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

Abstract

The application provides an alkyne selective hydrogenation catalyst with high activity and high selectivity and a preparation method. The catalyst is a composite of metal nickel and an alkali metal hydride, denoted as nickel-alkali metal hydride. By adjusting the ratio of nickel element and the alkali metal hydride, high catalytic reaction activity and high alkene selectivity can be achieved. Compared with metal nickel as a catalyst and the alkali metal hydride as a catalyst, the catalytic activity and the alkene selectivity are greatly improved. The nickel-alkali metal hydride catalyst of the application is suitable for alkyne selective hydrogenation reaction in a high-temperature and high-pressure fixed-bed gas-phase reaction system and 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 present application belongs to the field of hydrogenation reaction and catalysis technology, and particularly relates to an alkyne selective hydrogenation catalyst with high activity and high selectivity and a preparation method thereof. BACKGROUND

[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, drugs, spices, and pesticides. Selective hydrogenation of alkyne, i.e. selective hydrogenation of carbon-carbon triple bond to generate carbon-carbon double bond, is one of the most important hydrogenation reactions. The target product, alkene, has high reactivity and can participate in various chemical reactions such as oxidation, addition, and polymerization, and is an important basic raw material for industrial production. Taking ethylene as an example, according to statistics, ethylene and its derivative products account for more than 75% of petrochemical products. The production technology, yield, and scale of ethylene mark the development level of the national oil and chemical industry. However, due to the limitations of existing processes, the prepared alkenes usually still contain a small amount of alkyne. The presence of these alkyne impurities can cause irreversible poisoning of the catalyst for downstream polymerization reactions, resulting in reduced quality and efficiency of downstream products. Catalytic selective hydrogenation is the most effective and economical method for removing a small amount of alkyne impurities in alkenes, and the development of alkyne semi-hydrogenation processes with high alkyne conversion rate and high alkene selectivity has attracted widespread attention. Therefore, exploring catalysts with high activity and high selectivity is a major challenge for alkyne selective hydrogenation processes.

[0003] Heterogeneous catalysts overcome the shortcomings of homogeneous catalysts such as difficult separation and recovery, poor thermal stability, and become a more promising choice for selective hydrogenation catalysts. Classic hydrogenation catalysts are mainly noble metals (Pd, Pt, Rh), which exhibit excellent catalytic activity for a variety of alkyne substrates. Taking palladium catalysts as an example, high hydrogenation activity for acetylene, phenylacetylene, diene, nitroaromatics, and other substances was reported as early as the last century. Therefore, research on Pd-based catalysts is the most extensive. The widely used Lindlar catalyst is prepared by adsorbing palladium on a carrier (calcium carbonate or barium sulfate) and adding a small amount of inhibitor (lead acetate or quinoline). The content of palladium in the catalyst is 5%-10%. This catalyst improves the selectivity of the target alkene product by introducing an active inhibitor, but the utilization efficiency of palladium is low. Recent research has focused on emerging catalytic systems such as bimetallic alloy catalysts and single-atom catalysts, and noble metals are still important active components.

[0004] Due to the low abundance of noble metals on earth, in recent years, a large number of researches have turned to non-noble metal catalysts to reduce the dependence on noble metals and reduce the cost of catalysts. Among them, transition metal Ni has attracted attention due to its superior hydrogenation activity. The research on Ni-based catalysts mainly focuses on Raney nickel catalyst, supported nickel catalyst and amorphous nickel catalyst, etc. 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 for hydrogenolysis and polymerization of carbon-carbon bond, which easily leads to over hydrogenation of alkyne or formation of green oil and other polymers.

[0005] Therefore, developing a new type of selective hydrogenation catalyst with high efficiency and low cost is a key problem to be solved in the field of alkyne hydrogenation. SUMMARY

[0006] In view of the above technical status, the present application provides a catalyst for selective hydrogenation of alkyne to prepare olefin, which has 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 application is: a selective hydrogenation catalyst for alkyne with high activity and high selectivity, which is a composite of metal nickel and alkali metal hydride, denoted 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%.

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

[0009] In view of high catalytic activity (i.e. high conversion rate of alkyne substrate), as a preferred embodiment, the mass percentage of metal nickel in the catalyst is preferably higher, preferably above 50%.

[0010] In view of high olefin selectivity and low alkane selectivity, as a preferred embodiment, the mass percentage of metal nickel in the catalyst is preferably lower, preferably below 50%.

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

[0012] As a preferred embodiment, 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, and as one implementation, the preparation method comprises the following steps:

[0014] The nickel precursor powder is mixed with the alkali metal hydride powder to react to obtain nickel element, alkali metal salt and unreacted alkali metal hydride; the alkali metal salt is removed by centrifugal washing with a solvent to obtain a composite of nickel element and alkali metal hydride.

