A pretreatment method and application of an alumina-supported copper oxide-rare earth metal oxide catalyst

Abstract

The present invention discloses a pretreatment method and application of an alumina-supported copper oxide-rare earth metal oxide catalyst. The pretreatment method is as follows: adding the alumina-supported copper oxide-rare earth metal oxide catalyst used for the reaction of ethanol to higher alcohols into a mixture of one or several C1-C8 alcohols, impregnating at 10-90 °C for 1-24 h, filtering to remove the excess alcohol after impregnation is completed, and then drying in an oven at 40-200 °C for 1-24 h to complete the pretreatment of the catalyst. The present invention provides the application of the alumina-supported copper oxide-rare earth metal oxide catalyst pretreated by the pretreatment method in the reaction of ethanol to higher alcohols. The pretreatment method of the present invention significantly increases the selectivity of the product higher alcohols and keeps the conversion rate of ethanol unchanged or slightly improved, thus solving the problem that it is difficult to balance both the conversion rate and selectivity in the prior art.

Description

(1) Technical Field

[0001] The present invention relates to a pretreatment method of an alumina-supported copper oxide-rare earth metal oxide catalyst for ethanol to higher alcohol reaction and its application in ethanol to higher alcohol reaction. (2) Background Art

[0002] Nowadays, governments of various countries are seeking effective ways to solve environmental problems such as the global energy crisis and greenhouse effect. Carbon-containing biomass is an important raw material for producing clean energy such as renewable biomass fuels and other chemicals. Among them, bioethanol is the product with the largest production and the highest degree of commercialization today, and its production technology has been quite mature. However, as a fuel, ethanol has problems such as low energy density, strong hygroscopicity, and corrosion of automobile engine cylinders, so it is not an ideal gasoline blending component. Compared with ethanol, n-butanol has a high energy density, is insoluble in water, and can be mixed with gasoline in a higher proportion (close to 20%), so it becomes an ideal gasoline blending component. Similar to butanol, higher alcohols such as hexanol and octanol can also be used as excellent fuel blending components. In particular, their high cetane numbers are suitable for use as diesel additives to increase the oxygen content of diesel, which can significantly reduce particulate matter and nitrogen oxides generated during diesel combustion. In addition to being used as fuels, these higher alcohols are also important industrial solvents and synthetic raw materials, and can be used in industries such as coatings, rubber, plastics, cosmetics, and fragrances.

[0003] Under mild reaction conditions, ethanol dehydrogenation coupling follows the Guerbet reaction mechanism, and the formation of the target product n-butanol undergoes four consecutive reaction steps: first, the ethanol molecule dehydrogenates to form acetaldehyde, then acetaldehyde aldol-condenses to form 3-hydroxybutyraldehyde, then 3-hydroxybutyraldehyde dehydrates to form crotonaldehyde, and finally crotonaldehyde hydrogenates to form n-butanol. The product n-butanol can further undergo the Guerbet reaction to form higher carbon alcohols (such as hexanol, 2-ethylbutanol, octanol, 2-ethylhexanol, etc.). In addition to the main reaction, ethanol will dehydrate to form diethyl ether and ethylene, and a series of side reactions such as the reaction of ethanol and acetaldehyde to form ethyl acetate and 1,1-diethoxyethane are not conducive to the improvement of the selectivity of higher alcohols such as n-butanol and n-hexanol.

