CN109433218B

CN109433218B - Unsaturated hydrocarbon selective hydrogenation catalyst and preparation method thereof

Info

Publication number: CN109433218B
Application number: CN201811183050.2A
Authority: CN
Inventors: 陈明海; 施清彩; 陈新忠; 庄旭森
Original assignee: Yantai Baichuan Huitong Technology Co ltd
Current assignee: YANTAI BAICHUAN HUITONG TECHNOLOGY Co.,Ltd.
Priority date: 2018-10-11
Filing date: 2018-10-11
Publication date: 2022-03-29
Anticipated expiration: 2038-10-11
Also published as: CN109433218A

Abstract

The invention relates to an unsaturated hydrocarbon selective hydrogenation catalyst, which comprises a silicon oxide-alumina carrier and metal active components of nickel, molybdenum and magnesium loaded on the carrier, wherein the catalyst comprises the following components by taking the total weight of the catalyst as a reference: the content of nickel oxide is 7-18 wt%, the content of molybdenum oxide is 3.5-12 wt%, and the content of magnesium oxide is 0.05-2.0%; the content of the silica-alumina carrier is 75-91 wt%. The mesopores of the carrier account for 3-70% of the total pores, the macropores account for 1.5-55% of the total pores, the catalyst is prepared by adopting an impregnation method, and the catalyst has good colloid resistance, strong arsenic resistance, sulfur resistance and strong water resistance.

Description

Unsaturated hydrocarbon selective hydrogenation catalyst and preparation method thereof

Technical Field

The invention relates to a selective hydrogenation catalyst for unsaturated hydrocarbon and a preparation method thereof, in particular to a nickel-based selective hydrogenation catalyst for one-stage selective hydrogenation of pyrolysis gasoline.

Background

The pyrolysis gasoline is an important byproduct of ethylene and propylene produced by steam cracking industry and comprises C5-C10 fractions. The pyrolysis gasoline has complex composition, mainly comprises benzene, toluene, xylene, monoolefin, diolefin, straight-chain alkane, cycloparaffin, nitrogen, sulfur, oxygen, chlorine and heavy metal organic compounds, and the like, and has more than 200 components, wherein the benzene, the toluene and the xylene (generally called BTX) are about 50-90%, and the unsaturated hydrocarbon is 25-30%. According to the characteristic that pyrolysis gasoline contains a large amount of aromatic hydrocarbon, the application of the pyrolysis gasoline is wide, and the pyrolysis gasoline can be used as a blending component of gasoline to produce gasoline with high octane number, and can also be used for producing aromatic hydrocarbon and the like through separation.

Because the pyrolysis gasoline has complex composition and poor thermal stability, usually, the diolefin and the styrene are removed by first-stage selective hydrogenation, and the pyrolysis gasoline is mainly used for extracting the aromatic hydrocarbon after second-stage hydrodesulfurization. At present, the catalyst for selective hydrogenation of pyrolysis gasoline in industry is mainly Pd-series or Ni-series catalyst, and middle distillate (C)₆～C₈Hydrocarbon compound fraction) hydrogenation or whole fraction (C)₅Hydrocarbon-hydrocarbon compound fraction having a dry point of 204 deg.c). Due to the difference between the pyrolysis raw materials and the pyrolysis conditions of all ethylene units, the composition of the pyrolysis gasoline raw materials of all the ethylene units has larger difference, and particularly, the contents of diene, colloid (high molecular polymer generated by polymerization reaction of unsaturated components such As diene, styrene and the like) As well As As and heavy metal of the pyrolysis gasoline have larger difference; some crude pyrolysis gasoline has high diene and colloid content, some crude pyrolysis gasoline has high colloid content, As, heavy metal and other toxic matter content, and some crude pyrolysis gasoline has diene and colloid content,The content of colloid and poisons such As As, heavy metal and the like is high.

Diolefins and alkynes in the pyrolysis gasoline are easy to polymerize into colloid at high temperature, deposit on the surface of the catalyst, easily cause the deactivation of the catalyst, and need to be frequently activated and regenerated. The first-stage hydrogenation catalyst for pyrolysis gasoline mainly comprises Pd/Al₂O₃And Ni/Al₂O₃Two catalysts.

