A hydrodeoxygenation catalyst for a methanol to olefin product and a method of making the same

Abstract

The application provides a methanol-to-olefin product hydrogenation de-alkyne 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 Ni, 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 the catalyst. The catalyst has excellent hydrogenation activity, selectivity, anti-coking performance and long-term operation stability.

Description

Technical Field

[0001] This invention relates to a hydrogenation catalyst for removing alkynes from methanol-to-olefins products and its preparation method, belonging to the field of hydrogenation catalyst technology. Background Technology

[0002] Ethylene, propylene, and other low-carbon olefins are important basic chemical raw materials. To date, the primary method for producing ethylene, propylene, and other low-carbon olefins remains the catalytic cracking and pyrolysis of naphtha and light diesel oil (both derived from petroleum). However, the development of technologies for producing low-carbon olefins from non-petroleum resources is increasingly attracting attention.

[0003] The MTO (methanol-to-ethylene) and MTP (methanol-to-propylene) processes are important chemical technologies. These technologies use methanol synthesized from coal or natural gas as feedstock to produce low-carbon olefins and are core technologies for developing the production of ethylene, propylene, and other products from non-petroleum resources.

[0004] Methanol-to-olefins (MTO) is a key step in the coal-based olefins industry chain. The process flow mainly involves using methanol as feedstock under suitable operating conditions and selecting appropriate catalysts (such as ZSM-5 molecular sieve catalysts and SAPO-34 molecular sieves) to produce low-carbon olefins through methanol dehydration in fixed-bed and sulfided-bed reactors. Depending on the target product, MTO processes are divided into methanol-to-ethylene (MTO) and methanol-to-propylene (MTP) processes. Representative technologies for MTO include UOP / Hydro MTO and DMTO technologies; representative technologies for MTP include Lurgi MTP and FMTP technologies.

[0005] The methanol-to-olefins reaction can be divided into two stages: the dehydration stage and the cracking reaction stage. Their main reaction processes are as follows:

[0006] 1. Dehydration stage:

[0007] 2CH3OH→CH3OCH3+H2O+Q

[0008] 2. Pyrolysis reaction stage:

[0009] The reaction process mainly involves the catalytic cracking of dimethyl ether, the dehydration product, and a small amount of unconverted methanol, including:

[0010] Main reaction (forming an olefin):

[0011] nCH3OH→C n H 2n +nH2O+Q

[0012] nCH3OH→2Cn H 2n +nH2O+Q

[0013] n = 2 and 3 (primary), 4, 5 and 6 (minor)

[0014] All of the above olefin products are in the gaseous state;

[0015] Side reactions (forming alkanes, aromatics, carbon oxides, and coking):

[0016] (n+1)CH3OH→C n H 2n+2 +C+(n+1)H2O+Q

[0017] (2n+1)CH3OH→2C n H 2n+2 +CO + 2nH2O + Q

[0018] (3n+1)CH3OH→3C n H 2n+2 +CO2+(3n-1)H2O+Q

[0019] n = 1, 2, 3, 4, 5...

[0020] nCH3OCH3→C n H 2n-6 +3H2+nH2O+Q

[0021] n = 6, 7, 8...

[0022] The above products can be divided into gaseous (alkanes, aromatics, etc. such as CO, H2, H2O, CO2, CH4, etc.) and solid (high molecular weight hydrocarbons and coke).

[0023] After methanol undergoes dehydration, cracking, and separation, the ethylene feed at the top of the de-ethaner tower still contains 5–100 ppm of acetylene. This acetylene affects the ethylene polymerization process and causes a decline in product quality, necessitating its removal through selective hydrogenation. The selective hydrogenation of trace amounts of acetylene in the ethylene feed has a crucial impact on the ethylene polymerization process. Besides ensuring sufficient activity in the hydrogenation process to achieve good acetylene removal performance under low acetylene content conditions, guaranteeing that both the acetylene and hydrogen content at the reactor outlet meet standards, excellent catalyst selectivity is also required to minimize the formation of ethane from ethylene, ensuring that the hydrogenation process does not result in any loss of ethylene in the unit.

[0024] In methanol-to-olefins (MTO) plants, the separation units generally employ sequential separation processes. Ethylene refining can utilize either pre-hydrogenation or post-hydrogenation. Pre-hydrogenation involves the hydrogenation reactor being located before the separation unit, while post-hydrogenation involves the reactor being located after the separation unit. Currently, MTO plants commonly use the post-hydrogenation process, where ethylene separated from the cracking products is hydrogenated to remove acetylene, while propylene is not hydrogenated; the separated C4 mixture undergoes selective hydrogenation to remove butadiene. However, this process has drawbacks; separating ethylene and refining propylene separately results in relatively high energy consumption. Therefore, researchers have proposed a pre-hydrogenation process route that places a refining reactor before the separation unit to remove acetylene before further separation. This approach helps reduce energy consumption and improve the plant's economic efficiency.