[0015] As preferred, the nickel precursor powder is mixed with the alkali metal hydride powder in an inert atmosphere. In order to improve the reaction efficiency, as preferred, the nickel precursor powder is ball milled after being mixed with the alkali metal hydride powder.

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

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

[0018] In the 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 gaseous alkyne substrate, hydrogen and inert gas are introduced to carry out selective hydrogenation of the alkyne to prepare olefin. The reaction temperature can be in the range of 25-400℃; the gaseous alkyne substrate, hydrogen and inert gas constitute a mixed gas, and the pressure of the mixed gas can be 0.01-1MPa; the molar ratio of the gaseous alkyne substrate, hydrogen and inert gas can be 1:(1-20):(1-20); the reaction gas space velocity can be 1000-100000mL·g cat -1 ·h -1 As preferred, the molar ratio of the catalyst to the hydrocarbon substrate is 1:20-1:5.

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

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

[0021] (1) The present application adopts nickel-alkali metal hydride as a catalyst for selective hydrogenation of alkynes to prepare olefins, wherein the active component of the catalyst is metal nickel and alkali metal hydride, and the catalytic activity can be improved and the excessive hydrogenation of alkynes caused by single nickel as a catalyst can be reduced by the complex of alkali metal hydride. By adjusting the ratio of single nickel and alkali metal hydride, high catalytic activity and high olefin selectivity can be achieved. Compared with metal nickel as a catalyst and alkali metal hydride as a catalyst, the catalytic activity and the selectivity of olefins are greatly improved.

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

[0023] In the high-temperature and high-pressure fixed-bed gas-phase reaction system, when the catalyst of the present application is used, the conversion rate of alkynes can be higher than 90% at normal pressure and below 50℃ (i.e. less than or equal to 50℃), and high conversion rate of alkynes and high selectivity of olefins can be achieved at normal pressure and below 200℃ (i.e. less than or equal to 200℃), for example, the conversion rate of alkynes can be higher than 80% and the selectivity of olefins can be higher than 50%, which is much higher than the conversion rate of alkynes and the selectivity of olefins when single nickel is used as a catalyst and alkali metal hydride is used as a catalyst.

[0024] In the high-temperature and high-pressure reaction kettle, when the catalyst of the present application is used, the conversion rate of alkynes can be higher than 90% at a pressure lower than 1 MPa and close to room temperature (25±5℃), preferably higher than 95%, and even 100%, and the selectivity of olefins can be higher than 40%, even higher than 50%, which is much higher than the conversion rate of alkynes and the selectivity of olefins when single nickel is used as a catalyst and alkali metal hydride is used as a catalyst.

[0025] (3) In the present application, the catalyst does not need an additional carrier, the preparation method is simple, the cost is low, high catalytic activity and high selectivity can be achieved under mild conditions, and the catalyst has good application prospect.

[0026] In the present application, the conversion rate of alkynes, the selectivity of olefins and the selectivity of alkanes are defined as follows:

[0027] DETAILED DESCRIPTION

[0028] The present application will be further described in detail below with reference to examples. It should be pointed out that the examples described below are intended to facilitate the understanding of the present application, and non-essential improvements and adjustments made to the present application by those skilled in the art based on the content of the present application still fall within the protection scope of the present application.

[0029] The use of the terms “including,” “containing,” and similar words in this disclosure should be interpreted as an open-ended meaning that also covers excluding various instances of the listed items; that is, there are items belonging to the group of items on the containing item list that are not to be read as being contained in the item.

[0030] Example 1:

[0031] In an inert gas glove box, 200 mg of anhydrous nickel chloride and 90.74 mg of LiH were accurately weighed, mixed uniformly in a mortar, and then transferred to a stainless steel ball mill jar. Stainless steel balls were added, and the ball-to-material ratio was 10:1. After sealing the ball mill jar, it was ball milled in a ball mill at a speed of 200 revolutions per minute for 3 h.

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

[0033] After the ball milling was completed, the product was taken out and placed in a centrifuge tube. 20 mL of tetrahydrofuran was added, and centrifugation was performed at a speed of 10,000 revolutions per minute for 5 min. This was repeated three times to thoroughly wash the LiCl. The washed product was vacuum dried in a vacuum drying oven overnight to obtain a nickel-lithium hydride catalyst, in which the mass percentage of Ni was 50%, and the mass percentage of LiH was 50%, denoted as 50% Ni-50% LiH.

