A supported catalyst for the hydrogenation of fatty acid methyl esters, a method of preparation and a method of preparing higher fatty alcohols

Abstract

The application discloses a kind of supported fatty acid methyl ester hydrogenation catalyst, preparation method and the method for preparing higher fatty alcohol, including carrier and active component loaded on carrier, the carrier is zinc oxide, the active component includes first metal and second metal, the first metal is selected from Ni, the second metal is selected from Cu, Mn, Fe or In.The carrier accounts for 96-98% of the total weight of catalyst, the active component accounts for 2-4% of the total weight of catalyst, the mass ratio of the first metal and second metal is 4:1-1:4.The catalyst of the application uses zinc oxide as carrier, loads Ni and second metal, can form alloy or intermetallic compound, change the adsorption configuration of fatty acid methyl ester, is conducive to inhibiting the occurrence of side reaction;Metal-support interface is formed, can be realized at lower temperature fatty acid methyl ester high-efficiency selective hydrogenation preparation higher fatty alcohol.

Description

Technical Field

[0001] This invention belongs to the field of biomass chemical engineering, specifically, it relates to a supported fatty acid methyl ester hydrogenation catalyst, its preparation method, and a method for preparing higher fatty alcohols. Background Technology

[0002] Higher fatty alcohols generally refer to fatty alcohols with carbon chain lengths between C6 and C22. Their carbon chains are primarily straight-chain and contain only one hydroxyl group, lacking double bonds or containing one or more unsaturated C=C double bonds. The hydroxyl groups in higher fatty alcohols typically provide strong hydrophilic sites at the carbon chain ends, while the hydrocarbon portions of the molecule are hydrophobic. This gives fatty alcohols the characteristic of combining hydrophilicity and hydrophobicity within the same molecule, making them excellent raw materials for surfactants. In addition, fatty alcohols can be used as raw materials to prepare wetting agents, thickeners, food additives, pharmaceuticals, and daily necessities. These products are widely used in daily life, industry, and agriculture. Therefore, the demand for fatty alcohols is substantial; currently, global demand exceeds 2 million tons, and it is projected to exceed 4.7 million tons by 2025.

[0003] Currently, the industrial preparation of fatty alcohols generally employs the hydrogenation of oils and fats. Methanol and oils undergo transesterification to produce fatty acid methyl esters, which are then hydrogenated and reduced to obtain the fatty alcohols under the action of a catalyst. Cu-Cr-based catalysts are commonly used, but this reaction must be carried out under harsh conditions of high temperature and high pressure (250-350℃ and 10-20MPa), and there is also the problem of Cr ion leaching contamination.

[0004] In addition, noble metals are also used as catalysts. Noble metal catalysts exhibit high performance in carboxylic acid conversion, but considering cost and sustainability, non-noble metal catalysts are gaining increasing attention. Compared to copper-based catalysts used in industry, nickel-based catalysts have significantly lower costs and exhibit higher hydrogenation activity and anti-sintering properties, thus showing broad application prospects. However, besides hydrodeoxygenation reactions, metallic nickel also has high decarboxylation / decarbonylation and C / C single bond hydrogenolysis activity, resulting in lower selectivity for fatty alcohols in fatty acid ester hydrogenation reactions using nickel-based catalysts.

[0005] Chinese patent CN101468939A discloses a method for preparing higher alcohols by supercritical hydrogenation of fatty acid methyl esters. It uses a CuCr catalyst and n-pentane, n-hexane, or a mixture thereof, or reforming residue oil as the supercritical solvent, with the addition amount accounting for 80%-90% of the total mass of the reactants. This reduces mass transfer resistance, thereby reducing hydrogen consumption. Under conditions of a hydrogen-to-oil molar ratio of 1.5-2.5:1, a reaction temperature of 220-280℃, and a reaction pressure of 5-7 MPa, the conversion rate of fatty acid methyl esters is 85.3%-85.8%, which is relatively low. Furthermore, it suffers from a large consumption of supercritical solvent.

[0006] The problem to be solved is how to provide a low-cost, highly selective catalyst that can achieve the hydrogenation of fatty acid methyl esters to higher fatty alcohols under relatively low reaction conditions.

[0007] In view of this, the present invention is proposed. Summary of the Invention

[0008] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a catalyst for the hydrogenation of supported fatty acid methyl esters, a preparation method, and a method for preparing higher fatty alcohols. The catalyst of this invention uses zinc oxide as a support, and supports Ni and a second metal, which can form an alloy or intermetallic compound, changing the adsorption configuration of fatty acid methyl esters and helping to suppress side reactions. The formation of the metal-support interface enables efficient and selective hydrogenation of fatty acid methyl esters to prepare higher fatty alcohols at lower temperatures.