CN200610029962.5 relates to a method for selective hydrogenation of full-range pyrolysis gasoline, which mainly solves the technical problem that the full-range pyrolysis gasoline with high content of colloid and free water is difficult to be selectively hydrogenated in the prior art. The invention adopts C₅Cracking gasoline of hydrocarbon compound fraction with a hydrocarbon-dry point of 204 ℃ and hydrogen are used as raw materials, the reaction temperature is 30-80 ℃, the reaction pressure is 2.0-3.0 MPa, and the space velocity of fresh oil is 2.5-5.0 hours^－1Under the condition that the volume ratio of hydrogen to oil is 60-120: 1, the raw material is contacted with a catalyst for reaction to convert diolefin and olefin-based aromatic hydrocarbon components in the raw material into mono-olefin and alkyl aromatic hydrocarbon, wherein the catalyst comprises an alumina carrier, an active component of metallic palladium or an oxide thereof, at least one element selected from IA or IIA in a periodic table of elements or an oxide thereof, and at least one element selected from IVA or VA in the periodic table of elements or an oxide thereof, the specific surface area of the carrier is 40-160 m²The catalyst has the advantages that the catalyst can be used for the selective hydrogenation of full fraction pyrolysis gasoline, the total pore volume is 0.3-1.2 ml/g, and the carrier has the technical scheme of composite pore distribution, so that the problem is solved well, and the catalyst can be used for the industrial production of the selective hydrogenation of the full fraction pyrolysis gasoline. CN200610118522.7 relates to a nickel catalyst with a composite pore structure for selective hydrogenation, which mainly solves the technical problems of low-temperature activity, weak anti-interference capability, low gel-holding capability, poor stability and poor free water resistance of the catalyst in the prior art. The invention comprises the following components in percentage by weight: (a) 5.0-40.0% of metallic nickel or its oxide; (b)0.01 to 20.0% of at least one element selected from molybdenum or tungsten or an oxide thereof; (c) 0.01-10.0% of at least one element selected from rare earth or oxide thereof; (d) 0.01-2.0% of at least one element selected from IA or IIA of periodic Table of elements or their mixtureAn oxide; (e)0 to 15.0% of at least one element selected from silicon, phosphorus, boron and fluorine or an oxide thereof; (f) 0-10.0% of at least one element selected from IVB in the periodic table of elements or an oxide thereof; (g) the balance of carrier alumina, wherein the total pore volume of the carrier is 0.5-1.2 ml/g, the pore volume with the pore diameter smaller than 30 nm accounts for 5-65% of the total pore volume, the pore volume with the pore diameter larger than 30-60 nm accounts for 20-80% of the total pore volume, and the pore volume with the pore diameter larger than 60 nm accounts for 20-50% of the total pore volume.

CN201210349977.5 this invention is a selective hydrogenation catalyst of pyrolysis gasoline nickel series and its preparation method. Belonging to catalysts comprising metals or metal oxides or hydroxides. The catalyst is characterized by having a mesoporous-macroporous or double-mesoporous composite pore passage, taking alumina as a carrier, nickel as a main active component, molybdenum as an auxiliary active component and metal oxide as an auxiliary agent, wherein the weight percentage of the nickel-based selective hydrogenation catalyst for the pyrolysis gasoline is as follows: 15-19 parts of nickel oxide, 6.5-20.0 parts of molybdenum oxide, 2.2-4.5 parts of an auxiliary agent and the balance of aluminum oxide; the auxiliary agent is one or the combination of more than two of potassium oxide, magnesium oxide and lanthanum oxide.

The prior art mainly changes the chemical composition and type of a carrier and adds a promoter to improve the performance of a catalyst. As the contents of impurities such As As, S, O, N and the like and colloid in the pyrolysis gasoline are high, the catalyst is easy to inactivate, so that the pyrolysis gasoline catalyst is required to have the characteristics of good colloid resistance and water resistance, and strong arsenic resistance and sulfur resistance.

