A CuCo catalyst for preparing lower alcohols from syngas, a preparation method and uses thereof

Abstract

A CuCo catalyst, a preparation method and a use for preparing lower alcohols from syngas. The CuCo catalyst uses zinc-aluminum composite oxide Zn(Al)O as a carrier, and bimetallic nanoparticles of Cu and Co are loaded on the surface of the carrier. The Co loading of the CuCo catalyst is 0.5 wt% - 22 wt%, and the Cu loading is 0.5 wt% - 22 wt%. By regulating the synthesis method of the hydrotalcite precursor and controlling the process conditions during the preparation, a CuCo bimetallic catalyst with controllable structure is obtained. Due to the characteristic of uniform distribution of dual active sites, the catalyst can achieve high selectivity, activity and stability when used for preparing C 2+ OH from syngas and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of syngas conversion, and particularly relates to providing a CuCo catalyst for preparing lower alcohols from syngas, a preparation method and uses thereof. Background Art

[0002] Lower alcohols (alcohol products containing 2 or more carbon atoms, C 2+ OH), as a renewable clean energy source, have important economic value and application prospects. Lower alcohols are not only important raw materials in the energy and chemical industry, but can also be used as alternative fuels and clean additives for improving the octane number of gasoline. Therefore, the application value of lower alcohols in the fields of chemical industry, fuel and environmental protection has been increasing in recent years. Syngas is a mixture of CO and H 2 and can be obtained by coal gasification, natural gas reforming and biomass gasification or fermentation. Lower alcohols can be produced through catalytic conversion of syngas. The route of syngas conversion to lower alcohols has the characteristics of cleanness and high efficiency, so the related research on syngas to lower alcohols has received great attention from researchers.

[0003] The catalysts reported in the prior art for catalytic conversion of syngas to lower alcohols can be divided into four categories: noble metal Rh-based catalysts, modified methanol catalysts, modified Mo-based catalysts and modified Fischer-Tropsch catalysts (also known as modified F-T catalysts). Among them, the supported Rh-based catalysts have good activity and ethanol selectivity, but the high price of the noble metal Rh limits their industrial application. Mo-based catalysts have good anti-coking and sulfur tolerance properties, but the reaction conditions require high temperature and high pressure, and the active components are prone to loss during the reaction, which affects their stability. Modified methanol synthesis catalysts include Zn-Cr-based catalysts and Cu-Zn-based catalysts. Zn-Cr catalysts require high temperature and high pressure conditions and have high selectivity for methanol and isobutanol; Cu-Zn-based catalysts have mild reaction conditions and high total alcohol selectivity, but mainly produce methanol, and the selectivity of C 2+ OH is low. At present, the most widely studied for syngas to C 2+ OH is the modified F-T catalyst. Co and Fe-based catalysts are the most important industrial catalysts for Fischer-Tropsch synthesis at present due to their high reaction activity, mild reaction conditions and low price. Adding alkali metal promoters or modifying the Cu active center to the Fischer-Tropsch catalysts can obtain oxygen-containing compounds such as alcohols. According to the different active components of the Fischer-Tropsch catalysts, they are mainly divided into two categories: Cu-Fe and Cu-Co-based catalysts. The reaction conditions of these two types of catalysts are relatively mild, and the selectivity of lower alcohols is also relatively high. Therefore, they are considered to be one of the most promising catalyst systems for synthesizing lower alcohols industrially. The Cu-Fe catalysts have high activity for the water-gas shift reaction, resulting in a high content of CO 2It has relatively high selectivity for hydrocarbons. Cu-Co was first proposed by the Institut Français du Pétrole (IFP) (US Patent, 4122110, 1978). The Cu-Co catalyst contains two active components, Cu and Co. The metal Co nanoparticles have low activity for the water-gas shift reaction, are responsible for the dissociative adsorption of CO, and have a high ability for the dissociative adsorption of CO. Therefore, the CO conversion rate is high. The literature (Journal of the American Chemical Society, 2013, 135, 16284-16287) reported that the hexagonal close-packed Co nanoparticles with more stepped sites and other coordinatively unsaturated sites exposed on the surface have better CO dissociation ability. The Cu sites on the metal Cu nanoparticles are responsible for the non-dissociative adsorption of CO, have a high ability for the non-dissociative activation of CO, and have a high selectivity for methanol. The literature (Science, 2012, 336, 893-897) reported that the selectivity of methanol on the Cu-Zn-based catalyst is proportional to the density of the stacking faults on the surface of the Cu nanoparticles. The CuCo catalyst provides the dual active sites required in the reaction process according to the reaction mechanism, not only maintaining the advantages of the Cu-based catalyst but also being beneficial to improving the C 2+ OH selectivity.

[0004] In recent years, researchers have been committed to improving the activity of the CuCo catalyst and the C 2+ OH selectivity, promoting the process progress of synthesizing C 2+ OH from syngas. The literature (Journal of Catalysis, 2012, 286, 51-61) reported a series of xCuyCo / γ-Al 2 O 3 (x = 0 - 0.5) prepared by the co-impregnation method. When x = y = 0.5, the catalyst precursor was calcined at 673K and further reduced at this temperature to obtain γ-Al 2 O 3 -supported CuCo nanoparticles with a particle size of about 10nm. Under the reaction conditions of H 2 / CO of 2:1, 2MPa, and 523K, the CO conversion rate can reach 16.5%, the hydrocarbon selectivity is 82.6%, the total alcohol selectivity is 17.1%, and the C 2+ OH accounts for 64.3% of the total alcohol content. It is analyzed that the catalyst prepared by this method is a CuCoO x mixed oxide after calcination, and separate Cu and Co metal particles are obtained after reduction, and the distribution of the active components is uneven, thus weakening the synergistic effect between Cu-Co and being not conducive to C 2+Generation of OH. The literature (Catalysis Science Technology, 2018, 8, 3936) reported that the catalyst obtained by reducing CuCoAl-LDHs was ordinary CuCo alloy nanoparticles with a particle size of about 20 nm, a surface Cu / Co ratio close to 1, and the main product was C 1 -C 3 alcohol, the CO conversion rate was 36.5%, and the mass distribution of C 2+ OH was 59.3 wt%.

[0005] The reported CuCo catalysts have problems such as large CuCo metal particle size, low dispersion degree, and uneven surface CuCo distribution, resulting in low conversion rate and low C 2+ OH selectivity in the synthesis of lower alcohols from syngas. Therefore, it is an urgent problem to develop a CoCu catalyst with a controllable structure and uniform distribution of dual active sites, which can catalyze the conversion of syngas to prepare C 2+ OH with higher activity by improving the dispersion degree of active components and regulating the surface defect structure of the catalyst, and to improve the C 2+ OH selectivity. Summary of the Invention

[0006] In order to solve the problems of the prior art, the purpose of the present invention is to provide a CuCo catalyst for preparing lower alcohols from syngas and a preparation method thereof. The catalyst is a CuCo bimetallic catalyst with a controllable structure obtained by regulating the synthesis method of the hydrotalcite precursor and controlling the process conditions during the preparation. Due to the characteristic of uniform distribution of dual active sites, the catalyst can be used for the preparation of C 2+ OH from syngas with high selectivity, activity and stability, and has good application prospects.

