impurities and coking, but its catalytic selectivity is not ideal.

[0009] CN112679301A discloses a hydrogenation catalyst in which the active components include Pd, Ag, and Ni. Pd and Ag are supported using an aqueous solution impregnation method, while Ni is supported using a W / O microemulsion impregnation method. In the catalyst prepared by this method, Pd / Ag and Ni are located in channels of different pore sizes. The green oil generated during the reaction is saturated with hydrogen in the macropores, reducing the amount of coking on the catalyst. However, the reduction temperature of Ni often reaches around 500℃. At this temperature, reduced Pd atoms easily aggregate, causing a significant decrease in catalyst activity. A substantial increase in the amount of active components is needed to compensate for the activity loss, but this in turn leads to a decrease in selectivity.

[0010] CN106654300A discloses a method for preparing monodisperse metal atom / graphene composite materials by electrochemically swelling graphite, providing a novel method for efficiently preparing monodisperse metal atom / graphene composite catalysts with controllable metal atom types and quantities by electrochemically swelling graphite-based raw materials. This method is an electrochemical exfoliation method for preparing monodisperse metal atom / graphene composite materials from graphite in one step under milder conditions, mainly including the following steps: (1) making graphite-based raw materials into electrodes; (2) electrolyzing the electrodes in an electrolytic cell, separating solids and liquids, and recycling the electrolyte; (3) further exfoliating the separated solids to obtain crude monodisperse metal atom / graphene composite materials; (4) separating and purifying the crude monodisperse metal atom / graphene composite materials to obtain monodisperse metal atom / graphene composite materials; (5) heat-treating the composite materials obtained in step (4) and / or the composite materials uniformly mixed with a non-gas-phase nitrogen source under an inert atmosphere and / or an ammonia atmosphere, and cooling to obtain monodisperse metal atom / graphene composite catalysts. In this material, the metal is dispersed in the graphene framework as single atoms. The type and composition of the central metal atoms can be adjusted as needed, and it can be either mononuclear or binuclear. Furthermore, the binuclear metal component can be either a single metal or a bimetallic component. However, this literature does not describe the content and metal state of the active metal component, only prepares a single-atom catalyst, and does not evaluate the catalyst performance for any specific system.

[0011] CN109126857A discloses a metal single-atom catalyst based on a carbon nanocage support and its preparation method. This metal single-atom catalyst based on a carbon nanocage support includes a carbon nanocage support and metal single atoms embedded in the microporous channels of the cage wall of the carbon nanocage support; the metal single atoms are Pt, Pd, Ru, Ir, Ag, or Au; the carbon nanocage support is a doped carbon nanocage, the loading of the metal single atoms is less than 8 wt%, the doped carbon nanocage is a single-element doped carbon nanocage or a co-doped carbon nanocage, the single-element doped carbon nanocage is N-doped, B-doped, S-doped, or P-doped carbon nanocage, the P doping amount in the P-doped carbon nanocage is less than 8 at%, and the pore size of the cage wall micropores of the carbon nanocage support is 0.4–1.5 nm. The preparation method of this metal single-atom catalyst includes: impregnating doped carbon nanocages in a metal precursor solution, followed by separation and heat treatment to obtain a metal single-atom catalyst based on a carbon nanocage support; the metal precursor is a water-soluble metal ion compound corresponding to Pt, Pd, Ru, Ir, Ag, or Au; the heat treatment temperature is 40–600℃, the heat treatment time is 0.5–24 h, the impregnation temperature is 0–100℃, and the impregnation time is 0.5–50 h. The loading of Pd metal single atoms in this catalyst is below 8 wt%, which has a wide range, requires a large amount, and results in high cost.

[0012] CN112808288A discloses a catalyst with nitrogen-phosphorus or nitrogen-phosphorus-sulfur co-doped carbon supporting metal single atoms and its microwave-assisted preparation method. The catalyst includes a support and an active metal component supported on the support; the support is a nitrogen-phosphorus or nitrogen-phosphorus-sulfur co-doped carbon material, and the metal includes any one of palladium, ruthenium, rhodium, iridium, platinum, iron, cobalt, and nickel. By mass percentage, the metal loading in the catalyst is 0.1% to 5%. The preparation method of the catalyst includes the following steps: (1) phytic acid and any one or more of nitrogen- and sulfur-containing organic molecules such as thiourea, urea, melamine, dicyandiamide, cyanuric acid, aniline, and pyrrole are mixed at a certain mass ratio and placed in a microwave oven for microwave heating. The obtained black product is a nitrogen-phosphorus or nitrogen-phosphorus-sulfur doped carbon support; (2) a certain amount of metal precursor solution is mixed with the support and reducing agent in step (1), stirred, washed, and dried to obtain the catalyst material with nitrogen-phosphorus or nitrogen-phosphorus-sulfur doped carbon material supporting metal single atoms.