Disclosure of Invention

The invention provides an unsaturated hydrocarbon selective hydrogenation catalyst, which is particularly suitable for one-stage selective hydrogenation of pyrolysis gasoline. The catalyst has higher activity, better selectivity, good colloid resistance and water resistance, strong arsenic resistance and sulfur resistance in the reaction, the carrier of the catalyst is a silicon oxide-aluminum oxide carrier, the carrier comprises nickel doped lanthanum ferrite, the active components comprise nickel, molybdenum, magnesium and the like, and the catalyst is particularly suitable for the first-stage selective hydrogenation of pyrolysis gasoline.

The invention provides an unsaturated hydrocarbon selective hydrogenation catalyst, which comprises a silicon oxide-alumina carrier and metal active components of nickel, molybdenum and magnesium loaded on the carrier, wherein the catalyst comprises the following components by taking the total weight of the catalyst as a reference: the content of nickel oxide is 7-18 wt%, the content of molybdenum oxide is 3.5-12 wt%, and the content of magnesium oxide is 0.05-2.0%; the content of the silicon oxide-alumina carrier is 65-85 wt%, the silicon oxide-alumina carrier comprises 0.1-10 wt% of silicon oxide, 0.1-12 wt% of nickel-doped lanthanum ferrite and 0.05-5.5 wt% of magnesium oxide, mesoporous pores of the carrier account for 3-70% of total pores, macroporous pores account for 1.5-55% of the total pores, and micropores, mesopores and macropores in the carrier are not uniformly distributed.

Preferably, the nickel oxide content is 7-15 wt% and the molybdenum oxide content is 4.5-10 wt%. The content of the magnesium oxide is 0.1-1.6%; the carrier mesopores account for 2-60% of the total pores, and the macropores account for 3-50% of the total pores.

In the method for preparing the catalyst of the present invention, the nickel and molybdenum compounds used may be any of those disclosed in the prior art as being suitable for preparing the catalyst, such as nickel nitrate, nickel sulfate, nickel acetate, ammonium molybdate, molybdenum oxide, etc.

The preparation method of the silica-alumina carrier comprises the following steps: adding pseudo-boehmite and sesbania powder into a kneading machine, uniformly mixing, adding an inorganic acid solution and an organic polymer, uniformly kneading, then adding nickel-doped lanthanum ferrite, and uniformly mixing to obtain an alumina precursor for later use; adding a silicon source and pseudo-boehmite into acid liquor of an organic polymer, and uniformly mixing to obtain a silicon source-pseudo-boehmite-organic polymer mixture, wherein the content of the organic polymer in the unit content of an alumina precursor is more than 2 times higher than that of the organic polymer in the silicon source-pseudo-boehmite-organic polymer mixture (abbreviated as silicon-aluminum-organic matter mixture), then mixing the silicon source-pseudo-boehmite-organic polymer mixture with the alumina precursor, adding a magnesium source, extruding, forming, drying and roasting to obtain the silica-alumina carrier. The silicon source is silica gel, sodium silicate or silica micropowder. The alumina in the silicon-aluminum-organic matter mixture accounts for 1-35 wt% of the alumina in the carrier.

In the preparation process of the silicon oxide-alumina carrier, the organic polymer is one or more of polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, polyethylene glycol and polyacrylate.

Preferably, the nickel-doped lanthanum ferrite in the silica-alumina carrier is 0.1-12 wt%, more preferably 0.2-8 wt%, and the nickel in the nickel-doped lanthanum ferrite accounts for 0.1-8 wt% of the lanthanum ferrite.

The preparation method of the nickel-doped lanthanum ferrite comprises the following steps: dissolving citric acid in deionized water, stirring and dissolving, then adding lanthanum nitrate and ferric nitrate into the citric acid, stirring and dissolving, and adding sodium polyacrylate, polyacrylate or polyacrylic acid, wherein the adding amount of the sodium polyacrylate, the polyacrylate or the polyacrylic acid is 0.1-10 wt% of the nickel-doped lanthanum ferrite, and preferably 0.1-8.0 wt%. Adding nickel-containing compound, stirring, drying, roasting and grinding to obtain the finished product. The nickel-containing compound includes nickel nitrate, nickel acetate, and the like. The cracking gasoline catalyst contains high content Al₂O₃In the process of reducing nickel ions at high temperature, nickel aluminate or nickel metaaluminate is easy to generate, so that the activity of the catalyst is reduced, and the stability of the catalyst is poor. The carrier of the invention contains silicon oxide added with organic polymer and nickel doped lanthanum ferrite, thereby effectively inhibiting the generation of nickel aluminate or nickel metaaluminate and improving the activity stability of the nickel catalyst.

