A large pore composite oxide catalyst, a method for preparing the same, and a method for producing higher alcohols from ethanol

Abstract

The application discloses a macroporous composite oxide catalyst and a preparation method thereof and a method for preparing higher alcohols from ethanol. The macroporous composite oxide catalyst comprises copper oxide, lanthanum oxide and aluminum oxide. The macroporous composite oxide catalyst is prepared by a coprecipitation method, and a non-ionic surfactant is added as a pore-expanding agent in the preparation process. The application provides a method for preparing higher alcohols from ethanol, wherein a reaction device used in the method comprises a main reactor and a side reactor which are connected in series, the main reactor is filled with the macroporous composite oxide catalyst according to the first aspect, and the side reactor is filled with a Cu-Zn-Al composite oxide catalyst used for aldehyde ester hydrogenation. The method improves ethanol conversion rate and the yield of higher aliphatic alcohols with carbon number of 6 or more.

Description

Technical Field

[0001] This invention relates to a macroporous composite oxide catalyst and its preparation method, as well as a method for producing higher alcohols from ethanol. Background Technology

[0002] Due to the increasing depletion of fossil resources and the greenhouse effect caused by their use, the development and utilization of renewable biomass fuels are receiving increasing attention. Bioethanol, as a renewable and clean fuel, is widely used as a gasoline additive in Europe, the United States, Brazil, and China. However, as a fuel, ethanol has drawbacks such as high hygroscopicity and low energy density. Compared to ethanol, butanol has an energy density close to gasoline, lower water solubility, and lower heat of vaporization, and can be used directly without structural modifications to existing engines, thus showing potential to become a new generation of biofuel for widespread use. Similar to butanol, higher alcohols such as hexanol and octanol can also serve as excellent fuel blending components, especially given their high cetane numbers, making them suitable as diesel additives to increase the oxygen content of diesel fuel, thereby significantly reducing particulate matter and nitrogen oxides produced during diesel combustion. Besides being used as fuel, these higher alcohols are also important industrial solvents and raw materials for organic synthesis, widely used in coatings, rubber, plastics, cosmetics, and fragrance industries. C12-C20 fatty alcohols, with even higher carbon numbers, are major raw materials for detergents and surfactants, widely used in cleaning products, personal care products, and cosmetics, with a large market demand. Hydrogenation of vegetable oils such as coconut oil and palm oil is currently the main production method for C12-C20 higher fatty alcohols.

[0003] The dehydrogenation condensation of ethanol to higher alcohols is achieved via the Guerbet reaction mechanism, which mainly includes three steps: ethanol dehydrogenation to acetaldehyde, acetaldehyde aldol condensation to crotonaldehyde, and crotonaldehyde hydrogenation to butanol. This mechanism involves multiple catalytically active sites, including metal centers and acid-base centers. Metal catalysts supported on porous solid acid-base materials are widely used in the dehydrogenation coupling of ethanol to higher alcohols. For example, patent CN113578327A discloses a CuNiAl composite oxide catalyst for the coupling of ethanol to butanol, which performs well at 523 K, 3 MPa (N2), and LHSV = 4.8 mL / (g). catUnder reaction conditions of 533 K and 3 MPa (N2), the catalyst exhibited an ethanol conversion rate of 39.8%, but the main product was n-butanol, with a selectivity of 48.2%. Patent CN114130399A discloses an ordered mesoporous copper-rare earth metal-aluminum composite oxide catalyst, which exhibits an ethanol conversion rate of 48.1%, a butanol selectivity of 52.7%, and a C6-C8 higher alcohol selectivity of 21.5% under reaction conditions of 533 K and 3 MPa (N2). Patent CN113332989A discloses an alumina-supported copper-rare earth metal oxide catalyst, which exhibits a conversion rate of 39.8% under reaction conditions of 533 K, 3 MPa (N2), and a liquid hourly space velocity of 2 mL / (g·h). cat Under reaction conditions of nitrogen / ethanol (v / v) = (250:1), the method exhibits an ethanol conversion rate of 51.3%, a butanol selectivity of 51.5%, and a higher alcohol selectivity of 22.4%. CN 117645528 A discloses a method for the continuous catalytic conversion of ethanol to higher alcohols. The reaction is carried out continuously in a two-stage fixed-bed reactor. The reactor mainly consists of a main reactor and a secondary reactor connected in series. The main reactor is loaded with a copper-based multifunctional catalyst I for the synthesis of higher alcohols from ethanol (the catalyst is the same as the Cu-La2O3 / Al2O3 catalyst in CN113976184), and the secondary reactor is loaded with a catalyst II for the catalytic hydrogenation of aldehydes and esters. The reactant ethanol is first converted into higher alcohols and their aldehyde and ester byproducts through the main reactor and catalyst I, and then the aldehyde and ester byproducts in the material are hydrogenated into alcohol products through the secondary reactor and catalyst II. This method achieves an ethanol conversion rate of 62.46%, a butanol selectivity of 50.07%, and a C6-C2 alcohol selectivity of 41.65%. 12 The reaction exhibits selectivity for alcohols; however, butanol, which has a lower added value, accounts for a large proportion, and the economic value of the reaction needs to be further improved.

