Method for synthesizing fatty alcohol by coupling ethanol dehydrogenation with animal and plant grease hydrogenation

Abstract

The method comprises the following steps: adding raw material animal and vegetable oil, a hydrogen donor ethanol, a silicon dioxide supported metal-oxide catalyst and a reaction solvent into a high-pressure kettle, reacting for 5-10 hours under the conditions of inert gas protection, temperature of 200-300 DEG C and pressure of 4-10 MPa, separating the reaction liquid, and purifying to obtain the fatty alcohol. A product fatty alcohol is obtained; ethanol is used as the hydrogen donor for the first time, the fatty alcohol (such as laurinol) is prepared through hydrogenation of animal and vegetable oil (such as methyl laurate), the synthesis method is simple in route, the raw materials and the catalyst are cheap and easy to obtain, the raw material conversion rate is high, and the method has industrial application prospects.

Description

Technical Field

[0001] The present invention relates to the technical fields of catalytic hydrogenation and catalytic dehydrogenation, and particularly to a method for using hydrogen obtained by dehydrogenation of alcohols to participate in the hydrogenation synthesis of fatty alcohols from fatty acids or fatty acid esters, and a supported catalyst applied to such coupling reactions. Background Art

[0002] Due to their excellent biodegradability, high solubility, and good low-temperature resistance, fatty alcohols have become important basic raw materials for fine chemical products such as detergents, surfactants, and plasticizers. They are widely used in the chemical industry, with large demand, high added value, and significant economic value. Generally speaking, fatty alcohols refer to alcohol compounds with 6 - 22 carbon atoms in the carbon chain and the hydroxyl group directly connected to the aliphatic hydrocarbon. The sources of fatty alcohols are mainly divided into two categories: one is natural fatty alcohols prepared from animal and vegetable oils and fats, and the other is synthetic fatty alcohols synthesized from fossil resources. In comparison, natural fatty alcohols perform better in terms of surface tension, biodegradability, and safety, and preparing fatty alcohols from animal and vegetable oils and fats is more in line with the concept of green chemistry. Therefore, the production of fatty alcohols based on animal and vegetable oils and fats has advantages in environmental protection and performance over synthetic fatty alcohols and has greater development potential.

[0003] Based on the current literature reports, the mainstream process for producing fatty alcohols from animal and vegetable oils and fats mainly involves the hydrogenation of fatty acids and fatty acid methyl esters. Patent document CN201280003718.5 proposes a method of staged hydrogenation. First, fatty acids react with methanol to form fatty acid methyl esters. Subsequently, the methyl esters are vaporized and mixed with hydrogen, and the reaction rate is promoted by increasing the hydrogen diffusion rate. In the first hydrogenation zone, the raw materials contact the catalyst at a temperature above the dew point for the hydrogenation reaction of fatty acid methyl esters. Unreacted fatty acid methyl esters and the product fatty alcohols will react in a subsequent wax ester reactor to form wax esters. Then, the wax esters are further hydrogenated in the second hydrogenation zone to form fatty alcohols, and the unreacted wax esters will be recycled, and methanol can also be recycled. The specific operating conditions of this process are as follows: the temperature in the first hydrogenation zone is 140 - 240 °C, the pressure is 6 MPa, and the molar ratio of hydrogen to ester is 100 - 2000; the temperature in the second hydrogenation zone is 180 - 220 °C, and the pressure is 4 - 10 MPa. This process requires multiple distillation towers and hydrogenation reactors, resulting in high energy consumption, a long process, and large carbon emissions. Moreover, due to the complex device system, the requirements for the safety and operating conditions of the equipment are relatively high, increasing the production cost and management difficulty.

[0004] Patent document CN101939280B proposed a hydrogenation catalyst, whose main components are copper and copper-chromium oxides, and the secondary components include zinc, aluminum, iron, silicon and alkaline earth metal elements. The catalyst is formed, with a length of 0.5 - 6 mm, composed of multiple tightly combined units, and the perimeter diameter of each unit is 2.5 - 3.5 mm. The technological process is that vegetable oil and animal fat are in countercurrent contact with steam and cracked into fatty acids and glycerol under pressure. The reaction products are physically separated to obtain a fatty acid phase containing fatty acids and a glycerol aqueous phase containing glycerol. After the fatty acids are purified by distillation, a fatty acid fraction is obtained. Subsequently, the fatty acid fraction is vigorously mixed with fatty alcohols under normal pressure at 230 - 270 °C, and wax esters are formed through an esterification reaction. Finally, the wax esters are subjected to a hydrogenation reaction with hydrogen under the action of a fixed-bed catalyst to produce fatty alcohols, and the reaction products are separated into fatty alcohols and hydrogen. However, the catalyst used in this method contains chromium (Cr), and its strong environmental toxicity and biological toxicity limit its industrial application.

