Method for preparing fatty alcohol by hydrogenation of fatty acid wax ester

Abstract

The invention relates to a method for preparing fatty alcohol by hydrogenation of fatty acid wax ester. According to the method, an efficient copper-based catalyst is adopted, and the catalyst is a copper-based catalyst with dendritic mesoporous silica nanospheres as a carrier; when the catalyst is applied to a reaction for preparing fatty alcohol through hydrogenation of fatty acid wax ester with a long carbon chain, the three-dimensional open ordered mesoporous structure has a short diffusion path, and diffusion of reactant wax ester molecules to active sites and removal of the product fatty alcohol from the active sites are facilitated. Therefore, higher wax ester conversion rate and fatty alcohol selectivity are obtained. According to the method, the fatty acid wax ester is subjected to hydrogenation reaction by using the reaction kettle, the highest wax ester conversion rate of 98.1% is obtained under the mild conditions of 210 DEG C and 5 MPa, and the selectivity of the byproduct alkane is only 0.16%.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical engineering, and relates to a method for preparing fatty alcohol by hydrogenating fatty acid wax ester. BACKGROUND

[0002] Fatty alcohol, as an important fine chemical raw material, is the main component of emollients, plasticizers, thickening agents, detergents and other products, and is widely used in daily chemical industry, metallurgy, leather, medicine and health, food processing and other fields.

[0003] At present, the industrial production of fatty alcohol can be divided into natural fatty alcohol obtained by hydrogenation of biological oils such as coconut oil and palm oil, and synthetic fatty alcohol obtained by petroleum route. In recent years, due to the lack of petroleum resources and the advantages of natural fatty alcohol such as wide raw material sources, environmental friendliness, high purity, colorless and odorless, good safety, etc., the market size of natural fatty alcohol has been expanding year by year.

[0004] In industry, natural fatty alcohol is prepared by further catalytic hydrogenation of fatty acid and triglyceride, which are the main components of natural oils. However, the direct hydrogenation of fatty acid requires harsh conditions, such as corrosion-resistant structural materials and acid-resistant catalysts, and high temperature. In contrast, the process of first esterifying triglyceride and methanol to obtain fatty acid methyl ester, and then catalytically hydrogenating fatty acid methyl ester to obtain fatty alcohol, can be carried out under relatively mild conditions. Therefore, the route of preparing natural fatty alcohol by methyl ester route has been deeply developed. However, the methyl ester route produces methanol as a byproduct. The toxicity and environmental hazards of methanol and the cost of subsequent methanol treatment limit the further research and development of the methyl ester route.

[0005] In recent years, the wax ester hydrogenation process CN101939280B developed by Lurgi Company has gradually entered the field of vision. The process uses fatty acid to esterify with fatty alcohol to obtain wax ester, and then uses Cu-Cr catalyst to hydrogenate the wax ester to obtain fatty alcohol. This process conforms to the national strategy of developing renewable energy in China, has good atom economy, almost no byproduct, and avoids the problem of methanol treatment in the methyl ester route. However, since Cu-Cr catalyst is used in the hydrogenation process, Cr, as a toxic metal, will cause serious environmental pollution. Therefore, it is necessary to develop an environmentally friendly wax ester hydrogenation catalyst with high performance under relatively mild conditions.

[0006] CN116348203A discloses a chromium-free copper-calcium silicate catalyst, which can obtain a wax ester conversion rate of 94.1% in a reaction kettle at 300℃, 30MPa for fatty acid wax ester hydrogenation reaction. Compared with commercial Cu-Cr catalyst, it has higher activity and alcohol yield, and less alkane by-products, but the reaction condition is harsh. CN113661001A discloses a copper-aluminum manganese-zirconium catalyst, which is used for wax ester hydrogenation reaction in a fixed bed at 7MPa and 0.73h -1 The catalyst shows increased conversion rate at lower temperature than commercial copper-silicon dioxide catalyst. However, due to the small specific surface area of the catalyst and the large particle size of copper particles, the conversion rate is not high, and the highest conversion rate is only 91.3% at 220℃.

[0007] Copper-silicon dioxide is often used as an ester hydrogenation catalyst. In particular, ordered mesoporous silica has been widely used as an ester hydrogenation catalyst carrier due to its uniform and regular mesoporous channels, large surface area and good accessibility of larger reactant molecules. In previous research CN107118076B, mesoporous silica (HPS) was used as a carrier, and Cu-HPS catalyst was obtained by ammonia evaporation method. The catalyst is used for hydrogenation reaction of larger molecule dimethyl adipate, and the one-dimensional ordered mesoporous structure can significantly improve the accessibility of reactant molecules to active sites of the catalyst. Thus, the catalyst can achieve >92% conversion rate of dimethyl adipate at high space velocity of 1.8h -1 However, due to the poor mass transfer and diffusion performance of one-dimensional ordered mesoporous structure, more deep hydrogenation by-products of hexanol are produced. SUMMARY

[0008] The purpose of the present application is to provide a method for hydrogenation of fatty acid wax ester to fatty alcohol. The method uses a high-efficiency copper-based catalyst, which is a dendritic mesoporous silica nanosphere supported copper-based catalyst. When the catalyst is used in the reaction of hydrogenation of long-chain fatty acid wax ester to fatty alcohol, the three-dimensional open ordered mesoporous structure has a short diffusion path, which is beneficial to the diffusion of reactant wax ester molecules to active sites and the removal of product fatty alcohol from active sites. Thus, higher conversion rate of wax ester and selectivity of fatty alcohol are obtained. In the present application, a reaction kettle is used for hydrogenation reaction of fatty acid wax ester, and the highest conversion rate of wax ester is 98.1% under mild conditions of 210℃ and 5MPa, and the selectivity of by-product alkane is only 0.16%.