[0004] In summary, to date, existing heterogeneous catalysts for the production of higher alcohols from ethanol still exhibit low selectivity for higher alcohols with higher carbon numbers than butanol, and there are no reports on the production of higher value-added long-chain C12-C20 fatty alcohols via fixed-bed catalytic coupling of ethanol.

[0005] This invention provides a catalyst for the continuous catalytic conversion of ethanol to higher alcohols, as well as a method for preparing higher alcohols from ethanol. The reaction is carried out continuously in a two-stage fixed-bed reactor. The main reactor is loaded with a macroporous composite oxide catalyst (catalyst I), and the auxiliary reactor is loaded with a Cu-Zn-Al composite oxide catalyst (catalyst II). Its key feature is that the main reactor is loaded with a macroporous composite oxide catalyst. The larger pore size facilitates the diffusion of reactants and reaction intermediates, while also promoting the formation of higher molecular weight higher alcohols. This results in not only high ethanol conversion activity but also higher selectivity for C6 and above fatty alcohols, particularly producing higher value-added C12-C20 long-chain higher fatty alcohols. This opens up a new pathway for the production of long-chain higher fatty alcohols and is of great significance in solving the global supply shortage in the higher fatty alcohol industry. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols. This catalyst has high catalytic activity and is conducive to the generation of higher alcohols with relatively large molecular weights, thereby improving the yield of higher alcohols with C6 and above.

[0007] The second technical problem to be solved by the present invention is to provide a method for preparing a macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols.

[0008] The third technical problem of the present invention is to provide a method for producing higher alcohols from ethanol, so as to further improve the ethanol conversion rate and the yield of higher fatty alcohols with C6 or more carbons.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols, the macroporous composite oxide catalyst comprising alumina, copper oxide, and lanthanum oxide, the content of each component in the macroporous composite oxide catalyst being expressed as a mass percentage as follows:

[0011] Copper oxide 0.1%~6%

[0012] Lanthanum oxide 1%~15%

[0013] Alumina 79%~98.9%

[0014] The macroporous composite oxide catalyst is in particulate form with a specific surface area of ​​250~550 m². 2 / g, pore volume 1.0~2.0 cm³ 3 / g, with an average pore size of 10~30 nm.

[0015] Preferably, the macroporous composite oxide catalyst is prepared by co-precipitation, and a nonionic surfactant is added as a pore-expanding agent during the preparation process. More preferably, the nonionic surfactant is at least one of fatty alcohol polyoxyethylene ether, fatty alcohol amide, etc.

[0016] Preferably, the content of each component in the macroporous composite oxide catalyst is expressed as a mass percentage as follows:

[0017] Copper oxide 0.1%~5%

[0018] Lanthanum oxide 2%~12%

[0019] Alumina content: 83%~97.9%.

[0020] As a further preferred embodiment, the content of each component in the macroporous composite oxide catalyst is expressed as a mass percentage as follows:

[0021] Copper oxide 0.25%~3%

[0022] Lanthanum oxide 3%~12%

[0023] Alumina content: 85%~96.75%.

[0024] Preferably, the macroporous composite oxide catalyst is in particulate form with a specific surface area of ​​300~550 m². 2 / g, pore volume 1.3~2.0 cm³ 3 / g, with an average pore size of 15~30 nm. Further preferably, the macroporous composite oxide catalyst is in particulate form with a specific surface area of ​​300~400 m². 2 / g, pore volume 1.3~2.0 cm³ 3 / g, with an average pore size of 15~30 nm.

[0025] Secondly, the present invention provides a method for preparing a macroporous composite oxide catalyst for the reaction of ethanol to higher alcohols, comprising the following steps:

[0026] (1) Mix and stir the prepared copper, lanthanum and aluminum precursor salts and alkaline precipitant solution at 40~95℃ for 20~120 min to obtain a suspension;

[0027] (2) Filter the above suspension to obtain a filter cake, and then wash the filter cake thoroughly with water to obtain a wet filter cake;

[0028] (3) Prepare a slurry by mixing the wet filter cake with nonionic surfactant and deionized water, and then add it to the reaction vessel and mix and react at 20~120℃ for 1~12 h;

[0029] (4) Centrifuge the reaction solution obtained in step (3) to obtain a solid precipitate;

[0030] (5) Place the above solid precipitate in an oven and dry at 40~120℃ for 2~8 h;

[0031] (6) The dried solid precipitate is placed in a muffle furnace and calcined at 300~800℃ in air or an inert gas atmosphere for 0.5~24 h to obtain the macroporous composite oxide catalyst.