[0034] The 50% Ni-50% LiH was used as a catalyst for the hydrogenation of acetylene. 50 mg of the 50% Ni-50% LiH catalyst was accurately weighed and placed in a quartz tube. The hydrogenation of acetylene was carried out in a high-temperature and high-pressure fixed bed reactor. The reaction atmosphere was acetylene gas (a mixture of acetylene and argon, with the volume fraction of acetylene being 2.5%), hydrogen, and Ar gas. The reaction temperature range was 25-300°C, the reaction pressure was 0.01 MPa (i.e., normal pressure), the reaction gas space velocity was 36,000 mL·g cat -1 ·h -1 .

[0035] Example 2:

[0036] In an inert gas glove box, 200 mg of anhydrous nickel chloride and 90.74 mg of LiH were accurately weighed, mixed uniformly in a mortar, and then transferred to a stainless steel ball mill jar. Stainless steel balls were added, and the ball-to-material ratio was 10:1. After sealing the ball mill jar, it was ball milled in a ball mill at a speed of 200 revolutions per minute for 3 h.

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

[0038] The product was taken out after the ball milling and placed in a centrifuge tube, 20 mL of tetrahydrofuran was added, and centrifugation was performed at a speed of 10,000 r / min for 5 min, and the operation was repeated three times to sufficiently wash away the LiCl. The washed product was 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%, denoted as 20% Ni-80% LiH.

[0039] The 20% Ni-80% LiH was used as a catalyst for the hydrogenation reaction of acetylene. 50 mg of the 20% Ni-80% LiH catalyst was accurately weighed and placed in a quartz tube to perform the hydrogenation reaction of acetylene in a high-temperature and high-pressure fixed bed reaction. The reaction gas atmosphere (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 36,000 mL·g cat -1 ·h -1 .

[0040] Comparative Example 1:

[0041] In a glove box under the protection of high-purity argon, 200 mg of anhydrous nickel chloride and 24.6 mg of LiH were accurately weighed, mixed uniformly in a mortar, and then transferred to a stainless steel ball mill jar, and stainless steel balls were added, with a ball-to-material ratio of 10:1. After the ball mill jar was sealed, ball milling was performed in a ball mill at a speed of 200 r / min for 3 h.

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

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

[0044] The metal Ni powder was used as a catalyst for the hydrogenation reaction of acetylene. 50 mg of the Ni powder was accurately weighed and placed in a quartz tube to perform the hydrogenation reaction of acetylene in a high-temperature and high-pressure fixed bed reaction evaluation system. The reaction gas atmosphere (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 36,000 mL·g cat -1 ·h -1 .

[0045] Comparative Example 2:

[0046] LiH powder was used as catalyst for hydrogenation of acetylene. 50 mg LiH was accurately weighed and placed in a quartz tube for acetylene hydrogenation reaction in a high temperature and high pressure fixed bed reaction evaluation system. The reaction atmosphere (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] Example 3:

[0048] Preparation of 20% Ni-80% LiH was the same as Example 2.

[0049] The 20% Ni-80% LiH was used as catalyst for hydrogenation of 3-nitrophenylacetylene. 3-nitrophenylacetylene substrate, 30 mg 20% Ni-80% LiH, 5 mL toluene were placed in a quartz liner, the molar ratio of 3-nitrophenylacetylene to the active component of the catalyst nickel was 10:1, and the hydrogenation reaction of 3-nitrophenylacetylene 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] Example 4:

[0051] Preparation of 50% Ni-50% LiH was the same as Example 1.

[0052] The 50% Ni-50% LiH was used as catalyst for hydrogenation of 3-nitrophenylacetylene. 3-nitrophenylacetylene substrate, 30 mg 50% Ni-50% LiH, 5 mL toluene were placed in a quartz liner, the molar ratio of 3-nitrophenylacetylene to the active component of the catalyst nickel was 10:1, and the hydrogenation reaction of 3-nitrophenylacetylene 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 catalyst for hydrogenation of acetylene. 3-nitrophenylacetylene substrate, 30 mg LiH, 5 mL toluene were placed in a quartz container, the molar ratio of 3-nitrophenylacetylene to the active component of the catalyst LiH was 10:1, and the hydrogenation catalytic activity test of 3-nitrophenylacetylene 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] Preparation of metal Ni powder was the same as Comparative Example 1.

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

[0058] Example 5:

[0059] The 50% Ni-50% LiH is prepared according to Example 1.

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

[0061] Example 6:

[0062] The 50% Ni-50% LiH is prepared according to Example 1.

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

[0064] Example 7:

[0065] The 50% Ni-50% LiH is prepared according to Example 1.