[0025] For the pre-hydrogenation process, selective hydrogenation of trace amounts of acetylene in the ethylene feedstock of a methanol-to-olefins unit mainly employs a single-stage reactor process. In this process, the volumetric concentrations of each substance are typically: acetylene 5–100 ppm, CO 1–10 ppm, and the hydrogen gas used is the hydrogen already present in the feedstock, with an H2 content typically of 1.2%–2.5%; the reaction pressure is 1.5–2.5 MPa, and the space velocity is 2000–10000 h⁻¹. -1 The inlet temperature is 25℃~50℃. The reactor material composition of this process is relatively complex, and the representative material composition is shown in Table 1.

[0026] Table 1. Composition of inlet material for the acetylene hydrogenation reactor in the pre-hydrogenation process of the methanol-to-olefins unit.

[0027]

[0028] Selective hydrogenation catalysts for alkynes and dienes are obtained by supporting noble metals such as palladium on porous inorganic material supports, such as the catalyst disclosed in US4762956. To increase catalyst selectivity and reduce catalyst deactivation caused by green oil generated during oligomerization during hydrogenation, existing technologies employ methods such as adding Group IB elements as co-catalytic components: Pd-Au (US4490481), Pd-Ag (US4404124), Pd-Cu (US3912789), or adding alkali metals or alkaline earth metals (US5488024), etc. The supports used mainly include alumina, silica (US5856262), and honeycomb lapis lazuli (CN1176291A), etc.

[0029] US5856262 reports a method for preparing a low-acid palladium catalyst using potassium hydroxide (or hydroxides of barium, strontium, rubidium, etc.) modified silica as a support, at a space velocity of 3000 h⁻¹. -1Under conditions of an inlet temperature of 35℃, an inlet acetylene molar fraction of 0.71%, and a hydrogen-acetylene molar ratio of 1.43, the outlet acetylene molar fraction is less than 0.1 μL / L, and the ethylene selectivity reaches 56%. US4404124 describes a high-performance C2 hydrogenation catalyst prepared using alumina as a support and with the addition of silver and palladium as co-catalysts. This catalyst exhibits characteristics such as reducing ethane production, inhibiting partial hydrogenation dimerization of acetylene adsorbed on the catalyst surface, inhibiting 1,3-butadiene formation, reducing green oil formation, improving ethylene selectivity, and reducing the formation of oxygen-containing compounds, and has been widely used in the ethylene industry. However, the above catalysts are all prepared using an impregnation method, which limits the metal dispersion to only about 30%, and the catalyst performance also has many shortcomings, requiring further improvement.

[0030] CN101745389A discloses an eggshell-type catalyst for the selective hydrogenation of acetylene to ethylene and its preparation method. The method uses alumina (Al₂O₃) microspheres as a support and prepares a supported catalyst with the active component palladium distributed in an eggshell pattern using an impregnation method. The eggshell-type Pd / Al₂O₃ catalyst is then modified with Ag. The Pd loading is 0.01–0.1 wt%, and the Ag to Pd atomic ratio is 1–5. This eggshell-type catalyst for the selective hydrogenation of acetylene to ethylene achieves high ethylene selectivity under high acetylene conversion conditions, especially at near-100% acetylene conversion.

[0031] CN1972885A discloses a selective hydrogenation catalyst for acetylene and dienes in light olefin feedstocks. This catalyst consists of a first component selected from copper, gold, and silver, and a second component selected from nickel, platinum, palladium, iron, cobalt, ruthenium, and rhodium. Additionally, the catalyst includes at least one inorganic salt and oxide selected from zirconium, lanthanides, and a mixture of alkaline earth metals. After calcination, use, or regeneration, the catalyst forms a fluorite structure. The total oxide content of the catalyst is 0.01–50%, and the calcination temperature is 700–850°C. The addition of a third oxide and a modified alumina or silica support helps increase the catalyst's selectivity and its activity and selectivity after regeneration. This technology still uses copper, gold, silver, palladium, etc., as active components, and nickel, platinum, palladium, iron, cobalt, ruthenium, rhodium, etc., as auxiliary components, improving the catalyst's regeneration performance through oxide modification of the support.