[0032] In the above-mentioned method for preparing macroporous composite oxide catalysts, the copper precursor can be at least one of soluble copper salts such as copper nitrate, copper chloride, copper acetate, and copper acetylacetonate, and the mass percentage concentration of the copper precursor salt in the copper precursor salt solution is 1-60%. The lanthanum precursor can be at least one of lanthanum nitrate, lanthanum acetate, and lanthanum acetylacetonate, and the mass percentage concentration of the lanthanum precursor salt in the lanthanum precursor salt solution is 3-60%. The aluminum precursor salt is at least one of soluble aluminum salts such as aluminum nitrate, aluminum sulfate, and aluminum chloride, and the mass percentage concentration of the aluminum precursor salt in the aluminum precursor salt solution is 5-60%. The alkaline precipitant can be at least one of alkaline substances such as sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia, and the mass percentage concentration of the alkaline precipitant in the alkaline precipitant solution is 5-75%. The ratio of the total amount of copper, lanthanum and aluminum precursors to the amount of alkaline precipitant is 1:0.5 to 1:5; the nonionic surfactant is at least one of fatty alcohol polyoxyethylene ether, fatty alcohol amide, etc., and the mass percentage concentration of the nonionic surfactant in the slurry prepared by mixing wet filter cake, nonionic surfactant and deionized water is 5% to 50%.

[0033] Thirdly, the present invention provides a method for producing higher alcohols from ethanol, wherein the reaction apparatus used in the method comprises a main reactor and a secondary reactor connected in series, the main reactor being loaded with the macroporous composite oxide catalyst (catalyst I) described in the first aspect, and the secondary reactor being loaded with a Cu-Zn-Al composite oxide catalyst for the hydrogenation of aldehydes and esters; the method comprises the following steps:

[0034] First, ethanol is introduced into the main reactor to reduce the macroporous composite oxide catalyst. Then, a mixture of nitrogen and hydrogen is introduced into the auxiliary reactor to reduce the Cu-Zn-Al composite oxide catalyst. After reduction, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde esters byproducts by catalyst I. The mixture containing higher alcohols and aldehyde esters byproducts is continuously introduced into the auxiliary reactor, where the aldehyde esters byproducts are further converted into corresponding higher alcohol products by hydrogenation reaction with hydrogen introduced into the auxiliary reactor under the action of Cu-Zn-Al composite oxide catalyst.

[0035] The Cu-Zn-Al composite oxide catalyst described in this invention is a commonly used aldehyde-ester hydrogenation catalyst. Typically, the mass percentages of CuO, ZnO, and Al2O3 in the Cu-Zn-Al composite oxide catalyst are 10%~60%, 5%~40%, and 5~80%, respectively. Those skilled in the art can prepare this catalyst themselves according to the methods reported in the literature, or use commercially available products.

[0036] Preferably, the method specifically includes the following steps:

[0037] (1) First, ethanol is introduced into the main reactor to reduce the macroporous composite oxide catalyst. The reduction conditions are: temperature 100~325℃ (preferably 150~300℃), pressure atmospheric pressure~6.0 MPa (preferably atmospheric pressure~5.0 MPa), and ethanol liquid hourly space velocity 0.2~6.0 mL / (g) cat •h ) (preferably 0.5~5.0 mL / (g) cat The reduction time is 0.5~12h.

[0038] (2) A mixture of nitrogen and hydrogen is introduced into the auxiliary reactor to reduce the Cu-Zn-Al composite oxide catalyst. The reduction conditions are: 150~300℃, atmospheric pressure, using a mixture of H2 and N2 with a volume ratio of 10:1~1:20, and the space velocity of the mixture is 500~3000 h⁻¹. -1 The restoration time is 1~6 hours;

[0039] (3) After the reduction of the large-pore composite oxide catalyst and the Cu-Zn-Al composite oxide catalyst is completed, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde ester byproducts by catalyst I. The mixture containing higher alcohols and aldehyde ester byproducts is continuously fed into the secondary reactor, where the aldehyde ester byproducts are further converted into the corresponding higher alcohol products by hydrogenation reaction with hydrogen gas fed into the secondary reactor under the action of Cu-Zn-Al composite oxide catalyst.