[0013] CN111389437A discloses a molybdenum carbide-supported single-atom hydrogenation catalyst, its preparation method, and its application in the semi-hydrogenation of alkynes. The hydrogenation catalyst comprises: a support comprising MoC; and a metal single atom supported on the support, wherein the metal single atom is chemically bonded to molybdenum atoms in the MoC; wherein the metal single atom comprises at least one selected from single-atom nickel, single-atom cobalt, and single-atom copper.

[0014] CN108250024A discloses a method for hydrogenating a C3 fraction. This method involves selectively hydrogenating the C3 fraction, used as a hydrogenation feedstock, through a Fe-Mn catalyst, converting propyne (MA) and propadiene (PD) in the feedstock into propylene. The Fe-Mn catalyst is supported by a high-temperature resistant inorganic oxide, and the active components contain at least Fe and Mn. Based on 100% of the total mass of the catalyst, it contains 5-15% Fe and 0.5-2% Mn. The specific surface area of ​​the catalyst is 10-300 μm. 2 The catalyst has a pore volume of 0.2–0.65 mL / g and is prepared by impregnation of Fe and Mn onto a support, followed by calcination and reduction under a hydrogen atmosphere. The reaction conditions for hydrogenation of C3 fractions using this catalyst are: reactor inlet temperature 30–50 °C, reaction pressure 1.5–3.5 MPa, and liquid hourly space velocity 15–120 h⁻¹. -1 The hydrogen / MAPD ratio is 1–10. This catalyst uses Fe as the active component and does not involve selective hydrogenation catalysts for C3 fractions using Pd as the active component.

[0015] CN106925279A discloses an Fe-based selective hydrogenation catalyst, its preparation method, and its application. The catalyst's active component comprises 2–15 wt% Fe and 0–2 wt% X, where X is selected from one or more of K, La, and Ce, with the remainder being oxygen and a support. The catalyst has a specific surface area of ​​10–300 μm. 2 The catalyst has a pore volume of 0.2–0.65 mL / g and a pore volume of 0.2–0.65 mL / g. This catalyst can be used for the selective hydrogenation of acetylene, propyne, and propadiene (MAPD) ​​in C2–C3 cracked fractions. This literature describes a catalyst for selective hydrogenation of C2 and C3 fractions prepared by impregnation loading of the active component and metal reduction via calcination, without involving single-atom catalyst preparation techniques.

[0016] Developing a novel selective hydrogenation catalyst for C3 fractions and its preparation method has become one of the urgent problems to be solved in this field. Summary of the Invention

[0017] To address the aforementioned technical problems, the present invention aims to provide a C3 fraction selective hydrogenation catalyst and its preparation method. The C3 fraction selective hydrogenation catalyst of 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 C3 fraction selective hydrogenation catalyst, the C3 fraction selective hydrogenation 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 Pb, 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 C3 fraction selective hydrogenation catalyst, the content of the main active component is 0.10-0.50%, the content of the co-active component is 0.10-4.0%, and the balance is the support. More preferably, based on 100% of the total mass of the C3 fraction selective hydrogenation catalyst, the content of the main active component is 0.15-0.35%, the content of the co-active component is 0.10-2.0%, and the balance is the support.

[0020] According to a specific embodiment of the present invention, preferably, the C3 fraction selective hydrogenation catalyst comprises a support and an active component, wherein the support is a phosphorus-doped carbon material, and the active component comprises Pd and Pb, wherein Pd and Pb are atomically dispersed on the support, and based on 100% of the total mass of the catalyst, the Pd content is 0.10-0.50%, the Pb content is 0.10-4.0%, and the balance is the support; more preferably, based on 100% of the total mass of the C3 fraction selective hydrogenation catalyst, the Pd content is 0.15-0.35%, the Pb content is 0.10-2.0%, and the balance is the support.

[0021] In the aforementioned C3 fraction selective hydrogenation catalyst, 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. Preferably, the specific surface area of ​​the support is 500–700 cm². 2 / g, with most probable pore size of 2–30 nm and pore volume of 0.8–1.5 mL / g.

[0022] According to a specific embodiment of the present invention, preferably, the C3 fraction selective hydrogenation catalyst 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 C3 fraction selective hydrogenation 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) involves loading the active component onto the phosphorus-doped carbon material support using photodeposition.

[0036] In the catalyst preparation steps described above, preferably, step (2) specifically includes:

[0037] (2)-a1 The phosphorus-doped carbon material support is added to the precursor 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.

[0038] (2)-a2 The support carrying the main active component is added to the precursor 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.

[0039] Alternatively, step (2) may specifically include:

[0040] (2)-b1 The phosphorus-doped carbon material support is added to the precursor 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.

[0041] (2)-b2 The carrier loaded with the auxiliary active component is added to the precursor 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.

[0042] 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.