The preparation method of the catalyst can adopt the methods of dipping, spraying and the like, dipping and spraying the solution containing the active components of nickel, magnesium and molybdenum on the silicon oxide-carrier, and then drying and roasting the catalyst to obtain the catalyst. The catalyst can be prepared, for example, by the following steps: preparing a nickel nitrate, magnesium nitrate and ammonium molybdate solution to dip the silicon oxide-alumina carrier, drying for 3-9 hours at 110-160 ℃, and roasting for 4-9 hours at 400-650 ℃ to finally obtain a catalyst product.

Compared with lanthanum ferrite, the nickel-doped lanthanum ferrite is added into the silicon oxide-aluminum oxide carrier, so that the arsenic resistance, sulfur resistance and water resistance are effectively improved, and the hydrogenation selectivity of alkyne or diene is effectively improved by the prepared nickel-molybdenum catalyst. In the preparation process of the silicon oxide-aluminum oxide carrier, the content of organic polymers in unit content in the aluminum oxide precursor is more than 2 times higher than that of organic polymers in a silicon-aluminum-organic matter mixture, which is different from simple hole expansion, so that the pore structure of the carrier can be improved, micropores, mesopores and macropores of the carrier are not uniformly distributed, the colloid resistance of the catalyst is improved, the stability and the service life of the catalyst are improved, and the long-period operation of the device is facilitated; but also promotes the surface of the carrier to generate more active site loading centers and improves the hydrogenation activity of the nickel catalyst.

Detailed Description

The present invention is described in further detail below by way of examples, which should not be construed as limiting the invention thereto.

The main raw material sources for preparing the catalyst are as follows: the raw material reagents used in the invention are all commercial products.

Example 1

1. Preparation of nickel-doped lanthanum ferrite

Dissolving 2.51mol of lanthanum nitrate in 120mL of water under the condition of stirring, adding citric acid, and stirring for dissolving; then adding 4.79mol of ferric nitrate, then adding 190g of sodium polyacrylate, then adding the water solution containing 42g of nickel nitrate, continuously stirring for 30min, and obtaining the nickel-doped lanthanum ferrite through drying, roasting and grinding.

2. Preparation of silica-alumina Carrier

4.5g of nickel-doped lanthanum ferrite is added with citric acid for standby. Adding 300g of pseudo-boehmite powder and 25.0g of sesbania powder into a kneader, adding nitric acid, adding 40.2g of sodium polyacrylate nitric acid solution, uniformly mixing, adding nickel-doped lanthanum ferrite, and uniformly mixing to obtain an alumina precursor. 5g of sodium polyacrylate is dissolved in nitric acid, 38g of silica powder and 50g of pseudo-boehmite powder are added and stirred uniformly to obtain a silica powder-pseudo-boehmite-sodium polyacrylate mixture (abbreviated as silica-alumina-organic matter mixture). 1/8 silicon-aluminum-organic matter mixture is taken, the alumina precursor and 4.2g magnesium nitrate are added, the mixture is evenly kneaded, and the mixture is kneaded and extruded to form clover shape. Drying at 130 ℃ for 7 hours, and roasting at 620 ℃ for 7 hours to obtain the nickel-doped lanthanum ferrite-containing silica-alumina carrier 1. The mesopores of the carrier account for 55.2 percent of the total pores, and the macropores account for 28.3 percent of the total pores.

3. Preparation of the catalyst

Preparing nickel nitrate, magnesium nitrate and ammonium molybdate solution to impregnate the carrier 1, drying at 140 ℃ for 6 hours, and roasting at 560 ℃ for 5 hours to obtain the catalyst 1. The catalyst 1 had a nickel oxide content of 17.1 wt%, a molybdenum oxide content of 3.4 wt%, and a magnesium oxide content of 0.53 wt%.