[0040] The reaction conditions within the main reactor are as follows: temperature 150~325℃ (preferably 200~300℃), pressure atmospheric pressure to 6.0 MPa (preferably atmospheric pressure to 5.0 MPa), and liquid hourly space velocity (LHSV) of ethanol 0.2~6.0 mL / (g). cat •h ) (Preferred 0.5~5.0mL / (g) cat ·h ));

[0041] The reaction conditions within the auxiliary reactor are as follows: temperature 150~250℃ (preferably 180~240℃); pressure within the auxiliary reactor controlled by the introduced hydrogen gas, at atmospheric pressure to 6.0 MPa (preferably atmospheric pressure to 5.0 MPa); and liquid hourly space velocity (LHSV) of the feedstock 0.2~6.0 mL / (g). cat •h ) (preferably 0.5~5.0 mL / (g) cat The molar ratio of hydrogen and ethanol feedstock is 1~300:1 (preferably 5~100:1).

[0042] The higher alcohols described in this invention include C4-C20 alcohols, namely n-butanol, 2-ethylbutanol, n-hexanol, 2-ethylhexanol, n-octanol, 2-ethyloctanol, n-decanol, lauryl alcohol, myristol, 1-hexadecanol, 1-octadecanol, 1-eicosanool, and other higher carbon fatty alcohols.

[0043] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0044] (1) When the macroporous composite oxide catalyst provided by the present invention is applied to the reaction of ethanol to higher alcohols, its large pore size and specific surface area are conducive to the diffusion of raw materials, reaction intermediates and the like in the pore channels, especially to the generation of higher alcohols with relatively large molecular weight. Therefore, the catalyst has high reactivity and high selectivity for higher alcohols above C6: it not only has higher selectivity for C6-C10 high carbon fatty alcohols, but can also produce C12-C20 long chain higher fatty alcohols that are in short supply in the market.

[0045] (2) The large-pore alumina support provided by the present invention has both large pore size and high specific surface area. The large pore size significantly improves the diffusion rate of raw materials and reaction intermediates in the catalyst channels. The high specific surface area makes copper highly dispersed on the catalyst surface. Therefore, even with a low Cu loading, it still maintains high catalytic activity, which reduces the production cost of the catalyst. At the same time, the catalyst preparation method is simple and reliable and the reaction conditions are relatively mild, which brings great advantages to the industrial application of the catalyst.

[0046] (3) This invention develops a method for the continuous catalytic conversion of ethanol into higher alcohols. The method adopts a two-stage fixed-bed reaction process: the reaction device mainly includes a main reactor and a secondary reactor connected in series. The main reactor is filled with a large-pore composite oxide catalyst (catalyst I), and the secondary reactor is filled with a Cu-Zn-Al hydrogenation catalyst (catalyst II). The raw material ethanol is first converted into higher alcohols and aldehyde ester by-products through the main reactor and catalyst I, and then the aldehyde ester by-products in the product are further hydrogenated into alcohol products through the secondary reactor and catalyst II, thereby further improving the selectivity of higher alcohols in the product and reducing the complexity and cost of subsequent product separation. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of a fixed-bed reactor for the dehydrogenation condensation of ethanol to higher alcohols. The reactor mainly consists of a main reactor and a secondary reactor connected in series. The main reactor is loaded with a large-pore composite oxide catalyst (catalyst I), and the secondary reactor is loaded with a commercial Cu-Zn-Al hydrogenation catalyst (catalyst II). Ethanol, the feedstock, enters from the bottom of the main reactor and flows upward through the catalyst bed. After the reaction, the material overflows from the top of the main reactor. In the secondary reactor, the feedstock enters from the top and flows downward through the catalyst bed. After the reaction, the material flows out from the bottom of the reactor. 1-Nitrogen cylinder, 2-Hydrogen cylinder, 3-... 1-Pressure reducing valve, 4-Stop valve, 5-Mass flow meter, 6-Ethanol raw material bottle, 7-High pressure constant flow pump, 8-First three-way valve, 9-First check valve, 10-Main reactor, 11-Secondary reactor, 12-Condenser, 13-Condensate outlet, 14-Condensate inlet, 15-Filter, 16-Back pressure valve, 17-Product collection tank, 31-Second three-way valve, 32-Third three-way valve, 33-Second pressure reducing valve, 34-Second stop valve, 35-Second mass flow meter, 36-Second check valve, 37-Third check valve, 38-Fourth check valve, 39-Fifth check valve, 40-Third stop valve. Detailed Implementation

[0048] The present invention will be further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0049] Unless otherwise specified in the embodiments of this invention, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained through conventional technical means or commercially available.

[0050] like Figure 1 As shown, the reaction apparatus includes a main reactor 10 and a secondary reactor 11 connected in series, both of which are fixed-bed reactors. The main reactor includes a main reactor inlet at the bottom and a main reactor outlet at the top, and the secondary reactor includes a secondary reactor inlet at the top and a secondary reactor outlet at the bottom; the main reactor outlet is connected to the secondary reactor inlet; the main reactor is filled with the aforementioned large-pore composite oxide catalyst (catalyst I), and the secondary reactor is filled with a commercial Cu-Zn-Al composite oxide hydrogenation catalyst (catalyst II).