[0009] The technical solution adopted by the present application is as follows:

[0010] A method for hydrogenation of fatty acid wax ester to fatty alcohol, the method comprising the following steps:

[0011] Put the catalyst, fatty acid wax ester, n-hexane into the reaction kettle, fill in hydrogen to the pressure of 4-6MPa, then warm up to 200-220℃, under the stirring speed of 700-900rpm, react for 5-10 hours, get the product fatty alcohol;

[0012] The added mass of the solvent n-hexane is 25-50 times of the mass of the fatty acid wax ester; the added mass of the fatty acid wax ester is 5-8 times of the mass of the catalyst.

[0013] The fatty acid wax ester is specifically lauryl laurate, myristyl myristate, palmitoyl palmitate or stearyl stearate.

[0014] The catalyst is a dendritic mesoporous silica sphere catalyst with copper supported by ammonia evaporation method, which comprises a carrier and an active component; the carrier is a dendritic mesoporous silica sphere prepared by an oil-water two-phase method, and the mesoporous pore size is 3-5.5nm; the active component is Cu, and the proportion of the active component Cu in the total mass of the catalyst is 10-40%.

[0015] The reaction time is preferably 5.3-8 hours; and the proportion of the active component Cu in the total mass of the catalyst is preferably 20-30%.

[0016] The preparation method of the dendritic mesoporous silica sphere catalyst with copper supported by ammonia evaporation method comprises the following steps:

[0017] (1) After dissolving cetyltrimethylammonium chloride (CTAC) in deionized water by stirring, add triethanolamine (TEA) solution, and then stir in a water bath at 50-80℃ for 0.5-2h; then add tetraethyl orthosilicate (TEOS) solution. Stir in a water bath at 60-90℃ for 20-30h to obtain solution A with oil-water two-phase separation;

[0018] In the formula, 30-50g of cetyltrimethylammonium chloride, 150-200mL of triethanolamine (TEA) solution and 80-120mL of tetraethyl orthosilicate (TEOS) solution are added to every 120mL of deionized water; 0.8-1.0g of triethanolamine is contained in every 180mL of triethanolamine solution.

[0019] The concentration of the tetraethyl orthosilicate (TEOS) solution is 15-25v%;

[0020] (2) Centrifuge the lower water phase of solution A in step (1), wash with anhydrous ethanol and deionized water for three times respectively, dry at 60-120℃ overnight, and then calcine at 500-600℃ in air atmosphere for 4-6h to obtain silica sphere powder;

[0021] (3) Cu(NO3)2.3H2O and deionized water are mixed, and after dissolution, ammonia is added to control the pH of the solution to 10-11, and the solution is stirred at 25-40°C for 10-40 min, and then silica sphere powder is added, and the solution is continuously stirred at 25-40°C for 3-6 h;

[0022] wherein 0.5-6 g of Cu(NO3)2.3H2O and 1.5-2.5 g of silica sphere powder are added per 100 mL of deionized water;

[0023] (4) the solution in (3) is heated to 70-90°C to evaporate ammonia in the solution, and deionized water is added at regular intervals to keep the solution level stable during the process. After the pH of the solution is reduced to 6-7, the solution is filtered, washed, dried overnight, and calcined at 350-450°C in air for 4-6 h to obtain solid A;

[0024] (5) solid A is sieved after tabletting to form particles with a size of 40-60 mesh, and the particles are reduced in a tube furnace at 250-350°C in hydrogen for 3-6 h, and then passivated in a mixture of 1% O2 and 99% Ar for 0.5-1 h after the temperature is reduced to room temperature to obtain a copper-loaded dendritic mesoporous silica sphere catalyst.

[0025] In step (1), the solvent used for the TEOS solution is one of 1-octadecene, decaline, and cyclohexane.

[0026] The mesopore size of the silica sphere is controlled by changing the solvent used for the TEOS solution in step (1).

[0027] In the biphasic stratified reaction system, the surfactant CTAC will assemble with the silicate oligomers formed by the organic solvent molecules and TEOS at the interface to form "oil-in-water" semi-emulsion micelles. Such micelles are templates for the continuous growth and assembly of mesoporous silica. During the interface assembly process, the key factor for the mesopore size is the interface curvature of the semi-emulsion micelles, which depends on the molecular size and hydrophobicity of the organic solvent. Therefore, using different organic solvents with different molecular sizes and hydrophobicities will result in semi-emulsion micelle templates with different interface curvatures, thereby assembling dendritic mesoporous silica spheres with different pore sizes.

[0028] The preparation method of the copper-loaded dendritic mesoporous silica sphere catalyst is characterized in that the dendritic silica sphere has three-dimensional open ordered mesopores, can realize the pre-dispersion of the copper precursor, and the specific surface area of the mesoporous silica sphere carrier is large, which can realize the uniform distribution of copper nanoparticles.