[0009] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0010] The first objective of this invention is to provide a catalyst for the hydrogenation of supported fatty acid methyl esters, comprising a support and an active component supported on the support, wherein the support is a reducible metal oxide, and the active component comprises a first metal and a second metal, wherein the first metal is selected from Ni, and the second metal is selected from Cu, Mn, Fe, or In.

[0011] In this invention, a second metal is used to modify the nickel-based catalyst to form an alloy or intermetallic compound, which helps to suppress the occurrence of side reactions and improve selectivity.

[0012] In a further embodiment, the support comprises 96-98% of the total weight of the catalyst, and the active component comprises 2-4% of the total weight of the catalyst.

[0013] Preferably, the support accounts for 96-97% of the total weight of the catalyst;

[0014] Preferably, the active component accounts for 2-3% of the total weight of the catalyst.

[0015] In a further embodiment, the mass ratio of the first metal to the second metal is 4:1 to 1:4;

[0016] Preferably, the mass ratio of the first metal to the second metal is 2:1 to 1:2.

[0017] To further improve the reactivity of nickel-based bimetallic catalysts at lower temperatures, the hydrogen cracking mechanism can be altered by constructing a metal-support interface on the surface of metal nanoparticles, effectively addressing the low hydrogenation activity caused by the poor electrophilicity of carbonyl carbon. Generally, activating the surface of reducible metal oxides with hydrogen at high temperatures leads to thermodynamic migration and the formation of encapsulation structures. Based on this, by loading nickel-based bimetals onto the surface of reducible metal oxides, efficient and selective hydrogenation of fatty acid methyl esters to prepare higher fatty alcohols can be achieved at lower temperatures.

[0018] Therefore, this invention uses a reducible metal oxide as a carrier and then loads a nickel-based and a second metal, which can suppress side reactions and achieve efficient and highly selective hydrogenation at lower temperatures.

[0019] As a preferred embodiment, the carrier is zinc oxide and the second metal is Fe.

[0020] As a preferred embodiment, the catalyst of this invention uses zinc oxide as a support, loads NiFe, and utilizes the characteristic of ZnO growth under a high-temperature H2 atmosphere to prepare a NiFe / ZnO catalyst with a ZnO-coated structure, forming a rich metal-support interface. The formation of the NiFe-ZnO interface strongly influences the electronic structure on both sides of the interface. Generally, space charge and band bending tend to separate electrons and protons. Therefore, the NiFe-ZnO interface promotes the transfer of H2 to H2. δ+ and H δ- The heterolytic cleavage of Fe significantly improved the difficulty of hydrogenating positively charged carbonyl carbons. Simultaneously, Fe, acting as a Lewis acid site, can adsorb and activate the CO / C=O bond through electron pair interactions with oxygen atoms, promoting the adsorption and activation of the reaction substrate. Ultimately, this enabled the highly selective hydrogenation and alcoholysis of fatty acid methyl esters at relatively low temperatures.

[0021] In a further embodiment, the mass ratio of Ni to Fe is 2:1 to 1:2, more preferably 1:1.

[0022] In this invention, the mass ratio of Ni to Fe is 2:1 to 1:2, more preferably 1:1. Experiments have shown that when the mass ratio of Ni to Fe is 1:1, the selectivity and conversion rate are the highest. If the Fe content is too high, the excessive introduction of Fe will reduce the adsorption energy of H on the catalyst, thus reducing both selectivity and conversion rate. This may be due to the increase in Fe patches on the catalyst surface, which isolates adjacent Ni, and excessive iron content also inhibits hydrogenation. Conversely, when the Ni content is too high, the number of Fe adsorption sites decreases, weakening the adsorption and activation ability of fatty acid methyl esters, and thus reducing the conversion rate.

[0023] A second objective of this invention is to provide a method for preparing a catalyst for the hydrogenation of supported fatty acid methyl esters, comprising:

[0024] (1) Preparation of zinc oxide support;

[0025] (2) Prepare a mixture of Ni salt and salt of the second metal;

[0026] (3) The mixture is evenly impregnated onto the zinc oxide support, left to stand at room temperature, dried, calcined, and reduced with hydrogen to obtain the catalyst.