[0051] Furthermore, the reaction apparatus also includes an ethanol raw material bottle 6, which is connected to the feed inlet of the main reactor 10; the reaction apparatus also includes a nitrogen cylinder 1 and a hydrogen cylinder 2, with the nitrogen cylinder 1 connected to the feed inlet of the main reactor and the feed inlet of the auxiliary reactor; and the hydrogen cylinder 2 connected to the feed inlet of the auxiliary reactor 11.

[0052] Furthermore, the reaction apparatus also includes a condenser 12 and a product collection tank 17. The outlet of the auxiliary reactor is connected to the inlet of the condenser 12, and the outlet of the condenser 12 is connected to the product collection tank 17. Even further, the product collection tank 17 is also connected to a back pressure valve 16 via a filter 15.

[0053] Valves and other devices are conventional choices for controlling flow direction and velocity in the field, and can be equipped as needed. In the embodiment of the present invention, the raw material bottle 6 is connected to the inlet of the main reactor in sequence via a high-pressure constant flow pump 7, a first three-way valve 8, and a first one-way valve 9; the outlet of the main reactor 10 is connected to the inlet of the auxiliary reactor 11 via a second three-way valve 31; the nitrogen cylinder 1 is connected to the inlet of the main reactor 10 and the inlet of the auxiliary reactor 11 in sequence via a first pressure reducing valve 3, a first shut-off valve 4, a first mass flow meter 5, and a third three-way valve 32; the hydrogen cylinder 2 is connected to the inlet of the auxiliary reactor 11 in sequence via a second pressure reducing valve 33, a second shut-off valve 34, and a second mass flow meter 35. Furthermore, for safety reasons, a second check valve 36 is provided between the third three-way valve 32 and the inlet of the main reactor 10; a third check valve 37 is provided between the third three-way valve 32 and the inlet of the auxiliary reactor 11; a fourth check valve 38 is provided between the second mass flow meter 35 and the inlet of the auxiliary reactor 11; and a fifth check valve 39 is provided between the outlet of the auxiliary reactor 11 and the inlet of the condenser 12. Additionally, the product collection tank 17 also has a product outlet, controlled by a third shut-off valve 40.

[0054] The commercial Cu-Zn-Al composite oxide catalyst used in the embodiments of this invention was produced by Nanjing Zunlong New Material Technology Co., Ltd., and its model number is QC-1.

[0055] Example 1

[0056] 56.2775 g Al(NO3)3·9H2O, 0.2912 g Cu(NO3)3·3H2O, and 1.3 g La(NO3)3·6H2O were dissolved in 100 mL of deionized water, and 37.2685 g NaHCO3 was dissolved in 250 mL of deionized water. The two solutions were then mixed at 80 °C and stirred for 60 min to form a blue suspension, which was then filtered to obtain a filter cake. The filter cake was washed in 600 mL of deionized water for 60 min and then filtered again, repeating the process three times. The obtained filter cake was mixed with 13.2572 g fatty alcohol polyvinyl ether (AEO-9) and 100 mL of deionized water to form a slurry, which was then added to a reaction vessel lined with polytetrafluoroethylene and reacted at 100 °C for 6 h. The resulting liquid was centrifuged to obtain a blue solid. The obtained solid was dried in an oven at 80℃ for 6 h, and then calcined in a muffle furnace at 600℃ for 2 h to obtain catalyst I-A. The specific surface area, pore volume, and average pore size of catalyst I-A were determined by N2 physical adsorption. The specific test method is as follows: First, the sample was degassed under vacuum at 200℃ for 4 h to remove adsorbed moisture and impurity gases. Then, N2 physical adsorption was performed at liquid nitrogen temperature (-196℃). Finally, the adsorption-desorption isotherms of the sample were obtained according to the static method. The specific surface area of ​​the sample was calculated from the adsorption isotherms according to the Brunauer-Emmett-Teller (BET) equation, and the pore volume and average pore size were calculated from the desorption isotherms according to the single-point method (P / P0=0.99) and the BJH equation. The specific surface area of ​​catalyst I-A was measured to be 320.2 m². 2 / g, pore volume 1.7cm 3 / g, with an average pore size of 20.1nm. The mass percentages of CuO, La2O3, and Al2O3 in catalyst I-A are 1.2%, 5.9%, and 92.9%, respectively.