[0007] In order to achieve the above purpose, the present invention is realized by the following technical methods:

[0008] A CuCo catalyst for preparing lower alcohols from syngas, wherein the CuCo catalyst uses zinc-aluminum composite oxide Zn(Al)O as a carrier, and dual-metal nanoparticles of Cu and Co are loaded on the surface of the carrier. The Co loading of the CuCo catalyst is 0.5 wt% - 22 wt%, and the Cu loading is 0.5 wt% - 22 wt%.

[0009] Further, the Co loading of the CuCo catalyst is 5.0 wt% - 10.0 wt%, and the Cu loading is 9.0 wt% - 15 wt%.

[0010] Further, the molar ratio of Cu to Co, Cu / Co, is 0.5 - 2.0. Preferably, the molar ratio of Cu / Co is 1.0.

[0011] Further, the carrier is a ZnAl composite oxide carrier prepared by topotactic transformation roasting and reduction of hydrotalcite.

[0012] Further, the carrier is prepared by the nucleation crystallization isolation method or the constant pH coprecipitation method to prepare Cu x Co y ZnAl-CO 3 2- -LDHs, where x and y represent the molar ratio, and the range of the x / y ratio is 0.5 - 2.0.

[0013] Further, the particle size of the metal particles of the CuCo catalyst is 4 - 10 nm.

[0014] Further, the amount of Zn in terms of substance is 1 - 4 times that of Co, preferably 2 - 3 times.

[0015] Further, the amount of Al in terms of substance is 1 - 3 times that of Co, preferably 1 - 2 times.

[0016] Further, the structure of the CoCu metal center is adjustable, and the structure includes any one of a multiple included - angle twin - boundary CuCo alloy, a multiple parallel twin - boundary CuCo alloy, a common CuCo alloy, a Cu@Co core - shell structure, a CuCo alloy with a multi - Cu compatibility, or a CuCo alloy structure with a multi - Co compatibility.

[0017] In the present invention, the multiple included - angle twin - boundary CuCo alloy structure means that two twin interfaces on the surface of the CuCo alloy nanoparticles form an included angle. The multiple parallel twin - boundary CuCo alloy structure means that the twin interfaces on the surface of the CuCo alloy nanoparticles are parallel.

[0018] In the present invention, the Cu@Co core - shell structure represents nanoparticles with a core - shell structure where Cu is the core and Co is the shell.

[0019] In the present invention, the CuCo alloy with a multi - Cu compatibility means that a small amount of Co is doped into the surface of Cu nanoparticles to form a CuCo alloy structure with a multi - Cu compatibility; the CuCo alloy with a multi - Co compatibility means that a small amount of Cu is doped into the surface of Co nanoparticles to form a CuCo alloy structure with a multi - Co compatibility.

[0020] The present invention also provides a preparation method of the CuCo catalyst, and the method includes the following steps:

[0021] Step S1: Prepare a CuCo - based hydrotalcite precursor Cu x Co y ZnAl - CO 32- -LDHs, where x and y represent the molar ratio, and the value range of the x / y ratio is 0.5 - 2.0:

[0022] Dissolve Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O in deionized water to prepare a mixed nitrate solution A;

[0023] Weigh a certain mass of Na 2 CO 3 and NaOH and dissolve them in deionized water, denoted as solution B. The concentration range of NaOH is 1.8 - 2.5 times the concentration of metal cations. The concentration of Na 2 CO 3 is 0.18 - 0.25 times the concentration of A1(NO 3 ) 3 ·9H 2 O;

[0024] While stirring, simultaneously drip solutions A and B into deionized water, control the pH to be between 9 and 10. After titration, control the crystallization temperature at 65 - 80 °C, the crystallization time at 18 - 24 h. After crystallization, perform vacuum filtration, wash with deionized water, dry, and grind to obtain Cu x Co y ZnA1-CO 3 2- -LDHs-s powder;

[0025] Step S2: Programmed temperature reduction of the CuCo-based hydrotalcite precursor obtained in step S1 in an H 2 atmosphere. Heat up to the target reduction temperature of 500 - 800 °C at a heating rate of 1 - 20 °C / min, and keep the temperature for 0.1 - 3 h to obtain the CuCo catalyst.

[0026] Furthermore, in step S1, in the mixed nitrate solution A, the concentration range of Cu(NO 3 ) 2 ·3H 2 O is 0.03 - 0.09 mol / L, and the concentration range of Co(NO 3 ) 2 ·6H 2The concentration range of O is 0.03 - 0.09 mol / L, Zn(NO 3 ) 2 ·6H 2 The concentration range of O is 0.09 - 0.18 mol / L, A1(NO 3 ) 3 ·9H 2 The concentration range of O is 0.06 - 0.12 mol / L.

[0027] Furthermore, in step S2, the temperature-raising reduction includes two methods. The obtained CuCo-based hydrotalcite precursor is directly heated to the target reduction temperature and kept warm for 0 - 3 h; or it is first heated to the plateau temperature, kept warm for 0.1 - 3.0 h, then heated to the target reduction temperature and kept warm for 0 - 3 h. The plateau temperature range is 200°C - 700°C. The target reduction temperature is the final reduction temperature of the catalyst and is the highest temperature of the programmed temperature rise.

[0028] The present invention also provides a preparation method of the CuCo catalyst, and the method includes the following steps:

[0029] Step T1: Prepare the CuCo-based hydrotalcite precursor Cu x Co y ZnA1-CO 3 2- -LDHs, where x and y represent the molar ratio, and the x / y ratio range is 0.5 - 2.0:

[0030] Dissolve Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O in deionized water to form a mixed nitrate solution A;

[0031] Weigh a certain mass of Na 2 CO 3 and NaOH and dissolve them in deionized water to form a mixed alkali solution B with a concentration of [NaOH] = (1.5 - 2.0)([M 2+ +[M 3+ ) and [Na 2 CO 3 = (0.2 - 1.0)[M 3+ ;

[0032] Pour solutions A and B into a running colloid mill simultaneously. After completion, continue stirring for 2 - 5 minutes, then place it in a water bath at 50 - 80 °C for static crystallization for 6 - 24 h. After the crystallization is completed, wash with deionized water and perform suction filtration. Dry the sample and grind it to obtain Cu x Co y ZnA1-CO 3 2- -LDHs powder;

[0033] Step T2: Programmed temperature reduction of the CuCo-based hydrotalcite precursor obtained in step T1 is carried out in an H 2 atmosphere. Heat it up to the target reduction temperature of 500 - 800 °C at a heating rate of 1 - 20 °C / min, and keep it for 0 - 3 h to obtain the CuCo catalyst.