[0032] CN102218323A discloses a hydrogenation catalyst for unsaturated hydrocarbons. The active component 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 technology 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. This technology is primarily used for the full hydrogenation of ethylene, propylene, butene, etc., in various industrial tail gases rich in CO and hydrogen, but is not suitable for the selective hydrogenation of alkynes and dienes.

[0033] The above-mentioned traditional C2 hydrogenation catalysts are all prepared by impregnation, and their active phases are mainly Pd and Ag bimetals. This method has the following disadvantages: (1) Due to the influence of the pore structure of the support, the dispersion of the active components cannot be precisely controlled and has strong randomness; (2) Due to the influence of the surface tension and solvation effect of the impregnation liquid, the precursor of the metal active component is deposited on the surface of the support in the form of aggregates and cannot form a uniform distribution; (3) C2 hydrogenation has high requirements for catalyst selectivity. The traditional preparation method promotes the role of Ag promoter by increasing the amount of Ag, which leads to the obstruction of hydrogen transfer, the increased possibility of oligomerization reaction, and the increase of green oil generation, which affects the catalyst lifetime. The occurrence of the above three phenomena easily leads to poor dispersion of metal active components, low reaction selectivity, and high green oil generation, which in turn affects the overall performance of the catalyst.

[0034] CN102205243A involves adsorbing specific polymeric compounds onto a support, forming a polymeric coating of a certain thickness on the support surface. The compound with functional groups reacts with the polymer, imbuing it with functional groups capable of complexing with the active component. Through the complexation reaction of the active component on the functional groups on the support surface, the active component is ensured to be ordered and highly dispersed. Using this method, the support adsorbs specific polymeric compounds, and the polymer undergoes chemisorption through the hydroxyl groups of alumina. However, the amount of polymeric compound adsorbed by the support is limited by the number of hydroxyl groups in the alumina. Furthermore, the complexation 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, thus increasing the catalyst cost.

[0035] To improve the anti-coking performance of catalysts and reduce the degree of surface coking, C2 selective hydrogenation catalysts and their preparation methods using bimodal porous supports and microemulsion methods for loading active components have been disclosed in recent years. CN104098427A discloses a selective hydrogenation catalyst whose support is mainly alumina with a bimodal porous structure, wherein the pore size is less than 50 nm and the macropore size is 60–800 nm. Based on 100% of the total mass of the catalyst, it contains 0.01–0.5% Pd in ​​a shell distribution with a thickness of 1–500 μm; and 0.2–5% Ni. The anti-coking component Ni is controlled by microemulsion method, where the microemulsion particle size is larger than the support pore size, so that Ni is mainly distributed in the macropores of the support. CN104096573A discloses a method for preparing a hydrogenation catalyst, where the catalyst support is mainly alumina with a bimodal porous structure. This catalyst contains two active components, Pd and Ni. During catalyst preparation, the anti-coking component Ni is introduced into the macropores of the support in the form of a microemulsion, while the active component Pd is mainly distributed on the support surface, particularly in the micropores. CN104098426A discloses a selective hydrogenation method for C2 fractions suitable for pre-propane dehydrogenation processes. This method uses a selective hydrogenation catalyst whose support is alumina or mainly alumina, with a bimodal pore distribution structure, containing two active components, Pd and Ni. The anti-coking component Ni is mainly distributed in the macropores. While this method improves the catalyst's anti-coking performance, the single-component Ni in the macropores of the catalyst support reaches reduction temperatures above 500℃. Reduction at this temperature causes the active component Pd to aggregate, significantly reducing catalyst activity. To compensate for the loss of catalyst activity, the amount of active component needs to be increased, leading to a decrease in catalyst selectivity and a reduction in the utilization rate of the active component.

[0036] 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.

[0037] 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 the 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 0.5-24h, the impregnation temperature is 0-100℃, and the impregnation time is 0.5-50h.

[0038] CN112808288A discloses a catalyst with nitrogen-phosphorus or nitrogen-phosphorus 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%-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-sulfur-phosphorus 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.

[0039] 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.

[0040] CN112844406A discloses a method for preparing a catalyst for selective hydrogenation of the C2 fraction in light hydrocarbon cracking. The catalyst uses alumina or primarily alumina as the support, and has a bimodal pore distribution structure. The catalyst contains at least Pd, Ga, Ni, and Cu. The active component Pd is supported in both solution and microemulsion methods. Ga is supported in solution, and the solution-supported Pd is mainly distributed in the pores of the support at 58–75 nm. Ni and Cu are supported using a microemulsion impregnation method, and the microemulsion-supported Pd is mainly distributed in the macropores of the support at 350–700 nm, and are loaded after Ni and Cu.