[0004] In the published literature, Ishii and his colleagues first reported the first truly homogeneous catalytic system for the production of n-butanol from ethanol. They prepared a noble metal iridium complex catalyst with phosphine as a ligand and 1,7-butadiene as a hydrogen acceptor, and catalyzed the upgrading of ethanol to higher alcohols in the presence of strong base sodium ethoxide. Finally, the ethanol conversion rate and the total higher alcohol selectivity reached 41% and 90% respectively. The dehydrogenation of alcohol and the hydrogenation of aldehyde steps in the Guerbet reaction pathway can be achieved on the metal iridium complex, while the aldol condensation step is carried out on strong base sodium ethoxide [Chemistry Letters, 2009, 38(8): 838 - 839]. Dowson et al. prepared a series of Ru-based complex homogeneous catalysts and applied them to the reaction of ethanol to n-butanol. Among them, the catalyst using 2 (η 6 -p-cymene)] 2 as the catalyst precursor and bis(diphenylphosphino)methane as the ligand achieved an ethanol conversion rate of 20.4% and a n-butanol selectivity as high as 90% after reacting for 4 h under the alkaline condition of 423 K in the presence of sodium ethoxide [Angewandte Chemie, 2013, 52(34): 9005 - 9008]. Although the above two catalysts showed good catalytic effects, the preparation process of their catalysts was cumbersome. Using soluble strong bases such as sodium hydroxide and sodium ethoxide as catalysts for the aldol condensation step of acetaldehyde, the catalyst separation was difficult, the reaction time was long, and the reaction was difficult to be carried out continuously, so it was not conducive to industrial scale-up production. In recent years, metal-supported catalysts have been widely used in the reaction of ethanol dehydrogenation condensation to higher alcohols and have shown excellent catalytic performance. For example, He et al. reported a single-atom Ru catalyst supported on layered Mg-Al composite oxides and used it in the reaction of ethanol condensation to higher alcohols. At 623 K, 0.1 MPa N 2 , WHSV = 3.2 h -1 , the Ru / Mg 3 Al 1 -LDO catalyst with a Ru loading of 1.04 wt% showed an ethanol conversion rate of 29.6% and a C 4 and above higher alcohol selectivity of 82.6%. The catalyst characterization results showed that atomically dispersed Ru promoted the dehydrogenation of ethanol and adjusted the acid-base properties of the catalyst to a certain extent, thus further promoting the aldol condensation of acetaldehyde [Applied Catalysis B: Environmental, 2022, 309: 121271 - 121280]. Jordison et al. used La 2 O 3 to modify Ni / γ-Al 2 O 3The catalyst undergoes the reaction of synthesizing higher alcohols from ethanol in a reaction kettle. At 503K, the total selectivity of higher alcohols in the reaction exceeds 85%, and the yield is as high as 38%. Under the same conditions, the total yield of higher alcohols on the Ni / γ-Al 2 O 3 catalyst is only 26%. Through CO 2 -TPD and NH 3 -TPD characterization, it is known that the addition of La 2 O 3 effectively reduces the number of acidic sites and significantly increases the number of basic sites. This not only facilitates the promotion of the aldol condensation of acetaldehyde to form higher alcohols but also inhibits the formation of by-products such as diethyl ether, ethylene, and ethyl acetate [Industrial&Engineering Chemistry Research, 2015, 54(44): 10991 - 11000]. The Cu-MO x / Al 2 O 3 catalyst (MO x is a rare earth metal oxide) developed by this research group shows an ethanol conversion rate of 45.6% and a higher alcohol yield of 26.9% in the continuous catalytic conversion of ethanol to higher alcohols in a fixed bed (reaction conditions: 523K, 3MP N 2， LHSV = 2mL / (h·g cat ). The addition of rare earth metal oxides increases the active sites for aldol condensation, and at the same time, the stability of the catalyst is significantly improved due to the interaction between Cu active sites and rare earth metal oxides [CN202110593460.X; CN113443964B]. In the present invention, by using one or several of C1-C8 alcohols to pretreat the alumina-supported copper oxide-rare earth metal oxide catalyst, hydrophobic groups are introduced on the catalyst surface, promoting the condensation coupling of reaction intermediates such as acetaldehyde and butyraldehyde, thereby further improving the selectivity of higher alcohols. Moreover, since water is generated in the reaction of ethanol to higher alcohols, the weakened water adsorption ability on the surface of the hydrophobic catalyst is also beneficial to the forward progress of the overall reaction. (III) Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a pretreatment method for an alumina-supported copper oxide-rare earth metal oxide catalyst used in the reaction of synthesizing higher alcohols from ethanol.

[0006] The second technical problem of the present invention is to provide the application of the pretreated alumina-supported copper oxide-rare earth metal oxide catalyst in the reaction of synthesizing higher alcohols from ethanol.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a pretreatment method for an alumina-supported copper oxide-rare earth metal oxide catalyst for the reaction of ethanol to higher alcohols. The method is as follows: adding the alumina-supported copper oxide-rare earth metal oxide catalyst for the reaction of ethanol to higher alcohols into a mixture of one or more of C1-C8 alcohols, impregnating at 10-90 °C for 1-24 h, filtering to remove the excess alcohol after impregnation is completed, and then drying in an oven at 40-200 °C for 1-24 h to complete the pretreatment of the catalyst.

[0009] Preferably, the impregnation is carried out under oscillating conditions.

