Alkyne selective hydrogenation catalyst with high activity and high selectivity and preparation method thereof

Abstract

The invention provides an alkyne selective hydrogenation catalyst with high activity and high selectivity and a preparation method thereof. The catalyst is a compound of metallic nickel and alkali metal hydride and is marked as nickel-alkali metal hydride, high catalytic reaction activity and high olefin selectivity can be both considered by regulating and controlling the proportion of the nickel elementary substance and the alkali metal hydride, and compared with the metallic nickel and the alkali metal hydride as the catalyst, the catalyst has the advantages that the catalytic activity is high; the catalytic activity and the olefin selectivity are greatly improved. The nickel-alkali metal hydride catalyst is suitable for alkyne selective hydrogenation reaction in a high-temperature and high-pressure fixed bed gas phase reaction system, is also suitable for alkyne selective hydrogenation reaction in a high-temperature and high-pressure reaction kettle liquid-solid phase reaction system, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogenation reaction and catalysis, and in particular relates to an alkyne selective hydrogenation catalyst with both high activity and high selectivity and a preparation method thereof. Background Art

[0002] Hydrogenation reaction plays an important role in industrial production and is an important step in the production process of high value-added products such as petrochemicals, medicines, spices, pesticides, etc. Selective hydrogenation of alkynes, that is, the selective hydrogenation of carbon-carbon triple bonds to form carbon-carbon double bonds, is one of the most important hydrogenation reactions. Its target product olefins have high reactivity and can participate in a variety of chemical reactions such as oxidation, addition, and polymerization. They are important basic raw materials for industrial production. Taking ethylene as an example, according to statistics, ethylene and its derivatives account for more than 75% of petrochemical products. The production technology, output and scale of ethylene mark the development level of the country's petrochemical industry. However, due to the limitations of existing processes, the olefins obtained usually contain a small amount of alkynes. The presence of these alkyne impurities will have an irreversible poisoning effect on the catalyst of the downstream polymerization reaction, resulting in a decrease in the quality of downstream products and a decrease in reaction efficiency. Catalytic selective hydrogenation is currently the most effective and economical method for removing a small amount of alkyne impurities in olefins. The development of alkyne semi-hydrogenation processes with high alkyne conversion and high olefin selectivity has received widespread attention. Therefore, exploring catalysts with both high activity and high selectivity is the main challenge of the alkyne selective hydrogenation process.

[0003] Heterogeneous catalysts overcome the shortcomings of homogeneous catalysts such as difficulty in separation and recovery and poor thermal stability, and become selective hydrogenation catalysts with more application prospects. Classic hydrogenation catalysts are mainly precious metals (Pd, Pt, Rh), which show excellent catalytic activity for a variety of alkyne substrates. Taking palladium catalysts as an example, its high hydrogenation activity for acetylene, phenylacetylene, dienes, nitroaromatics and other substances was reported as early as the last century, so the research on Pd-based catalysts is the most extensive. The Lindlar catalyst widely used in industry is made of palladium adsorbed on a carrier (calcium carbonate or barium sulfate) and a small amount of inhibitor (lead acetate or quinoline) is added. The palladium content in the catalyst is 5%-10%. The catalyst improves the selectivity of the target olefin product by introducing an active inhibitor, but the utilization efficiency of metal palladium is low. Research in recent years has focused on emerging catalytic systems such as bimetallic alloy catalysts and single-atom catalysts, and precious metals are still important active components.

[0004] Due to the low abundance of precious metals on the earth, in order to reduce dependence on precious metals and reduce catalyst costs, a large number of studies have turned to non-precious metal catalysts in recent years. Among them, the transition metal Ni has attracted attention due to its superior hydrogenation activity. Research on Ni-based catalysts mainly revolves around Raney nickel catalysts, supported nickel catalysts and amorphous nickel catalysts. Taking the widely used Raney nickel catalyst in industry as an example, although it is low in cost, the commercially available Raney nickel is unstable and difficult to handle. In addition, Ni has strong activity in the hydrogenolysis and polymerization of carbon-carbon bonds, which can easily lead to excessive hydrogenation of alkynes or the formation of polymers such as green oil.

[0005] Therefore, the development of new, efficient and low-cost selective hydrogenation catalysts is a key issue that needs to be urgently addressed in the field of alkyne hydrogenation. Summary of the invention

[0006] In view of the above technical status, the present invention provides a catalyst for selective hydrogenation of alkynes to prepare olefins, which has both high catalytic activity and high olefin selectivity, and can achieve high catalytic activity and high olefin selectivity under mild conditions.