[0057] Example 2

[0058] The preparation method of catalyst I-B is the same as in Example 1, but the amount of Cu(NO3)2·3H2O weighed is 0.5824 g. The specific surface area, pore volume, and average pore size of catalyst I-B are determined using the same method as in Example 1, and the specific surface area of ​​catalyst I-B is measured to be 315.8 m². 2 / g, pore volume 1.6 cm 3 / g, with an average pore size of 20.6 nm. The mass percentages of CuO, La2O3, and Al2O3 in catalyst I-B are 2.3%, 5.9%, and 91.8%, respectively.

[0059] Example 3

[0060] The preparation method of catalyst I-C was the same as in Example 1, but the calcination temperature of the catalyst in the muffle furnace was 500°C. The specific surface area, pore volume, and average pore size of catalyst I-C were determined using the same methods as in Example 1, and the specific surface area of ​​catalyst I-C was measured to be 321.0 m². 2 / g, pore volume 1.5 cm 3 / g, with an average pore size of 18.4 nm. The mass percentages of CuO, La2O3, and Al2O3 in catalyst I-C are 1.2%, 6.0%, and 92.8%, respectively.

[0061] Comparative Example 1

[0062] The preparation method of catalyst I-D is the same as that of the Cu-La2O3 / Al2O3 catalyst in Chinese patent CN113976184. The specific preparation method is as follows: 0.4562 g of copper nitrate (Cu(NO3)2·3H2O) and 0.4088 g of lanthanum nitrate (La(NO3)3·6H2O) were added to 10 mL of anhydrous ethanol. After dissolving and mixing evenly, 2 g of commercial alumina support was added and impregnated for 4 h. The mixture was first dried at 50 °C and 0.01 MPa for 3 h on a rotary evaporator, and then dried again at 80 °C and 0.01 MPa for 2 h, uniformly loading the copper and lanthanum precursors onto the inner and outer surfaces of the alumina support. The dried solid was calcined in a muffle furnace at 450 °C in air for 3 h to obtain catalyst I-D. The specific surface area, pore volume, and average pore size of catalysts I-D were determined using the same methods as in Example 1. The specific surface area of ​​catalyst I-C was measured to be 232.6 m². 2 / g, pore volume 0.73 cm³ 3 / g, average pore size 7.6 nm. The mass percentage contents of CuO, La2O3 and Al2O3 are 6.6%, 6.7% and 86.7%, respectively.

[0063] Comparative Example 2

[0064] The preparation method of catalyst I-E is the same as that of Comparative Example 1, but the amounts of Cu(NO3)2·3H2O and La(NO3)3·6H2O weighed are 0.0752 g and 0.3388 g, respectively. The specific surface area, pore volume, and average pore size of catalyst I-E are determined using the same method as in Example 1, and the specific surface area of ​​catalyst I-E is measured to be 238 m². 2 / g, pore volume 0.74 cm 3 / g, with an average pore size of 7.7 nm. The mass percentages of CuO, La2O3, and Al2O3 in catalyst I-E are 1.2%, 5.9%, and 92.9%, respectively.

[0065] Comparative Example 3

[0066] The preparation method of catalysts I-F is the same as that of Comparative Example 1, but the amounts of Cu(NO3)2·3H2O and La(NO3)3·6H2O weighed are 0.1557 g and 0.3388 g, respectively. The specific surface area, pore volume, and average pore size of catalysts I-F are determined using the same methods as in Example 1, and the specific surface area of ​​catalysts I-F is measured to be 235.4 m². 2 / g, pore volume 0.74 cm 3 / g, with an average pore size of 7.6 nm. The mass percentages of CuO, La2O3, and Al2O3 in catalysts I-F are 2.4%, 5.8%, and 91.8%, respectively.

[0067] Example 6

[0068] Reaction apparatus such as Figure 1 As shown, catalysts I-A, I-B, I-C, I-D, I-E and IF (catalyst I) prepared in the above examples and comparative examples were respectively loaded into the main reactor of the fixed-bed reactor, while the commercial Cu-Zn-Al composite oxide catalyst (catalyst II) was loaded into the auxiliary reactor of the fixed-bed reactor.

[0069] The method is performed according to the following steps:

[0070] (1) First, ethanol is introduced into the main reactor to reduce the macroporous composite oxide catalyst. The reduction conditions are: temperature 250℃, pressure atmospheric pressure, and ethanol liquid hourly space velocity 1.0 mL / (g). cat The reduction time is 4 hours (·h).

[0071] (2) A mixture of nitrogen and hydrogen gas is introduced into the auxiliary reactor to reduce the Cu-Zn-Al composite oxide catalyst. The reduction conditions are: 250℃, atmospheric pressure, using a mixture of H2 and N2 with a volume ratio of 1~10, and the space velocity of the mixture is 1500 h⁻¹. -1 The restoration time is 3 hours;

[0072] (3) After the reduction of the large-pore composite oxide catalyst and the Cu-Zn-Al composite oxide catalyst is completed, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde ester byproducts by catalyst I. The mixture containing higher alcohols and aldehyde ester byproducts is continuously fed into the secondary reactor, where the aldehyde ester byproducts are further converted into the corresponding higher alcohol products by hydrogenation reaction with hydrogen gas fed into the secondary reactor under the action of Cu-Zn-Al composite oxide catalyst.