[0010] In the present invention, the C1-C8 alcohols are selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, n-pentanol, n-hexanol, n-heptanol, and n-octanol.

[0011] The alumina-supported copper oxide-rare earth metal oxide catalyst for the reaction of ethanol to higher alcohols in the present invention comprises an alumina support and copper oxide and rare earth metal oxide supported on its surface. The contents of the components in the alumina-supported copper oxide-rare earth metal oxide catalyst are as follows in mass percentage:

[0012] Alumina support 55% - 96.5%

[0013] Copper oxide 2% - 25%

[0014] Rare earth metal oxide 1.5% - 20%

[0015] The rare earth metal elements contained in the alumina-supported copper oxide-rare earth metal oxide catalyst are lanthanum, samarium or praseodymium.

[0016] Preferably, in the alumina-supported copper oxide-rare earth metal oxide catalyst, the molar ratio of copper oxide to rare earth metal oxide is 3:1 - 3:6.

[0017] The alumina-supported copper oxide-rare earth metal oxide catalyst described in the present invention may contain other components that do not substantially affect its catalytic performance, such as a small amount of impurities introduced due to the use of commercial alumina supports, soluble copper salts, and rare earth metal salts during the preparation process.

[0018] In the present invention, the carrier alumina is granular, and there is no special requirement for its particle size. Generally, the particle diameter of the used alumina support is 0.2 - 5 mm. Preferably, the alumina support is granular, with a specific surface area of 180 - 450 m 2 / g, an average pore diameter of 1 - 15 nm, and a pore volume of 0.3 - 1.5 mL / g.

[0019] The copper oxide-rare earth metal oxide catalyst supported on alumina is prepared by an impregnation method, that is, copper oxide and rare earth metal oxide precursors are loaded onto the surface of the alumina support by impregnation, and then the alumina support loaded with copper oxide and rare earth metal oxide precursors is calcined in an air or inert gas atmosphere to obtain the copper oxide-rare earth metal oxide catalyst supported on alumina. The specific preparation steps of the copper oxide-rare earth metal oxide catalyst supported on alumina of the present invention are as follows:

[0020] (1) Immerse the dried alumina support in a mixed solution of copper oxide and rare earth metal oxide precursors, shake well and let stand for 1 to 48 h;

[0021] (2) Dry the mixture obtained in step (1) to uniformly load the precursors of copper oxide and rare earth metal oxide onto the inner and outer surfaces of the alumina support;

[0022] (3) Put the alumina support loaded with copper oxide and rare earth metal oxide precursors obtained by drying in step (2) into a muffle furnace and calcine it at 300 to 800 °C in an air or inert gas atmosphere for 0.5 to 24 h to obtain the copper oxide-rare earth metal oxide catalyst supported on alumina.

[0023] In the above preparation method, the copper oxide precursor can be a soluble copper salt such as copper nitrate, copper chloride, copper acetate, copper acetylacetonate, etc. The rare earth metal oxide precursor can be a mixture of one or more of rare earth metal nitrates and acetylacetonates. The solvent for preparing the mixed solution of copper oxide and rare earth metal oxide precursors can be one or a mixture of two or more of deionized water, methanol, ethanol, isopropanol, acetylacetone, chloroform, tetrahydrofuran, N,N-dimethylformamide, etc. in any proportion.

[0024] Preferably, the drying treatment in step (2) is carried out in a rotary evaporator and an oven. First, dry it in the rotary evaporator at 10 to 60 °C and 0.005 to 0.1 MPa for 1 to 24 h, and then dry it in the oven at 50 to 150 °C for 1 to 48 h.

[0025] In the second aspect, the present invention provides the application of the catalyst treated by the pretreatment method according to the first aspect in the reaction of ethanol to higher alcohols.

[0026] Preferably, the reaction of ethanol to higher alcohols is carried out continuously in a fixed-bed reactor. The catalyst pretreated with C1-C8 alcohols is in-situ reduced with ethanol before use. The reduction conditions are: the temperature is 150 to 300 °C, the pressure is normal pressure to 6.0 MPa, and the liquid hourly space velocity of ethanol is 0.5 to 5.0 mL / (h·g cat) The ratio of nitrogen to ethanol is 100 - 800:1 (volume ratio). The reaction conditions for the production of higher alcohols from ethanol are as follows: the temperature is 200 - 300 °C, the pressure is from atmospheric pressure to 6.0 MPa, and the liquid hourly space velocity of ethanol is 0.5 - 5.0 mL / (h·g cat ). Under these conditions, the selectivity and yield of higher alcohols of the catalyst are high, and it has excellent stability. The main by-products of the reaction are diethyl ether, ethyl acetate, etc., and the unreacted ethanol can be recycled and reused.