[0041] 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 can be used for the selective hydrogenation of acetylene, propyne, and propadiene in C2–C3 cracked fractions. Summary of the Invention

[0042] To address the aforementioned technical problems, the present invention aims to provide a hydrogenation catalyst for removing alkynes from methanol-to-olefins products and its preparation method. The catalyst provided by the present invention has its active components atomically dispersed on the support, exhibiting excellent hydrogenation activity, selectivity, and anti-coking properties.

[0043] To achieve the above objectives, the first aspect of the present invention provides a hydrogenation catalyst for removing alkynes from methanol-to-olefins products. The catalyst includes a support and an active component. The support is a phosphorus-doped carbon material. The active component includes a main active component and a co-active component. The main active component includes Pd, and the co-active component includes Ni. The main active component and the co-active component are atomically dispersed on the support.

[0044] 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 0.025-0.60%, the content of the co-active component is 0.01-1.2%, 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 0.025-0.20%, the content of the co-active component is 0.01-0.4%, and the balance is the support.

[0045] 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 Ni, wherein Pd and Ni are atomically dispersed on the support, and based on 100% of the total mass of the catalyst, the Pd content is 0.025-0.60%, the Ni content is 0.01-1.2%, and the balance is the support; more preferably, based on 100% of the total mass of the catalyst, the Pd content is 0.025-0.20%, the Ni content is 0.01-0.4%, and the balance is the support.

[0046] 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.

[0047] According to a specific embodiment of the present invention, preferably, the catalyst is prepared by the following steps:

[0048] (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.

[0049] (2) The active component is loaded onto the phosphorus-doped carbon material support to obtain a catalyst semi-finished product;

[0050] (3) The catalyst semi-finished product is reduced to obtain the reduced catalyst, which is the hydrogenation and alkyne removal catalyst of methanol to olefins product.

[0051] In the catalyst preparation steps described above, preferably, in step (1), the phosphorus-containing compound includes phosphoric acid and / or phytic acid, etc.

[0052] In the catalyst preparation steps described above, preferably, in step (1), the carbohydrates include glucose and / or sucrose, etc.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] In the catalyst preparation steps described above, preferably, step (2) specifically includes:

[0061] (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.

[0062] (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.

[0063] Alternatively, step (2) of preparing the catalyst may specifically include:

[0064] (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.

[0065] (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.

[0066] 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.

[0067] In the catalyst preparation steps described above, preferably, in step (2), the precursor of the main active component includes one or a combination of palladium chloride, palladium nitrate, and palladium sulfate.

[0068] In the catalyst preparation steps described above, preferably, in step (2), the precursor of the co-active component includes one or a combination of nickel nitrate, nickel sulfate, nickel chloride, nickel aminosulfonate, and nickel bromide.

[0069] 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.

[0070] 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 Ni / mL Ni precursor aqueous solution.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] A second aspect of the present invention provides a method for preparing the above-mentioned hydrogenation and alkyne removal catalyst for methanol-to-olefins products, comprising the following steps:

[0077] (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.

[0078] (2) The active component is loaded onto the phosphorus-doped carbon material support to obtain a catalyst semi-finished product;

[0079] (3) The catalyst semi-finished product is reduced to obtain the reduced catalyst, which is the hydrogenation and alkyne removal catalyst of methanol to olefins product.

[0080] In the above preparation method, preferably, in step (1), the phosphorus-containing compound includes phosphoric acid and / or phytic acid, etc.

[0081] In the above preparation method, preferably, in step (1), the carbohydrate includes glucose and / or sucrose, etc.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] In the above preparation method, preferably, in step (1), the drying temperature is 120-160°C and the time is 4-12 hours.

[0087] 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.

[0088] 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.

[0089] In the above preparation method, preferably, step (2) specifically includes:

[0090] (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.

[0091] (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.

[0092] Alternatively, step (2) may specifically include:

[0093] (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.

[0094] (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.

[0095] 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.

[0096] In the above preparation method, preferably, in step (2), the precursor of the main active component includes one or a combination of palladium chloride, palladium nitrate and palladium sulfate.

[0097] In the above preparation method, preferably, in step (2), the precursor of the auxiliary active component includes one or a combination of nickel nitrate, nickel sulfate, nickel chloride, nickel aminosulfonate and nickel bromide.

[0098] 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.

[0099] 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 Ni / mL Ni precursor aqueous solution.