[0029] The copper-loaded dendritic mesoporous silica ball catalyst is characterized in that: the copper particle size is small, the dispersion degree is high, and the three-dimensional open mesopore can fully expose the active sites, has good active site accessibility, and is beneficial to the mass transfer diffusion of large wax ester molecules.

[0030] The substantial features of the present application are:

[0031] The industrial catalyst for hydrogenating fatty acid wax ester into fatty alcohol is a Cu-Cr catalyst, and Cr is a toxic metal, which can cause serious environmental pollution.

[0032] The copper-loaded dendritic mesoporous silica ball catalyst developed by the present application is prepared by the ammonia evaporation method, and the dendritic mesoporous silica nanoball (DMSN) has a three-dimensional open ordered mesoporous structure. Compared with conventional one-dimensional or two-dimensional mesoporous silica carriers, the dendritic mesoporous silica nanoball can better promote the dispersion of active sites. At the same time, it is more conducive to the mass transfer diffusion of macromolecular reactants and products and the accessibility to active sites; the ammonia evaporation method can also make copper and silica form a strong interaction, thereby generating more highly dispersed copper active sites and improving the catalytic activity.

[0033] Since the mesoporous silica ball carrier used in the present application provides a large specific surface area, and the pore size thereof is adjustable. In addition, the Cu precursor can be pre-dispersed in the dendritic mesopores of the silica ball, and the confinement effect of the mesoporous channel can limit the growth of Cu nanoparticles. Therefore, the catalyst prepared by the present application has a high specific surface area, a small Cu particle size, and a high dispersion degree. The three-dimensional open mesopore of the catalyst can expose more active sites, improve the accessibility of the active sites, and at the same time promote the diffusion of the wax ester reactant molecules and the migration of the fatty alcohol reaction product, thereby reducing the hydrocarbon by-products. Therefore, when applied to the hydrogenation reaction of fatty acid wax ester, the catalyst has a high wax ester conversion rate and a high fatty alcohol selectivity under relatively mild conditions.

[0034] The present application has the following beneficial effects:

[0035] The application provides a method for preparing fatty alcohol by hydrogenating fatty acid wax ester. The method uses a reaction kettle to carry out hydrogenation reaction of fatty acid wax ester, and high fatty alcohol yield is obtained under relatively mild conditions of 5 MPa and 210 DEG C. The application also provides a high-efficiency copper-based catalyst and a preparation method thereof. In the preparation method, first, dendritic mesoporous silica sphere carriers with pore sizes of 3 nm, 4.2 nm and 5.5 nm are prepared by an oil-water two-phase method, and then Cu is loaded in the radial mesopores of the silica sphere by an ammonia evaporation method, so that a copper-loaded dendritic mesoporous silica sphere catalyst is obtained. The Cu content of the catalyst is 10-40%. Using the dendritic mesoporous silica sphere as the carrier can make the catalyst have a relatively large specific surface area, improve the dispersion degree of Cu, reduce the particle size of Cu, and improve the catalytic activity. In addition, the three-dimensional open mesoporous structure is beneficial to the exposure of active sites, improves the accessibility of the active sites, reduces the diffusion resistance of the wax ester molecules, and is also beneficial to the removal of the fatty alcohol product from the active sites, so that the conversion rate of the wax ester is improved and the product fatty alcohol is prevented from being further hydrogenated and deoxidized into a hydrocarbon byproduct. The catalyst provided by the application can obtain a wax ester conversion rate of up to 98.1% under the condition of 1 h -1 space velocity. In the patent CN113661001A, the wax ester conversion rate is only 91.3% under the condition of 220 DEG C, 7 MPa and 0.73 h -1 space velocity. Compared with the conventional copper-silica catalyst, the catalyst prepared in the application can increase the conversion rate by 25% at most under the condition of 1.5 h -1 space velocity. The catalyst prepared in the application has little hydrocarbon byproduct, and the selectivity of the product fatty alcohol is basically close to 100%. The method for preparing fatty alcohol by hydrogenating fatty acid wax ester provided by the application has relatively mild reaction conditions, high wax ester conversion rate and fatty alcohol selectivity, and the catalyst used is non-toxic and simple in composition, which has important significance for the industry of preparing fatty alcohol by hydrogenating fatty acid wax ester. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 XRD spectra of the dendritic mesoporous silica sphere catalysts with different Cu loadings obtained in Examples 1-4 and the catalysts of Comparative Examples 1-2.

[0037] Figure 2 TEM images of the dendritic mesoporous silica sphere catalysts with different Cu loadings obtained in Examples 1-4 and the catalysts of Comparative Examples 1-2, wherein, Figure 2 a is the image of 10Cu-DMSNs-4.2, Figure 2 b is the image of 20Cu-DMSNs-4.2, Figure 2 c is the image of 30Cu-DMSNs-4.2, Figure 2 d is the image of 40Cu-DMSNs-4.2, Figure 2 e is the image of 20Cu-SiO2,Figure 2 f is the plot of 30Cu-SiO2. DETAILED DESCRIPTION

[0038] In order to better understand the present application, the content of the present application is further illustrated below in combination with examples, but the content of the present application is not limited only to the following examples.

