CN116474778A - Catalyst for preparing low-carbon alkane and preparation and application thereof - Google Patents

Catalyst for preparing low-carbon alkane and preparation and application thereof Download PDF

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CN116474778A
CN116474778A CN202210037338.9A CN202210037338A CN116474778A CN 116474778 A CN116474778 A CN 116474778A CN 202210037338 A CN202210037338 A CN 202210037338A CN 116474778 A CN116474778 A CN 116474778A
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catalyst
copper
iron
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vacuum chamber
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孙剑
司志岩
葛庆杰
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Dalian Institute of Chemical Physics of CAS
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/80—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with zinc, cadmium or mercury
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
    • B01J37/349—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation making use of flames, plasmas or lasers
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
    • C07C1/02—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon
    • C07C1/12—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon from carbon dioxide with hydrogen
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/15—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
    • C07C29/151—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
    • C07C29/153—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases characterised by the catalyst used
    • C07C29/156—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases characterised by the catalyst used containing iron group metals, platinum group metals or compounds thereof
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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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Abstract

The invention relates to a catalyst which is prepared by taking ZnO as a carrier and Cu and Fe as active components and adopting a physical sputtering method for one step. The chemical components and the weight content are as follows: 5-98 parts of copper, 1-90 parts of iron and 1-90 parts of zinc oxide. Compared with the traditional precipitationThe advantages of the invention are mainly expressed in the following steps: (1) Nitrate is not needed to be used as a metal source, the steps of high-temperature roasting and the like are not needed, and the problem that the metal component is easy to sinter in the preparation process is avoided; (2) The active metal has the characteristics of uniform particle size, high dispersity and easy reduction; (3) During the preparation process, unique FeCu is formed 4 The alloy active phase can be used for the reaction of preparing low-carbon alkane by carbon dioxide hydrogenation.

Description

Catalyst for preparing low-carbon alkane and preparation and application thereof
Technical Field
The invention relates to the field of catalysts and applications for carbon dioxide hydrogenation reactions, in particular to a method for preparing low-carbon alkane (C) through carbon dioxide hydrogenation 1 -C 4 ) Alloy catalysts and applications thereof.
Background
Carbon dioxide (CO) 2 ) The discharge of isothermal chamber gases increases year by year, causing a number of environmental problems including ocean acidification, greenhouse effect. At present, cheap metals such as copper-based, iron-based, cobalt-based and the like are widely used in catalysts, and the use in preparing low-carbon olefin, high-carbon alcohol and high-carbon hydrocarbon is wide. It is difficult to clearly understand how the co-catalytic mechanism between the active components is.
It is currently widely recognized that copper-based catalysts are primarily active sites for methanol synthesis and reverse water gas shift. For example Cu-ZnO-Al 2 O 3 Is an industrial catalyst with wide application, low price and high activity. In addition to this, cu-ZnO-ZrO 2 Other series of copper-based catalysts enrich the application of the catalyst.
Iron-based and cobalt-based catalysts in CO 2 Hydroconversion reactions for synthesizing higher hydrocarbons, wherein Fe x C y 、CoC x Are considered active sites that promote C-C chain growth. The addition of alkali metal auxiliary agents can continue to enhance the chain growth capacity and further improve the selectivity of long-chain substances.
From the results of the studies published so far, CO of Cu/ZnO catalysts 2 The product is methanol, but after the addition of the Fe component, the main product becomes olefin. It is a difficult research to change the product selectivity by adjusting the metal introduction mode to change the intimacy degree, regardless of the impregnation method or the precipitation method.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a simple copper-iron alloy catalyst with low cost and convenient use, which is applied to hydrogenation reaction of carbon dioxide.
The invention adopts a physical sputtering method, copper atoms and iron atoms are fully mixed under the condition of Ar ion bombardment, and an alloy is formed on the surface of a carrier. In this state, the copper and iron components have a very close relationship, so that the catalyst has a unique catalytic effect.