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

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

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

[0069]

[0070] From Table 1, it can be seen that:

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

[0072] (2) LiH and Ni are essential components of the catalyst in the present application, and both are indispensable;

[0073] (3) In Example 1, the mass percentage of nickel in the nickel-alkali metal hydride is 50%, and at 50°C, the conversion rate can reach 100%, 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 is 20% at 50°C, compared with the nickel as a catalyst in Comparative Example 1, although the conversion rate is slightly lower, but the olefin selectivity is greatly improved, compared with LiH as a 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 a 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 liquid / solid phase alkyne substrate hydrogenation reaction in Examples 3-8 and Comparative Examples 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, it can be seen that:

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

[0080] (2) LiH and Ni are essential components of the catalyst in the present application, and both are indispensable;

[0081] (3) when the catalyst of the application is used, the conversion rate of alkyne is higher than 95% and even reaches 100% and the selectivity of olefin is higher than 50% at 0.6 MPa and 25 DEG C, compared with the catalyst of elemental nickel and the catalyst of LiH, the conversion rate of alkyne is greatly improved, and compared with the catalyst of elemental nickel and the catalyst of LiH, the selectivity of olefin is also greatly improved and can be higher than 50%.

[0082] The above-mentioned embodiments are used to explain the technical solutions of the application in detail, and it should be understood that the above-mentioned are only specific embodiments of the application and are not used to limit the application, and any modification, supplement or similar replacement within the principle range of the application should be included in the protection range of the application.

Claims

1. An acetylene selective hydrogenation catalyst having both high activity and high selectivity, characterized by: The catalyst is a composite of metallic nickel and alkali metal hydride, denoted as nickel-alkali metal hydride, wherein the mass percentage of metallic nickel is 1%-20%, and the mass percentage of alkali metal hydride is 80%-99%. The preparation method of the catalyst comprises the following steps: The nickel precursor powder is mixed with the alkali metal hydride powder to react, to obtain elemental nickel, an alkali metal salt, and unreacted alkali metal hydride; the alkali metal salt is removed by centrifugal washing with a solvent, and the composite of elemental nickel and alkali metal hydride is obtained.

2. The catalyst of claim 1, wherein: The alkali metal hydride comprises one or more of lithium hydride, sodium hydride, potassium hydride, rubidium hydride, and cesium hydride.

3. The catalyst of claim 1 wherein: In the catalyst, the mass percentage of metallic nickel is 5%-20%, and the mass percentage of alkali metal hydride is 80%-95%.

4. The catalyst of claim 1 wherein: The alkynes comprise one or more of ethyne, 3-nitrophenylacetylene, 4-fluorophenylacetylene, 4-aminophenylacetylene, 1-heptyne, and phenylheptyne.

5. The catalyst of claim 1 wherein: The molar ratio of the catalyst to the alkyne substrate is 1:20-1:

5.

6. The catalyst of claim 1 wherein: The selective hydrogenation reaction of the alkyne is achieved in a high-temperature and high-pressure fixed-bed gas-phase reaction system, or in a high-temperature and high-pressure reaction kettle liquid-solid phase reaction system.

7. The catalyst of claim 1 wherein: The precursor of the metallic nickel comprises one or more of nickel chloride, nickel nitrate, nickel carbonate, and nickel acetate.

8. The catalyst of claim 7, wherein: The nickel precursor powder is mixed with the alkali metal hydride powder in an inert atmosphere.

9. The catalyst of claim 7 wherein: The nickel precursor powder is mixed with the alkali metal hydride powder and then ball milled.

10. A process for the selective hydrogenation of acetylenes to olefins in a high temperature, high pressure, fixed bed gas phase reaction system, characterized by: The catalyst according to any one of claims 1-6 is used; Under normal pressure, the conversion rate of the alkyne is higher than 90% at 50°C or below; Under normal pressure, the conversion rate of the alkyne is higher than 80% at 200°C or below, and the selectivity of the olefin is higher than 50%.

11. A method for preparing olefins by selective hydrogenation of acetylenes in a high-temperature high-pressure autoclave liquid-solid phase reaction system, characterized in that: The catalyst according to any one of claims 1-6 is used; Under a pressure lower than 1 MPa and close to room temperature, the conversion rate of the alkyne is higher than 90%, and the selectivity of the olefin is higher than 40%.

12. The method of claim 11 wherein: The conversion rate of the alkyne is higher than 95%.

13. The method of claim 12, wherein: The conversion rate of the alkyne is 100%.

14. The method of claim 11 wherein: Under a pressure lower than 1 MPa and close to room temperature, the conversion rate of the alkyne is higher than 90%, and the selectivity of the olefin is higher than 50%.

15. The method according to claim 12, wherein the selectivity of the olefin is higher than 50%.

16. The method of claim 13 wherein: The selectivity of the olefin is higher than 50%.

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