[0034] Furthermore, in step T1, in the mixed nitrate solution A, the concentration range of Cu(NO 3 ) 2 ·3H 2 O is 0.03 - 0.09 mol / L, the concentration range of Co(NO 3 ) 2 ·6H 2 O is 0.03 - 0.09 mol / L, the concentration range of Zn(NO 3 ) 2 ·6H 2 O is 0.09 - 0.18 mol / L, and the concentration range of A1(NO 3 ) 3 ·9H 2 O is 0.06 - 0.12 mol / L.

[0035] Furthermore, in step T1, in the mixed nitrate solution A, the total metal cation concentration is 0.3 mol / L.

[0036] Furthermore, weigh a certain mass of Na 2 CO 3 and NaOH and dissolve them in deionized water to prepare a mixed alkali solution B with a concentration of [NaOH] = 1.8([M 2+ +[M 3+ ) and [Na 2 CO 3 = 0.5[M 3+ . Here, M 2+ is the concentration of divalent metal ions, and M 3+ refers to the concentration of trivalent metal ions

[0037] Further, in step S2 or T2, the platform temperature range is preferably 220°C - 700°C, more preferably 250°C - 600°C.

[0038] Further, in step T2, the temperature-raising reduction includes two methods. The obtained CuCo-based hydrotalcite precursor is directly heated to the target reduction temperature and held for 0 - 3 h; or it is first heated to the platform temperature, held for 0.1 - 3.0 h, then heated to the target reduction temperature and held for 0 - 3 h. The platform temperature range is 200°C - 700°C. The target reduction temperature is the final reduction temperature of the catalyst and is the highest temperature of the programmed temperature rise.

[0039] The present invention also provides a preparation method of the CuCo catalyst, and the method includes the following steps:

[0040] Step R1: Prepare a Cu-based hydrotalcite precursor CuZnAl-LDHs or a Co-based hydrotalcite precursor CoZnAl-LDHs by using a constant pH coprecipitation method or a nucleation crystallization isolation method;

[0041] Step R2: After the CuZnAl-LDHs are reduced, they are impregnated with a part of Co by incipient wetness impregnation 2+ , to obtain a Co 2+ / Cu-Zn(Al)O catalyst precursor; or after the CoZnAl-LDHs are reduced, Co-Zn(Al)O is obtained, and then Cu 2+ is used to replace a part of the surface metal Co to obtain a Cu / Co-Zn(Al)O catalyst precursor;

[0042] Step R3: The Co 2+ / Cu-Zn(Al)O and Cu / Co-Zn(Al)O catalyst precursors obtained in step R2 are subjected to programmed temperature reduction in an H 2 atmosphere. They are heated to the target reduction temperature of 500 - 800°C at a heating rate of 1 - 20°C / min and held for 0 - 3 h to obtain the CuCo alloy catalyst with a multi-Cu compatibility or multi-Co compatibility.

[0043] The present invention also provides a use of the CuCo catalyst for the preparation of lower alcohols from syngas, and the use includes the following steps:

[0044] Weigh a certain mass of the catalyst and load it into a fixed-bed reactor. The reaction temperature is 200 - 300°C, the reaction pressure is 2 - 6 MPa, the reaction feed gas contains CO, H 2 and Ar. The volume ratio of CO to H 2 is 0.5 - 2.0, Ar is used as a balance gas, and the volume percentage range of Ar is 2.0 - 6.0%. The volume space velocity of the reaction gas is 1000 - 9000 h -1Based on the mass of CO passing through the catalyst in 1 h, the mass ratio of the catalyst to CO is 0.0001 - 0.002.

[0045] Furthermore, when using the CuCo catalyst prepared by the nucleation crystallization isolation method, the reaction temperature is 260 °C, the pressure is 3 MPa, and the space velocity is 1800 h -1 , the CO conversion rate is 46.0%, the ROH selectivity is 24.3%, and the C 2+ OH space-time yield is 0.38 g·g cat -1 ·h -1 , C 2+ The molar ratio of OH in the total alcohol ROH is 92.9%; when the space velocity is 2400 h -1 , the CO conversion rate is 18.9%, and the total alcohol selectivity is 17.0%. The space-time yield of C 2+ OH reaches the highest value of 0.53 g·g cat -1 ·h -1 , C 2+ The molar ratio of OH in the total alcohol ROH is 90.9%.

[0046] The beneficial effects of the present invention are as follows:

[0047] 1. The CuCo catalyst of the present invention can obtain a CuCo bimetallic catalyst with controllable structure by regulating the synthesis method of the hydrotalcite precursor and regulating the heating rate, reduction temperature, reduction temperature holding time, platform temperature range, and platform temperature holding time during the programmed heating process, and can achieve efficient conversion of syngas under mild conditions. When the proportion of C 2+ OH in the total alcohol is 90.9%, the yield of C 2+ OH can reach a maximum of 0.53 g·g cat -1 ·h -1 .

[0048] 2. The present invention uses the nucleation crystallization isolation method to prepare the CuCo-based hydrotalcite precursor Cu x Co y ZnA1-CO 3 2- -LDHs. In the nucleation crystallization isolation method, nucleation occurs after passing through a 500 nm slit in a colloid mill running at high speed and then remixing. Therefore, the synthesized hydrotalcite precursor has a small size, the hydrotalcite sheet length is about 30 - 100 nm, the thickness is 8 - 18 nm, and the aspect ratio is 0.20, which is prone to generating more oxygen defects or metal vacancy defects. Therefore, during the calcination reduction process, alloy particles containing more defects and including angle twin boundaries can be formed due to the topological transformation effect of the hydrotalcite precursor. Thus, a highly active and high C 2+The OH-selective CuCo catalyst is attributed to the fact that the surface of the CuCo alloy with multiple included-angle twin boundaries contains more stacking faults, generating more coordinatively unsaturated sites, and the CuCo sites are evenly distributed.

[0049] 3. In order to improve the activity of the catalyst and the selectivity of C 2+ OH, it is necessary to increase the specific surface area of the catalyst, expose more CuCo dual active sites, control the surface to contain more coordinatively unsaturated defect sites, and the two active sites are evenly distributed and close in position to avoid the existence of a single metal phase. Brief Description of the Drawings

[0050] Figure 1 are the electron micrographs of the catalysts in Examples 1-3 of the present invention. Among them,

[0051] Figure (a) is the electron micrograph of the catalyst in Example 1, which are the high-resolution transmission electron microscope (HRTEM) and line-scanning energy spectrum of the MA-TBs CuCo alloy catalyst structure in sequence;

[0052] Figure (b) is the electron micrograph of the catalyst in Example 2, which are the high-resolution transmission electron microscope (HRTEM) and line-scanning energy spectrum of the MP-TBs CuCo alloy catalyst structure in sequence;

[0053] Figure (c) is the electron micrograph of the catalyst in Example 3, which are the high-resolution transmission electron microscope (HRTEM) and line-scanning energy spectrum of the Cu@Co-Zn(Al)O catalyst structure in sequence. Detailed Embodiments

[0054] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

[0055] Example 1

[0056] A CuCo catalyst for preparing lower alcohols from syngas. The CuCo catalyst uses zinc-aluminum composite oxide Zn(Al)O as a carrier, and bimetallic nanoparticles of Cu and Co are loaded on the surface of the carrier. The Co loading of the CuCo catalyst is 8.8%, and the Cu loading is 13.2%;

[0057] Among them, the molar ratio of Cu / Co is 1.4; the particle size of the metal center is 5.9 nm.