[0100] 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.

[0101] In the above preparation method, preferably, in step (2), the irradiation time under ultraviolet xenon lamp is 0.5 to 5.0 h.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] This invention provides a selective hydrogenation catalyst for removing acetylene from methanol-to-olefins products. More specifically, the catalyst of this invention is preferably a highly resistant coking Pd-Ni-PC catalyst that hydrogenates trace amounts of acetylene, propyne (MA), and propadiene (PD) contained in methanol-to-olefins products to ethylene and / or propylene.

[0106] Traditional hydrogenation catalysts for the removal of alkynes often have active components existing in nanoparticle or sub-nano cluster structures, which affects catalyst performance. The catalyst of 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 (preferably palladium and nickel) are dispersed in a single-atom state on the support (surface and within the pores) using a photoreduction method, rather than forming nanoparticle or sub-nano cluster structures. A Pd-Ni-PC single-atom catalyst was preferably prepared. The atomically dispersed active components exhibit the following characteristics in the selective hydrogenation of alkynes: the active components are atomically dispersed, increasing the utilization rate of metal atoms and thus improving the catalyst's hydrogenation activity; the adsorption capacity for olefins is reduced, thus improving the catalyst's hydrogenation selectivity; and the probability of polymerization and coking due to simultaneous adsorption of alkynes / diolefins at adjacent active sites is significantly reduced, thus improving the catalyst's anti-coking performance. Therefore, the hydrogenation catalyst for the removal of alkynes from methanol-to-olefins products provided by this invention exhibits excellent hydrogenation activity, selectivity, and long-term operational stability. Attached Figure Description

[0107] Figure 1 Aberration-corrected transmission electron microscope image of the catalyst provided in Example 1.

[0108] Figure 2 Transmission electron microscopy (TEM) image of the catalyst provided for Comparative Example 5.

[0109] Figure 3 This is a process flow diagram of hydrogenation and sequential separation of methanol-to-olefins products according to a specific embodiment of the present invention.

[0110] Explanation of main component symbols: 1—Single-stage adiabatic fixed-bed reactor, 2—Regenerator, 3—Separator, 4—Alkali washing tower, 5—Drying tower, 6—Methanation tower, 7—Ethylene removal tower, 8—Ethylene separation tower, 9—Propylene separation tower, 10—Propane removal tower, 11—Ethylene refining reactor. Detailed Implementation

[0111] 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.

[0112] According to a specific embodiment of the present invention, preferably, the catalyst of the present invention is prepared by the following steps:

[0113] (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;

[0114] 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; more preferably 0.02 to 0.4;

[0115] (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.

[0116] (2) a2 The palladium-supported support is added to the nickel 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;

[0117] or,

[0118] (2)-b1 The phosphorus-doped carbon material support is added to the nickel 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 nickel-loaded support.

[0119] (2)-b2 The nickel-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;

[0120] The palladium precursor includes 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;

[0121] The nickel precursor includes one or a combination of nickel nitrate, nickel sulfate, nickel chloride, nickel sulfamate, and nickel bromide; the concentration of nickel in the aqueous solution of the nickel precursor is 0.1–10 mg Ni / mL.

[0122] (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 catalyst mentioned above.

[0123] The technical solution of the present invention will be further described below through specific embodiments.

[0124] In the following specific embodiments and comparative examples, the analytical testing methods used include:

[0125] Content of active component in catalyst: atomic absorption spectrometry;

[0126] Single-atom morphology characterization: aberration-corrected transmission electron microscopy;

[0127] Conversion rate and selectivity are calculated using the following formula:

[0128] Acetylene conversion rate (%) = 100 × (inlet acetylene content - outlet acetylene content) / inlet acetylene content,

[0129] Ethylene selectivity (%) = 100 × (outlet ethylene content - inlet ethylene content) / (inlet acetylene content - outlet acetylene content),

[0130] MAPD conversion rate (%) = 100 × (inlet MAPD content - outlet MAPD content) / inlet MAPD content,

[0131] Propylene selectivity (%) = 100 × (outlet propylene content - inlet propylene content) / (inlet MAPD content - outlet MAPD content).

[0132] Example 1

[0133] This embodiment provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0134] (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;

[0135] (2) Take 10 mL of 0.25 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;

[0136] The palladium-supported support was added to an aqueous solution of nickel nitrate containing 3.1 mg of nickel 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.

[0137] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0138] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.025%, the Ni content is 0.01%, and the balance is a phosphorus-doped carbon material support.