Example 2

The nickel-doped lanthanum ferrite is prepared as in example 1, except that 260g of sodium polyacrylate is added, and the silica-alumina carrier is prepared as in example 1, wherein the silica-alumina carrier contains 4.4 wt% of silica, 5.7 wt% of nickel-doped lanthanum ferrite and 1.2 wt% of magnesium, the mesopores of the carrier account for 63.8% of the total pores, and the macropores account for 25.9% of the total pores. The unit content of sodium polyacrylate in the alumina precursor is 3 times higher than that of sodium polyacrylate in the silicon source-organic polymer mixture. The catalyst 2 was prepared in the same manner as in example 1 except that the catalyst 2 had a nickel oxide content of 11.4 wt%, a molybdenum oxide content of 4.75 wt% and a magnesium oxide content of 1.4 wt%.

Example 3

The nickel-doped lanthanum ferrite is prepared as in example 1, except that 220g of polyacrylic acid is added, and the silica-alumina carrier is prepared as in example 1, wherein the silica-alumina carrier contains 8.4 wt% of silica, 2.6 wt% of nickel-doped lanthanum ferrite and 2.1 wt% of magnesium, mesoporous pores of the carrier account for 54.9% of total pores, and macroporous pores account for 33.1% of total pores. The unit content of polyacrylic acid in the alumina precursor is 3.3 times higher than that of polyacrylic acid in the silicon source-organic polymer mixture. The catalyst 3 was prepared in the same manner as in example 1 except that the catalyst 3 had a nickel oxide content of 22.3 wt%, a molybdenum oxide content of 4.1 wt% and a magnesium oxide content of 0.32 wt%.

Example 4

The nickel-doped lanthanum ferrite was prepared as in example 1 except that 280g of sodium polyacrylate was added, and the silica-alumina carrier was prepared as in example 1, wherein the silica-alumina carrier contained 8.4 wt% of silica, 2.6 wt% of nickel-doped lanthanum ferrite, and 2.8 wt% of magnesium, the mesopores of the carrier accounted for 50.1% of the total pores, and the macropores accounted for 39.7% of the total pores. The polyacrylate content per unit content in the alumina precursor was 3.3 times higher than the polyacrylate content in the silicon source-organic polymer mixture. The catalyst 3 was prepared in the same manner as in example 1 except that the catalyst 4 had a nickel oxide content of 15.2 wt%, a molybdenum oxide content of 2.4 wt% and a magnesium oxide content of 1.6 wt%.

Comparative example 1

1. Preparation of lanthanum ferrite

Dissolving 2.51mol of lanthanum nitrate in 120mL of water under the condition of stirring, adding citric acid, and stirring for dissolving; then adding 4.79mol of ferric nitrate, then adding 190g of sodium polyacrylate, stirring for 30min, drying, roasting and grinding to obtain the nickel-doped lanthanum ferrite.

2. Preparation of silica-alumina Carrier

5g of sodium polyacrylate is dissolved in nitric acid, 38g of silica powder and 50g of pseudo-boehmite powder are added and uniformly stirred to obtain a silica powder-pseudo-boehmite-sodium polyacrylate mixture (abbreviated as a silica-alumina-organic matter mixture), 1/8 is taken for later use, and 4.5g of lanthanum ferrite is added with citric acid for later use. Adding 300g of pseudo-boehmite powder and 25.0g of sesbania powder into a kneader, adding nitric acid, adding 40.2g of sodium polyacrylate nitric acid solution, uniformly mixing, adding the silicon micropowder-sodium polyacrylate mixture, uniformly kneading, adding lanthanum ferrite and 4.2g of magnesium nitrate, uniformly mixing, and kneading and extruding to form the clover shape. Drying at 130 deg.C for 7 hr, and calcining at 620 deg.C for 7 hr to obtain the carrier 1-1 of silicon oxide-aluminium oxide containing lanthanum ferrite.

3. Preparation of comparative catalyst 1

Preparing nickel nitrate, magnesium nitrate and ammonium molybdate solution to impregnate the carrier 1-1, drying at 140 ℃ for 6 hours, and roasting at 560 ℃ for 5 hours to obtain the comparative catalyst 1. Comparative catalyst 1 had a nickel oxide content of 17.1 wt%, a molybdenum oxide content of 3.4 wt%, and a magnesium oxide content of 0.53 wt%.