[0058] The preparation method is as follows:

[0059] Step T1: Prepare a hydrotalcite precursor by the nucleation crystallization isolation method:

[0060] Accurately weigh a certain amount of Cu(NO 3 ) 2 ·3H 2 O, Co(NO3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O are dissolved in 200 mL of deionized water, and the corresponding concentrations of the four metal nitrates are 0.0375 mol / L, 0.0375 mol / L, 0.15 mol / L, and 0.075 mol / L respectively. The mixed nitrate solution is stirred until completely dissolved to obtain a purple transparent salt solution A;

[0061] Weigh accurately a certain mass of Na 2 CO 3 and NaOH and dissolve them in deionized water to prepare a mixed alkali solution B with a NaOH concentration of 0.18 mol / L and a Na 2 CO 3 concentration of 0.0125 mol / L;

[0062] Pour the two solutions into a running colloid mill simultaneously. After stirring for a certain time, transfer the product to a four-necked flask, and place the flask in a 65 °C water bath for static crystallization for 24 h. After the crystallization is completed, filter and wash with deionized water, dry the sample, and grind it to obtain Cu 1 Co 1 ZnA1-CO 3 2- -LDHs powder;

[0063] Step T2: The catalyst precursor in Step T1 is reduced in H 2 at a flow rate of 40 mL / min. The selected heating rate is 2 °C / min, no plateau temperature is set, the reduction temperature is 600 °C, and the heating program is: first heat from room temperature to 600 °C at a heating rate of 2 °C / min, hold for 0 h, and then naturally cool to room temperature to obtain a CuCo alloy catalyst with multiple included angle twin boundaries.

[0064] Application: Press and granulate the catalyst powder obtained in the previous step, sieve to obtain particles with a mesh size of 20 - 40, weigh a certain mass of the catalyst and load it into a fixed-bed reactor. The reaction temperature is 260 °C, the pressure is 3 MPa, the space velocity is 1800 h -1 , the CO conversion rate is 46.0%, the ROH selectivity is 24.3%, the space-time yield of C 2+ OH is 0.38 g·g cat -1 ·h -1 , and the molar ratio of C 2+ OH in the total alcohol ROH is 92.9%; when the space velocity is 2400 h -1At this time, the CO conversion rate was 18.9%, and the total alcohol selectivity was 17.0%. C 2+ The space-time yield of C cat -1 OH reached a maximum of 0.53 g·g -1 , C 2+ The molar ratio of OH to the total alcohol ROH was 90.9%.

[0065] The high activity and high C 2+ OH selectivity of the catalyst in Example 1 was attributed to the fact that the surface of the CuCo alloy with multiple included-angle twin boundaries contained more stacking faults, generating more coordinatively unsaturated sites, and the CuCo sites were evenly distributed. The nucleation crystallization isolation method was to pass through a 500-nm slit in a high-speed colloid mill and then remix and nucleate. Therefore, the size of the synthesized hydrotalcite precursor was small. The length of the hydrotalcite flakes was about 30 - 100 nm, the thickness was 8 - 18 nm, and the aspect ratio was 0.20, which was prone to generating more oxygen defects or metal vacancy defects. Therefore, during the calcination reduction process, due to the topological transformation effect of the hydrotalcite precursor, alloy particles with included-angle twin boundaries containing more defects could be formed.

[0066] Figure (a) is the electron microscope image of the catalyst in Example 1. They are the high-resolution transmission electron microscope (HRTEM) and the line-scanning energy spectrum of the structure of the MA-TBs CuCo alloy catalyst in sequence. It can be found that the surface structure of the CuCo alloy is a CuCo alloy twin interface with multiple included angles, and the surface contains more Cu and Co defect sites generated by stacking faults. The lattice fringes show that the particles are CuCo alloys. The line-scanning energy spectrum shows that the Cu and Co elements of the catalyst are evenly distributed, indicating that the CuCo active sites are evenly distributed.

[0067] Example 2

[0068] A CuCo catalyst for the preparation of lower alcohols from syngas. The CuCo catalyst uses zinc-aluminum composite oxide Zn(Al)O as the carrier, and bimetallic nanoparticles of Cu and Co are loaded on the surface of the carrier. The Co loading of the CuCo catalyst is 8.8 wt%, and the Cu loading is 12.3 wt%;

[0069] Among them, the molar ratio of Cu / Co is 1.4; the particle size of the metal center is 6.0 nm.

[0070] The preparation method is as follows:

[0071] Step S1: Prepare a hydrotalcite precursor by the constant pH coprecipitation method:

[0072] Dissolve Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O are dissolved in deionized water. The corresponding concentrations of the four metal nitrates are 0.0125 mol / L, 0.0125 mol / L, 0.05 mol / L, and 0.025 mol / L respectively. After stirring until completely dissolved to form a purple transparent solution, a mixed nitrate solution A is obtained;

[0073] Weigh a certain mass of Na 2 CO 3 and NaOH and dissolve them in deionized water to prepare a mixed alkali solution B with a NaOH concentration of 0.18 mol / L and a Na 2 CO 3 concentration of 0.0125 mol / L;

[0074] The mixed alkali solution B;

[0075] While stirring, solutions A and B are simultaneously dropped into deionized water, and the pH is controlled between 9 and 10;

[0076] After titration, the crystallization temperature is controlled at 65 - 80 °C, and the crystallization time is 18 - 24 h. After crystallization, vacuum filtration is carried out, washed with deionized water, dried, and ground to obtain CuCoZnA1 - CO 3 2- -LDHs-s powder.

[0077] Step S2: The catalyst precursor prepared in step S1 is reduced in H 2 at a flow rate of 40 mL / min. The selected heating rate is 2 °C / min, no platform temperature is set, and the reduction temperature is 600 °C. The heating program is: first heat from room temperature to 600 °C at a heating rate of 2 °C / min, hold for 0 h, and then naturally cool to room temperature to obtain a CuCo alloy catalyst with multiple parallel twin boundaries.