[0043] In the catalyst preparation steps described above, preferably, in step (2), the precursor of the main active component includes a palladium salt compound (more preferably a palladium soluble salt compound), specifically including one or a combination of palladium chloride, palladium nitrate, and palladium sulfate.

[0044] In the catalyst preparation steps described above, preferably, in step (2), the precursor of the co-active component includes lead salt compounds (more preferably lead soluble salt compounds), specifically including lead nitrate and / or lead acetate, etc.

[0045] In the catalyst preparation steps described above, preferably, in step (2), the concentration of the main active component in the precursor solution of the main active component is 0.1 to 5 mg Pd / mL Pd precursor solution.

[0046] In the catalyst preparation steps described above, preferably, in step (2), the concentration of the co-active component in the precursor solution of the co-active component is 0.1 to 10 mg Pb / mL Pb precursor solution.

[0047] In the catalyst preparation step (2) above, the amount of support added to the active component precursor solution 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] A second aspect of the present invention provides a method for preparing the above-mentioned selective hydrogenation catalyst for C3 fractions, comprising the following steps:

[0053] (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.

[0054] (2) The active component is loaded onto the phosphorus-doped carbon material support to obtain a catalyst semi-finished product;

[0055] (3) The catalyst semi-finished product is reduced to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0056] In the above preparation method, preferably, in step (1), the phosphorus-containing compound includes phosphoric acid and / or phytic acid, etc.

[0057] In the above preparation method, preferably, in step (1), the carbohydrate includes glucose and / or sucrose, etc.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] In the above preparation method, preferably, in step (1), the drying temperature is 120-160°C and the time is 4-12 hours.

[0063] 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.

[0064] 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.

[0065] In the above preparation method, preferably, step (2) is to load the active component onto the phosphorus-doped carbon material carrier by photodeposition.

[0066] In the above preparation method, preferably, step (2) specifically includes:

[0067] (2)-a1 The phosphorus-doped carbon material support is added to the precursor 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.

[0068] (2)-a2 The support carrying the main active component is added to the precursor 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.

[0069] Alternatively, step (2) may specifically include:

[0070] (2)-b1 The phosphorus-doped carbon material support is added to the precursor 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.

[0071] (2)-b2 The carrier loaded with the auxiliary active component is added to the precursor 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.

[0072] 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.

[0073] In the above preparation method, preferably, in step (2), the precursor of the main active component includes a palladium salt compound (more preferably a palladium soluble salt compound), specifically including one or a combination of palladium chloride, palladium nitrate and palladium sulfate.

[0074] In the above preparation method, preferably, in step (2), the precursor of the auxiliary active component includes lead salt compounds (more preferably lead soluble salt compounds), specifically including lead nitrate and / or lead acetate, etc.

[0075] In the above preparation method, preferably, in step (2), the concentration of the main active component in the precursor solution of the main active component is 0.1 to 5 mg Pd / mL Pd precursor solution.

[0076] In the above preparation method, preferably, in step (2), the concentration of the co-active component in the precursor solution of the co-active component is 0.1 to 10 mg Pb / mL Pb precursor solution.

[0077] In step (2) of the above preparation method, the amount of support added to the active component precursor solution 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.

[0078] In the above preparation method, preferably, in step (2), the irradiation time under ultraviolet xenon lamp is 0.5 to 5.0 h.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] This invention provides a selective hydrogenation catalyst for alkynes and its preparation method, particularly a selective hydrogenation catalyst for C3 fractions and its preparation method. Hydrogenation catalysts prepared by conventional methods often have active components existing in nanoparticle or sub-nano cluster structures, thus affecting catalyst performance. The C3 fraction selective hydrogenation catalyst provided by this invention uses a phosphorus-doped carbon material as a support. This support has a porous structure and a high specific surface area. A photoreduction method is used to disperse the active components (preferably palladium and lead) in a single-atom state on the support (both on the surface and within the pores), rather than forming nanoparticle or sub-nano cluster structures. Atomic-scale dispersed Pd and Pb exhibit the following characteristics in the selective hydrogenation of alkynes, particularly in the selective hydrogenation of propyne (MA) + propadiene (PD): the atomic-scale dispersion of the active components increases the utilization rate of metal atoms, thereby enhancing the catalyst's hydrogenation activity; the reduced adsorption capacity for olefins (e.g., ethylene, propylene) improves the catalyst's hydrogenation selectivity; and the 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 C3 fraction selective hydrogenation catalyst provided by this invention possesses excellent hydrogenation activity, selectivity, and anti-coking properties. In application, the C3 fraction selective hydrogenation catalyst provided by this invention shows significantly improved activity and selectivity compared to palladium-containing bimodal pore distribution catalysts. Even when the hydrogenation reactants contain 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 C3 fraction selective hydrogenation catalyst provided by this invention. Attached Figure Description

[0083] Figure 1 is an aberration-corrected transmission electron microscope image of the C3 fraction selective hydrogenation catalyst provided in Example 1.