[0007] The technical solution provided by the present invention is: an alkyne selective hydrogenation catalyst with both high activity and high selectivity, wherein the catalyst is a complex of metal nickel and alkali metal hydride, recorded as nickel-alkali metal hydride, wherein the mass percentage of the metal nickel is 1%-80%, and the mass percentage of the alkali metal hydride is 20%-99%.

[0008] The alkali metal hydride is not limited, including lithium hydride, sodium hydride, potassium hydride, rubidium hydride, cesium hydride, etc.

[0009] Taking high catalytic activity (ie, high conversion rate of alkyne substrate) into consideration, preferably, the mass percentage of metallic nickel in the catalyst is relatively high, preferably above 50%.

[0010] Taking into account high olefin selectivity and low alkane selectivity, it is preferred that the mass percentage of metallic nickel in the catalyst is relatively low, preferably below 50%.

[0011] When considering both high catalytic activity and high olefin selectivity, the mass percentage of the metal nickel in the catalyst needs to be optimized. After a lot of experimental exploration by the inventors, it is found that the mass percentage of the metal nickel is preferably 5%-80%, and more preferably 10%-50%.

[0012] Preferably, the molar ratio of the catalyst to the hydrocarbon substrate is 1:20-1:5.

[0013] The preparation method of the nickel-alkali metal hydride is not limited. As an implementation method, the preparation method comprises the following steps:

[0014] The nickel precursor powder and the alkali metal hydride powder are mixed and reacted to obtain nickel element, alkali metal salt and unreacted alkali metal hydride; the alkali metal salt is dissolved in the solvent and removed by centrifugation washing with a solvent to obtain a complex of nickel element and alkali metal hydride.

[0015] Preferably, the nickel precursor powder is mixed with the alkali metal hydride powder in an inert atmosphere. In order to improve the reaction efficiency, preferably, the nickel precursor powder is mixed with the alkali metal hydride powder and then ball milled.

[0016] The precursor of the nickel metal is not limited, and includes one or more of nickel chloride, nickel nitrate, nickel carbonate, nickel acetate, etc.

[0017] When the nickel-alkali metal hydride is used as the selective hydrogenation catalyst for alkynes in the present invention, it can be realized in a high-temperature and high-pressure fixed-bed gas phase reaction system, or in a high-temperature and high-pressure reactor liquid-solid phase reaction system.

[0018] In a high-temperature and high-pressure fixed-bed gas phase reaction system, the catalyst is placed in a high-temperature and high-pressure fixed bed, and a gas-phase alkyne substrate, hydrogen and an inert gas are introduced to carry out the selective hydrogenation of alkynes to prepare olefins. The reaction temperature can be in the range of 25-400°C; the gas-phase alkyne substrate, hydrogen and the inert gas form a mixed gas, and the mixed gas pressure can be 0.01-1MPa; the molar ratio of the gas-phase alkyne substrate, hydrogen and the inert gas can be 1:(1-20):(1-20); the reaction gas space velocity can be 1000-100000mL·g cat -1 ·h -1 Preferably, the molar ratio of the catalyst to the hydrocarbon substrate is 1:20-1:5.

[0019] In a high-temperature and high-pressure reactor, the catalyst is placed in a high-temperature and high-pressure reactor, and a liquid phase alkyne substrate, hydrogen and an inert gas are introduced to carry out the selective hydrogenation of alkynes to prepare olefins. The molar ratio of the catalyst to the alkyne substrate can be 1:5-100:1; the reaction temperature can be 25-300°C; the reaction pressure can be 0.01-20MPa; and the reaction time can be 1-50h. Preferably, the molar ratio of the catalyst to the hydrocarbon substrate is 1:20-1:5.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention uses nickel-alkali metal hydride as a catalyst for selective hydrogenation of alkynes to prepare olefins, wherein the active components of the catalyst are metal nickel and alkali metal hydride. The composite of alkali metal hydride can not only improve the catalytic activity, but also reduce the over-hydrogenation of alkynes caused by the use of single nickel as a catalyst. By adjusting the ratio of nickel element to alkali metal hydride, high catalytic reaction activity and high olefin selectivity can be taken into account. Compared with metal nickel as a catalyst and alkali metal hydride as a catalyst, the catalytic activity and olefin selectivity are greatly improved.