The catalyst is prepared by taking oxide materials with high specific surface areas as carriers and copper and iron as active components by adopting a physical sputtering method in one step.
The preparation method of the CuFe catalyst by the physical sputtering method comprises the following steps: (1) Preparing a catalyst by using a magnetron sputtering device, cleaning the surface of a target before preparation, and bombarding copper and iron targets (with the mass purity of more than 99.9%) for 1-30 minutes, preferably 10-30 minutes, respectively by Ar ions generated by two plasma generators; (2) Placing the carrier powder in a circular rotary barrel, and vacuumizing the vacuum chamber until the pressure reaches 9.9X10 -4 Pa or less, preferably 9.9X10 -6 -9.9×10 -4 Pa; (3) Ar (with the volume purity of more than 99.9%) is introduced into the vacuum chamber, the flow is 10-50ml/min, preferably 12-30ml/min, and the pressure of the vacuum chamber is maintained to be 0.5-3.0Pa, preferably 0.5-1.5Pa; (4) The power of the two plasma generators is respectively adjusted to 100-400W, the ion generator with the copper target is preferably 100-200W, and the ion generator with the iron target is preferably 250-350W; barrel speed is increased to 1-20rpm, preferably 5-10rpm; cu and Fe metal nano particles generated by Ar ion bombardment of the target material can be uniformly deposited on the surface of the carrier; (5) After sputtering is finished, introducing O into the vacuum chamber 2 Passivating Ar mixed gas for 30min, continuously introducing Ar until the pressure reaches normal pressure, wherein O 2 The volume concentration is 0.5-5%, preferably 1-3%.
The mass content of the active component copper in the prepared catalyst is 10-30%, preferably 15-25%; the mass content of iron is 3-8%, preferably 3-5%, and the rest is carrier. The carrier may be SiO 2 、Al 2 O 3 、CeO 2 、ZrO 2 、MgO、 Fe 3 O 4 One or more of them having a high specific surface area (50-200 m 2 /g) oxide material. The catalyst prepared by the method does not need roasting, the species on the fresh catalyst is zero-valent metal, the reduction temperature is low, and the catalyst is not easy to oxidize in the reaction.
The hydrogenation reaction conditions for the catalyst are as follows: the raw materials are hydrogen and carbon dioxide, and the molar ratio of the hydrogen to the carbon dioxide is 1-10, preferably 3-5; the reaction temperature is 200-400 ℃, preferably 250-350 ℃; the reaction pressure is 1.0-10.0MPa, preferably 2.0-4.0MPa; the mass space velocity of the raw material gas is 3000-10000 ml/(g) cat H), preferably 5000-8000 ml/(g) cat ·h)。
The invention has the advantages that: (1) The catalyst is prepared by adopting a physical sputtering method in one step, so that a series of steps of nitrate solution and high-temperature roasting in a common preparation method are avoided, and the problems of environmental pollution, excessive energy consumption and the like are effectively prevented; (2) Alloy nano particles are uniformly dispersed (TEM), the particle radius is small (at 5-7 nm), the metal utilization rate is high, and sintering and aggregation are not easy to occur; (3) Intermetallic alloy of Cu and Fe (FeCu 4 ) In the form of (2) are stable under reducing atmosphere and reaction conditions. Under the combination mode, special electronic action exists in the Cu-Fe-carrier, so that the selectivity of alkane is higher, and conversely, the strong interaction between Cu and Fe can be broken by using an impregnation method or adding an alkali auxiliary agent, so that the selectivity of alkene is increased; (4) The preparation of the catalyst is little influenced by environment and human factors, has no pollutant emission, and is suitable for large-scale industrial production of hydrogenation chemicals. The application method for preparing the catalyst and being used in the reaction of preparing alkane by hydrogenating carbon dioxide is not reported, and has wide application prospect.
Drawings
Table 1 shows the catalyst reactivity of example 1, example 8, comparative example 1, and comparative example 2.