Comparative example 2

1. Preparation of nickel-doped lanthanum ferrite

2. Preparation of silica-alumina Carrier

Adding citric acid into 4.5g of nickel-doped lanthanum ferrite for later use, adding 350g of pseudo-boehmite powder and 25.0g of sesbania powder into a kneader, adding nitric acid, adding 40.7g of sodium polyacrylate nitric acid solution, uniformly mixing, adding 4.8g of silicon micropowder, uniformly kneading, adding nickel-doped lanthanum ferrite and 4.2g of magnesium nitrate, uniformly mixing, and kneading and extruding to form the clover shape. Drying at 130 deg.C for 7 hr, and calcining at 620 deg.C for 7 hr to obtain the carrier 1-2 containing lanthanum ferrite and silica-alumina.

3. Preparation of comparative catalyst 2

Preparing nickel nitrate, magnesium nitrate and ammonium molybdate solution to impregnate the carrier 1-1, drying at 140 ℃ for 6 hours, and roasting at 560 ℃ for 5 hours to obtain a comparative catalyst 2. Comparative catalyst 2 had a nickel oxide content of 17.1 wt%, a molybdenum oxide content of 3.4 wt%, and a magnesium oxide content of 0.53 wt%.

Respectively loading catalysts 1-4 and comparative catalysts 1 and 2 into 100ml adiabatic bed reactor, reducing at 440 deg.C for 8 hr under hydrogen, cooling to 50 deg.C, inactivating with cyclohexane for 3 hr, and making into pyrolysis gasoline C₅-C₉A fraction having a diene content of 35.76g iodine/100 g oil, an iodine value of 87.2g iodine/100 g oil, a gum content of 65mg/100ml oil, a free water content of 1254ppm, a sulphur content of 145ppm and an arsenic content of 112 ppb; the reaction process conditions are as follows: the inlet temperature is 50 ℃, the volume ratio of hydrogen to oil is 120: 1, the reaction pressure is 2.6MPa, and the space velocity of fresh oil is 3.0h^-1(ii) a After running for 180 hours, the diene of the catalyst 1 hydrogenation product is 0.91 g of iodine/100 g of oil, the iodine value is 37.1g of iodine/100 g of oil, and the diene hydrogenation rate is 99.1%; the diene of the hydrogenation product of the catalyst 2 is 1.65 g of iodine/100 g of oil, the iodine value is 38.7g of iodine/100 g of oil, and the hydrogenation rate of the diene is 98.9 percent; the diene of the hydrogenation product of the catalyst 3 is 0.89 g of iodine/100 g of oil, the iodine value is 36.9g of iodine/100 g of oil, and the hydrogenation rate of the diene is 98.9 percent; the diene of the hydrogenation product of the catalyst 4 is 1.32 g of iodine/100 g of oil, the iodine value is 37.2g of iodine/100 g of oil, and the hydrogenation rate of the diene is 98.5 percent. The catalyst has high activity, good selectivity, and strong colloid resistance, water resistance, arsenic resistance and sulfur resistance. The diene of the hydrogenated product of comparative catalyst 1 was 4.78 g iodine/100 g oil, iodine number43.2g iodine/100 g oil, diene hydrogenation rate 93.5%; the diene of the hydrogenated product of the comparative catalyst 2 is 3.98 g of iodine/100 g of oil, the iodine value is 42.3g of iodine/100 g of oil, and the hydrogenation rate of the diene is 94.8%. Compared with the comparative catalysts 1 and 2, the catalyst carrier of the invention contains silicon oxide added with organic polymer and nickel-doped lanthanum ferrite, thereby effectively inhibiting the generation of nickel aluminate or nickel metaaluminate and improving the activity stability of the nickel catalyst.

After running for 500h, the diene of the hydrogenation product of the catalyst 1 is 0.93 g of iodine/100 g of oil, the iodine value is 37.3g of iodine/100 g of oil, and the hydrogenation rate of the diene is 99.0 percent; the diene of the hydrogenation product of the catalyst 3 is 0.88 g of iodine/100 g of oil, the iodine value is 37.1g of iodine/100 g of oil, and the hydrogenation rate of the diene is 98.8 percent. The catalyst carrier contains nickel-doped lanthanum ferrite, which is beneficial to inhibiting polymerization reaction of unsaturated components such as diene, styrene and the like; the catalyst is not sensitive to impurities such as water, colloid and the like, and has good colloid resistance and water resistance, strong arsenic resistance and sulfur resistance and stable catalytic performance. The catalyst carrier has non-uniform distribution of micropores, mesopores and macropores, and has the advantages of good catalyst activity, good stability, long service life and long-period operation of the device.