[0022] (2) The nickel-alkali metal hydride catalyst of the present invention is suitable for the selective hydrogenation reaction of alkynes in a high-temperature and high-pressure fixed-bed gas-phase reaction system, and is also suitable for the selective hydrogenation reaction of alkynes in a liquid-solid phase in a high-temperature and high-pressure reactor.

[0023] In a high-temperature and high-pressure fixed-bed gas-phase reaction system, when the catalyst of the present invention is used, an alkyne conversion rate of more than 90% can be achieved at normal pressure and below 50° C. (i.e., less than or equal to 50° C.), and a high alkyne conversion rate and a high olefin selectivity can be achieved at normal pressure and below 200° C. (i.e., less than or equal to 200° C.). For example, an alkyne conversion rate of more than 80% and an olefin selectivity of more than 50% can be achieved, which are much higher than the alkyne conversion rate and olefin selectivity when elemental nickel is used as a catalyst and when alkali metal hydrides are used as catalysts.

[0024] In a high-temperature and high-pressure reactor, when the catalyst of the present invention is used, under conditions below 1 MPa, close to room temperature (25±5° C.), an alkyne conversion rate of more than 90%, preferably more than 95%, or even 100% can be achieved, and at the same time, the olefin selectivity can be more than 40%, or even more than 50%, achieving excellent technical effects, which are much higher than the alkyne conversion rate and olefin selectivity when elemental nickel is used as a catalyst and alkali metal hydride is used as a catalyst.

[0025] (3) In the present invention, the catalyst does not require an additional carrier, has a simple preparation method, is low in cost, can achieve high catalytic activity and high selectivity under mild conditions, and has good application prospects.

[0026] In the present invention, the alkyne conversion, olefin selectivity, and alkane selectivity are defined as follows:

[0027] DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with embodiments. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention, and non-essential improvements and adjustments made to the present invention by those skilled in the art based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0029] The words “include”, “including” and the like used in the present invention should be interpreted as including rather than being exclusive or exhaustive; that is, the meaning is “including but not limited to”.

[0030] Embodiment 1:

[0031] In an inert gas glove box, accurately weigh 200 mg of anhydrous nickel chloride and 90.74 mg of LiH, mix them evenly in a mortar, and then transfer them to a stainless steel ball mill, add stainless steel balls, and the ball-to-material ratio is 10:1. After sealing the ball mill, ball mill the mixture at 200 rpm for 3 h.

[0032] The main chemical reaction in the reaction is: NiCl2+7LiH=Ni+2LiCl+5LiH+H2

[0033] After the ball milling, the product was taken out and placed in a centrifuge tube, 20 mL of tetrahydrofuran was added, and centrifuged at a speed of 10,000 rpm for 5 min, and repeated three times to fully wash the LiCl. The washed product was vacuum dried in a vacuum drying oven overnight to obtain a nickel-lithium hydride catalyst, wherein the mass percentage of Ni was 50%, and the mass percentage of LiH was 50%, recorded as 50% Ni-50% LiH.

[0034] The 50% Ni-50% LiH is used as a catalyst for acetylene hydrogenation. Accurately weigh 50 mg of 50% Ni-50% LiH catalyst, place it in a quartz tube, and carry out acetylene hydrogenation in a high-temperature and high-pressure fixed-bed reactor. The reaction atmosphere is acetylene gas (a mixture of acetylene and argon, in which acetylene accounts for 2.5% by volume), hydrogen and Ar gas. (2.5% C2H2-Ar): H2:Ar = 1:1:1, the reaction temperature range is 25-300°C, the reaction pressure is 0.01MPa (ie, normal pressure), and the reaction gas space velocity is 36000mL·g cat -1 ·h -1 .

[0035] Embodiment 2:

[0036] In a glove box protected by high-purity argon, accurately weigh 200 mg of anhydrous nickel chloride and 387 mg of LiH, mix them evenly in a mortar, and then transfer them to a stainless steel ball mill, add stainless steel balls, and the ball-to-material ratio is 10:1. After sealing the ball mill, ball mill it in a ball mill at 200 rpm for 3 h.

[0037] The main chemical reaction in the reaction is: NiCl2+7LiH=Ni+2LiCl+5LiH+H2

[0038] After the ball milling, the product was taken out and placed in a centrifuge tube, 20 mL of tetrahydrofuran was added, and centrifuged at a speed of 10,000 rpm for 5 min, and repeated three times to fully wash and remove LiCl. The washed product was vacuum dried in a vacuum drying oven overnight to obtain a nickel-lithium hydride catalyst, wherein the mass percentage of Ni was 20%, and the mass percentage of LiH was 80%, recorded as 20% Ni-80% LiH.