[0005] The Cu-Zn catalyst not only effectively compensates for the environmental toxicity problem of the Cr catalyst by optimizing its preparation method and adding different promoters, but also achieves the goals of reducing the reaction pressure and increasing the raw material conversion rate and fatty alcohol selectivity. Patent document CN106622379A discloses a preparation method and application of a copper-based catalyst for hydrogenation of fatty acid methyl esters. This catalyst is prepared by the co-precipitation method. Different alkaline precipitants are added dropwise to a mixed salt solution to obtain a Cu-Zn-Al-Ba quaternary oxide or composite oxide material. The specific steps include: adjusting the pH value, crystallization, filtration, washing, drying, crushing and calcination. Subsequently, the material is transferred to a tubular furnace and reduced in a hydrogen environment at 220 - 300 °C for 1 - 3 hours, and then uniformly coated with methyl stearate in a nitrogen environment to finally obtain the finished catalyst. Using this catalyst, with n-hexane as the solvent, fatty acid methyl esters can be catalyzed into higher alcohols. The experimental results show that the highest conversion rate of methyl stearate can reach 99.21%, and the highest yield of stearyl alcohol is 94.34%. However, the preparation process of this catalyst is relatively complex and requires the addition of multiple components, which limits the feasibility of its industrial application.

[0006] The hydrogen produced by the reforming of methanol and water is an important source of hydrogen, and nickel-based catalysts are commonly used catalysts. Patent document CN1911883A proposed a method for in-situ reducing acetophenone to α-phenylethyl alcohol by using a commercial Raney Ni catalyst to catalyze the aqueous phase reforming reaction of methanol and water to produce hydrogen. At 403K, 0.6MPa, with the acetophenone concentration of 0.43 mol / L and the molar ratio of water to methanol of 1.33, at 0.71 h -1The reaction was carried out in a fixed-bed reactor with an airspeed of [specific airspeed value] to obtain an acetophenone conversion rate of 66.4% and a selectivity for α-phenylethyl alcohol of 95.1%. Jiang reported in the paper "In-Situ Hydrodeoxygenation of Methyl Palmitate on a TiO2-ZrO2 Supported Ni3Sn2 Intermetallic Compound with Methanol as a Hydrogen Donor in the Aqueous Phase" that the in-situ hydrogenation reaction of methyl palmitate with methanol as a hydrogen donor was achieved by preparing a Ni3Sn2 / TiO2-ZrO2 catalyst through the sol-gel method. Ti-O-Zr bonds were generated in the TiO2-ZrO2 composite oxide, resulting in more L acid centers on Ni3Sn2 / TiO2-ZrO2 than on Ni3Sn2 / TiO2 and Ni3Sn2 / ZrO2. The L acid centers may contribute to the cleavage of the C-O bond. The catalytic performance of the in-situ hydrodeoxygenation reaction of methyl palmitate in the aqueous phase depends on the number of Ni centers and acid centers on the catalyst surface. Ni3Sn2 / TiO2-ZrO2(2:1) has the smallest Ni3Sn2 IMC particles and an appropriate amount of acid centers, and the n-C 15 The yield reached 91.2% at 330 °C and remained at about 87.0% after 5 runs. The decrease in catalyst activity was due to carbon deposition and slight sintering of the Ni3Sn2 IMC particles. The above research demonstrated the possibility of coupling the hydrogen production from the reforming of methanol with water and the hydrogenation reaction of animal and vegetable oils and fats.

[0007] Isopropanol is cheap as a hydrogen donor and is easy to remove from the reaction system. Patent document CN116813578A provides a method for synthesizing furfuryl alcohol by hydrogenating furfural with isopropanol as a hydrogen donor. The inventor prepared a magnetic zirconium-based catalyst by the precipitation method, which contains abundant acid-base centers (unsaturated Zr 4+ -O 2- acid-base pairs, and strong Lewis base center MgO); at the same time, there are also abundant strong Lewis acid centers in the doped Fe3O4. The inventor adjusted the number of acid-base sites of the catalyst by adjusting the metal molar ratios of Zr, Mg, and Fe3O4 to optimize its catalytic activity, and the magnetic iron-containing catalyst can achieve the efficient recovery of the catalyst. The activity of primary alcohols is usually lower than that of secondary alcohols. The improvement in the hydrogenation ability of secondary alcohols is attributed to the highest reduction potential of the corresponding ketone bodies. Compared with two alkyl groups, the electron-releasing inductive effect of one alkyl group is smaller. Compared with the lower electron-donating ability of one methyl group and one ethyl group in methanol and ethanol, the two methyl groups in 2-propanol provide more electrons to activate the O-H bond.