[0039] Example 1

[0040] Preparation of 10Cu-DMSNs-4.2 catalyst:

[0041] Take 40 g of cetyltrimethylammonium chloride (CTAC) and dissolve it in 120 mL of deionized water, stir until dissolved at room temperature, move into a flask, then add 0.9 g of triethanolamine (TEA) and 180 mL of deionized water. Stir in a water bath at 60°C for 1 h. Then add 100 mL of tetraethyl orthosilicate (TEOS) solution (concentration of 20v%, solvent is decalin). Stir at 150 rpm for 24 h in a water bath at 60°C. Get the solution of oil and water two-phase separation, take the lower water phase of the solution for centrifugation, wash with anhydrous ethanol and deionized water respectively for three times, dry at 80°C overnight. Finally, calcine at 550°C for 4 h in air atmosphere, get the dendritic silica sphere carrier DMSNs-4.2 with mesopore size of 4.2 nm.

[0042] In a three-necked flask, add 0.845 g of Cu(NO3)2·3H2O, then add 100 mL of deionized water, after dissolving, add ammonia water with a concentration of 25wt%, control the pH of the solution to be 10-11, stir in a water bath at 30°C for 30 min, then add 2 g of DMSNs-4.2 carrier. Stir continuously at 30°C for 4 h. Then heat the solution to 80°C to evaporate the ammonia in the solution, and add deionized water at regular intervals to keep the solution level stable. After the pH of the solution is reduced to 6-7, filter, wash, dry overnight, and calcine at 400°C for 4 h. After calcination, the powder is pressed into a tablet and sieved to form particles with a size of 40-60 mesh, and then reduced in a tube furnace at 300°C for 4 h under hydrogen atmosphere, and then passivated with 1% O2 and 99% Ar mixed gas for 1 h after cooling to room temperature. Get 10% copper loaded dendritic mesoporous silica sphere catalyst with mesopore size of 4.2 nm. The catalyst is named as 10Cu-DMSNs-4.2.

[0043] The catalyst of the present application is named as xCu-DMSNs-y. x represents the loading of Cu, which is 10-40%. y represents the mesopore size of the silica sphere, which is 3-5.5 nm.

[0044] The catalyst was evaluated in a 100 mL reactor. 0.1 g catalyst, 0.8 g lauryl laurate, 23.2 g n-hexane were added into the reactor. The reactor was purged with hydrogen before reaction, and then pressurized to 5 MPa with hydrogen. The temperature was raised to 210 °C, and the reaction was carried out for 8 h at a stirring speed of 800 rpm. The liquid product was filtered with a 0.22 μm organic filter membrane, and then analyzed with a high performance gas chromatograph (Fuli GC9720 Plus) equipped with a HP5-MS column and a flame ionization detector (FID). The liquid sample contained the target product lauryl alcohol, the by-product dodecane and part of the unreacted lauryl laurate. The results are shown in Table 1. The 10Cu-DMSNs-4.2 catalyst had a low activity, and only 21.6% of lauryl laurate was converted in 1.0 h -1 The lauryl alcohol selectivity was 99.75%, and the dodecane selectivity was 0.25%. This was because the Cu loading was low, and the number of active sites was insufficient.

[0045] Example 2

[0046] Preparation of 20Cu-DMSNs-4.2 catalyst:

[0047] A three-necked flask was charged with 1.901 g Cu(NO3)2-3H2O, and then 100 mL deionized water was added. After dissolution, 25 wt% ammonia water was added to control the pH of the solution to 10-11. The solution was stirred at 30 °C for 30 min, and then 2 g of the DMSNs-4.2 support obtained in Example 1 was added. The solution was continuously stirred at 30 °C for 4 h. Then the solution was heated to 80 °C to evaporate the ammonia in the solution. During this process, deionized water was added from time to time to keep the solution level stable. When the pH of the solution decreased to 6-7, the solution was filtered, washed and dried overnight. The dried powder was calcined at 400 °C for 4 h. The calcined powder was tabletted and sieved to form particles with a size of 40-60 mesh. The particles were reduced with hydrogen at 300 °C for 4 h in a tube furnace, and then passivated with 1% O2 / 99% Ar for 1 h after the temperature decreased to room temperature. A 20% copper-loaded dendritic mesoporous silica sphere catalyst was obtained, and the mesopore size of the catalyst was 4.2 nm. The catalyst was named as 20Cu-DMSNs-4.2.

[0048] The catalyst evaluation process of this example was the same as that of Example 1. The results are shown in Table 1. The 20Cu-DMSNs-4.2 catalyst had a high activity, and 96.9% of lauryl laurate was converted in 1.0 h -1 The lauryl alcohol selectivity was more than 99.9%, and the dodecane selectivity was only 0.06%.

[0049] Example 3

[0050] Preparation of 30Cu-DMSNs-4.2 catalyst:

[0051] A three-neck flask was charged with 3.259 g Cu(N03)2-3H20, 100 mL of deionized water, and 25 wt% ammonia solution. The solution was stirred at 30 °C for 30 min, and then 2 g of DMSNs-4.2 support obtained in Example 1 was added. The solution was continuously stirred at 30 °C for 4 h. The solution was then heated to 80 °C to evaporate ammonia, and deionized water was added to maintain the solution level. After the pH of the solution decreased to 6-7, the solution was filtered, washed, and dried overnight. The dried powder was calcined at 400 °C for 4 h. The calcined powder was tabletted and sieved to form particles with a size of 40-60 mesh. The particles were reduced in a tube furnace at 300 °C for 4 h under hydrogen, and then passivated at room temperature for 1 h with 1% O2 / 99% Ar. A 30% copper-loaded dendritic mesoporous silica sphere catalyst was obtained, and the mesoporous pore size was 4.2 nm. The catalyst was named 30Cu-DMSNs-4.2.