[0039] The 20% Ni-80% LiH was used as a catalyst for acetylene hydrogenation. 50 mg of 20% Ni-80% LiH catalyst was accurately weighed and placed in a quartz tube. The acetylene hydrogenation reaction was carried out in a high temperature and high pressure fixed bed reaction. The reaction atmosphere was (2.5% C2H2-Ar): H2:Ar = 1:1:1, the reaction temperature range was 25-300°C, the reaction pressure was 0.01 MPa, and the reaction gas space velocity was 36000 mL·g cat -1 ·h -1 .

[0040] Comparative Example 1:

[0041] In a glove box protected by high-purity argon, accurately weigh 200 mg of anhydrous nickel chloride and 24.6 mg of LiH, mix them evenly in a mortar, and then transfer them to a stainless steel ball mill, add stainless steel balls, and the ball-to-material ratio is 10:1. After sealing the ball mill, ball mill it in a ball mill at 200 rpm for 3 h.

[0042] The main chemical reaction in the reaction is: NiCl2+2LiH=Ni+2LiCl+H2

[0043] After the ball milling, the product was taken out and placed in a centrifuge tube, 20 mL of tetrahydrofuran was added, and centrifuged at a speed of 10,000 rpm for 5 min, and repeated three times to fully wash and remove LiCl. The washed product was vacuum dried in a vacuum drying oven overnight to obtain metal Ni powder.

[0044] The metal Ni powder was used as a catalyst for acetylene hydrogenation reaction. 50 mg Ni powder was accurately weighed and placed in a quartz tube. The acetylene hydrogenation reaction was carried out in a high temperature and high pressure fixed bed reaction evaluation system. The reaction atmosphere was (2.5% C2H2-Ar): H2:Ar = 1:1:1, the reaction temperature range was 25-300 ° C, the reaction pressure was normal pressure, and the reaction gas space velocity was 36000 mL·g cat -1 ·h -1 .

[0045] Comparative Example 2:

[0046] LiH powder was used as a catalyst for acetylene hydrogenation. 50 mg of LiH was accurately weighed and placed in a quartz tube. The acetylene hydrogenation reaction was carried out in a high temperature and high pressure fixed bed reaction evaluation system. The reaction atmosphere was (2.5% C2H2-Ar): H2:Ar = 1:1:1, the reaction temperature range was 25-300 °C, the reaction pressure was atmospheric pressure, and the reaction gas space velocity was 36000 mL·g cat -1 ·h -1 .

[0047] Embodiment 3:

[0048] The preparation of 20% Ni-80% LiH is the same as in Example 2.

[0049] The 20% Ni-80% LiH was used as a catalyst for the hydrogenation reaction of 3-nitrobenzeneacetylene. The 3-nitrobenzeneacetylene substrate, 30 mg of 20% Ni-80% LiH, and 5 mL of toluene were placed in a quartz liner, and the molar ratio of the 3-nitrobenzeneacetylene substrate to the catalyst active component nickel was 10:1. The 3-nitrobenzeneacetylene hydrogenation reaction was carried out in a high-pressure reactor. The reaction temperature was room temperature, the reaction pressure was 0.6 MPa, and the reaction time was 12 h.

[0050] Embodiment 4:

[0051] The preparation of 50% Ni-50% LiH is the same as in Example 1.

[0052] The 50% Ni-50% LiH was used as a catalyst for the hydrogenation reaction of 3-nitrobenzeneacetylene. The 3-nitrobenzeneacetylene substrate, 30 mg of 50% Ni-50% LiH, and 5 mL of toluene were placed in a quartz liner, and the molar ratio of 3-nitrobenzeneacetylene to the catalyst active component nickel was 10:1. The 3-nitrobenzeneacetylene hydrogenation reaction was carried out in a high-pressure reactor. The reaction temperature was room temperature, the reaction pressure was 0.6 MPa, and the reaction time was 12 h.

[0053] Comparative Example 3:

[0054] LiH powder was used as a catalyst for acetylene hydrogenation. 3-Nitrophenylacetylene substrate, 30 mg LiH, and 5 mL toluene were placed in a quartz container. The molar ratio of 3-nitrophenylacetylene to the catalyst active component LiH was 10:1. The catalytic activity test of 3-nitrophenylacetylene hydrogenation was carried out in a high-pressure reactor. The reaction temperature was room temperature, the reaction pressure was 0.6 MPa, and the reaction time was 12 h.