[0008] Hydrogen production by the reforming of ethanol and water has a high hydrogen yield, a relatively low reaction rate, and is a strongly endothermic reaction. Patent document CN101357334A discloses an iridium catalyst supported on cerium dioxide, with an iridium content of 0.2 - 5% and cerium dioxide of 95 - 99.8%. The support is cerium dioxide prepared by the coprecipitation method of industrial cerium dioxide and urea, and the specific surface area is 90 m 2 / g - 150 m 2 / g. Ethanol: water: oxygen = 1: 1.0 - 3.0: 0.6 - 1.8 (molar ratio), and the reaction temperature is 300 °C - 700 °C. Ethanol is completely converted at 350 °C. The molar concentration of hydrogen in the product increases with the increase of the reaction temperature, and the hydrogen concentration approaches the theoretical hydrogen production amount at 550 °C. Zhang reported in the paper "CuZnCoO x multifunctional catalyst for in situ hydrogenationof5-hydroxymethylfurfural with ethanol as hydrogen carrier" that a CuZnCoO x ternary catalyst was prepared using ethanol as the hydrogen donor and 5-hydroxymethylfurfural (5-HMF) as the raw material, and the yield of DMF could reach 99%. The study of the reaction mechanism revealed the results that CoO x promoted the in-situ hydrogen production of ethanol, zinc oxide promoted the hydrogenation of aldehyde groups to hydroxymethyl, and the Cu-Co alloy promoted the hydrogenation of 5-HMF.

[0009] In summary, at the process level, exogenous hydrogen is generally used as the hydrogen source in current industry. However, due to the large molecular weight and high viscosity of fatty acid methyl esters, there are problems of difficult hydrogen diffusion and dissolution during the hydrogenation reaction with hydrogen. The current improvements and optimizations mainly focus on fixed-bed or trickle-bed processes, and the process efficiency is improved by means such as pre-separation of raw materials, vaporization hydrogenation, catalyst development, and introduction of solvents. In terms of catalysts, Cu-based heterogeneous catalysts are widely used, and their preparation methods are diverse, including ion exchange, hydrothermal method or solvothermal method, impregnation method, and coprecipitation method in aqueous solution or other solvents. However, these preparation methods have complex processes, and some catalysts also contain environmentally toxic components, which limit the sustainability and safety of their applications. These problems have attracted extensive attention from researchers and urgently need further research and solution. Summary of the Invention

[0010] The present invention aims to provide a method for synthesizing fatty alcohols by dehydrogenation coupling of ethanol and hydrogenation of animal and vegetable oils and fats. This method uses an endogenous hydrogen source and an in-situ hydrogen supply method that reduces the transportation, storage, and diffusion risks of exogenous hydrogen sources, and uses a silica-supported metal-oxide as the catalyst and ethanol as the hydrogen donor to achieve the hydrogenation of animal and vegetable oils and fats to synthesize fatty alcohols.

[0011] The components of the silica-supported metal-oxide catalyst used in the present invention cooperate with each other, showing good catalytic activity, selectivity and stability. It is very suitable for the process of catalytic hydrogenation of fatty acid methyl esters to prepare fatty alcohols, is easy to be popularized industrially, and has industrial application prospects. Moreover, the catalyst has fewer component types, and each component has less impact on and pollution to the environment, having good environmental benefits.

[0012] The technical solution of the present invention is as follows:

[0013] A method for synthesizing fatty alcohols by coupling ethanol dehydrogenation with hydrogenation of animal and vegetable oils and fats, comprising:

[0014] Adding raw material animal and vegetable oils and fats, hydrogen donor ethanol, silica-supported metal-oxide catalyst, and reaction solvent into an autoclave, reacting for 5-10 h under the conditions of inert gas protection, temperature of 200-300 °C, and pressure of 4-10 MPa, and then separating the reaction solution to obtain the product fatty alcohol;

[0015] Among them,

[0016] The raw material animal and vegetable oils and fats are, for example, methyl laurate;

[0017] The mass ratio of ethanol to animal and vegetable oils and fats is 1-2:1;

[0018] The mass ratio of the silica-supported metal-oxide catalyst to animal and vegetable oils and fats is 0.2:1-5;

[0019] The reaction solvent is selected from one or more of n-hexane, n-heptane, benzene, toluene, chloroform, carbon tetrachloride, and preferably n-heptane.

[0020] In the present invention, the silica-supported metal-oxide catalyst is obtained by loading copper salt and oxide precursor on a silicon source by an ammonia evaporation method and then calcining.

[0021] The copper salt is, for example, copper nitrate trihydrate; the oxide precursor is selected from zinc nitrate hexahydrate, cerium nitrate hexahydrate or lanthanum nitrate hexahydrate;

[0022] The silicon source is selected from silica sol, sodium silicate, organosilicon sources of silicate esters (such as methyl orthosilicate, ethyl orthosilicate), natural silicon sources (such as diatomite, kaolin), precipitated silica, mesoporous silicon materials (such as MCM-41, SBA-15, KIT-6), fumed silica, etc., and preferably fumed silica, ethyl orthosilicate, SBA-15;

[0023] The conditions for calcination are: calcining at 450 °C for 4 h in an air atmosphere, and the heating rate is 1 °C·min -1 。

[0024] Before use, the catalyst was reduced and activated as follows: 0.2 g of the catalyst was taken and reduced at a H2 flow rate of 30 mL·min -1 , 400 °C (heating rate 1 °C·min -1 ) for 4 h; after the reduction was completed, it was cooled to room temperature and immediately put into the reaction.