[0052] The catalyst evaluation process of this example was the same as that of Example 1. The results are shown in Table 1. The 30Cu-DMSNs-4.2 catalyst had a lauryl laurate conversion of 98.1% and a lauryl alcohol selectivity of 99.84% at 1.0 h -1 The highest lauryl laurate conversion of 98.1% was obtained at 1.0 h

[0053] Example 4

[0054] Preparation of 40Cu-DMSNs-4.2 catalyst:

[0055] A three-neck flask was charged with 5.069 g Cu(N03)2-3H20, 100 mL of deionized water, and 25 wt% ammonia solution. The solution was stirred at 30 °C for 30 min, and then 2 g of DMSNs-4.2 support obtained in Example 1 was added. The solution was continuously stirred at 30 °C for 4 h. The solution was then heated to 80 °C to evaporate ammonia, and deionized water was added to maintain the solution level. After the pH of the solution decreased to 6-7, the solution was filtered, washed, and dried overnight. The dried powder was calcined at 400 °C for 4 h. The calcined powder was tabletted and sieved to form particles with a size of 40-60 mesh. The particles were reduced in a tube furnace at 300 °C for 4 h under hydrogen, and then passivated at room temperature for 1 h with 1% O2 / 99% Ar. A 40% copper-loaded dendritic mesoporous silica sphere catalyst was obtained, and the mesoporous pore size was 4.2 nm. The catalyst was named 40Cu-DMSNs-4.2.

[0056] The catalyst evaluation process of this example was the same as that of Example 1. The results are shown in Table 1. The 40Cu-DMSNs-4.2 catalyst had a lauryl laurate conversion of 98.1% and a lauryl alcohol selectivity of 99.84% at 1.0 h -1The conversion of lauryl laurate was 75.5%. The selectivity of lauryl alcohol was 99.18%, and the selectivity of dodecane was 0.82%. The Cu loading of 40Cu-DMSNs-4.2 was increased, but the activity was lower than that of 20Cu-DMSNs-4.2 and 30Cu-DMSNs-4.2. The main reason is that the silica support is difficult to support the ultra-high Cu loading of 40%, resulting in a large amount of Cu particles agglomerating, and the Cu used for ester carbonyl adsorption activation is insufficient. + There are fewer active sites, so its catalytic activity is poor.

[0057] Table 1

[0058]

[0059] Table 1 shows the hydrogenation activity data of lauryl laurate in Examples 1-6 and Comparative Examples 1-2.

[0060] Table 2

[0061]

[0062]

[0063] Table 2 shows the hydrogenation activity data of lauryl laurate in Examples 7-12 and Comparative Examples 3-4.

[0064] As shown in Table 1 and Table 2, the ester conversion rate of 20Cu-DMSNs-4.2 catalyst is higher than that of the comparative example 20Cu-SiO2 in 1 h. -1 The airspeed is increased by more than 15% in 1.5h -1 The space velocity of 30Cu-DMSNs-4.2 catalyst increased by 25% in 1h -1 The highest ester conversion rate at the space velocity was 98.1%, and the lauryl alcohol selectivity was 99.84%. Furthermore, the catalyst activity of the examples with different mesopore diameters was improved compared to the control. All the catalysts in the examples showed improved lauryl alcohol selectivity compared to the control, and the selectivity for the byproduct dodecane was extremely low.

[0065] like Figure 1 As shown, except for the 40Cu-DMSNs-4.2 with too high loading, no Cu was observed in the other xCu-DMSNs-4.2. 0 The diffraction peak of Cu2O in xCu-DMSNs is smaller than that in the comparative example xCuSiO2, indicating that the dispersion of Cu species is better. Figure 2 (a) Figure 2 (b) Figure 2 (c) It can also be seen that xCu-DMSNs-4.2 still maintains a certain spherical structure, and the Cu nanoparticles are highly dispersed.Figure 2 (e)、 Figure 2 (f)It can be seen that the comparative examples are amorphous silica as support, Cu nanoparticles are supported thereon.

[0066] Table 3

[0067]

[0068] Table 3 is the specific surface area, pore volume, average pore size, average particle size, Cu dispersion data of the catalysts prepared in Examples 1-6 and Comparative Examples 1-2.