[0084] Figure 2 is a transmission electron microscope image of the C3 fraction selective hydrogenation catalyst provided in Comparative Example 1.

[0085] Figure 3 is a transmission electron microscope image of the C3 fraction selective hydrogenation catalyst provided in Comparative Example 5.

[0086] Figure 4 is a flow chart of the C3 fraction hydrogenation process in the propylene preparation process without the pre-hydrogenation process.

[0087] Figure 5 is a flow chart of the C3 fraction hydrogenation process using the pre-hydrogenation process in the propylene preparation process.

[0088] Explanation of icon numbers:

[0089] 1- Cracking furnace; 2- Quenching system; 3- Oil washing tower; 4- Water washing tower; 5- Heat exchanger; 6- Alkali washing tower; 7- Demethanizer; 8- Deethanerizer; 9- Depropanizer; 10- C3 fraction hydrogenation reactor; 11- Pre-propanizer; 12- C2 fraction hydrogenation reactor; 13- Compressor. Detailed Implementation

[0090] 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.

[0091] According to a specific embodiment of the present invention, preferably, the C3 fraction selective hydrogenation catalyst of the present invention is prepared by the following steps:

[0092] (1) A phosphorus-containing compound and a carbohydrate are thoroughly mixed in water for 30 to 120 minutes to obtain a mixed solution; the mixed solution is subjected to a hydrothermal reaction in a hydrothermal reactor in an oven at 160 to 300°C for 4 to 12 hours, then dried at 120 to 160°C for 4 to 12 hours, and then ball-milled for 3 to 10 minutes to obtain a powder; the powder is calcined at 600 to 1000°C for 1 to 5 hours under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0093] 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;

[0094] (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.

[0095] (2) a2 The palladium-supported support is added to the lead 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;

[0096] or,

[0097] (2)-b1 The phosphorus-doped carbon material support is added to the lead 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 lead-loaded support.

[0098] (2)-b2 The lead-supported carrier is added to the palladium precursor aqueous solution, stirred evenly, and then rapidly frozen in liquid nitrogen. 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;

[0099] The palladium precursor includes a soluble salt compound of palladium, 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;

[0100] The lead precursor includes soluble salt compounds of lead, specifically lead nitrate and / or lead acetate, etc.; the concentration of lead in the aqueous solution of the lead precursor is 0.1 to 10 mg Pb / mL Pb precursor aqueous solution;

[0101] (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 C3 fraction selective hydrogenation catalyst.

[0102] The technical solution of the present invention will be further described below through specific embodiments.

[0103] In the following specific embodiments and comparative examples, the analytical testing methods used include:

[0104] Content of active component in catalyst: atomic absorption spectrometry;

[0105] Specific surface area of ​​the carrier: GB / T-5816;

[0106] Single-atom morphology characterization: aberration-corrected transmission electron microscopy;

[0107] Conversion rate and selectivity are calculated using the following formula:

[0108] Propylene-propadiene (MAPD) ​​conversion rate (%) = 100 × (inlet MAPD content - outlet MAPD content) / inlet MAPD content.

[0109] Propylene selectivity (%) = 100 × (outlet propylene content - inlet propylene content) / (inlet MAPD content - outlet MAPD content).

[0110] Example 1

[0111] This embodiment provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0112] (1) 10g of phosphoric acid and 120g of glucose were thoroughly mixed in water for 40 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;

[0113] (2) Take an appropriate amount of 1 mg Pd / mPd(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 1 h under inert atmosphere to obtain palladium-loaded support;

[0114] The palladium-supported support was added to an aqueous solution of lead nitrate containing 63.9 mg of lead nitrate. After stirring 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 1 h under an inert atmosphere to obtain a catalyst semi-finished product.

[0115] (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 65°C, a reduction pressure of 0.5 MPa, and a reduction time of 1 h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0116] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.15%, the Pb content is 0.4%, and the remainder is a phosphorus-doped carbon material support.

[0117] The specific surface area of ​​the phosphorus-doped carbon material carrier is 589 cm². 2 / g, with a most probable pore size of 3.5nm and a pore volume of 1.1mL / g.

[0118] Figure 1 shows the aberration-corrected transmission electron microscope image of the C3 fraction selective hydrogenation catalyst provided in this embodiment. As can be seen from Figure 1, Pd and Pb are atomically dispersed on the support.

[0119] Example 2

[0120] This embodiment provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0121] (1) 10g of phytic 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 200℃ for 6 hours, then dried at 130℃ for 6 hours, and then ball-milled for 5 minutes to obtain powder; the powder was calcined at 700℃ for 2 hours under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0122] (2) Take an appropriate amount 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 2.5 h, and then calcine at 300 °C for 2 h under inert atmosphere to obtain palladium-loaded support.