[0025] It should be noted that: after the catalyst prepared by the ammonia evaporation method is calcined, each supported component is in the oxide state; before being put into the reaction, after being reduced and activated under the above conditions, the Cu component is reduced to metallic Cu, and other components are not reduced and remain in the oxide state. Therefore, the silica-supported metal-oxide catalyst is obtained after reduction and activation.

[0026] The reaction principle and innovation of the present invention are described as follows:

[0027] The present invention proposes to use renewable ethanol as a raw material, and through the coupling of ethanol dehydrogenation reaction and oil hydrogenation reaction, fatty alcohol and ethyl acetate are synthesized. This reaction process consists of four basic reactions: (I) dehydrogenation reaction: ethanol is dehydrogenated to acetaldehyde; (II) condensation reaction: ethanol and acetaldehyde are condensed to hemiacetal; (III) dehydrogenation reaction: hemiacetal is dehydrogenated to ethyl acetate; (IV) hydrogenation reaction: oil is hydrogenated to fatty alcohol. Taking the synthesis of lauryl alcohol from methyl laurate as an example, the reaction pathway is shown in the appendix Figure 1 .

[0028] At present, there is no report on using ethanol as a hydrogen donor to use the hydrogen released during the conversion of ethanol to ethyl acetate under anhydrous and anaerobic conditions for the hydrogenation of oil to synthesize fatty alcohol. Comparing the dehydrogenation activities of isopropanol, methanol, and ethanol, methanol has the highest dehydrogenation activity because its molecular structure is simpler, the hydroxyl hydrogen is more easily activated and the activation energy is low; although isopropanol has a larger steric hindrance, the product acetone is stable and the activity is the second; ethanol is the most difficult to dehydrogenate due to steric hindrance and side reactions. Therefore, the dehydrogenation catalysts applied to isopropanol and methanol cannot be directly used in the dehydrogenation reaction of ethanol, and reasonable component and structure design of the catalyst is required.

[0029] In the catalyst designed in the present invention, an oxide-modified Cu-based catalyst is obtained by the ammonia evaporation method. The role of Cu: as an active center, Cu plays a key role in the dehydrogenation (ethanol → ethyl acetate) and hydrogenation (methyl laurate → lauryl alcohol) reactions. Its dispersion and electronic state are regulated by the oxide. The role of the oxide: providing basic sites to inhibit side reactions (such as ethylene formation); adjusting the electronic structure of Cu to enhance the selectivity of specific paths. SiO2 support: improving the metal dispersion, stabilizing the catalyst structure, and reducing sintering.

[0030] In addition, ethyl acetate, a byproduct of the present invention, can also be reconverted into ethanol by combining it with existing renewable green hydrogen. Through this process, ethanol becomes an excellent liquid hydrogen carrier, achieving the renewability of the entire fatty alcohol production from the source of raw materials.

[0031] The beneficial effects of the present invention are as follows:

[0032] Current technologies for hydrogenating fatty alcohols usually require a large amount of hydrogen to be filled, consuming a lot of energy, and having too high a pressure at the reaction temperature, presenting safety hazards. Compared with the synthesis route of catalytic hydrogenation of fatty acid methyl esters using exogenous hydrogen as the hydrogen source to prepare fatty alcohols, the present invention does not require external hydrogen, and hydrogen is provided by the hydrogen donor ethanol, with a simple and safe process, being green and environmentally friendly.

[0033] During the preparation process of current Cr-containing catalysts, the discharged Cr causes serious environmental pollution and has disadvantages such as a complex reaction process. Compared with the synthesis route of using Cr-containing catalysts for catalytic hydrogenation of fatty acid methyl esters to produce fatty alcohols, the present invention avoids using Cr elements and designs catalysts with Cu, Zn, etc. as the metal centers.

[0034] The method of the present invention is safe and green, with advantages such as high conversion rate, high selectivity, simple process, and strong operability. It is suitable for industrial-scale production and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 : Reaction pathway for the synthesis of lauryl alcohol by dehydrogenation coupling of ethanol and hydrogenation of methyl laurate. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention will be further described below through specific examples, but the protection scope of the present invention is not limited thereto.