FIG. 1 shows XRD diffraction patterns of catalysts of example 8 (sp-Cu 15Fe5 Zn), comparative example 1 (im-Cu 15Fe5 Zn) and comparative example 2 (sp-Cu 15Fe5 ZnK) before and after the reaction.
FIG. 2 is a TEM image of example 8 (sp-Cu 15Fe5 Zn).
The specific implementation method comprises the following steps:
the technical details of the present invention are described in detail by the following examples. It should be noted that the illustrated embodiments are only used for further illustrating the technical features of the present invention, and are not limiting the present invention.
Example 1
The catalyst was prepared using a commercial magnetron sputtering apparatus (manufacturer: shenyang scientific instruments Co., ltd., china academy of sciences, the same applies hereinafter) with two targets (one plasma generator for each target). The copper target and the iron target are respectively arranged on two targets, ar ions generated by two plasma generators are respectively bombarded on the high-purity copper target (the mass purity is 99.99%) and the iron target (the mass purity is 99.9%) in advance for 30 minutes, and then 10g of ZnO carrier (the specific surface area is 70 m) 2 Per g) the powder was placed in a cylindrical rotating drum and the vacuum chamber was evacuated to a pressure of 9.9X10 -4 Pa, introducing high-purity Ar gas (the volume purity is 99.95%) at a flow rate of 20ml/min, maintaining until the pressure reaches 0.5Pa, respectively adjusting the power of an iron target ion generator to 300W, adjusting the power of a copper target to 200W, and increasing the rotating speed of a rotary drum to 5rpm to uniformly deposit nano metal particles (the nano particle diameter of the copper-iron alloy is 5-7nm observed by a TEM (transmission electron microscope)) generated by Ar ion bombardment of the target material on the surface of a carrier, and sputtering for 3 hours. After sputtering is finished, the vacuum chamber is filled with the volume content 1%O 2 And passivating the Ar mixed gas for 30min, and then introducing Ar to restore to normal pressure. Through detection, a catalyst with a mass loading of Cu of 25% and an iron loading of 5% is obtained and is marked as sp-Cu25Fe5Zn. 50-70% of Fe as active component FeCu 4 In the form of (the remainder being Cu, fe nanoparticles alone), cu—fe metallic bonds can be observed by EXAFS analysis.
A fixed bed reactor was charged with 0.5g of sp-Cu25Fe5Zn catalyst prepared in example 1 above, pure H at 250℃under normal pressure 2 Reducing for 8H, and introducing feed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 340 ℃, the pressure is 3MPa, and the mass airspeed of the raw material gas is 7200 ml/(g) cat H), data were collected after 8h of reaction. 2. Carbon oxide conversion was 35.8% and carbon monoxide selectivity was 12.1%; is an organic product other than carbon monoxide. In the organic product, alkane selectivity was 77.5%, wherein C 1 -C 4 Alkane accounts for 50.2%; olefins (C) 4 -C 14 ) Selectivity was 18.5%, alcohols (CH 3 OH、CH 3 CH 2 OH) selectivity 4.0%.
Example 2
A fixed bed reactor was charged with 0.5g of sp-Cu25Fe5Zn catalyst prepared in example 1 above, pure H at 250℃under normal pressure 2 Reducing for 8H, and introducing feed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 310 ℃, the pressure is 3MPa, and the mass airspeed of the raw material gas is 7200 ml/(g) cat H), data were collected after 8h of reaction. 2. The carbon oxide conversion was 23.1% and the carbon monoxide selectivity was 18.5%; is an organic product other than carbon monoxide. In the organic product, alkane selectivity was 80.1%, wherein C 1 -C 4 Alkane accounts for 56.4%; olefins (C) 4 -C 14 ) Selectivity 14.7%, alcohols (CH) 3 OH、CH 3 CH 2 OH) selectivity was 5.2%.