[0027] The higher alcohols described in the present invention include C4 - C10 alcohols, i.e., aliphatic primary alcohols such as n-butanol, 2-ethylbutanol, n-hexanol, 2-ethylhexanol, n-octanol, 2-ethyloctanol, and n-decanol.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The C1 - C8 alcohol pretreatment of the copper oxide - rare earth metal oxide catalyst supported on alumina increases the hydrophobicity of the catalyst, making it easier for reaction intermediates with lower polarity than ethanol and water, such as acetaldehyde and butyraldehyde, to undergo condensation coupling reactions, thus significantly increasing the selectivity of the product higher alcohols.

[0030] (2) Water is generated during the reaction of producing higher alcohols from ethanol, and the C1 - C8 alcohol pretreatment of the copper oxide - rare earth metal oxide catalyst supported on alumina increases the hydrophobicity of the catalyst. Therefore, it drives the reaction to proceed to the right and promotes the conversion of ethanol, making the conversion rate of ethanol remain unchanged or slightly increase, thus solving the problem that it is difficult to balance both the conversion rate and selectivity in the prior art.

[0031] (3) The catalyst preparation and pretreatment methods described in the present invention are simple, reliable, and have low production costs. At the same time, a fixed-bed continuous reaction process is used when applied to the reaction of producing higher alcohols from ethanol, so it is suitable for industrial applications. (IV) Description of the Drawings

[0032] Figure 1 Schematic diagram of a fixed-bed reaction device for the dehydrogenation and condensation of ethanol to produce higher alcohols by the catalyst: 1 - hydrogen gas cylinder, 2 - nitrogen gas cylinder, 3 - raw material bottle, 4 - high-pressure constant flow pump, 5 - three-way valve, 6 - pressure reducing valve, 7 - stop valve, 8 - mass flowmeter, 9 - one-way valve, 10 - reaction tube, 11 - reaction furnace, 12 - condenser, 13 and 14 - condensate inlets and outlets, 15 - filter, 16 - back pressure valve, 17 - product collection tank, 18 - catalyst bed. (V) Specific Embodiments

[0033] The present invention will be further described below through specific examples, but the protection scope of the present invention is not limited thereto.

[0034] In the embodiments of the present invention, those without specific conditions are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained by conventional technical means or purchased commercially.

[0035] The specific surface area of the alumina support used in the embodiments of the present invention is 289 m 2 / g, the pore volume is 0.61 cm 3 / g, and the average pore diameter is 7.2 nm.

[0036] Example 1

[0037] Weigh 0.4562 g of Cu(NO 3 ) 2 ·3H 2 O and 0.4769 g of La(NO 3 ) 3 ·6H 2 O and add them to 8 mL of absolute ethanol. After complete dissolution and uniform mixing, add 2 g of the alumina support and oscillate for impregnation for 4 h. Rotate evaporate the above mixture on a rotary evaporator at 60 °C and 0.07 MPa for 1 h. Place the solid after rotary evaporation in an oven and dry at 110 °C for 4 h. Finally, calcine in a muffle furnace at 500 °C in an air atmosphere for 3 h to obtain an alumina-supported copper oxide-rare earth metal oxide catalyst. Take 2 g of the calcined catalyst and add it to 20 ml of methanol, heat and oscillate at 30 °C for 5 h. After oscillation, filter to remove the excess methanol, and then dry in an oven at 110 °C for 4 h to obtain catalyst A.

[0038] Example 2

[0039] The preparation method of catalyst B is the same as that of Example 1, but the calcined catalyst is added to 20 ml of ethanol, heated and oscillated at 40 °C for 5 h, and then filtered and dried in an oven at 110 °C for 4 h.

[0040] Example 3

[0041] The preparation method of catalyst C is the same as that of Example 1, but the calcined catalyst is added to 20 ml of n-propanol, heated and oscillated at 50 °C for 5 h, and then filtered and dried in an oven at 110 °C for 4 h.