[0123] The palladium-supported support was added to an aqueous solution of lead nitrate containing 159.9 mg of lead 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 2.5 hours and then calcined at 300 °C for 2 hours under an inert atmosphere to obtain a catalyst semi-finished product.

[0124] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 20% H2, at a reduction temperature of 90°C, a reduction pressure of 0.8 MPa, and a reduction time of 2 h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0125] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.25%, the Pb content is 1.0%, and the remainder is a phosphorus-doped carbon material support.

[0126] Example 3

[0127] This embodiment provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0128] (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 800℃ for 3h under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0129] (2) 10g of the phosphorus-doped carbon support was added to a lead nitrate aqueous solution containing 319.7mg of lead nitrate. After stirring evenly at room temperature, the solution was placed in liquid nitrogen for rapid freezing and then irradiated under a UV xenon lamp for 2h. After that, it was freeze-dried under a vacuum of 17Pa for 3h and then calcined at 350℃ for 3h under an inert atmosphere to obtain a lead-loaded support.

[0130] Take an appropriate amount of 1 mg Pd / mL palladium sulfate aqueous solution, add it to the lead-supported carrier, stir evenly at room temperature, place it in liquid nitrogen for rapid freezing, and then irradiate it under ultraviolet xenon lamp for 2 hours; then freeze-dry it under vacuum of 17 Pa for 3 hours, and then calcine it at 350 °C for 3 hours under an inert atmosphere to obtain the catalyst semi-finished product.

[0131] (3) The catalyst semi-finished product is reduced by a mixture of H2 and He with a volume percentage of 40% H2, at a reduction temperature of 130°C, a reduction pressure of 1 MPa, and a reduction time of 4 h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0132] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.3%, the Pb content is 2.0%, and the remainder is a phosphorus-doped carbon material support.

[0133] Example 4

[0134] This embodiment provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0135] (1) 10g of phytic acid and 120g of glucose were thoroughly mixed in water for 60min to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 250℃ for 10h, then dried at 150℃ for 10h, and then ball-milled for 8min to obtain powder; the powder was calcined at 900℃ for 4h under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0136] (2) 10g of the phosphorus-doped carbon support was added to a lead nitrate aqueous solution containing 479.6mg of lead nitrate. After stirring evenly at room temperature, the solution was placed in liquid nitrogen for rapid freezing and then irradiated under a UV xenon lamp for 3h. After that, it was freeze-dried under a vacuum of 18Pa for 5.5h and then calcined at 400℃ for 4h under an inert atmosphere to obtain a lead-loaded support.

[0137] Take an appropriate amount of 1 mg Pd / mL Pd(NO3)2 aqueous solution, add it to the lead-supported carrier, stir evenly at room temperature, place it in liquid nitrogen for rapid freezing, and then irradiate it under ultraviolet xenon lamp for 3 h; then freeze-dry it under 18 Pa vacuum for 5.5 h, and then calcine it at 400 °C for 4 h under an inert atmosphere to obtain the catalyst semi-finished product.

[0138] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 60% H2, at a reduction temperature of 200℃, a reduction pressure of 1.5MPa, and a reduction time of 6h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0139] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.4%, the Pb content is 3.0%, and the remainder is a phosphorus-doped carbon material support.

[0140] Example 5

[0141] This embodiment provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0142] (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;

[0143] (2) Take an appropriate amount 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 4.5 h; then freeze dry under 20 Pa vacuum for 6 h, and then calcine at 500 °C for 5 h under inert atmosphere to obtain palladium-loaded support.

[0144] The palladium-supported support was added to an aqueous solution of lead nitrate containing 639.4 mg of lead nitrate. After stirring at room temperature, the solution was rapidly frozen in liquid nitrogen and then irradiated under a xenon lamp for 4.5 h. After that, it was freeze-dried under a vacuum of 20 Pa for 6 h and then calcined at 500 °C for 5 h under an inert atmosphere to obtain a catalyst semi-finished product.

[0145] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 80% H2, at a reduction temperature of 250°C, a reduction pressure of 2MPa, and a reduction time of 8h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0146] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.5%, the Pb content is 4.0%, and the remainder is a phosphorus-doped carbon material support.

[0147] Comparative Example 1

[0148] This comparative example provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0149] (1) 120g of glucose was thoroughly mixed in water for 40 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 carbon material carrier.

[0150] (2) Take an appropriate amount of 1 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, 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 1 h under inert atmosphere to obtain palladium-loaded support.

[0151] The palladium-supported support was added to an aqueous solution of lead nitrate containing 63.9 mg of lead nitrate. After stirring 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 1 h under an inert atmosphere to obtain a catalyst semi-finished product.

[0152] (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 65°C, a reduction pressure of 0.5 MPa, and a reduction time of 1 h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0153] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.15%, the Pb content is 0.4%, and the remainder is a carbon material support.