Example 3
A fixed bed reactor was charged with 0.5g of sp-Cu25Fe5Zn catalyst prepared in example 1 above, pure H at 250℃under normal pressure 2 Reducing for 8H, and introducing feed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 370 ℃, the pressure is 3MPa, and the mass airspeed of the raw material gas is 7200 ml/(g) cat H), data were collected after 8h of reaction. 2. The carbon oxide conversion was 43.1% and the carbon monoxide selectivity was 10.8%; is an organic product other than carbon monoxide. In the organic product, alkane selectivity was 77%, wherein C 1 -C 4 Alkane accounts for 50.2%; olefins (C) 4 -C 14 ) Selectivity was 20.9%, alcohols (CH 3 OH、CH 3 CH 2 OH) selectivity was 2.1%.
Example 4
A fixed bed reactor was charged with 0.5g of sp-Cu25Fe5Zn catalyst prepared in example 1 above, pure H at 250℃under normal pressure 2 Reducing for 8H, and introducing feed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 340 ℃, the pressure is 2MPa, and the mass airspeed of the raw material gas is 7200 ml/(g) cat H), data were collected after 8h of reaction. 2. The carbon oxide conversion was 32.6% and the carbon monoxide selectivity was 23.1%;is an organic product other than carbon monoxide. In the organic product, alkane selectivity was 68.8%, wherein C 1 -C 4 Alkane accounts for 47.2%; olefins (C) 3 -C 14 ) Selectivity was 30.4%, alcohol (CH) 3 OH、CH 3 CH 2 OH) selectivity was 0.8%.
Example 5
A fixed bed reactor was charged with 0.5g of sp-Cu25Fe5Zn catalyst prepared in example 1 above, pure H at 250℃under normal pressure 2 Reducing for 8H, and introducing feed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 340 ℃, the pressure is 4MPa, and the mass airspeed of the raw material gas is 7200 ml/(g) cat H), data were collected after 8h of reaction. 2. Carbon oxide conversion was 35.8% and carbon monoxide selectivity was 16.6%; is an organic product other than carbon monoxide. In the organic product, alkane selectivity was 66.2%, wherein C 1 -C 4 Alkane accounts for 44%; olefins (C) 3 -C 14 ) Selectivity was 30.5%, alcohol (CH) 3 OH、CH 3 CH 2 OH) selectivity was 3.3%.
Example 6
A fixed bed reactor was charged with 0.5g of sp-Cu25Fe5Zn catalyst prepared in example 1 above, pure H at 250℃under normal pressure 2 Reducing for 8H, and introducing feed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 340 ℃, the pressure is 3MPa, and the mass airspeed of the raw material gas is 4800 ml/(g) cat H), data were collected after 8h of reaction. 2. The carbon oxide conversion was 33.6% and the carbon monoxide selectivity was 18.7%; is an organic product other than carbon monoxide. In the organic product, alkane selectivity was 70.2%, wherein C 1 -C 4 Alkane accounts for 50%; olefins (C) 3 -C 14 ) Selectivity 25.2%, alcohols (CH) 3 OH、CH 3 CH 2 OH) selectivity was 4.6%.
Example 7
A fixed bed reactor was charged with 0.5g of sp-Cu25Fe5Zn catalyst prepared in example 1 above, pure H at 250℃under normal pressure 2 Reducing for 8h, and introducing the raw materialsGas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 340 ℃, the pressure is 3MPa, and the mass airspeed of the raw material gas is 9600 ml/(g) cat H), data were collected after 8h of reaction. 2. Carbon oxide conversion was 28.7% and carbon monoxide selectivity was 27.9%; is an organic product other than carbon monoxide. In the organic product, alkane selectivity was 68.1%, wherein C 1 -C 4 Alkane accounts for 51.9%; olefins (C) 3 -C 10 ) Selectivity was 27.6%, alcohol (CH) 3 OH、CH 3 CH 2 OH) selectivity 4.3%.