[0055] Comparative Example 4:

[0056] The preparation of metal Ni powder is the same as that of Comparative Example 1.

[0057] The metal Ni powder was used as a catalyst for the hydrogenation reaction of 3-nitrosphenylacetylene. The 3-nitrosphenylacetylene substrate, 30 mg Ni powder, and 5 mL toluene were placed in a quartz container, and the molar ratio of 3-nitrosphenylacetylene to the catalyst active component Ni was 10:1. The catalytic activity test of the hydrogenation of 3-nitrosphenylacetylene was carried out in a high-pressure reactor. The reaction temperature was room temperature, the reaction pressure was 0.6 MPa, and the reaction time was 12 h.

[0058] Embodiment 5:

[0059] The preparation of 50% Ni-50% LiH is the same as in Example 1.

[0060] The 50% Ni-50% LiH was used as a catalyst for the hydrogenation of 4-fluorophenylacetylene. The 3-nitrophenylacetylene substrate, 30 mg of 50% Ni-50% LiH catalyst, and 5 mL of toluene were placed in a quartz liner, and the molar ratio of 4-fluorophenylacetylene to the active component of the catalyst, nickel, was 10:1. The hydrogenation of 4-fluorophenylacetylene was carried out in a high-pressure reactor. The reaction temperature was room temperature, the reaction pressure was 0.6 MPa, and the reaction time was 12 h.

[0061] Embodiment 6:

[0062] The preparation of 50% Ni-50% LiH is the same as in Example 1.

[0063] The 50% Ni-50% LiH was used as a catalyst for the hydrogenation reaction of 4-aminophenylacetylene. 4-aminophenylacetylene, 30 mg 50% Ni-50% LiH, and 5 mL toluene were placed in a quartz liner, and the molar ratio of 4-aminophenylacetylene to the catalyst active component nickel was 10:1. The hydrogenation reaction of 4-aminophenylacetylene was carried out in a high-pressure reactor. The reaction temperature was room temperature, the reaction pressure was 0.6 MPa, and the reaction time was 12 h.

[0064] Embodiment 7:

[0065] The preparation of 50% Ni-50% LiH is the same as in Example 1.

[0066] The 50% Ni-50% LiH was used as a catalyst for the hydrogenation of benzooctyne. Benzene octyne, 30 mg 50% Ni-50% LiH, and 5 mL toluene were placed in a quartz liner, and the molar ratio of benzooctyne to the active component of the catalyst, nickel, was 10:1. The hydrogenation of benzooctyne was carried out in a high-pressure reactor. The reaction temperature was room temperature, the reaction pressure was 0.6 MPa, and the reaction time was 12 h.

[0067] The catalytic performance of the gas-phase acetylene hydrogenation reaction in Example 1-2 and Comparative Example 1-2 is shown in Table 1 below.

[0068] Table 1: Catalytic performance of gas-phase acetylene hydrogenation reaction in Example 1-2 and Comparative Example 1-2

[0069]

[0070] From Table 1 we can see that:

[0071] (1) In a high-temperature and high-pressure fixed-bed gas-phase reaction system, the reaction activity and selectivity can be controlled by adjusting the ratio of metal to hydride;

[0072] (2) LiH and Ni are essential components of the catalyst of the present invention, and neither of them can be missing;

[0073] (3) In Example 1, the nickel mass percentage in the nickel-alkali metal hydride is 50%, and the conversion rate can reach 100% at 50° C., which is much higher than the conversion rate when nickel is used as a catalyst in Comparative Example 1 and the conversion rate when LiH is used as a catalyst in Comparative Example 2, but the olefin selectivity is still low;

[0074] In Example 2, the mass percentage of nickel in the nickel-alkali metal hydride at 50°C is 20%. Compared with the nickel as catalyst in Comparative Example 1, although the conversion rate is slightly reduced, the olefin selectivity is greatly improved. Compared with LiH as the catalyst in Comparative Example 2, not only the conversion rate is greatly improved, but also the olefin selectivity is greatly improved from 0% to 20%. In Example 2, at 200°C, compared with LiH as the catalyst in Comparative Example 2, not only the conversion rate is greatly improved, but also the olefin selectivity is greatly improved from 2% to 44%.