[0154] The specific surface area of ​​the carbon material carrier is 383 cm². 2 / g, with a most probable pore size of 3.5nm and a pore volume of 0.3mL / g.

[0155] The transmission electron microscope image of the C3 fraction selective hydrogenation catalyst provided in this comparative example is shown in Figure 2. As can be seen from Figure 2, the active components in this catalyst are not all dispersed as single atoms, and nanoparticles are generated.

[0156] Comparative Example 2

[0157] This comparative example provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0158] (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.

[0159] (2) Take an appropriate amount of 1 mg Pd / mPdCl2 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 2.5 h, and then calcine at 300 °C for 2 h under inert atmosphere to obtain palladium-loaded support.

[0160] The palladium-supported support was added to an aqueous solution of lead nitrate containing 159.9 mg of lead 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 2.5 hours and then calcined at 300 °C for 2 hours under an inert atmosphere to obtain a catalyst semi-finished product.

[0161] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 20% H2, at a reduction temperature of 90°C, a reduction pressure of 0.8 MPa, and a reduction time of 2 h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0162] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.25%, the Pb content is 1.0%, and the remainder is the catalyst support.

[0163] Comparative Example 3

[0164] This comparative example provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0165] (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 800℃ for 3h under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0166] (2) 10g of the phosphorus-doped carbon support was added to a lead nitrate aqueous solution containing 319.7mg of lead nitrate. After stirring evenly at room temperature, the solution was placed in liquid nitrogen for rapid freezing and then irradiated under a UV xenon lamp for 2h. After that, it was freeze-dried under a vacuum of 17Pa for 3h and then calcined at 350℃ for 3h under an inert atmosphere to obtain a lead-loaded support.

[0167] Take an excess of 1 mg Pd / mL palladium sulfate aqueous solution, add it to the lead-supported carrier, stir evenly at room temperature, place it in liquid nitrogen for rapid freezing, and then irradiate it under ultraviolet xenon lamp for 2 h; then freeze-dry it under vacuum of 17 Pa for 3 h, and then calcine it at 350 °C for 3 h under an inert atmosphere to obtain the catalyst semi-finished product.

[0168] (3) The catalyst semi-finished product is reduced by a mixture of H2 and He with a volume percentage of 40% H2, at a reduction temperature of 130°C, a reduction pressure of 1 MPa, and a reduction time of 4 h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0169] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst as 100%, the Pd content is 3.0%, the Pb content is 2.0%, and the balance is a phosphorus-doped carbon material support.

[0170] Comparative Example 4

[0171] This comparative example provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0172] (1) 10g of phytic acid and 120g of glucose were thoroughly mixed in water for 60min to obtain a mixed solution; the mixed solution was subjected to hydrothermal reaction in a hydrothermal reactor in an oven at 250℃ for 10h, then dried at 150℃ for 10h, and then ball-milled for 8min to obtain powder; the powder was calcined at 900℃ for 4h under an inert atmosphere to obtain a phosphorus-doped carbon material carrier;

[0173] (2) 10g of the phosphorus-doped carbon support was added to a lead nitrate aqueous solution containing 959.1mg of lead nitrate. After stirring evenly at room temperature, the solution 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 5.5h and then calcined at 400℃ for 4h under an inert atmosphere to obtain a lead-loaded support.

[0174] Take an appropriate amount of 1 mg Pd / mL Pd(NO3)2 aqueous solution, add it to the lead-supported carrier, stir evenly at room temperature, place it in liquid nitrogen for rapid freezing, and then irradiate it under ultraviolet xenon lamp for 3 h; then freeze-dry it under 18 Pa vacuum for 5.5 h, and then calcine it at 400 °C for 4 h under an inert atmosphere to obtain the catalyst semi-finished product.

[0175] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 60% H2, at a reduction temperature of 200℃, a reduction pressure of 1.5MPa, and a reduction time of 6h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0176] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.4%, the Pb content is 6.0%, and the remainder is a phosphorus-doped carbon material support.

[0177] Comparative Example 5

[0178] This comparative example provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0179] (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;

[0180] (2) Take an appropriate amount 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 carrier, stir evenly, 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 carrier.

[0181] The palladium-supported support was added to an aqueous solution of lead nitrate containing 639.4 mg of lead nitrate. After stirring evenly, the solution 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.

[0182] (3) The catalyst semi-finished product is reduced with a mixture of H2 and He with a volume percentage of 80% H2, at a reduction temperature of 250°C, a reduction pressure of 2MPa, and a reduction time of 8h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0183] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.50%, the Pb content is 4.0%, and the remainder is a phosphorus-doped carbon material support.

[0184] The transmission electron microscope image of the C3 fraction selective hydrogenation catalyst provided in this comparative example is shown in Figure 3. As can be seen from Figure 3, most of the active components in this catalyst exist in the form of nanoparticles.