Example 8
The catalyst was prepared using a commercial magnetron sputtering apparatus (manufacturer: shenyang scientific instruments Co., ltd.) with two targets, one for each target. The copper target and the iron target are respectively arranged on two targets, ar ions generated by two plasma generators are respectively bombarded on the high-purity copper target (the mass purity is 99.99%) and the iron target (the mass purity is 99.9%) for 30 minutes in advance, and then 10g of ZnO carrier (the specific surface area is 70m 2 Per g) the powder was placed in a cylindrical rotating drum and the vacuum chamber was evacuated to a pressure of 9.9X10 -4 Pa, introducing high-purity Ar gas (the volume purity is 99.95%) at a flow rate of 20ml/min, maintaining until the pressure reaches 0.5Pa, respectively adjusting the power of an iron target ion generator to 300W, adjusting the power of a copper target to 100W, and rotating a rotary drum to 5rpm to ensure that nano metal particles (the nano particle diameter of the copper-iron alloy is 5-7nm observed by a TEM electron microscope) generated by Ar ion bombardment of a target material are uniformly deposited on the surface of a carrier, and sputtering for 3 hours. After sputtering is finished, the vacuum chamber is filled with the volume content 1%O 2 And passivating the Ar mixed gas for 30min, and then introducing Ar to restore to normal pressure. The mass loading of Cu is 15%, and the iron loading is 5%, which is marked as sp-Cu15Fe5Zn. 50-70% of Fe as active component FeCu 4 In the form of (the remainder being Cu, fe nanoparticles alone), cu—fe metallic bonds can be observed by EXAFS analysis.
A fixed bed reactor was charged with 0.5g of sp-Cu15Fe5/ZnO catalyst prepared as described in example 8 above, pure H at 250℃under normal pressure 2 Reducing for 8h, introducingFeed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 340 ℃, the pressure is 3MPa, and the mass airspeed of the raw material gas is 7200 ml/(g) cat H), data were collected after 8h of reaction. The carbon dioxide conversion rate is 33.4%, and the carbon monoxide selectivity is 18.0%; is an organic product other than carbon monoxide. Alkane selectivity in the organic product was 76.5%, wherein C 1 -C 4 Alkane accounts for 53.9%; olefins (C) 3 -C 10 ) Selectivity was 19.4%, alcohols (CH 3 OH、CH 3 CH 2 OH) selectivity 4.1%.
Comparative example 1
Preparation of the impregnation catalyst: 4.51gFe (NO) 3 ) 3 ·9H 2 O and 7.09g Cu (NO) 3 ) 2 ·3H 2 O is dissolved in 12ml of deionized water together, then 10g of ZnO powder is dropwise added into the solution by a dropper, the solution is stirred uniformly, and the solution is immersed overnight after being subjected to ultrasonic treatment for 30 min. Then placing the sample into an oven at 80 ℃ for 6 hours for drying, transferring the sample into a muffle furnace, and roasting the sample at 400 ℃ for 4 hours. The mass loading of Cu is 15% and the mass loading of iron is 5% as measured by XRF characterization, and the catalyst is marked as im-Cu15Fe5Zn. XRD characterization shows that the Cu and Fe components exist in the form of oxides respectively, and no alloy is formed in the preparation process.
The fixed bed reactor was charged with 0.5g of the im-Cu15Fe5Zn catalyst prepared in comparative example 1 obtained in comparative example 1 above, and the pretreatment conditions for reduction of the catalyst before the reaction were: pure hydrogen was reduced at normal pressure for 8h at a reduction temperature of 350 ℃. Introducing feed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 340 ℃, the pressure is 3MPa, and the mass airspeed of the raw material gas is 7200 ml/(g) cat H), data were collected after 8h of reaction. The carbon dioxide conversion was 31.3%, the carbon monoxide selectivity was 22.8%, and the carbon monoxide was an organic product other than carbon monoxide. The selectivity to paraffins in the organic product was 27.5%, where C 1 -C 4 Alkane accounts for 21.6%; olefins (C) 2 -C 10 ) The selectivity was 63.5%, alcohols (CH 3 OH、 CH 3 CH 2 OH) selectivity 9%.