[0073] The reaction conditions within the main reactor are: temperature 260℃, pressure 5.0 MPa, and ethanol liquid hourly space velocity (LHSV) 1 mL / (g). cat ·h );

[0074] The reaction conditions within the auxiliary reactor are as follows: temperature 220℃, pressure controlled by introduced hydrogen gas at 5.0 MPa, and liquid hourly space velocity (LHSV) of the feedstock at 1.0 mL / (g). cat The molar ratio of hydrogen to ethanol feedstock is 11:1.

[0075] The reaction conditions are detailed in Table 1. The obtained liquid product was analyzed using gas chromatography equipped with a flame ionization detector (FID) and an HP-5 column (30 m, 0.25 mm). 2-Ethylhexanol was used as an internal standard for quantification of the liquid product.

[0076] The methods for calculating ethanol conversion rate, higher alcohol selectivity, and yield are as follows:

[0077]

[0078]

[0079]

[0080] The carbon molar number refers to the total number of carbon atoms contained in the product or raw material ethanol.

[0081] The reaction results are shown in Table 2.

[0082] Table 1 Summary of conditions for a two-stage fixed-bed reaction of ethanol continuous dehydrogenation condensation to higher alcohols

[0083]

[0084] Table 2. Reaction performance of different catalysts in the continuous catalytic synthesis of higher alcohols from ethanol in a fixed-bed reactor.

[0085]

[0086] As shown in Table 2, the ethanol conversion and selectivity for higher alcohols on the macroporous composite oxide catalyst are significantly higher than those on catalysts prepared using commercial alumina with smaller pore sizes as a support. In particular, it not only exhibits higher selectivity for C6 and above fatty alcohols but also produces C12-C20 long-chain higher fatty alcohols, which are in short supply in the market. Its larger pore size and specific surface area increase the diffusion rate of raw ethanol and reaction intermediates within its pores, and also facilitate the formation of higher molecular weight alcohols, thus significantly improving the catalyst activity (maintaining a high ethanol conversion even at lower Cu loadings). Simultaneously, it significantly improves the selectivity and yield of higher value-added C6-C20 higher alcohols.

Claims

1. A method for producing higher alcohols from ethanol, characterized in that: The method employs a reaction apparatus comprising a main reactor and a secondary reactor connected in series. The main reactor is loaded with a large-pore composite oxide catalyst, and the secondary reactor is loaded with a Cu-Zn-Al composite oxide catalyst for the hydrogenation of aldehydes and esters. The method includes the following steps: First, ethanol is introduced into the main reactor to reduce the macroporous composite oxide catalyst. Then, a mixture of nitrogen and hydrogen is introduced into the auxiliary reactor to reduce the Cu-Zn-Al composite oxide catalyst. After reduction, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde esters byproducts by the macroporous composite oxide catalyst. The mixture containing higher alcohols and aldehyde esters byproducts is continuously introduced into the auxiliary reactor. The aldehyde esters byproducts are then further converted into corresponding higher alcohol products by hydrogenation reaction with hydrogen introduced into the auxiliary reactor under the action of Cu-Zn-Al composite oxide catalyst. The macroporous composite oxide catalyst comprises alumina, copper oxide, and lanthanum oxide, and the content of each component in the macroporous composite oxide catalyst is expressed as a mass percentage as follows: Copper oxide 0.25%~3% Lanthanum oxide 3%~12% Alumina 85%~96.75% The macroporous composite oxide catalyst is in particulate form with a specific surface area of ​​300~550 m². 2 / g, pore volume 1.3~2.0cm 3 / g, with an average pore size of 15~30 nm; the preparation method of the macroporous composite oxide catalyst includes the following steps: (1) Mix and stir the prepared copper, lanthanum and aluminum precursor salts and alkaline precipitant solution at 40~95℃ for 20~120min to obtain a suspension; (2) Filter the above suspension to obtain a filter cake, and then wash the filter cake thoroughly with water to obtain a wet filter cake; (3) Prepare a slurry by mixing the wet filter cake with nonionic surfactant and deionized water, and then add it to the reaction vessel and mix and react at 20~120℃ for 1~12 h; (4) Centrifuge the reaction solution obtained in step (3) to obtain a solid precipitate; (5) Place the above solid precipitate in an oven and dry at 40~120℃ for 2~8 h; (6) The dried solid precipitate is placed in a muffle furnace and calcined at 300~800℃ in air or an inert gas atmosphere for 0.5~24 h to obtain the macroporous composite oxide catalyst.