[0037] The supported catalysts Cu-Zn / SiO2 in Examples 1-5 were prepared by the ammonia evaporation method. Taking 20Cu0.5Zn / SiO2 as an example, the preparation method was as follows: Weigh 1.5206 g of copper nitrate trihydrate and 0.0455 g of zinc nitrate hexahydrate, add them to a 100 mL beaker containing 40 mL of deionized water, and stir with a magnetic stirrer (450 r·min -1 ) for 4 h until copper nitrate trihydrate and zinc nitrate hexahydrate are completely dissolved. Then add 2 g of fumed silica, add deionized water to 60 mL, and continue to stir (450 r·min -1 ) for 3 h until evenly mixed. Then dropwise add ammonia water (2 mL) until the pH value of the solution in the beaker is 12, and continue to stir (450 r·min -1)Overnight. Ammonia was distilled off in a 90 °C oil bath until the pH of the solution in the beaker reached 7, and then it was continuously dried at 90 °C until dry. After drying, the substances in the beaker were transferred to a forced-air oven and dried at 80 °C for 8 h. Finally, after sufficient grinding, it was calcined in a muffle furnace at 450 °C for 4 h with a heating rate of 1 °C·min -1 . It was cooled to room temperature, ground again, bagged and stored for later use. The required 20Cu0.5Zn / SiO2 catalyst was thus obtained.

[0038] The supported catalysts Cu-Ce / SiO2 in Examples 6 - 10 were prepared by the ammonia distillation method. Taking 20Cu0.5Ce / SiO2 as an example, the preparation method was as follows: Weigh 1.5206 g of copper nitrate trihydrate and 0.0158 g of cerium nitrate hexahydrate, add them to a 100 mL beaker containing 40 mL of deionized water, and stir with a magnetic stirrer (450 r·min -1 ) for 4 h until the copper nitrate trihydrate and cerium nitrate hexahydrate were completely dissolved. Then add 2 g of fumed silica, add deionized water to 60 mL, and continue to stir (450 r·min -1 ) for 3 h until evenly mixed. Then add ammonia water (2 mL) until the pH value of the solution in the beaker reached 12, and continue to stir (450 r·min -1 ) overnight. Ammonia was distilled off in a 90 °C oil bath until the pH of the solution in the beaker reached 7, and then it was continuously dried at 90 °C until dry. After drying, the substances in the beaker were transferred to a forced-air oven and dried at 80 °C for 8 h. Finally, after sufficient grinding, it was calcined in a muffle furnace at 450 °C for 4 h with a heating rate of 1 °C·min -1 . It was cooled to room temperature, ground again, bagged and stored for later use. The required 20Cu0.5Ce / SiO2 catalyst was thus obtained.

[0039] The supported catalysts Cu-La / SiO2 in Examples 11 - 15 were prepared by the ammonia distillation method. Taking 20Cu0.5La / SiO2 as an example, the preparation method was as follows: Weigh 1.5206 g of copper nitrate trihydrate and 0.0247 g of lanthanum nitrate hexahydrate, add them to a 100 mL beaker containing 40 mL of deionized water, and stir with a magnetic stirrer (450 r·min -1 ) for 4 h until the copper nitrate trihydrate and lanthanum nitrate hexahydrate were completely dissolved. Then add 2 g of fumed silica, add deionized water to 60 mL, and continue to stir (450 r·min -1 ) for 3 h until evenly mixed. Then add ammonia water (2 mL) until the pH value of the solution in the beaker reached 12, and continue to stir (450 r·min -1)Overnight. Ammonia was distilled in a 90 °C oil bath until the pH of the solution in the beaker reached 7, and then it was continuously dried at 90 °C until dry. After drying, the substances in the beaker were transferred to a blast drying oven and dried at 80 °C for 8 h. Finally, after sufficient grinding, it was calcined in a muffle furnace at 450 °C for 4 h with a heating rate of 1 °C·min -1 . It was cooled to room temperature, ground again, bagged and stored for use. The required 20Cu0.5La / SiO2 catalyst was thus obtained.

[0040] The supported catalyst 20Cu / SiO2 in Comparative Example 1 was prepared by the ammonia distillation method. The preparation method was as follows:

[0041] Weighed 1.5206 g of copper nitrate trihydrate and added it to a 100 mL beaker containing 40 mL of deionized water. Stirred with a magnetic stirrer (450 r·min -1 ) for 4 h until the copper nitrate trihydrate was completely dissolved. Then added 2 g of fumed silica, added deionized water to 60 mL, and continued to stir (450 r·min -1 ) for 3 h until evenly mixed. Then added ammonia water (2 mL) until the pH value of the solution in the beaker reached 12, and continued to stir (450 r·min -1 ) overnight. Ammonia was distilled in a 90 °C oil bath until the pH of the solution in the beaker reached 7, and then it was continuously dried at 90 °C until dry. After drying, the substances in the beaker were transferred to a blast drying oven and dried at 80 °C for 8 h. Finally, after sufficient grinding, it was calcined in a muffle furnace at 450 °C for 4 h with a heating rate of 1 °C·min -1 . It was cooled to room temperature, ground again, bagged and stored for use. The required 20% Cu / SiO2 catalyst was thus obtained.