Comparative example 2
The catalyst obtained in example 8 was charged with anhydrous K in an amount of 0.5% by weight based on the catalyst obtained in example 8 by grinding 2 CO 3 sp-Cu15Fe5ZnK is obtained. XRD characterization found a shift in the FeCu diffraction peak to the metallic copper, indicating decomposition of the alloy during the reaction.
The fixed bed reactor was charged with 0.5g of the sp-Cu15Fe5ZnK catalyst prepared in comparative example 2 obtained in comparative example 2 above, and the pretreatment conditions for the reduction of the catalyst before the reaction were: pure hydrogen was reduced at normal pressure for 8h at a reduction temperature of 250 ℃. Introducing feed gas H 2 /CO 2 Mixture gas, H 2 /CO 2 The molar ratio is 3, the reaction temperature is 340 ℃, the pressure is 3MPa, and the mass airspeed of the raw material gas is 7200 ml/(g) cat H), data were collected after 8h of reaction. The carbon dioxide conversion was 34.8%, the carbon monoxide selectivity was 21.0%, and the carbon monoxide was an organic product other than carbon monoxide. The selectivity to paraffins in the organic product was 26.1%, where C 1 -C 4 Alkane accounts for 18.9%; olefins (C) 2 -C 10 ) Selectivity was 61.7%, alcohols (CH) 3 OH、 CH 3 CH 2 OH) selectivity was 12.2%.
Example results: from the above results, the selectivity of sp-Cu15Fe5Zn alkane prepared in one step by the physical sputtering method is higher under the same reaction conditions, which benefits from FeCu 4 The metal in the alloy has stronger interaction. As can be observed in XRD patterns, the sp-Cu15Fe5Zn catalyst prepared by the magnetron sputtering technology is 43.3 DEG FeCu in the unused fresh state 4 The alloy peaks of (2) are obvious, and the im-Cu15Fe5Zn metal components prepared by the impregnation method exist in the form of oxide; after 8h of reaction, the sp-Cu15Fe5Zn is a very strong alloy peak, and the im-Cu15Fe5Zn is metallic Cu (43.2 DEG) and Fe x C, while the diffraction peak of sp-Cu15Fe5ZnK is between the two, the alloy is decomposed under the influence of K promoter, the interaction between copper and iron is weakened, and the alkane content in the product is low and the alkene is high. The preparation method is less influenced by experimental operation conditions, but is limited by the yield of a sputtering device.
Note that: 1. selectivity means that after CO removal, the components account for the total organic products
2. The data in brackets are lower alkanes (C) 1 -C 4 ) Is selected from the group consisting of (1).
Table 1. Catalyst reactivity for example 1 (sp-Cu 25Fe5 Zn), example 8 (sp-Cu 15Fe5 Zn), comparative example 1 (im-CuFeZn), comparative example 2 (sp-Cu 15Fe5 ZnK).
Compared with the traditional precipitation method and impregnation method, the invention has the main advantages that: (1) Nitrate is not needed to be used as a metal source, the steps of high-temperature roasting and the like are not needed, and the problem that the metal component is easy to sinter in the preparation process is avoided; (2) The active metal has the characteristics of uniform particle size, high dispersity and easy reduction; (3) During the preparation process, unique FeCu is formed 4 The alloy active phase can be used for the reaction of preparing low-carbon alkane by carbon dioxide hydrogenation.

Claims (8)

1. A catalyst for the preparation of light alkanes, characterized in that:
the catalyst is a supported catalyst, which is obtained by taking a metal oxide material as a carrier, taking copper and iron as active components, and adopting a physical sputtering method to prepare the active components on the carrier in one step, wherein the copper and iron species on the carrier in the prepared catalyst are zero-valent metals; the mass content of copper in the catalyst is 15-30%, preferably 15-25%; the mass content of iron is 3-8%, preferably 3-5%.