[0069] From Table 3, it can be seen that the average particle size of Cu particles of 20Cu-DMSNs-4.2 and 30Cu-DMSNs-4.2 is 3.0 nm and 3.9 nm, which is smaller than 3.6 nm and 4.3 nm of the comparative examples. And the Cu dispersion of 20Cu-DMSNs-4.2 and 30Cu-DMSNs-4.2 is 26.5% and 16.9% respectively, which is also greater than 19.2% and 13.4% of the comparative examples. This shows that the silica spheres with ordered mesopores can well pre-disperse the Cu precursor, and the confinement effect of the mesoporous channels can limit the growth of Cu nanoparticles. Therefore, the Cu particle size of xCu-DMSNs-4.2 is smaller and the dispersion is higher than that of the comparative examples. From Table 3, it can also be seen that the specific surface area of 20Cu-DMSNs-4.2 and 30Cu-DMSNs-4.2 is 452 m 2 / g and 474 m 2 / g respectively, which is greater than 393 m 2 / g and 373 m 2 / g of the comparative examples. At the same time, the pore volume of 20Cu-DMSNs-4.2 and 30Cu-DMSNs-4.2 is 0.80 cm 3 / g and 0.72 cm 3 / g respectively, which is also greater than 0.63 cm 3 / g and 0.60 cm 3 / g of the comparative examples. In addition, the specific surface area and pore volume of 20Cu-DMSNs-3 and 20Cu-DMSNs-5.5 are also greater than those of 20CuSiO2. It shows that the dendritic mesoporous silica sphere catalyst loaded with copper has more open pore structure, which is conducive to the dispersion of Cu species, produces more Cu active sites, and thus improves the catalytic activity. In addition, the mesopores of the example catalysts are larger and more uniform than those of the comparative examples. The three-dimensional open ordered mesoporous channels with larger pore size can expose more active sites, improve the accessibility of active sites, and effectively promote the mass transfer and diffusion of reactant and product molecules, thereby improving the catalytic activity and reducing by-products.

[0070] Example 5

[0071] 20Cu-DMSNs-3 catalyst preparation:

[0072] Take 40 g of cetyltrimethylammonium chloride (CTAC) dissolved in 120 mL of deionized water, stir at room temperature until dissolved, move into a flask, then add 0.9 g of triethanolamine (TEA) and 180 mL of deionized water. Stir in a water bath at 60°C for 1 h. Then add 100 mL of tetraethyl orthosilicate (TEOS) solution (concentration of 20v%, solvent is 1-octadecene). Stir at 150 rpm for 24 h in a water bath at 60°C. Get the solution A with the upper and lower oil-water two-phase separation, take the lower aqueous phase of solution A for centrifugation, wash with anhydrous ethanol and deionized water respectively for three times, dry at 80°C overnight. Finally, calcine at 550°C for 4 h in air atmosphere to obtain dendritic silica sphere carrier DMSNs-3 with mesopore size of 3.0 nm.

[0073] In a three-necked flask, add 1.901 g of Cu(NO3)2·3H2O, then add 100 mL of deionized water, after dissolution, add 25wt% ammonia water, control the solution pH to 10-11, stir in a water bath at 30°C for 30 min, then add 2 g of DMSNs-3 carrier. Stir continuously at 30°C for 4 h. Then warm the solution to 80°C to evaporate the ammonia in the solution, and add deionized water at regular intervals to keep the solution level stable. After the solution pH drops to 6-7, filter, wash, dry overnight, and calcine at 400°C for 4 h. After calcination, the powder is pressed into a tablet and sieved to form particles with a size of 40-60 mesh, and then reduced in a tube furnace at 300°C for 4 h under hydrogen, and passivated with 1% O2 / 99% Ar for 1 h after cooling to room temperature. The obtained 20% copper-loaded dendritic mesoporous silica sphere catalyst has a mesopore size of 3 nm. The catalyst is named as 20Cu-DMSNs-3.

[0074] The catalyst evaluation process of this example is shown in Example 1. The results are shown in Table 1. The 20Cu-DMSNs-3 catalyst has a lauryl laurate conversion rate of 91.5% in 1.0 h -1 The lauryl alcohol selectivity is 99.68%, and the selectivity of dodecane is 0.32%.

[0075] Example 6

[0076] 20Cu-DMSNs-5.5 catalyst preparation:

[0077] Dissolve 40g of hexadecyltrimethylammonium chloride (CTAC) in 120mL of deionized water, stir at room temperature until dissolved, and transfer to a flask. Then add 0.9g of triethanolamine (TEA) and 180mL of deionized water. Stir in a 60°C water bath for 1h. Then add 100mL of ethyl orthosilicate solution (20% by volume, solvent: cyclohexane). Stir continuously at 150rpm in a 60°C water bath for 24h. A solution A with upper and lower oil-water phases is obtained. The lower aqueous phase of solution A is centrifuged, washed three times with anhydrous ethanol and deionized water, respectively, and dried at 80°C overnight. Finally, the solution is calcined at 550°C in air for 4h to obtain the dendritic silica sphere carrier DMSNs-5.5 with a mesoporous pore size of 5.5nm.

[0078] A three-necked flask was filled with 1.901 g of Cu(NO₃)₂·3H₂O and 100 mL of deionized water. After dissolution, 25 wt% ammonia was added, controlling the solution pH to 10-11. The solution was stirred in a 30°C water bath for 30 minutes, followed by the addition of 2 g of the DMSNs-5.5 support. Stirring continued at 30°C for 4 hours. The solution was then heated to 80°C to evaporate the ammonia, with deionized water added periodically to maintain a stable liquid level. After the pH dropped to 6-7, the solution was filtered, washed, dried overnight, and calcined at 400°C for 4 hours. The calcined powder was pressed and sieved to form 40-60 mesh particles. The calcined powder was reduced in a tube furnace with hydrogen at 300°C for 4 hours. After cooling to room temperature, it was passivated with a 1% O₂ 99% Ar gas mixture for 1 hour. This resulted in a 20% copper-loaded dendritic mesoporous silica sphere catalyst with a mesopore diameter of 5.5 nm. The catalyst was named 20Cu-DMSNs-5.5.

[0079] The catalyst evaluation process of this embodiment is shown in Example 1. The results are shown in Table 1. -1 The conversion rate of lauryl laurate was 90.6%, the selectivity of lauryl alcohol was 99.84%, and the selectivity of dodecane was 0.16%.