[0042] In the preparation method of the above catalyst, the fumed silica was provided by Aladdin, with the specification of S124038 - 500 g and the product CAS number of 112945 - 52 - 5.

[0043] Example 1

[0044] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n - heptane as the solvent environment, the following steps were carried out in sequence:

[0045] First, before using the catalyst, it needed to be reduced using high - purity hydrogen (H2 purity 99.999%, provided by Hangzhou Jingong Special Gases Co., Ltd.). The reduction conditions were: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduced at 400 °C for 4 h, with a heating rate of 1 °C·min -1 . After the reduction was completed, it was cooled to room temperature for use. Then, a 50 mL pressure - resistant reaction kettle with built - in temperature measurement and stirring was used. Added 16 mL of n - heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu - Zn / SiO2 catalyst (mCu：Zn = 20:0.5, where "m" represents the mass ratio, the same hereinafter), and seal the reaction kettle. After replacing the air with nitrogen by at least three filling and three standing operations, heat up to 300 °C, and the stirring speed is 800 r·min -1 . After maintaining this temperature for 8 h, the reaction ends.

[0046] The separation method of the reaction solution is as follows:

[0047] 1. Distill the reaction solution: Collect the fractions with a boiling point of about 77 - 80 °C (ethanol and ethyl acetate), collect the fractions with a boiling point of about 95 - 98 °C (n - heptane), and the high - boiling substances (methyl laurate, ethyl laurate, butyl laurate, lauryl alcohol) remain in the distillation flask.

[0048] 2. Treat the low - boiling components: Add saturated brine to the low - boiling fraction (77 - 80 °C). Utilize the salting - out effect to reduce the solubility of ethyl acetate. Ethyl acetate will form an organic layer (upper layer), while ethanol dissolves in the aqueous layer (lower layer). Separate the organic layer with a separating funnel to obtain pure ethyl acetate.

[0049] 3. Treat the high - boiling components (esters and lauryl alcohol): Add an aqueous NaOH solution to the residue in the distillation flask and heat under reflux. The esters (methyl laurate, ethyl laurate, butyl laurate) are hydrolyzed to form water - soluble carboxylates and lower alcohols (such as methanol, ethanol, butanol). Lauryl alcohol does not participate in the reaction and remains in the organic phase. Separate lauryl alcohol: After cooling, the mixture is layered: the aqueous layer contains carboxylates and lower alcohols, and the organic layer is lauryl alcohol. Separate the organic layer with a separating funnel to finally obtain pure lauryl alcohol.

[0050] The data is as follows:

[0051]

[0052] Example 2

[0053] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n - heptane as the solvent environment, perform the following steps in sequence:

[0054] First, the catalyst needs to be reduced with high - purity hydrogen before use. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and a heating rate of 1 °C·min -1 . After the reduction is completed, cool to room temperature for use. Then, use a 50 mL pressure - resistant reaction kettle equipped with temperature measurement and stirring, add 16 mL of n - heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu - Zn / SiO2 catalyst (m Cu：Zn = 20:1), and seal the reaction kettle. After replacing the air with nitrogen by at least three filling and three standing operations, heat up to 300 °C, and the stirring speed is 800 r·min-1 , after maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0055]

[0056] Example 3

[0057] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0058] First, the catalyst needs to be reduced with high-purity hydrogen before use. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 . After the reduction ends, it is cooled to room temperature for standby. Then, a 50 mL pressure-resistant reaction kettle equipped with temperature measurement and stirring is used to add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-Zn / SiO2 catalyst (m Cu：Zn = 20:3), and the reaction kettle is sealed. After replacing the air with nitrogen at least three times of charging and discharging, it is heated to 300 °C, and the stirring speed is 800 r·min -1 , after maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0059]

[0060] Example 4

[0061] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0062] First, the catalyst needs to be reduced with high-purity hydrogen before use. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 . After the reduction ends, it is cooled to room temperature for standby. Then, a 50 mL pressure-resistant reaction kettle equipped with temperature measurement and stirring is used to add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-Zn / SiO2 catalyst (m Cu：Zn = 20:5), and the reaction kettle is sealed. After replacing the air with nitrogen at least three times of charging and discharging, it is heated to 300 °C, and the stirring speed is 800 r·min -1 , after maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0063]

[0064] Example 5

[0065] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0066] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 . After the reduction is completed, it is cooled to room temperature for later use. Then, a 50 mL pressure-resistant reaction kettle with temperature measurement and stirring is used. Add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-Zn / SiO2 catalyst (m Cu：Zn = 20:10), and seal the reaction kettle. After replacing the air with nitrogen at least three times by filling and discharging, heat up to 300 °C, and the stirring speed is 800 r·min -1 . After maintaining this temperature for 8 h, the reaction ends. The data is as follows:

[0067]