Claims

1. The catalyst is characterized by comprising a silica-alumina carrier and metal active components of nickel, molybdenum and magnesium loaded on the carrier, wherein the catalyst comprises the following components by taking the total weight of the catalyst as a reference: the content of nickel oxide is 7-18 wt%, the content of molybdenum oxide is 3.5-12 wt%, and the content of magnesium oxide is 0.05-2.0%; the content of the silicon oxide-aluminum oxide carrier is 65-85 wt%, the silicon oxide-aluminum oxide carrier comprises 0.1-10 wt% of silicon oxide, 0.1-12 wt% of nickel-doped lanthanum ferrite and 0.05-5.5 wt% of magnesium oxide, the mesopores of the carrier account for 3-70% of the total pores, the macropores account for 1.5-55% of the total pores, and micropores, mesopores and macropores in the carrier are not uniformly distributed; the preparation method of the nickel-doped lanthanum ferrite comprises the following steps: dissolving citric acid in deionized water, stirring and dissolving, then adding lanthanum nitrate and ferric nitrate into the citric acid, stirring and dissolving, adding sodium polyacrylate, polyacrylate or polyacrylic acid, wherein the adding amount of the sodium polyacrylate, the polyacrylate or the polyacrylic acid is 0.1-10 wt% of that of the nickel-doped lanthanum ferrite, then adding a nickel-containing compound, stirring, drying, roasting and grinding to obtain a finished product; the preparation method of the silica-alumina carrier comprises the following steps: adding pseudo-boehmite and sesbania powder into a kneading machine, uniformly mixing, adding an inorganic acid solution and an organic polymer, uniformly kneading, then adding nickel-doped lanthanum ferrite, and uniformly mixing to obtain an alumina precursor for later use; adding a silicon source and pseudo-boehmite into acid liquor of an organic polymer, and uniformly mixing to obtain a silicon source-pseudo-boehmite-organic polymer mixture, wherein the content of the organic polymer in the unit content of an alumina precursor is more than 2 times higher than that of the organic polymer in the silicon source-pseudo-boehmite-organic polymer mixture, then mixing the silicon source-pseudo-boehmite-organic polymer mixture with the alumina precursor, adding a magnesium source, extruding, forming, drying and roasting to obtain a silica-alumina carrier; the organic polymer is sodium polyacrylate or polyacrylic acid; the preparation method of the catalyst comprises the following steps: dipping and spraying dipping liquid containing active components of nickel, molybdenum and magnesium on a carrier, and then drying and roasting the catalyst to obtain the catalyst.

2. The unsaturated hydrocarbon selective hydrogenation catalyst of claim 1, characterized in that the catalyst comprises the following components, based on the total weight of the catalyst: the content of nickel oxide is 7-15 wt%, the content of molybdenum oxide is 4.5-10 wt%, and the content of magnesium oxide is 0.1-1.6%.

3. The unsaturated hydrocarbon selective hydrogenation catalyst according to claim 1, wherein the carrier mesopores account for 2-60% of the total pores, and macropores account for 3-50% of the total pores.

4. The unsaturated hydrocarbon selective hydrogenation catalyst according to claim 1, wherein the silicon source is silica gel, sodium silicate or silica micropowder, and the alumina in the silicon source-pseudo-boehmite-organic polymer mixture accounts for 1-35 wt% of the alumina in the carrier.

5. The unsaturated hydrocarbon selective hydrogenation catalyst according to claim 1, wherein the nickel-doped lanthanum ferrite in the silica-alumina carrier is 0.2-8 wt%.

6. The catalyst for the selective hydrogenation of unsaturated hydrocarbons according to claim 1, wherein the catalyst is prepared by the following steps: preparing a nickel nitrate, magnesium nitrate and ammonium molybdate solution to dip the silicon oxide-alumina carrier, drying for 3-9 hours at 110-160 ℃, and roasting for 4-9 hours at 400-650 ℃ to finally obtain a catalyst product.