[0042] Example 4

[0043] The preparation method of catalyst D is the same as that of Example 1, but the calcined catalyst is added to 20 ml of isopropanol, heated and oscillated at 50 °C for 5 h, and then filtered and dried in an oven at 110 °C for 4 h.

[0044] Example 5

[0045] The preparation method of catalyst E is the same as that of Example 1, but the calcined catalyst is added to 20 ml of n-butanol and heated and shaken at 60 °C for 5 h, then filtered and dried in an oven at 120 °C for 4 h.

[0046] Example 6

[0047] The preparation method of catalyst F is the same as that of Example 1, but the calcined catalyst is added to 20 ml of sec-butanol and heated and shaken at 70 °C for 5 h, then filtered and dried in an oven at 120 °C for 4 h.

[0048] Example 7

[0049] The preparation method of catalyst G is the same as that of Example 1, but the calcined catalyst is added to 20 ml of n-pentanol and heated and shaken at 80 °C for 5 h, then filtered and dried in an oven at 140 °C for 4 h.

[0050] Example 8

[0051] The preparation method of catalyst H is the same as that of Example 1, but the calcined catalyst is added to 20 ml of n-hexanol and heated and shaken at 85 °C for 5 h, then filtered and dried in an oven at 160 °C for 4 h.

[0052] Example 9

[0053] The preparation method of catalyst I is the same as that of Example 1, but the calcined catalyst is added to 20 ml of n-heptanol and heated and shaken at 85 °C for 5 h, then filtered and dried in an oven at 180 °C for 4 h.

[0054] Example 10

[0055] The preparation method of catalyst J is the same as that of Example 1, but the calcined catalyst is added to 20 ml of n-octanol and heated and shaken at 85 °C for 5 h, then filtered and dried in an oven at 200 °C for 4 h.

[0056] Example 11

[0057] The preparation method of catalyst K is the same as that of Example 1, but the calcined catalyst is added to a mixture of 10 ml of ethanol and 10 ml of n-butanol and heated and shaken at 60 °C for 5 h, then filtered and dried in an oven at 120 °C for 4 h.

[0058] Example 12

[0059] The preparation method of catalyst L is the same as that of Example 1, but the calcined catalyst is added to a mixture of 10 ml of ethanol and 10 ml of n-hexanol and heated and shaken at 60 °C for 5 h, then filtered and dried in an oven at 160 °C for 4 h.

[0060] Example 13

[0061] The preparation method of catalyst M is the same as that of Example 1, but 0.4080 g of samarium nitrate (Sm(NO 3 ) 3 ·6H 2 O) is used to replace 0.4769 g of lanthanum nitrate (La(NO 3 ) 3 ·6H 2 O), and the calcined catalyst is added to 20 ml of n-butanol, heated and shaken at 60 °C for 5 h, then filtered and dried in an oven at 120 °C for 4 h.

[0062] Example 14

[0063] The preparation method of catalyst N is the same as that of Example 1, but 0.3993 g of praseodymium nitrate (Pr(NO 3 ) 3 ·6H 2 O) is used to replace 0.4769 g of lanthanum nitrate (La(NO 3 ) 3 ·6H 2 O), and the calcined catalyst is added to 20 ml of n-butanol, heated and shaken at 60 °C for 5 h, then filtered and dried in an oven at 120 °C for 4 h.

[0064] Comparative Example 1

[0065] The preparation method of catalyst O is the same as that of Example 1, but the calcined catalyst is not pretreated with alcohol.

[0066] Comparative Example 2

[0067] The preparation method of catalyst P is the same as that of Comparative Example 1, but 0.4080 g of samarium nitrate (Sm(NO 3 ) 3 ·6H 2 O) is used to replace 0.4769 g of lanthanum nitrate (La(NO 3 ) 3 ·6H 2 O).

[0068] Comparative Example 3

[0069] The preparation method of catalyst Q is the same as that of Comparative Example 1, but 0.3993 g of praseodymium nitrate (Pr(NO 3 ) 3 ·6H 2 O) is used to replace 0.4769 g of lanthanum nitrate (La(NO 3 ) 3 ·6H 2 O).