[0075] The catalytic performance of the liquid / solid phase alkyne substrate hydrogenation reaction in Example 3-8 and Comparative Example 3-4 is shown in Table 2.

[0076] Table 2: Catalytic performance of liquid / solid phase alkyne substrate hydrogenation reaction in Examples 3-8 and Comparative Examples 3-4

[0077]

[0078] From Table 2 we can see that:

[0079] (1) In the liquid / solid phase alkyne substrate hydrogenation reaction system in a high temperature and high pressure reactor, the reaction activity and selectivity can be controlled by adjusting the ratio of metal to hydride;

[0080] (2) LiH and Ni are essential components of the catalyst of the present invention, and neither of them can be missing;

[0081] (3) When the catalyst of the present invention is used, an alkyne conversion rate of more than 95%, or even 100%, can be achieved under the conditions of 0.6 MPa and 25° C., and an excellent technical effect of an olefin selectivity of more than 50% can be achieved. Compared with the case where nickel is used as a catalyst and LiH is used as a catalyst, the alkyne conversion rate is greatly improved; and compared with the case where nickel is used as a catalyst and LiH is used as a catalyst, the olefin selectivity is also greatly improved and can be higher than 50%.

[0082] The above-described embodiments provide a detailed description of the technical solutions of the present invention. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An alkyne selective hydrogenation catalyst having both high activity and high selectivity, characterized by: The catalyst is a complex of metal nickel and alkali metal hydride, recorded as nickel-alkali metal hydride, wherein the mass percentage of metal nickel is 1%-80%, and the mass percentage of alkali metal hydride is 20%-99%.

2. The catalyst according to claim 1, characterized in that: The alkali metal hydride includes one or more of lithium hydride, sodium hydride, potassium hydride, rubidium hydride, and cesium hydride.

3. The catalyst according to claim 1, characterized in that: In the catalyst, the mass percentage of metal nickel is 5%-80%, and the mass percentage of alkali metal hydride is 10%-50%.

4. The catalyst according to claim 1, characterized in that: The alkyne includes one or more of acetylene, 3-nitrobenzeneacetylene, 4-fluorophenylacetylene, 4-aminophenylacetylene, 1-heptyne and phenyloctyne.

5. The catalyst according to claim 1, characterized in that: The molar ratio of the catalyst to the alkyne substrate is 1:20-1:

5.

6. The catalyst according to claim 1, characterized in that: The selective hydrogenation reaction of alkynes is realized in a high-temperature and high-pressure fixed-bed gas phase reaction system, or in a high-temperature and high-pressure reactor liquid-solid phase reaction system.

7. The method for preparing a catalyst as claimed in claim 1, characterized in that: The steps include: The nickel precursor powder and the alkali metal hydride powder are mixed and reacted to obtain nickel element, alkali metal salt and unreacted alkali metal hydride; the alkali metal salt is dissolved in the solvent and removed by centrifugation washing with a solvent to obtain a complex of nickel element and alkali metal hydride.

8. The preparation method according to claim 7, characterized in that: The nickel metal precursor includes one or more of nickel chloride, nickel nitrate, nickel carbonate, and nickel acetate; Preferably, the nickel precursor powder is mixed with the alkali metal hydride powder in an inert atmosphere; Preferably, the nickel precursor powder and the alkali metal hydride powder are mixed and then ball-milled.

9. A method for preparing olefins by selective hydrogenation of alkynes in a high temperature and high pressure fixed bed gas phase reaction system, characterized in that: Using the catalyst described in any one of claims 1 to 6; Under normal pressure and below 50°C, the conversion rate of alkynes reaches more than 90%; At normal pressure and below 200°C, the alkyne conversion rate is higher than 80%, while the olefin selectivity is higher than 50%.

10. A method for preparing olefins by selective hydrogenation of alkynes in a high temperature and high pressure reactor liquid-solid phase reaction system, characterized in that: Using the catalyst described in any one of claims 1 to 6; Under the condition of less than 1 MPa, close to room temperature, the alkyne conversion rate is higher than 90%, preferably higher than 95%, and more preferably reaches 100%; at the same time, the olefin selectivity is higher than 40%.

11. The method according to claim 10, characterized in that: Under the condition of less than 1 MPa, close to room temperature, the alkyne conversion rate is higher than 90%, preferably higher than 95%, and more preferably reaches 100%; at the same time, the olefin selectivity is higher than 50%.

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