2. The method as described in claim 1, characterized in that: The method for producing higher alcohols from ethanol specifically includes the following steps: (1) First, ethanol is introduced into the main reactor to reduce the macroporous composite oxide catalyst. The reduction conditions are: temperature 100~325℃, pressure atmospheric pressure~6.0 MPa, and ethanol liquid hourly space velocity 0.2~6.0 mL / (g) cat The reduction time is 0.5~12 h. (2) A mixture of nitrogen and hydrogen is introduced into the auxiliary reactor to reduce the Cu-Zn-Al composite oxide catalyst. The reduction conditions are: 150~300℃, atmospheric pressure, using a mixture of H2 and N2 with a volume ratio of 10:1~1:20, and the space velocity of the mixture is 500~3000 h⁻¹. -1 The restoration time is 1~6 hours; (3) After the reduction of the macroporous composite oxide catalyst and the Cu-Zn-Al composite oxide catalyst is completed, ethanol is continuously added to the main reactor and converted into a mixture containing higher alcohols and aldehyde esters byproducts by the macroporous composite oxide catalyst. The mixture containing higher alcohols and aldehyde esters byproducts is continuously fed into the secondary reactor, where the aldehyde esters byproducts are further converted into the corresponding higher alcohol products by hydrogenation reaction with hydrogen gas fed into the secondary reactor under the action of the Cu-Zn-Al composite oxide catalyst. The reaction conditions within the main reactor are: temperature 150~325℃, pressure atmospheric pressure to 6.0 MPa, and ethanol liquid hourly space velocity (LHSV) 0.2~6.0 mL / (g). cat ·h ) ; The reaction conditions within the auxiliary reactor are as follows: temperature 150~250℃, pressure controlled by the introduced hydrogen gas at atmospheric pressure to 6.0 MPa, and liquid hourly space velocity (LHSV) of the feedstock 0.2~6.0 mL / (g). cat The molar ratio of hydrogen and ethanol feedstock is 1~300:

1.

3. The method as described in claim 2, characterized in that: In step (1) of the method for producing higher alcohols from ethanol, ethanol is first introduced into the main reactor to reduce the macroporous composite oxide catalyst. The reduction conditions are: temperature 150~300℃, pressure atmospheric pressure~5.0 MPa, and ethanol liquid hourly space velocity 0.5~5.0 mL / (g) cat The reduction time is 0.5~12 h.

4. The method as described in claim 2, characterized in that: In step (3) of the method for producing higher alcohols from ethanol, the reaction conditions in the main reactor are: temperature of 200~300℃, pressure of atmospheric pressure to 5.0 MPa, and liquid hourly space velocity of ethanol of 0.5~5.0 mL / (g). cat ·h ); The reaction conditions within the auxiliary reactor are as follows: temperature 180~240℃, pressure controlled by introduced hydrogen gas at atmospheric pressure to 5.0 MPa, and liquid hourly space velocity (LHSV) of the feedstock 0.5~5.0 mL / (g). cat The molar ratio of hydrogen and ethanol feedstock is 5~100:

1.

5. The method as described in claim 1, characterized in that: The macroporous composite oxide catalyst is granular with a specific surface area of ​​300-400 m². 2 / g, pore volume 1.3~2.0 cm³ 3 / g, with an average pore size of 15~30 nm.

6. The method as described in claim 1, characterized in that: In step (3) of the method for preparing the macroporous composite oxide catalyst, the nonionic surfactant is at least one of fatty alcohol polyoxyethylene ether and fatty alcohol amide, and the mass percentage concentration of the nonionic surfactant in the slurry prepared by mixing wet filter cake, nonionic surfactant and deionized water is 5-50%.

7. The method as described in claim 1, characterized in that: In step (1) of the preparation method of the macroporous composite oxide catalyst, the copper precursor is at least one of copper nitrate, copper chloride, copper acetate, and copper acetylacetonate, and the mass percentage concentration of the copper precursor salt in the copper precursor salt solution is 1-60%; the lanthanum precursor is at least one of lanthanum nitrate, lanthanum acetate, and lanthanum acetylacetonate, and the mass percentage concentration of the lanthanum precursor salt in the lanthanum precursor salt solution is 3-60%; the aluminum precursor salt is at least one of aluminum nitrate, aluminum sulfate, and aluminum chloride, and the mass percentage concentration of the aluminum precursor salt in the aluminum precursor salt solution is 5-60%; the alkaline precipitant is at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water, and the mass percentage concentration of the alkaline precipitant in the alkaline precipitant solution is 5-75%; the ratio of the total amount of copper, lanthanum, and aluminum precursors to the amount of alkaline precipitant is 1:0.5-1:5.

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