[0139] 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 Ni are atomically dispersed on the support.

[0140] Example 2

[0141] This embodiment provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0142] (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;

[0143] (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.

[0144] The palladium-supported support was added to an aqueous solution of nickel nitrate containing 31.1 mg of nickel 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.

[0145] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0146] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.1%, the Ni content is 0.1%, and the balance is a phosphorus-doped carbon material support.

[0147] Example 3

[0148] This embodiment provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0149] (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;

[0150] (2) 10g of the phosphorus-doped carbon material carrier was added to a nickel nitrate aqueous solution containing 124.5mg of nickel 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 nickel-loaded carrier.

[0151] Measure 20 mL of 1 mg Pd / mL palladium sulfate aqueous solution, add it to the nickel-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.

[0152] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0153] According to atomic absorption spectrometry, the catalyst contains 0.2% Pd and 0.4% Ni by mass, with the remainder being a phosphorus-doped carbon material carrier.

[0154] Example 4

[0155] This embodiment provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0156] (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.

[0157] (2) 10g of the phosphorus-doped carbon material carrier was added to a nickel nitrate aqueous solution containing 217.9mg of nickel 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 nickel-loaded carrier.

[0158] Measure 40 mL of 1 mg Pd / mL Pd(NO3)2 aqueous solution, add it to the nickel-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 vacuum of 18 Pa for 5 h, and then calcine it at 400 °C for 4 h under an inert atmosphere to obtain the catalyst semi-finished product.

[0159] (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 hydrogenation and alkyne removal catalyst for methanol-to-olefins products.

[0160] According to atomic absorption spectrometry, the catalyst contains 0.4% Pd and 0.7% Ni by mass, with the remainder being a phosphorus-doped carbon material carrier.

[0161] Example 5

[0162] This embodiment provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0163] (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;

[0164] (2) Take 60 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.

[0165] The palladium-supported support was added to an aqueous solution of nickel nitrate containing 373.6 mg of nickel 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.

[0166] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0167] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.6%, the Ni content is 1.2%, and the balance is a phosphorus-doped carbon material support.

[0168] Comparative Example 1

[0169] This comparative example provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0170] (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.

[0171] (2) Take 10 mL of 0.25 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;

[0172] The palladium-supported support was added to an aqueous solution of nickel nitrate containing 3.1 mg of nickel 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.

[0173] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0174] Atomic absorption spectrometry analysis revealed that, based on the total mass of the catalyst (100%), the Pd content was 0.025%, the Ni content was 0.01%, and the remainder was a carbon support. The active components in the catalyst provided in this comparative example are not entirely dispersed as single atoms; nanoparticles are present.

[0175] Comparative Example 2

[0176] This comparative example provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0177] (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.

[0178] (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.

[0179] The palladium-supported support was added to an aqueous solution of nickel nitrate containing 31.1 mg of nickel 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.

[0180] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0181] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.1%, the Ni content is 0.1%, and the balance is the catalyst support.

[0182] Comparative Example 3

[0183] This comparative example provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0184] (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 (same as Example 3);

[0185] (2) 10g of the phosphorus-doped carbon material carrier was added to a nickel nitrate aqueous solution containing 124.5mg of nickel 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 nickel-loaded carrier.

[0186] Measure 15 mL of 10 mg Pd / mL palladium sulfate aqueous solution, add it to the nickel-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.

[0187] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0188] According to atomic absorption spectrometry, the catalyst contains 1.5% Pd and 0.4% Ni by mass, with the remainder being a phosphorus-doped carbon material carrier.

[0189] Comparative Example 4

[0190] This comparative example provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0191] (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 (same as Example 4);

[0192] (2) 10g of the phosphorus-doped carbon material carrier was added to a nickel nitrate aqueous solution containing 1556.5mg of nickel 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 nickel-loaded carrier.

[0193] Measure 40 mL of 1 mg Pd / mL Pd(NO3)2 aqueous solution, add it to the nickel-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 vacuum of 18 Pa for 5 h, and then calcine it at 400 °C for 4 h under an inert atmosphere to obtain the catalyst semi-finished product.

[0194] (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 hydrogenation and alkyne removal catalyst for methanol-to-olefins products.

[0195] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.4%, the Ni content is 5%, and the balance is a phosphorus-doped carbon material support.

[0196] Comparative Example 5

[0197] This comparative example provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0198] (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°C for 12 hours, then dried at 160°C for 12 hours, and then ball-milled for 10 minutes to obtain powder; the powder was calcined at 1000°C for 5 hours under an inert atmosphere to obtain a phosphorus-doped carbon material carrier (same as Example 5);

[0199] (2) Take 60 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.