[0080] Example 7

[0081] The catalyst 10Cu-DMSNs-4.2 prepared in Example 1 was used and the catalyst evaluation method in Example 1 was used, except that the reaction time was 5.3 h. The results are shown in Table 2. -1 The conversion of lauryl laurate was 12.4%, the selectivity of lauryl alcohol was 99.84%, and the selectivity of dodecane was 0.16%.

[0082] Example 8

[0083] The catalyst 20Cu-DMSNs-4.2 prepared in Example 2 was operated according to the catalyst evaluation method in Example 1, except that the reaction time was 5.3 h. The results are shown in Table 2. -1 The conversion rate of lauryl laurate was 72.6%, the selectivity of lauryl alcohol was 99.96%, and the selectivity of dodecane was 0.04%.

[0084] Example 9

[0085] The catalyst 30Cu-DMSNs-4.2 prepared in Example 3 was used and the catalyst evaluation method in Example 1 was used, except that the reaction time was 5.3 h. The results are shown in Table 2. -1 The conversion rate of lauryl laurate was 78.1%, the selectivity of lauryl alcohol was 99.85%, and the selectivity of dodecane was 0.15%.

[0086] Example 10

[0087] The catalyst 40Cu-DMSNs-4.2 prepared in Example 4 was operated according to the catalyst evaluation method in Example 1, except that the reaction time was 5.3 h. The results are shown in Table 2. -1 The conversion rate of lauryl laurate was 45.7%, the selectivity of lauryl alcohol was 99.23%, and the selectivity of dodecane was 0.77%.

[0088] Example 11

[0089] The catalyst 20Cu-DMSNs-3 prepared in Example 5 was used and the catalyst evaluation method in Example 1 was used, except that the reaction time was 5.3 h. The results are shown in Table 2. -1 The conversion rate of lauryl laurate was 62.6%, the selectivity of lauryl alcohol was 99.75%, and the selectivity of dodecane was 0.25%.

[0090] Example 12

[0091] The catalyst 20Cu-DMSNs-5.5 prepared in Example 6 was operated according to the catalyst evaluation method in Example 1, except that the reaction time was 5.3 h. The results are shown in Table 2. -1 The conversion rate of lauryl laurate was 61.1%, the selectivity of lauryl alcohol was 99.89%, and the selectivity of dodecane was 0.11%.

[0092] Comparative Example 1

[0093] 20Cu-SiO2catalyst preparation:

[0094] A three-neck flask was charged with 8.5539 g Cu(N03)2-3H2O, 100 mL of deionized water, and 25 wt% ammonia solution. After dissolution, the solution was stirred at 30 °C for 30 min with pH controlled at 10-11. Then 25 mL of silica sol (30 wt% SiO2) was added. The solution was continuously stirred at 30 °C for 4 h. Subsequently, the solution was heated to 80 °C to evaporate ammonia. During this process, deionized water was added to maintain the solution level. After the pH of the solution dropped to 6-7, the solution was filtered, washed, and dried overnight. The dried powder was calcined at 400 °C for 4 h. The calcined powder was pressed into a pellet and sieved to form particles with a size of 40-60 mesh. The particles were reduced in a tube furnace at 300 °C for 4 h under hydrogen. After cooling to room temperature, the particles were passivated with 1% O2 / 99% Ar for 1 h. The copper catalyst with amorphous silica as the support was obtained. The Cu loading was 20%, and the catalyst was named 20Cu-SiO2.

[0095] The catalyst evaluation process of the comparative example was the same as that of Example 1. The results are shown in Table 2. The conversion of the wax ester over 20Cu-SiO2was 80.3% in 1 h -1 The selectivity of the fatty alcohol was 98.32%. However, the selectivity of the byproduct dodecane was 1.68%, which was much higher than that of Example 1. This indicates that the irregular pore structure is not conducive to the diffusion of the product, which leads to further hydrodeoxygenation of the product and the production of more byproduct dodecane.

[0096] Comparative Example 2

[0097] 30Cu-SiO2catalyst preparation:

[0098] A three-neck flask was charged with 14.6638 g Cu(N03)2-3H2O, 100 mL of deionized water, and 25 wt% ammonia solution. After dissolution, the solution was stirred at 30 °C for 30 min with pH controlled at 10-11. Then 25 mL of silica sol (30 wt% SiO2) was added. The solution was continuously stirred at 30 °C for 4 h. Subsequently, the solution was heated to 80 °C to evaporate ammonia. During this process, deionized water was added to maintain the solution level. After the pH of the solution dropped to 6-7, the solution was filtered, washed, and dried overnight. The dried powder was calcined at 400 °C for 4 h. The calcined powder was pressed into a pellet and sieved to form particles with a size of 40-60 mesh. The particles were reduced in a tube furnace at 300 °C for 4 h under hydrogen. After cooling to room temperature, the particles were passivated with 1% O2 / 99% Ar for 1 h. The copper catalyst with amorphous silica as the support was obtained. The Cu loading was 30%, and the catalyst was named 30Cu-SiO2.

[0099] The catalyst evaluation procedure for this comparative example is described in Example 1. The results are shown in Table 2. The 30Cu-SiO2had 92.4% ester conversion at 1 h -1 The lauryl alcohol selectivity was only 97.24% and the selectivity to the by-product dodecane was 2.76%.