[0185] Comparative Example 6

[0186] This comparative example provides a C3 fraction selective hydrogenation catalyst, which is prepared through the following steps:

[0187] (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.

[0188] (2) Take an appropriate amount of 1 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 it in liquid nitrogen for rapid freezing, and then irradiate it under ultraviolet xenon lamp for 0.5 h; then freeze dry it under vacuum of 15 Pa for 2 h, and then calcine it at 300 °C for 1 h under inert atmosphere to obtain the palladium-loaded support.

[0189] The palladium-supported support was added to an aqueous solution of lead nitrate containing 63.9 mg of lead nitrate. After stirring 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 1 h under an inert atmosphere to obtain a catalyst semi-finished product.

[0190] (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 65°C, a reduction pressure of 0.5 MPa, and a reduction time of 1 h to obtain the reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

[0191] According to atomic absorption spectrometry, based on the total mass of the C3 fraction selective hydrogenation catalyst (100%), the Pd content is 0.15%, the Pb content is 0.4%, and the balance is a nitrogen-phosphorus co-doped carbon support.

[0192] Catalyst performance evaluation

[0193] The C3 fraction selective hydrogenation catalysts provided in the above examples and comparative examples were evaluated in a single-stage fixed-bed reactor. The inlet composition of the single-stage fixed-bed reactor is shown in Table 1. The hydrogenation process conditions of the single-stage fixed-bed reactor were: catalyst loading of 50 mL, reactor inlet temperature of 32–35 °C, and reactant space velocity of 60 h⁻¹. -1 The operating pressure was 2.5 MPa, and the molar ratio of hydrogen to MAPD was 1.2. The evaluation results of the C3 fraction selective hydrogenation catalysts provided in the examples and comparative examples are shown in Table 2.

[0194] Table 1 Composition of reactants

[0195] Reactants C3H4(MAPD)C3H6C3H8C4 + Content (v / v%) 2.88 3.81 3.1 0.3 surface

[0196] Table 2 Catalyst Evaluation Results

[0197]

[0198] Note: Coking amount = (Loss on ignition at 600℃ ÷ Initial catalyst charge) × 100%

[0199] The material used in this performance evaluation experiment can come from the top of the depropanizer in a C3 fraction hydrogenation process that does not employ pre-hydrogenation in the propylene preparation process, or from the bottom of the deethaner in a C3 fraction hydrogenation process that employs pre-hydrogenation. The C3 fraction hydrogenation process in the propylene preparation process without pre-hydrogenation is shown in Figure 4. This process mainly includes: the raw materials (mainly petroleum hydrocarbon vapors) in the propylene preparation process are fed into the cracking furnace 1 for high-temperature cracking. The product is first cooled by the quench system 2, and then sequentially processed by the oil washing tower 3, water washing tower 4, heat exchanger 5, and alkali washing tower 6 before entering the demethanizer tower 7. Methane and hydrogen are separated from the top of the demethanizer tower 7, and the material at the bottom of the tower enters the deethaner tower 8. C2 fraction is separated from the top of the deethaner tower 8, and the material at the bottom of the tower enters the depropanizer tower 9. The material separated from the top of the depropanizer tower 9 enters the C3 fraction hydrogenation reactor 10 (a single-stage fixed-bed reactor in this performance evaluation) for hydrogenation to remove MAPD. The C4 and above fractions at the bottom of the depropanizer tower 9 are sent to subsequent units, and the product of the C3 fraction hydrogenation reactor 10 can be further sent to the propylene distillation unit.

[0200] The C3 fraction hydrogenation process using pre-hydrogenation in propylene production is shown in Figure 5. This process mainly includes: the raw materials (mainly petroleum hydrocarbon vapors) from the propylene production process are fed into cracking furnace 1 for high-temperature cracking; the product is first cooled by quench system 2, then sequentially processed through oil washing tower 3, water washing tower 4, heat exchanger 5, and alkali washing tower 6 before entering pre-propane stripper 11. Propane and propylene are separated at the bottom of pre-propane stripper 11, and the material at the top enters C2 fraction hydrogenation reactor 12 for hydrogenation. The reacted material is compressed by compressor 13 and then enters ethane stripper 8. Ethane and ethylene are separated at the top of ethane stripper 8, and the material at the bottom enters C3 fraction hydrogenation reactor 10 (a single-stage fixed-bed reactor in this performance evaluation) for hydrogenation to remove MAPD. The product from C3 fraction hydrogenation reactor 10 can be further sent to the propylene distillation unit.

[0201] The evaluation results above show that the C3 fraction selective hydrogenation catalyst provided by this invention has excellent hydrogenation activity, selectivity, and anti-coking performance. Even when the hydrogenation reactants contain 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 C3 fraction selective hydrogenation catalyst provided by this invention.