[0200] The palladium-supported support was added to an aqueous solution of nickel nitrate containing 373.6 mg of nickel nitrate, and impregnated and adsorbed at room temperature for 1 hour. Then it was dried at 100°C for 3 hours and calcined at 500°C for 4 hours to obtain a catalyst semi-finished product.

[0201] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0202] Atomic absorption spectrometry analysis revealed that, based on the total mass of the catalyst (100%), the Pd content was 0.6%, the Ni content was 1.2%, and the balance 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 Ni are almost dispersed at the nanoparticle level.

[0203] Comparative Example 6

[0204] This comparative example provides a catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, which is prepared through the following steps:

[0205] (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.

[0206] (2) Take 10 mL of 0.25 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;

[0207] The palladium-supported support was added to an aqueous solution of nickel nitrate containing 3.1 mg of nickel 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.

[0208] (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 and alkyne removal catalyst for methanol-to-olefins products.

[0209] According to atomic absorption spectrometry, the total mass of the catalyst is 100%, the Pd content is 0.025%, the Ni content is 0.01%, and the balance is a nitrogen-phosphorus co-doped carbon support.

[0210] The catalysts provided in the above embodiments and comparative examples were evaluated for performance in a single-stage adiabatic fixed-bed reactor. The reaction conditions in the single-stage adiabatic fixed-bed reactor were: space velocity 10000 h⁻¹. -1 The pressure was 2.0 MPa, and the reaction temperature was 40 °C. The composition of the reactants entering the single-stage adiabatic fixed-bed reactor is shown in Table 2. The evaluation results of the catalysts provided in the examples and comparative examples are shown in Table 3.

[0211] Table 2 Composition of reactants

[0212] <![CDATA[H2]]> 1.2～2.5 <![CDATA[C2H2]]> 0～0.01 <![CDATA[N2]]> 0.5～1.0 <![CDATA[C2H6]]> 1～2 <![CDATA[O2]]> 0.005～0.015 <![CDATA[C2H4]]> 40～60 CO 0.60～1.0 <![CDATA[C3H8]]> 1.5～3 <![CDATA[CO2]]> 0.20～0.60 <![CDATA[C3H6]]> 15～40 <![CDATA[H2S]]> 0～0.0008 <![CDATA[C3H4]]> 0～0.01 <![CDATA[CH4]]> 6～10 <![CDATA[C4]]> 3～6 <![CDATA[C 5+ ]]> 6～10

[0213] Table 3 Catalyst Evaluation Results

[0214]

[0215] Note: Coking amount = (Loss on ignition at 600℃ ÷ Initial catalyst charge) × 100%

[0216] As can be seen from Tables 2 and 3 above, the active components in the catalysts provided in Examples 1-5 of this invention are atomically dispersed, resulting in improved metal atom utilization and thus high catalyst hydrogenation activity. The catalyst's adsorption capacity for olefins is reduced, leading to high hydrogenation selectivity. The probability of polymerization and coking due to simultaneous adsorption of alkynes / diolefins at adjacent active sites is significantly reduced, thus demonstrating strong anti-coking performance. Therefore, the methanol-to-olefins hydrogenation catalyst for removing alkynes provided by this invention exhibits excellent hydrogenation activity, selectivity, and long-term operational stability.