[0070] Example 15

[0071] The reaction device is as Figure 1As shown, the catalysts A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, and Q prepared in the above examples and comparative examples were respectively loaded into the reaction tubes of a fixed-bed reactor. First, in-situ reduction treatment of the catalysts was carried out, and the reduction conditions were set as follows: temperature 250 °C, atmospheric pressure, liquid hourly space velocity of ethanol 1.0 mL / (h·g cat ), nitrogen / ethanol = 250:1 (volume ratio). Then, a reaction for continuous catalytic synthesis of higher alcohols in a fixed bed was carried out, and the reaction conditions were set as follows: 250 °C, 1 MPa, liquid hourly space velocity 1 mL / (h·g cat ). The results are shown in Table 1.

[0072] Table 1 Reaction performance of different catalysts in the reaction of continuous catalytic synthesis of higher alcohols in a fixed bed of ethanol

[0073]

[0074]

Claims

1. An application of an alumina-supported copper oxide-rare earth metal oxide catalyst in the reaction of ethanol to higher alcohols, characterized in that: The alumina-supported copper oxide-rare earth metal oxide catalyst is pretreated by the following method: adding the alumina-supported copper oxide-rare earth metal oxide catalyst used for the reaction of ethanol to higher alcohols to a mixed solution of one or more C1-C8 alcohols, impregnating at 10-90° C. for 1-24 h, filtering to remove excess alcohol after the impregnation, and then drying in an oven at 40-200° C. for 1-24 h to complete the pretreatment of the catalyst.

2. The use according to claim 1, characterized in that: The impregnation is carried out under shaking conditions.

3. The use according to claim 1, characterized in that: The C1-C8 alcohol is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, n-pentanol, n-hexanol, n-heptanol and n-octanol.

4. The use according to claim 1, characterized in that: The alumina-supported copper oxide-rare earth metal oxide catalyst for ethanol to higher alcohol reaction comprises an alumina carrier and copper oxide and rare earth metal oxide supported on the surface thereof. The content of each component in the alumina-supported copper oxide-rare earth metal oxide catalyst is expressed in mass percentage as follows: Alumina carrier 55%~96.5% Copper oxide 2%~25% Rare earth metal oxides 1.5%~20% The rare earth metal element contained in the alumina-supported copper oxide-rare earth metal oxide catalyst is lanthanum, samarium or praseodymium.

5. The use according to claim 1, characterized in that: In the alumina-supported copper oxide-rare earth metal oxide catalyst, the molar ratio of copper oxide to rare earth metal oxide is 3:1-3:

6.

6. The use according to claim 1, characterized in that: The alumina carrier is granular and has a specific surface area of ​​180-450 m 2 / g, average pore diameter 1~15 nm, pore volume 0.3~1.5 mL / g.

7. The use according to claim 1, characterized in that: The specific preparation steps of the alumina-supported copper oxide-rare earth metal oxide catalyst are as follows: (1) Immerse the dried alumina support in a mixed solution of copper oxide and rare earth metal oxide precursors, shake and mix, and then let stand for 1 to 48 hours; (2) drying the mixture obtained in step (1) so that the precursors of copper oxide and rare earth metal oxide are evenly loaded on the inner and outer surfaces of the alumina carrier; (3) The alumina carrier loaded with copper oxide and rare earth metal oxide precursor obtained by drying in step (2) is placed in a muffle furnace and calcined at 300-800° C. in air or inert gas atmosphere for 0.5-24 h to obtain an alumina-loaded copper oxide-rare earth metal oxide catalyst.

8. The use according to claim 7, characterized in that: The copper oxide precursor is a soluble copper salt; the rare earth metal oxide precursor is one or a mixture of rare earth metal nitrates and acetylacetonates; the solvent for preparing a mixed solution of copper oxide and rare earth metal oxide precursors is one or a mixture of any proportion of two or more of deionized water, methanol, ethanol, isopropanol, acetylacetone, chloroform, tetrahydrofuran and N,N-dimethylformamide.

9. The use according to claim 1, characterized in that: The reaction of preparing higher alcohols from ethanol is carried out continuously in a fixed bed reactor. The pretreated alumina-supported copper oxide-rare earth metal oxide catalyst is in-situ reduced with ethanol before use. The reduction conditions are: temperature of 150-300°C, pressure of normal pressure-6.0 MPa, and liquid space velocity of ethanol of 0.5-5.0 mL / (h·g cat ), volume ratio of nitrogen / ethanol = 100~800:1; the reaction conditions of the ethanol to higher alcohol reaction are: temperature of 200~300°C, pressure of normal pressure~6.0 MPa, liquid space velocity of ethanol of 0.5~5.0 mL / (h·g cat ).

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