[0202] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A C3 fraction selective hydrogenation 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 Pb, and the main active component and the co-active component are atomically dispersed on the support; the C3 fraction selective hydrogenation catalyst is prepared by the following steps: (1) mixing a phosphorus-containing compound and a carbohydrate in water, then performing a hydrothermal reaction, and then at least drying and calcining to obtain a phosphorus-doped carbon material support; (2) loading the active component onto the phosphorus-doped carbon material support using photodeposition to obtain a catalyst semi-finished product; (3) reducing the catalyst semi-finished product to obtain a reduced catalyst, which is the C3 fraction selective hydrogenation catalyst; wherein, Step (2) specifically includes: (2)-a1 adding the phosphorus-doped carbon material support to the precursor solution of the main active component, mixing evenly, freezing in liquid nitrogen, then irradiating under a xenon lamp, then freeze-drying, and then calcining to obtain the support loaded with the main active component; (2)-a2 adding the support loaded with the main active component to the precursor solution of the auxiliary active component, mixing evenly, freezing in liquid nitrogen, then irradiating under a xenon lamp, then freeze-drying, and then calcining to obtain the catalyst semi-finished product; or Step (2) specifically includes: (2)-b1 Adding the phosphorus-doped carbon material support to the precursor solution of the auxiliary active component, mixing evenly, freezing in liquid nitrogen, then irradiating under ultraviolet xenon lamp, then freeze-drying, and then calcining to obtain the support loaded with the auxiliary active component; (2)-b2 Adding the support loaded with the auxiliary active component to the precursor solution of the main active component, mixing evenly, freezing in liquid nitrogen, then irradiating under ultraviolet xenon lamp, then freeze-drying, and then calcining to obtain the catalyst semi-finished product.

2. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, Based on the total mass of the C3 fraction selective hydrogenation catalyst as 100%, the content of the main active component is 0.10~0.50%, the content of the co-active component is 0.10~4.0%, and the balance is the support.

3. The C3 fraction selective hydrogenation catalyst according to claim 2, wherein, Based on the total mass of the C3 fraction selective hydrogenation catalyst as 100%, the content of the main active component is 0.15~0.35%, the content of the co-active component is 0.10~2.0%, and the balance is the support.

4. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, The specific surface area of ​​the carrier is 500~700 cm². 2 / g, with most probable pore size of 2~30nm and pore volume of 0.8~1.5mL / g.

5. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (1), the phosphorus-containing compound includes phosphoric acid and / or phytic acid.

6. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (1), the carbohydrates include glucose and / or sucrose.

7. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.0001 to 1000.

8. The C3 fraction selective hydrogenation catalyst according to claim 7, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.001 to 10.

9. The C3 fraction selective hydrogenation catalyst according to claim 8, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.02 to 0.

4.

10. The C3 fraction selective hydrogenation catalyst according to claim 1, 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.

11. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (1), the temperature of the hydrothermal reaction is 160~300℃ and the time is 4~12h.

12. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (1), the drying temperature is 120~160℃ and the time is 4~12h.

13. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, 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.

14. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (1), the calcination is carried out under an inert atmosphere at a temperature of 600-1000°C for 1-5 hours.

15. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (2), the precursor of the main active component includes a palladium salt compound.

16. The C3 fraction selective hydrogenation catalyst according to claim 15, wherein, In step (2), the precursor of the main active component includes one or a combination of palladium chloride, palladium nitrate and palladium sulfate.

17. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (2), the precursor of the co-active component includes a salt compound of lead.

18. The C3 fraction selective hydrogenation catalyst according to claim 17, wherein, In step (2), the precursor of the co-active component includes lead nitrate and / or lead acetate.

19. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (2), the concentration of the main active component in the precursor solution of the main active component is 0.1~5 mgPd / mL Pd precursor solution.

20. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (2), the concentration of the co-active component in the precursor solution of the co-active component is 0.1~10 mgPb / mL Pb precursor solution.

21. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (2), the illumination time under the ultraviolet xenon lamp is 0.5~5.0h.

22. The C3 fraction selective hydrogenation catalyst according to claim 1, wherein, In step (2), the freeze-drying time is 2-7 hours and the vacuum degree of the freeze-drying is 15-20 Pa.

23. The C3 fraction selective hydrogenation catalyst according to claim 1, 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.

24. The C3 fraction selective hydrogenation catalyst according to claim 1, 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.

25. The C3 fraction selective hydrogenation catalyst according to claim 24, 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.

26. A method for preparing a C3 fraction selective hydrogenation catalyst according to any one of claims 1-25, 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 support is obtained. (2) The active component is loaded onto the phosphorus-doped carbon material support by photodeposition to obtain a catalyst semi-finished product. (3) The catalyst semi-finished product is reduced to obtain a reduced catalyst, which is the C3 fraction selective hydrogenation catalyst.

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