[0078] Application: The catalyst powder obtained in the previous step is tableted and granulated, and sieved to obtain particles with a mesh size of 20 - 40. Weigh a certain mass of the catalyst and load it into a fixed-bed reactor. The reaction temperature is 260 °C, the pressure is 3 MPa, the space velocity is 1800 h -1 , the CO conversion rate is 34.1%, and the total alcohol selectivity is 10.6%. The space-time yield of C 2+ OH is 0.21 g·g cat -1 ·h -1 , and the molar ratio of C 2+ OH in the total alcohol ROH is 87.6%,

[0079] Compared with Example 1, the activity of this catalyst and the selectivity for C 2+ OH decrease because the surface coordination unsaturated sites of the CuCo alloy with multiple parallel twin boundaries are fewer than those in Example 1, and the distribution of surface CuCo sites is uneven. The hydrotalcite obtained by the constant pH coprecipitation method has a complete morphology, fewer defects compared with the nucleation crystallization isolation method, and larger hexagonal sheet size of the hydrotalcite. The length of the hydrotalcite sheet is about 165 - 400 nm, the thickness is 11 - 25 nm, and the aspect ratio is 0.06.

[0080] Figure (b) is the electron microscope image of the catalyst in Example 2. They are the high-resolution transmission electron microscope (HRTEM) and line scan energy spectrum of the MP-TBs CuCo alloy catalyst structure in sequence. It can be found that the surface structure of the CuCo alloy is a CuCo alloy twin interface with multiple parallels, and there are Cu and Co defect sites generated by stacking faults on the surface. The lattice fringes show that the particles are CuCo alloy. The line scan energy spectrum shows that the Cu element on the catalyst surface is less than the Co element. Since Cu is the active site for alcohol formation, the low surface Cu content corresponds to the low total alcohol selectivity of this catalyst.

[0081] Example 3

[0082] A CuCo catalyst for synthesizing lower alcohols from syngas. The CuCo catalyst uses zinc-aluminum composite oxide Zn(Al)O as the carrier, and bimetallic nanoparticles of Cu and Co are loaded on the surface of the carrier. The Co loading of the CuCo catalyst is 7.7 wt%, and the Cu loading is 12.3 wt%.

[0083] Among them, the molar ratio of Cu / Co is 1.4; the particle size of the metal center is 6.2 nm.

[0084] The preparation method is as follows:

[0085] Step T1: Accurately weigh a certain amount of Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O and dissolve them in 200 mL of deionized water. The corresponding concentrations of the four metal nitrates are 0.0375 mol / L, 0.0375 mol / L, 0.15 mol / L, and 0.075 mol / L respectively. Stir the mixed nitrate solution until it is completely dissolved to obtain a purple transparent salt solution A;

[0086] Accurately weigh a certain mass of Na 2 CO 3 and NaOH, dissolve them in deionized water, and prepare a mixed alkali solution B with a NaOH concentration of 0.18 mol / L and a Na 2 CO 3 concentration of 0.0125 mol / L;

[0087] Pour the two solutions into a running colloid mill at the same time. After stirring for a certain time, transfer the product to a four-necked flask, and place the flask in a 65 °C water bath for static crystallization for 24 h;

[0088] After the crystallization is completed, filter and wash with deionized water, dry the sample, and grind to obtain CuCoZnA1-CO 3 2- -LDHs powder;

[0089] Step T2: Reduce the catalyst precursor prepared in step A in H 2 at a rate of 40 mL / min. Select two heating rates of 2 °C / min and 10 °C / min respectively, with a plateau temperature of 270 °C and a reduction temperature of 600 °C. The heating program is: first rise from room temperature to 270 °C at a rate of 2 °C / min, hold for 20 min, then rise to 600 °C at a rate of 10 °C / min, hold for 0 h, and naturally cool to room temperature to obtain the core-shell structured Cu@Co-Zn(Al)O catalyst. Since the reduction temperature of Cu 2+ is lower than that of Co 2+ , Cu is reduced first during reduction. When staying at 270 °C for 20 min, Cu 2+ can be completely reduced to zero-valent to become Cu nanoparticles. During the subsequent heating process, the Cu nanoparticles serve as the core, and Co 2+ is slowly reduced, and the reduced Co 0 grows on the surface of the Cu nanoparticles, thus forming Cu@Co core-shell structured nanoparticles.

[0090] Application: Press and granulate the catalyst powder obtained in the previous step, sieve to obtain 20-40 mesh particles, weigh a certain mass of the catalyst and load it into a fixed-bed reactor. The reaction temperature is 260 °C, the pressure is 3 MPa, the space velocity is 1800 h -1 , the CO conversion rate is 42.8%, and the total alcohol selectivity is 11.7%. The space-time yield of C 2+ OH is 0.17 g·g cat -1 ·h -1 , C 2+The molar ratio of OH to the total alcohol ROH is 90.9%. The high activity of this catalyst is attributed to its core-shell structure with Cu as the core and Co as the shell. More Co sites are exposed on the surface, while Cu sites are inside the particles, resulting in fewer surface CO non-dissociative activation sites and thus lower total alcohol selectivity.

[0091] Figure (c) shows the electron microscopy image of the catalyst in Example 3, which are the high-resolution transmission electron microscopy (HRTEM) and line-scanning energy spectrum of the Cu@Co-Zn(Al)O catalyst structure. It can be found from the high-resolution electron microscopy image, the measurement of lattice fringes, and the line-scanning energy spectrum that the catalyst metal particles have Cu as the core and CoO x as the shell (the presence of Co oxide may be caused by the oxidation of the sample during the sample preparation and characterization process. The surface cobalt oxide can be reduced by pre-treating the catalyst before the reaction). Since Cu is the active site for alcohol formation and Co is the site for alkane formation, there are more Co sites than Cu sites on the catalyst surface, corresponding to the higher activity and lower total alcohol selectivity of this catalyst.

[0092] Example 4

[0093] A CuCo catalyst for the preparation of lower alcohols from syngas. The CuCo catalyst uses zinc-aluminum composite oxide Zn(Al)O as the carrier, and bimetallic nanoparticles of Cu and Co are loaded on the surface of the carrier. The Co loading of the CuCo catalyst is 4.5 wt%, and the Cu loading is 10.8 wt%.

[0094] Among them, the molar ratio of Cu / Co is 0.5; the particle size of the metal center is 6.8 nm.