[0217] After hydrogenating the methanol-to-olefins (MTO) products using a single-stage adiabatic fixed-bed reactor, a sequential separation process can be implemented. The process flow diagram for hydrogenation, acetylene removal, and sequential separation of the MTO products is shown below. Figure 3As shown. The bottom of the single-stage adiabatic fixed-bed reactor 1 has an inlet for the methanol-to-olefins product (i.e., the mixed gas for hydrogenation). The outlet at the top of the single-stage adiabatic fixed-bed reactor 1 is connected to the inlet of separator 3 via a pipeline. The catalyst outlet at the bottom of the single-stage adiabatic fixed-bed reactor 1 is connected to the catalyst inlet of regeneration tower 2 via a pipeline; the hydrogenation catalyst is regenerated in regeneration tower 2. The mixed gas outlet at the top of separator 3 is connected to the inlet of alkaline washing tower 4 via a pipeline. The bottom of separator 3 has a water outlet. In step 3, water and other substances in the mixed gas after hydrogenation are separated. The mixed gas outlet at the top of the alkali washing tower 4 is connected to the inlet of the drying tower 5 via a pipeline. The alkali washing tower 4 has an alkali inlet at the top and a CO2 outlet at the bottom, where CO2 is removed from the mixed gas. The outlet of the drying tower 5 is connected to the inlet of the demethanizer 6 via a pipeline, where the mixed gas undergoes further dehydration and drying. The demethanizer 6 has a methane outlet at the top and a mixed gas outlet at the bottom via a pipeline. The inlet of the deethaner 7 is connected to the demethanizer 6, where methane is separated. The C2 mixture outlet at the top of the deethaner 7 is connected via a pipeline to the inlet of the ethylene refining reactor 11, and the C3+ mixture outlet at the bottom of the deethaner 7 is connected via a pipeline to the first inlet of the propylene separator 9, where the C2 mixture is separated. The outlet of the ethylene refining reactor 11 is connected via a pipeline to the inlet of the ethylene separator 8, which has an ethylene outlet at the top. The ethane outlet of the ethylene separator 8 is connected via... The pipeline is connected to the second inlet of propylene separation tower 9. After the C2 mixed gas passes through ethylene refining reactor 11 and ethylene separation tower 8, ethylene is separated and can be sent to the polyethylene process. The top of propylene separation tower 9 has a propylene outlet, and the mixed material outlet at the bottom of propylene separation tower 9 is connected to the inlet of propane removal tower 10 through a pipeline. Propylene is separated in propylene separation tower 9. The top of propane removal tower 10 has a propane outlet, and the bottom of propane removal tower 10 has a mixed material outlet. Propane is separated in propane removal tower 10.

Claims

1. A catalyst for the hydrogenation and removal of alkynes from methanol-to-olefins products, 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 Ni, and the main active component and the co-active component are atomically dispersed on the support; based on the total mass of the catalyst (100%), the content of the main active component is 0.025~0.60%, the content of the co-active component is 0.01~1.2%, 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 a reduced catalyst, which is the hydrogenation and acetylene removal catalyst for methanol-to-olefins product. 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 hydrogenation catalyst for removing yetane from methanol-to-olefins products according to claim 1, wherein, Based on the total mass of the catalyst (100%), the content of the main active component is 0.025~0.20%, the content of the co-active component is 0.01~0.4%, and the balance is the support.

3. A method for preparing a hydrogenation catalyst for removing yetane from methanol-to-olefins products according to claim 1 or 2, 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 a reduced catalyst, which is the hydrogenation and acetylene removal catalyst for methanol-to-olefins product. 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.

4. The preparation method according to claim 3, wherein, In step (1), the phosphorus-containing compound includes phosphoric acid and / or phytic acid.

5. The preparation method according to claim 3, wherein, In step (1), the carbohydrates include glucose and / or sucrose.

6. The preparation method according to claim 3, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.0001 to 1000.

7. The preparation method according to claim 6, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.001 to 10.

8. The preparation method according to claim 7, wherein, In step (1), the molar ratio of the phosphorus-containing compound and the carbohydrate is 0.02 to 0.

4.

9. The preparation method according to claim 3, 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.

10. The preparation method according to claim 3, wherein, In step (1), the temperature of the hydrothermal reaction is 160~300℃ and the time is 4~12h.

11. The preparation method according to claim 3, wherein, In step (1), the drying temperature is 120~160℃ and the time is 4~12h.

12. The preparation method according to claim 3, 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.

13. The preparation method according to claim 3, wherein, In step (1), the calcination is carried out under an inert atmosphere at a temperature of 600-1000°C for 1-5 hours.

14. The preparation method according to claim 3, wherein, In step (2), the precursor of the main active component includes one or a combination of palladium chloride, palladium nitrate and palladium sulfate.

15. The preparation method according to claim 3, wherein, In step (2), the precursor of the co-active component includes one or a combination of nickel nitrate, nickel sulfate, nickel chloride, nickel aminosulfonate and nickel bromide.

16. The preparation method according to claim 3, 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.

17. The preparation method according to claim 3, wherein, In step (2), the concentration of the active component in the precursor aqueous solution of the active component is 0.1~10 mgNi / mLNi precursor aqueous solution.

18. The preparation method according to claim 3, wherein, In step (2), the illumination time under the ultraviolet xenon lamp is 0.5~5.0h.

19. The preparation method according to claim 3, wherein, In step (2), the freeze-drying time is 2-7 hours and the vacuum degree of the freeze-drying is 15-20 Pa.

20. The preparation method according to claim 3, 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.

21. The preparation method according to claim 3, 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.

22. The preparation method according to claim 21, 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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