[0100] Comparative Example 3

[0101] The catalyst 20Cu-SiO2prepared in Comparative Example 1 was evaluated according to the procedure described in Example 1, except that the reaction time was 5.3 h. The results are shown in Table 2. The 20Cu-SiO2had 47.9% lauryl laurate ester conversion at 1.5 h -1 The lauryl alcohol selectivity was 98.95% and the selectivity to the by-product dodecane was 1.05%.

[0102] Comparative Example 4

[0103] The catalyst 30Cu-SiO2prepared in Comparative Example 2 was evaluated according to the procedure described in Example 1, except that the reaction time was 5.3 h. The results are shown in Table 2. The 30Cu-SiO2had 64.6% lauryl laurate ester conversion at 1.5 h -1 The lauryl alcohol selectivity was 97.89% and the selectivity to the by-product dodecane was 2.11%.

[0104] The details of the application not described herein are known in the art.

Claims

1. A method for preparing fatty alcohol by hydrogenating fatty acid wax ester, characterized in that the method comprises the following steps: putting the catalyst, fatty acid wax ester and n-hexane into a reaction kettle, filling hydrogen to a pressure of 4-6 MPa, then heating to 200-220℃, and reacting for 5-10 hours under stirring to obtain the product fatty alcohol; wherein the added mass of the solvent n-hexane is 25-50 times that of the fatty acid wax ester; the added mass of the fatty acid wax ester is 5-8 times that of the catalyst; the catalyst is a dendritic mesoporous silica sphere catalyst with copper supported by ammonia evaporation method, which comprises a carrier and an active component, and the active component is Cu, and the active component Cu accounts for 10-40% of the total mass of the catalyst.

2. The process for the hydrodeoxygenation of fatty acid wax esters to fatty alcohols as claimed in claim 1, characterized in that, the stirring rate is 700-900 rpm.

3. The process for the hydrodeoesterification of fatty acid wax esters to fatty alcohols according to claim 1, characterized in that, the fatty acid wax ester is specifically lauryl laurate, myristyl myristate, palmitoyl palmitate or stearyl stearate.

4. The process for the hydrodeoesterification of fatty acid wax esters to fatty alcohols according to claim 1, characterized in that, the carrier is a dendritic mesoporous silica sphere prepared by oil-water two-phase method, and the mesoporous pore size is 3-5.5 nm.

5. The process for the hydrodeoesterification of fatty acid wax esters to fatty alcohols as claimed in claim 1, characterized in that, the reaction time is 5.3-8 hours; the active component Cu accounts for 20-30% of the total mass of the catalyst.

6. The process for the hydrodeoesterification of fatty acid wax esters to fatty alcohols as claimed in claim 1, characterized in that, the preparation method of the dendritic mesoporous silica sphere catalyst with copper supported by ammonia evaporation method comprises the following steps: (1) dissolving cetyltrimethylammonium chloride (CTAC) in deionized water under stirring, then adding triethanolamine (TEA) solution, and then stirring in a water bath at 50-80℃ for 0.5-2h; then adding tetraethyl orthosilicate (TEOS) solution; continuously stirring in a water bath at 60-90℃ for 20-30h to obtain solution A with upper and lower oil-water two-phase layers; wherein, 30-50g of cetyltrimethylammonium chloride, 150-200mL of triethanolamine (TEA) solution and 80-120mL of tetraethyl orthosilicate (TEOS) solution are added to every 120mL of deionized water; 0.8-1.0g of triethanolamine is contained in every 180mL of triethanolamine solution; (2) centrifuging the lower aqueous phase of solution A in step (1), washing, drying at 60-120℃ overnight, and then calcining at 500-600℃ in air atmosphere for 4-6h to obtain silica sphere powder; (3) mixing Cu(NO3)2·3H2O and deionized water, dissolving, then adding ammonia water to control the pH of the solution to 10-11, stirring in a water bath at 25-40℃ for 10-40min, then adding the silica sphere powder, and continuously stirring at 25-40℃ for 3-6h; wherein, 0.5-6g of Cu(NO3)2·3H2O and 1.5-2.5g of silica sphere powder are added to every 100mL of deionized water; (4) heating the solution in step (3) to 70-90℃ to evaporate ammonia in the solution, and adding deionized water at regular time intervals to keep the solution level stable during the process; after the pH of the solution decreases to 6-7, filtering, washing, drying overnight, and calcining at 350-450℃ in air atmosphere for 4-6h to obtain solid A; (5) The solid A is sieved after tabletting to form particles with size of 40-60 mesh, and is reduced by hydrogen in a tube furnace at 250-350℃ for 3-6h, and then is passivated by mixed gas of O2 and Ar for 0.5-1h after being cooled to room temperature, to obtain a copper-loaded dendritic mesoporous silica sphere catalyst.

7. The process for the hydrodeoesterification of fatty acid wax esters to fatty alcohols as claimed in claim 6, characterized in that, In step (1), the solvent used in the TEOS solution is one of 1-octadecene, decaline, and cyclohexane; the concentration of the tetraethyl orthosilicate (TEOS) solution is 15-25v%.

8. The process for the hydrodeoesterification of fatty acid wax esters to fatty alcohols as claimed in claim 6, characterized in that, In step (5), the volume percentage in the mixed gas is 1% O2 and 99% Ar.

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