[0095] The preparation method is as follows:

[0096] Step R1: Accurately weigh a certain amount of Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O and dissolve them in deionized water. The concentration of Cu(NO 3 ) 2 ·6H 2 O is 0.05 mol / L, the concentration of Zn(NO 3 ) 2 ·6H 2 O is 0.2 mol / L, and the concentration of A1(NO 3 ) 3 ·9H 2The concentration of O is 0.05 mol / L. Stir until completely dissolved to prepare a blue transparent mixed nitrate solution;

[0097] Accurately weigh a certain mass of Na 2 CO 3 and NaOH, dissolve them in deionized water, and prepare a mixed alkali solution B with a NaOH concentration of 0.18 mol / L and a Na 2 CO 3 concentration of 0.0125 mol / L;

[0098] Pour the two solutions into a running colloid mill at the same time. After stirring for a certain time, transfer the product to a four-necked flask, place the flask in a 65 °C water bath for static crystallization for 24 h; after the crystallization is completed, filter and wash with deionized water, dry the sample, and grind to obtain CuZnA1-CO 3 2- -LDHs powder;

[0099] Reduce CuZnAl-LDHs in H 2 at a rate of 40 mL / min. Raise the temperature to the reduction temperature of 600 °C at a heating rate of 2 °C / min, keep the temperature for 0 h, naturally cool to room temperature and then take out to obtain the Cu-Zn(Al)O catalyst precursor, which is a black powder;

[0100] Step R2: According to the surface Cu / Co ratio of 1:1, synthesize Co 2+ / Cu-Zn(Al)O by the incipient wetness impregnation method: Weigh a certain mass of cobalt nitrate hexahydrate and dissolve it in absolute ethanol to obtain a pink solution of Co 2+ ethanol solution. Place the Cu-Zn(Al)O powder in a 10 mL round-bottom flask, and while vortexing, add the Co 2+ ethanol solution drop by drop until a wet and non-flowing black slurry is obtained, and then put it in an oven at 120 °C. After drying, the Co 2+ / Cu-Zn(Al)O catalyst precursor is obtained;

[0101] Step R3: Place the catalyst precursor Co 2+ / Cu-Zn(Al)O obtained in the previous step in a tubular furnace and perform temperature-programmed reduction in a H 2 atmosphere. Raise the temperature to 300 °C at a heating rate of 2 °C / min and keep the temperature for 0.5 h to obtain the multi-Cu compatibility CuCo alloy catalyst.

[0102] Application: Press and granulate the catalyst powder obtained in the previous step, sieve to obtain 20-40 mesh particles, weigh a certain mass of the catalyst and load it into a fixed-bed reactor, and in H at 40 mL / min 2Online pre-reduction is carried out to obtain a CuCo alloy catalyst with a high Co compatibility, namely the CoCu-Zn(Al)O-rep catalyst. After the reduction is completed, the reaction temperature is lowered to 260 °C, and the syngas is switched. The back pressure is started to 3 MPa, and the space velocity is 1800 h -1 , the CO conversion rate is 1.1%, and the total alcohol selectivity is 20.9%. C 2+ The space-time yield of OH is 0.02 g·g cat -1 ·h -1 , C 2+ The molar ratio of OH in the total alcohol ROH is 38.4%.

[0103] It can be found that the activity of the catalyst is very low. The reason is that the CuCo metal sites obtained by the impregnation method are not adjacent, indicating that the synergistic effect between Cu and Co in the catalyst prepared by the impregnation method is weak.

[0104] Example 5

[0105] A CuCo catalyst for the preparation of lower alcohols from syngas. The CuCo catalyst uses a zinc-aluminum composite oxide Zn(Al)O as a carrier, and bimetallic nanoparticles of Cu and Co are loaded on the surface of the carrier. The Co loading of the CuCo catalyst is 4.8 wt%, and the Cu loading is 0.2 wt%;

[0106] Among them, the molar ratio of Cu / Co is 0.04; the particle size of the metal center is 5.5 nm.

[0107] The preparation method is as follows:

[0108] Step R1: Accurately weigh a certain amount of Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O and dissolve them in 200 mL of deionized water. The concentration of Co(NO 3 ) 2 ·6H 2 O is 0.05 mol / L, the concentration of Zn(NO 3 ) 2 ·6H 2 O is 0.2 mol / L, and the concentration of A1(NO 3 ) 3 ·9H 2 O is 0.05 mol / L. Stir to completely dissolve to obtain a pink transparent solution, that is, obtain a mixed nitrate solution A;

[0109] Accurately weigh a certain mass of Na 2 CO 3 and NaOH, dissolve them in 200 mL of deionized water, and prepare a mixed alkali solution B with a NaOH concentration of 0.18 mol / L and a Na 2 CO 3 concentration of 0.0125 mol / L;

[0110] Pour the two solutions into a running colloid mill simultaneously. After stirring for a certain time, transfer the product to a four-necked flask, and place the flask in a 65 °C water bath for static crystallization for 24 h. After the crystallization is completed, filter and wash with deionized water by suction, dry the sample, and grind it to obtain CoZnA1-CO 3 2- -LDHs powder;

[0111] Step R2: Reduce the above catalyst precursor in H 2 with a flow rate of 40 mL / min, raise the temperature to the reduction temperature of 600 °C at a heating rate of 2 °C / min, keep the temperature for 0 h, and cool to room temperature to obtain Co-Zn(Al)O black powder;

[0112] Step R3: Place the catalyst precursor Cu / Co-Zn(Al)O obtained in the previous step in a tubular furnace and perform programmed temperature reduction in a H 2 atmosphere. Raise the temperature to 300 °C at a heating rate of 2 °C / min and keep the temperature for 0.5 h to obtain the multi-Co compatibility CuCo alloy catalyst.

[0113] Then seal the catalyst precursor liquid with fresh boiled deionized water free of CO 2 and O 2 , transfer it to 250 mL of deionized water, and protect it with nitrogen. Weigh a certain mass of copper nitrate trihydrate according to the molar ratio of surface Cu / Co of 1, dissolve it in 1 mL of deionized water free of CO 2 and O 2 to obtain a light blue Cu 2+ aqueous solution. Dropwise add the Cu salt solution under stirring conditions, stir for 30 min, and carry out a displacement reaction at a low temperature, with the temperature range being 0 - 15 °C; after completion, centrifuge, wash, and dry the black precipitate.

[0114] Application: Press and granulate the catalyst precursor powder obtained in the previous step, sieve to obtain particles with a mesh size of 20 - 40, weigh a certain mass of the catalyst and load it into a fixed-bed reactor, and perform on-line pre-reduction at 300 °C in a H 2 atmosphere to obtain a pseudo-alloy CuCo catalyst, namely the CuCo-Zn(Al)O-rep catalyst (rep represents obtained by the displacement method). When the reaction temperature is 260 °C, the pressure is 3 MPa, and the space velocity is 1800 h-1 , the CO conversion rate was 63.8%, and the total alcohol selectivity was 18.2%. C 2+ The space-time yield of C cat -1 ·h -1 , C 2+ The molar ratio of C

[0115] It can be found that the catalyst obtained by the replacement method has high activity. Since the main body of the catalyst is a Co catalyst, the Co catalyst has a strong CO dissociation ability, and the replacement method makes the Cu sites uniformly loaded on the catalyst surface, and the Co sites and Cu sites have good synergistic effects.