[0068] Example 6

[0069] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0070] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 . After the reduction is completed, it is cooled to room temperature for later use. Then, a 50 mL pressure-resistant reaction kettle with temperature measurement and stirring is used. Add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-Ce / SiO2 catalyst (m Cu：Ce = 20:0.5), and seal the reaction kettle. After replacing the air with nitrogen at least three times by filling and discharging, heat up to 300 °C, and the stirring speed is 800 r·min -1 . After maintaining this temperature for 8 h, the reaction ends. The data is as follows:

[0071]

[0072] Example 7

[0073] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0074] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min-1 After the reduction is completed, cool it to room temperature for later use. Then, use a 50 mL pressure-resistant reaction kettle equipped with temperature measurement and stirring, add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-Ce / SiO2 catalyst (m Cu：Ce = 20:1), and seal the reaction kettle. After replacing the air with nitrogen at least three times by filling and discharging, heat it to 300 °C, and the stirring speed is 800 r·min -1 . After maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0075]

[0076] Example 8

[0077] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0078] First, the catalyst needs to be reduced using high-purity hydrogen before use. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 . After the reduction is completed, cool it to room temperature for later use. Then, use a 50 mL pressure-resistant reaction kettle equipped with temperature measurement and stirring, add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-Ce / SiO2 catalyst (m Cu：Ce = 20:3), and seal the reaction kettle. After replacing the air with nitrogen at least three times by filling and discharging, heat it to 300 °C, and the stirring speed is 800 r·min -1 . After maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0079]

[0080] Example 9

[0081] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0082] First, the catalyst needs to be reduced using high-purity hydrogen before use. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 . After the reduction is completed, cool it to room temperature for later use. Then, use a 50 mL pressure-resistant reaction kettle equipped with temperature measurement and stirring, add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-Ce / SiO2 catalyst (m Cu：Ce=(20:5), seal the reactor. After replacing the air with nitrogen by at least three purges and three hold-ups, heat it up to 300 °C, and the stirring speed is 800 r·min -1 After maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0083]

[0084] Example 10

[0085] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0086] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 . After the reduction is completed, cool it to room temperature for standby. Then, use a 50 mL pressure-resistant reactor with self-temperature measurement and stirring, add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-Ce / SiO2 catalyst (m Cu：Ce =(20:10), seal the reactor. After replacing the air with nitrogen by at least three purges and three hold-ups, heat it up to 300 °C, and the stirring speed is 800 r·min -1 After maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0087]

[0088] Example 11

[0089] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0090] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 . After the reduction is completed, cool it to room temperature for standby. Then, use a 50 mL pressure-resistant reactor with self-temperature measurement and stirring, add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-La / SiO2 catalyst (m Cu：La =(20:0.5), seal the reactor. After replacing the air with nitrogen by at least three purges and three hold-ups, heat it up to 300 °C, and the stirring speed is 800 r·min -1 After maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0091]

[0092] Example 12

[0093] Using methyl laurate as the starting material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0094] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are as follows: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and a heating rate of 1 °C·min -1 . After the reduction is completed, it is cooled to room temperature for standby. Then, a 50 mL pressure-resistant reaction kettle equipped with temperature measurement and stirring is used. Add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-La / SiO2 catalyst (m Cu：La = 20:1), and seal the reaction kettle. After replacing the air with nitrogen at least three times by charging and discharging, it is heated to 300 °C, and the stirring speed is 800 r·min -1 . After maintaining this temperature for 8 h, the reaction ends. The data is as follows:

[0095]

[0096] Example 13

[0097] Using methyl laurate as the starting material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0098] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are as follows: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and a heating rate of 1 °C·min -1 . After the reduction is completed, it is cooled to room temperature for standby. Then, a 50 mL pressure-resistant reaction kettle equipped with temperature measurement and stirring is used. Add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-La / SiO2 catalyst (m Cu：La = 20:3), and seal the reaction kettle. After replacing the air with nitrogen at least three times by charging and discharging, it is heated to 300 °C, and the stirring speed is 800 r·min -1 . After maintaining this temperature for 8 h, the reaction ends. The data is as follows:

[0099]

[0100] Example 14

[0101] Using methyl laurate as the starting material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0102] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are as follows: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 After the reduction is completed, it is cooled to room temperature for standby. Then, a 50 mL pressure-resistant reactor equipped with temperature measurement and stirring is used. Add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-La / SiO2 catalyst (m Cu：La = 20:5), and seal the reactor. After replacing the air with nitrogen at least three times by filling and discharging, heat it to 300 °C, and the stirring speed is 800 r·min -1 After maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0103]

[0104] Example 15

[0105] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0106] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are as follows: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1 After the reduction is completed, it is cooled to room temperature for standby. Then, a 50 mL pressure-resistant reactor equipped with temperature measurement and stirring is used. Add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g of Cu-La / SiO2 catalyst (m Cu：La = 20:10), and seal the reactor. After replacing the air with nitrogen at least three times by filling and discharging, heat it to 300 °C, and the stirring speed is 800 r·min -1 After maintaining this temperature for 8 h, the reaction ends. The data are as follows:

[0107]

[0108] Comparative Example 1

[0109] Using methyl laurate as the initial raw material, ethanol as the hydrogen donor, and n-heptane as the solvent environment, the following steps are carried out in sequence:

[0110] First, before using the catalyst, it needs to be reduced with high-purity hydrogen. The reduction conditions are as follows: 0.2 g of catalyst, H2 flow rate of 30 ml / min, reduction at 400 °C for 4 h, and heating rate of 1 °C·min -1After the reduction is completed, the mixture is cooled to room temperature for later use. Then, a 50 mL pressure-resistant reactor with temperature measurement and stirring is used to add 16 mL of n-heptane, 1.7400 g of methyl laurate, 3.1560 g of ethanol, and 0.2 g (m Cu：SiO2 =0.2:1), make the reactor airtight. Use nitrogen to fill and stand for at least three times to replace the air, then heat to 300℃ and stir at 800r·min -1 After maintaining this temperature for 8 hours, the reaction is completed. The data are as follows:

[0111]

[0112] From the data of the examples and comparative examples, it can be seen that when the Cu content remains unchanged, the addition of oxides for modification generally shows a volcano-shaped activity curve. When a small amount of oxide is added, the activity increases compared to no addition; but when the amount of oxide reaches a certain value (this value is different when using different oxide precursors), continuing to add oxides will cover the Cu sites, resulting in a decrease in the activity of the catalyst. The catalyst corresponding to this value has the highest activity.

[0113] Finally, it should be noted that the above-mentioned examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above-mentioned embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A method for synthesizing fatty alcohols by dehydrogenating ethanol and coupling hydrogenation of animal and vegetable oils and fats, characterized in that, The method includes: Adding raw material animal and vegetable oils and fats, hydrogen donor ethanol, silica-supported metal-oxide catalyst, and reaction solvent into an autoclave, reacting under the conditions of inert gas protection, a temperature of 200-300°C, and a pressure of 4-10 MPa for 5-10 h, and then separating the reaction solution to obtain the product fatty alcohol; Among them, The silica-supported metal-oxide catalyst is obtained by loading copper salt and oxide precursor on a silicon source by the ammonia evaporation method and then calcining; and the catalyst is subjected to reduction activation treatment before use; The oxide precursor is selected from: zinc salt, cerium salt or lanthanum salt; The silicon source is selected from silica sol, sodium silicate, organosilicon sources of silicate esters, natural silicon sources, precipitated silica, mesoporous silica materials, and fumed silica.

2. The method for synthesizing fatty alcohols by dehydrogenation coupling of ethanol and hydrogenation of animal and vegetable oils as claimed in claim 1, wherein The raw material animal and vegetable oils and fats are: methyl laurate.

3. The method for synthesizing fatty alcohols by dehydrogenating ethanol and coupling hydrogenation of animal and vegetable oils as claimed in claim 1, wherein The mass ratio of ethanol to animal and vegetable oils and fats is 1-2:

1.

4. The method for synthesizing fatty alcohols by dehydrogenation coupling of ethanol and hydrogenation of animal and vegetable oils as claimed in claim 1, wherein The mass ratio of the silica-supported metal-oxide catalyst to animal and vegetable oils and fats is 0.2:1-5.

5. The method for synthesizing fatty alcohols by dehydrogenation coupling of ethanol and hydrogenation of animal and vegetable oils as claimed in claim 1, wherein The reaction solvent is selected from one or more of n-hexane, n-heptane, benzene, toluene, chloroform, and carbon tetrachloride.

6. The method for synthesizing fatty alcohols by dehydrogenation coupling of ethanol and hydrogenation of animal and vegetable oils as claimed in claim 1, wherein, The copper salt is: copper nitrate trihydrate.

7. The method for synthesizing fatty alcohols by dehydrogenation coupling of ethanol and hydrogenation of animal and vegetable oils as claimed in claim 1, wherein, The oxide precursor is selected from: zinc nitrate hexahydrate, cerium nitrate hexahydrate or lanthanum nitrate hexahydrate.

8. The method for synthesizing fatty alcohols by dehydrogenation coupling of ethanol and hydrogenation of animal and vegetable oils as claimed in claim 1, wherein, The conditions for calcining the catalyst are: calcining at 450°C in an air atmosphere for 4 h.

9. The method for synthesizing fatty alcohols by dehydrogenation coupling of ethanol and hydrogenation of animal and vegetable oils according to claim 1, characterized in that, The catalyst is subjected to the following reduction activation treatment before use: Take 0.2 g of the catalyst and reduce it at a H2 flow rate of 30 mL·min -1 and a temperature of 400 °C for 4 h.

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