2. The catalyst of claim 1, wherein: the active component in the catalyst is FeCu 4 Alloy, and the rest is carrier.
3. The catalyst according to claim 1 or 2, characterized in that: the carrier may be SiO 2 、Al 2 O 3 、CeO 2 、ZrO 2 、MgO、Fe 3 O 4 One or more materials with high specific surface area, the specific surface area is 50-200m 2 /g, preferably 50-80m 2 /g。
4. The catalyst of claim 1, wherein: the copper and iron-based catalyst prepared by physical sputtering does not need roasting treatment; the catalyst takes a material with high specific surface area as a carrier; the active components are stable in the reaction process, the copper-iron alloy nano particles are not sintered and aggregated, and the method can be used for the reaction of preparing low-carbon alkane by carbon dioxide hydrogenation.
5. A process for preparing the catalyst of any one of claims 1-4, comprising the steps of: preparing a catalyst by adopting a magnetron sputtering device, wherein two target heads are arranged in a vacuum chamber of the magnetron sputtering device, and each target head corresponds to one plasma generator;
(1) Firstly, pre-cleaning treatment is carried out on the surface of a target material before preparation: copper targets and iron targets are respectively arranged on two targets in a vacuum chamber, ar gas is used as working gas, ar ions generated by two plasma generators are used for respectively bombarding copper and iron targets (the mass purity is more than 99.9 percent) for 1-30 minutes, preferably 10-30 minutes;
(2) Placing the carrier powder into a rotary drum with circular radial section and capable of rotating axially in a vacuum chamber of a magnetron sputtering device, and vacuumizing the vacuum chamber until the pressure reaches 9.9X10 -4 Pa or less (pressure 9.9X10 or less) -4 Pa), preferably 9.9X10 -6 -9.9×10 -4 Pa；
(3) Ar gas (with the volume purity of more than 99.9%) is introduced into the vacuum chamber, the flow is 10-50ml/min, preferably 12-30ml/min, and the pressure of the vacuum chamber is maintained to be 0.5-3.0Pa, preferably 0.5-1.5Pa;
(4) The power of the two plasma generators is respectively adjusted to 100-400W, the ion generator with the copper target is preferably 100-200W, and the ion generator with the iron target is preferably 250-350W; the rotation speed of the rotary drum is increased to 1-20rpm, preferably 5-10rpm; copper and iron nano particles generated by Ar ion bombardment of a target material are uniformly deposited on the surface of a carrier; sputtering for 2-6 hours;
(5) After sputtering is finished, introducing O into the vacuum chamber 2 Passivating the Ar mixture for 30-60 minutes, preferably 20-30 minutes; then Ar is introduced until the pressure reaches normal pressure, and a magnetron sputtering vacuum chamber door is opened; o (O) 2 O in Ar gas mixture 2 The volume concentration is 0.5-5%, preferably 1-3%; the desired catalyst is obtained.
6. Use of a catalyst according to any one of claims 1 to 4, characterized in that: the catalyst can be used for preparing low-carbon alkane (C) by carbon dioxide hydrogenation 1 -C 4 Alkane).
7. The use according to claim 6, characterized in that: the catalyst is applied to a fixed bed reactor, and the hydrogenation reaction conditions are as follows: the raw materials are hydrogen and carbon dioxide, and the molar ratio of the hydrogen to the carbon dioxide is 1-10, preferably 3-5; the reaction temperature is 200-400 ℃, preferably 250-350 ℃; the reaction pressure is 1.0-10.0MPa, preferably 2.0-4.0MPa; the mass space velocity of the raw material gas is 3000-10000 ml/(g) cat H), preferably 5000-8000ml/g cat /h。
8. Use according to claim 6 or 7, characterized in that: the catalyst needs to be pure H under the normal pressure of 250-340 ℃ (preferably 250 ℃) before hydrogenation reaction 2 Reduction is carried out for 4-8h (preferably 8 h).
CN202210037338.9A 2022-01-13 2022-01-13 Catalyst for preparing low-carbon alkane and preparation and application thereof Pending CN116474778A (en)

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CN110871071A (en) * 2018-09-04 2020-03-10 中国科学院大连化学物理研究所 Copper-based catalyst for preparing methyl glycolate and preparation and application thereof
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