[0116] Comparative Example 1

[0117] Step A: Prepare a hydrotalcite precursor by the nucleation crystallization isolation method. Weigh accurately a certain amount of Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O and dissolve them in deionized water. Among them, the concentration of Cu(NO 3 ) 2 ·3H 2 O is 0.01875 mol / L, the concentration of Co(NO 3 ) 2 ·6H 2 O is 0.05625 mol / L, the concentration of Zn(NO 3 ) 2 ·6H 2 O is 0.15 mol / L, and the concentration of A1(NO 3 ) 3 ·9H 2 O is 0.075 mol / L, and the total metal cation concentration is 0.3 mol / L. Weigh accurately a certain mass of Na 2 CO 3 and NaOH and dissolve them in 200 mL of deionized water to prepare a mixed alkali solution B with a NaOH concentration of 0.18 mol / L and a Na 2 CO 3 concentration of 0.0125 mol / L;

[0118] Pour the two solutions into a running colloid mill simultaneously. After stirring for a certain period of time, transfer the product into a four-necked flask and place the flask in a 65 °C water bath for static crystallization for 24 h. After the crystallization is completed, filter and wash with deionized water, dry the sample, and grind to obtain Cu 1 Co 3 ZnA1-CO 3 2- -LDHs powder.

[0119] Step B: Reduce the catalyst precursor prepared in Step A in H 2 at a rate of 40 mL / min. The selected heating rate is 2 °C / min, no platform temperature is set, and the reduction temperature is 600 °C. The heating program is: first heat from room temperature to 600 °C at a heating rate of 2 °C / min, hold for 0 h, and naturally cool to room temperature to obtain Cu 1 Co 3 alloy catalyst.

[0120] Press the catalyst powder obtained in the previous step into pellets, sieve to obtain 20-40 mesh particles, weigh a certain mass of the catalyst and load it into a fixed-bed reactor, and pre-reduce it online in H 2 at a rate of 40 mL / min. After the reduction is completed, lower the reaction temperature to 260 °C, switch to syngas, start to backpressure to 3 MPa, the space velocity is 1800 h -1 , the CO conversion rate is 28.2%, the total alcohol selectivity is 9.1%, and the space-time yield of C 2+ OH is 0.23 g·g cat -1 ·h -1 , and the molar ratio of C 2+ OH in the total alcohol ROH is 90.4%. Since the Cu / Co feed ratio of this catalyst is 1 / 3, the Co 0 sites are rich on the catalyst surface, and the Cu 0 sites are less, so the selectivity of the total alcohol is lower. The Co 0 sites rich on the catalyst surface make the catalyst have better carbon chain growth ability.

[0121] Comparative Example 2

[0122] Step A: Prepare a hydrotalcite precursor by the nucleation crystallization isolation method. Accurately weigh a certain amount of Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H2 O is dissolved in deionized water, where the concentration of Cu(NO 3 ) 2 ·3H 2 O is 0.01237 mol / L, the concentration of Co(NO 3 ) 2 ·6H 2 O is 0.06187 mol / L, the concentration of Zn(NO 3 ) 2 ·6H 2 O is 0.15 mol / L, the concentration of A1(NO 3 ) 3 ·9H 2 O is 0.075 mol / L, and the total concentration of metal cations is 0.3 mol / L. Weigh accurately a certain mass of Na 2 CO 3 and NaOH and dissolve them in 200 mL of deionized water to prepare a mixed alkali solution B with a NaOH concentration of 0.18 mol / L and a Na 2 CO 3 concentration of 0.0125 mol / L. Pour the two solutions into a running colloid mill at the same time, stir for a certain time, then transfer the product to a four-necked flask, and place the flask in a 65 °C water bath for static crystallization for 24 h. After the crystallization is completed, filter and wash with deionized water, dry the sample, and grind it to obtain Cu 1 Co 5 ZnA1-CO 3 2- -LDHs powder.

[0123] Step B: Reduce the catalyst precursor prepared in Step A in H 2 at a rate of 40 mL / min, select a heating rate of 2 °C / min, without setting a platform temperature, and the reduction temperature is 600 °C. The heating program is: first heat from room temperature to 600 °C at a heating rate of 2 °C / min, hold for 0 h, and then cool naturally to room temperature to obtain the Cu 1 Co 5 alloy catalyst.

[0124] Press the obtained catalyst powder into tablets and granulate it, sieve to obtain 20-40 mesh particles, weigh a certain mass of the catalyst and load it into a fixed-bed reactor, and pre-reduce it online in H 2 at a rate of 40 mL / min. After the reduction is completed, lower the reaction temperature to 260 °C, switch to syngas, start to backpressure to 3 MPa, the space velocity is 1800 h -1 , the CO conversion rate is 40.0%, the total alcohol selectivity is 9.0%, and the space-time yield of C 2+ OH is 0.28 g·g cat -1 ·h-1 , C 2+ The molar ratio of C 0 OH to the total alcohol ROH is 90.0%. Since the Cu / Co feed ratio of the catalyst is 1 / 5, the catalyst surface is rich in Co 0 sites, and there are fewer Cu 0 sites. Therefore, the CO conversion rate of the catalyst is high, while the selectivity of the total alcohol is low. The Co

[0125] Comparative Example 3

[0126] A hydrotalcite precursor was prepared by the constant pH coprecipitation method. Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and A1(NO 3 ) 3 ·9H 2 O were dissolved in 200 mL of deionized water. The concentrations of the four metal nitrates were 0.0375 mol / L, 0.0375 mol / L, 0.15 mol / L, and 0.075 mol / L respectively. The mixed nitrate solution was stirred until completely dissolved to obtain a purple transparent salt solution A;

[0127] A certain mass of Na 2 CO 3 and NaOH were accurately weighed and dissolved in 200 mL of deionized water to prepare a mixed alkali solution B with a NaOH concentration of 0.18 mol / L and a Na 2 CO 3 concentration of 0.0125 mol / L. While stirring, solutions A and B were simultaneously dropped into deionized water, and the pH was controlled between 9 and 10. After titration, the crystallization temperature was controlled at 65 - 80 °C, and the crystallization time was 18 - 24 h. After crystallization, vacuum filtration was carried out, washed with deionized water, dried, and ground to obtain Cu 1 Co 1 ZnA1-CO 3 2- -LDHs-s powder.

[0128] Step B: The catalyst precursor prepared in Step A was treated in H 2For the reduction in the middle, the selected heating rate is 5 °C / min, no plateau temperature is set, and the reduction temperature is 600 °C. The heating program is as follows: First, heat from room temperature to 600 °C at a heating rate of 5 °C / min, hold for 3 h, and then naturally cool to room temperature to obtain the ordinary CuCo alloy catalyst.

[0129] Press and granulate the catalyst powder obtained in the previous step, sieve to obtain particles with a mesh size of 20-40, weigh a certain mass of the catalyst and load it into a fixed-bed reactor. The reaction temperature is 260 °C, the pressure is 3 MPa, and the space velocity is 1800 h -1 , the CO conversion rate is 26.2%, and the total alcohol selectivity is 28.1%. C 2+ The space-time yield of OH is 0.21 g·g cat -1 ·h -1 , C 2+ The molar ratio of OH in the total alcohol ROH is 64.6%. The CuCo alloy catalyst obtained by this method belongs to the ordinary CuCo alloy structure, and no obvious stacking faults and twin crystal structures can be observed on the surface. The Cu 0 and Co 0 sites are evenly distributed. Therefore, the CO conversion rate of the catalyst is moderate, and the total alcohol selectivity is also moderate.

[0130] The above is only a preferred embodiment of the present invention, and it is not a limitation of the present invention in any other form. Any modification or equivalent change made according to the technical essence of the present invention still belongs to the scope protected by the present invention.

Claims

1. A CuCo catalyst for preparing lower alcohols from syngas, characterized in that, the CuCo catalyst uses zinc-aluminum composite oxide Zn(Al)O as a carrier, and bimetallic nanoparticles of Cu and Co are loaded on the surface of the carrier. The Co loading of the CuCo catalyst is 0.5 wt% - 22 wt%, and the Cu loading is 0.5 wt% - 22 wt%; The preparation method of the catalyst comprises the following steps: Step T1: Prepare the CuCo-based hydrotalcite precursor Cu x Co y ZnAl-CO 3 2- -LDHs, where x and y represent the molar ratio, and the range of the x / y ratio is 0.5 - 2.0: Dissolve Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and Al(NO 3 ) 3 ·9H 2 O in deionized water to prepare a mixed nitrate solution A; Weigh a certain mass of Na 2 CO 3 and NaOH, dissolve them in deionized water, and prepare a mixed alkali solution B with a concentration of [NaOH] = (1.5 - 2.0)([M 2+ + [M 3+ ) and [Na 2 CO 3 = (0.2 - 1.0) [M 3+ ; Pour solutions A and B into a running colloid mill simultaneously. After completion, continue stirring for 2 - 5 minutes, and then place it in a water bath at 50 - 80 o °C for static crystallization for 6 - 24 h. After the crystallization is completed, wash with deionized water, filter by suction, dry the sample, and grind to obtain Cu x Co y ZnAl-CO 3 2- -LDHs powder; Step T2: Subject the CuCo-based hydrotalcite precursor obtained in Step T1 to temperature-programmed reduction in an H 2 atmosphere, and increase the temperature at a heating rate of 1-20 o °C / min to the target reduction temperature of 500-800 o °C, and keep the temperature for 0-3 h to obtain the CuCo catalyst; Or the preparation method of the catalyst comprises the following steps: Step R1: Prepare a Co-based hydrotalcite precursor CoZnAl-LDHs by the nucleation crystallization isolation method; Step R2: After the CoZnAl-LDHs are reduced, Co-Zn(Al)O is obtained, and then Cu 2+ is used to displace a part of the surface metal Co to obtain a Cu / Co-Zn(Al)O catalyst precursor; Step R3: The Cu / Co-Zn(Al)O catalyst precursor obtained in Step R2 is subjected to temperature-programmed reduction in an H 2 atmosphere, and the temperature is raised to the target reduction temperature of 500-800 o °C at a heating rate of 1-20 o °C / min, and the holding time is 0-3 h to obtain a CuCo alloy catalyst with a multi-Co compatibility degree.

2. The CuCo catalyst according to claim 1, characterized in that, the Co loading of the CuCo catalyst is 5.0 wt% - 10.0 wt%, and the Cu loading is 9.0 wt% - 15.0 wt%.

3. The CuCo catalyst according to claim 1 or 2, characterized in that, the molar ratio of Cu to Co, Cu / Co, is 0.5 - 2.

0.

4. The CuCo catalyst according to claim 1 or 2, characterized in that, the particle size of the metal particles of the CuCo catalyst is 4 - 10 nm.

5. The CuCo catalyst according to claim 1 or 2, characterized in that, the structure of the metal center of the CuCo catalyst is adjustable, and the structure includes a multi-angle twin boundary CuCo alloy or a CuCo alloy structure with a multi-Co compatibility.

6. A preparation method of the CuCo catalyst according to any one of claims 1 - 5, characterized in that, the method comprises the following steps: Step T1: Prepare the CuCo-based hydrotalcite precursor Cu x Co y ZnAl-CO 3 2- -LDHs, where x and y represent the molar ratio, and the value range of the x / y ratio is 0.5 - 2.0: Dissolve Cu(NO 3 ) 2 ·3H 2 O, Co(NO 3 ) 2 ·6H 2 O, Zn(NO 3 ) 2 ·6H 2 O and Al(NO 3 ) 3 ·9H 2 O in deionized water to prepare a mixed nitrate solution A; Weigh a certain mass of Na 2 CO 3 and NaOH, dissolve them in deionized water, and prepare a mixed alkali solution B with a concentration of [NaOH] = (1.5 - 2.0)([M 2+ + [M 3+ ) and [Na 2 CO 3 = (0.2 - 1.0) [M 3+ ; Pour solutions A and B into a running colloid mill simultaneously. After completion, continue stirring for 2 - 5 minutes, and then place it in a 50 - 80 o °C water bath for static crystallization for 6 - 24 h. After the crystallization is completed, wash with deionized water, filter by suction, dry the sample, and grind to obtain Cu x Co y ZnAl-CO 3 2- -LDHs powder; Step T2: The CuCo-based hydrotalcite precursor obtained in Step T1 is subjected to temperature-programmed reduction in an H 2 atmosphere, and is heated to the target reduction temperature of 500 - 800 o °C at a heating rate of 1 - 20 o °C / min, and the holding time is 0 - 3 h, thus obtaining the CuCo catalyst.

7. A preparation method of the CuCo catalyst according to any one of claims 1 - 5, characterized in that, the method comprises the following steps: Step R1: Prepare a Co-based hydrotalcite precursor CoZnAl-LDHs by the nucleation crystallization isolation method; Step R2: After the CoZnAl-LDHs are reduced, Co-Zn(Al)O is obtained, and then Cu 2+ is used to displace part of the metallic Co on the surface to obtain a Cu / Co-Zn(Al)O catalyst precursor; Step R3: The Cu / Co-Zn(Al)O catalyst precursor obtained in Step R2 is subjected to temperature-programmed reduction in an H 2 atmosphere, and is heated to a target reduction temperature of 500-800 o °C at a heating rate of 1-20 o °C / min, and is held for 0-3 h to obtain a CuCo alloy catalyst with a multi-Co compatibility degree.

8. A use of the CuCo catalyst according to any one of claims 1 - 5 for preparing lower alcohols from syngas, characterized in that, the use comprises the following steps: Weigh a certain mass of the catalyst and load it into a fixed-bed reactor. The reaction temperature is 200 - 300 o °C, the reaction pressure is 2 - 6 MPa, and the reaction feed gas contains CO, H 2 and Ar. The volume ratio of CO to H 2 is 0.5 - 2.

0. Ar is used as the balance gas, and the volume percentage range of Ar is 2.0 - 6.0%. The volume space velocity of the reaction gas is 1000 - 9000 h -1 . Calculated based on the mass of CO passing through the catalyst per hour, the mass ratio of the catalyst to CO is 0.0001 - 0.002.

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