[0027] In this invention, the carrier is prepared by a deposition precipitation method, using zinc nitrate as the zinc source and sodium carbonate as the precipitant. The active component is loaded by an equal-volume impregnation method.

[0028] In a further embodiment, step (1) involves preparing the zinc oxide support, including:

[0029] Zn(NO3)2 was dissolved in deionized water, and the resulting solution was rapidly stirred in a water bath at 60-80°C. Then, a certain amount of Na2CO3 solution was added dropwise to the above solution. The resulting white suspension was stirred at 60-80°C for 0.5-1.5 hours, cooled to room temperature, filtered, washed with distilled water until the pH stabilized, dried, and calcined to obtain a white solid as the carrier ZnO.

[0030] In a further embodiment, in step (1), the roasting temperature is 300-700℃ and the roasting time is 3-5h;

[0031] As a preferred option, in step (1), the roasting temperature is 400-600℃ and the roasting time is 4-5h.

[0032] In a further step, the drying temperature in step (1) is 90°C.

[0033] As a specific implementation method, in step (2), a mixed solution of Ni(NO3)2·6H2O and Fe(NO3)3·9H2O is prepared, wherein the concentration of Ni(NO3)2·6H2O is 0.038-0.077 g / mL and the concentration of Fe(NO3)3·9H2O is 0.056-0.112 g / mL.

[0034] In a further step, in step (3), the mixture is left to stand at room temperature for 9 hours.

[0035] In a further step, the drying temperature in step (3) is 90°C.

[0036] In a further embodiment, in step (3), the calcination temperature is 500-800℃, the calcination time is 3-5h, and the heating rate during calcination is 1-4℃ / min.

[0037] Preferably, the calcination temperature is 600-700℃, the calcination time is 4-5h, and the heating rate during calcination is 1-4℃ / min.

[0038] In a further scheme, in step (3), the temperature of hydrogen reduction is 500-800℃, the time of hydrogen reduction is 2-4h, and the heating rate is 3-5℃ / min;

[0039] Preferably, in step (3), the hydrogen reduction temperature is 600-700℃, the hydrogen reduction time is 2-3h, and the heating rate is 3-4℃ / min.

[0040] A third objective of this invention is to provide a method for preparing higher fatty alcohols, comprising:

[0041] Fatty acid methyl ester, organic solvent and catalyst as described above are added to a batch reactor, and hydrogen gas at a certain pressure is introduced to carry out the reaction; the product after the reaction is separated by distillation to obtain fatty alcohol product.

[0042] Preferably, the organic solvent is a C5-C8 alkane, and more preferably, n-hexane;

[0043] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0044] 1. This invention develops a novel supported catalyst for the hydrogenation of fatty acid methyl esters. It uses a reducible metal oxide as a support and loads a nickel-based and a second metal on the surface. The three work synergistically to suppress side reactions, improve selectivity, and achieve efficient hydrogenation at lower temperatures. This enables the hydrogenation of fatty acid methyl esters to prepare higher fatty alcohols at lower temperatures.

[0045] 2. In the catalyst of this invention, the selectivity and conversion rate are highest when the mass ratio of Ni to Fe is 1:1. If the Fe content is too high, the excessive introduction of Fe will reduce the adsorption energy of H on the catalyst, and both the selectivity and conversion rate will decrease. This may be due to the increase of Fe patches on the catalyst surface, which isolates adjacent Ni, and the fact that excessive iron content will also inhibit hydrogenation. When the Ni content is too high, the Fe adsorption sites decrease, the adsorption and activation ability of fatty acid methyl esters weakens, and the conversion rate decreases.

[0046] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0047] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0048] Figure 1 This is a scanning electron microscope (SEM) image of Example 1.

[0049] Figure 2 The image shown is an HRTEM image (10 nm) of Example 5.

[0050] Figure 3 This is another HRTEM image (5 nm) for Example 5.

[0051] Figure 4 The image shown is an HRTEM image (5 nm) of Example 6.

[0052] Figure 5 The image shown is an HRTEM image (5 nm) of Example 7.

[0053] Figure 6 The image is the HRTEM image (10 nm) of Comparative Example 1.

[0054] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0056] Example 1

[0057] Synthesis of ZnO

[0058] A precipitation method was used, with Na₂CO₃ as the precipitant. 5.95 g of Zn(NO₃)₂ was dissolved in 200 ml of water, and 200 ml of Na₂CO₃ solution (0.12 mol / L) was added dropwise while stirring in a 70°C water bath. The resulting white suspension was stirred at 70°C for 2 h. It was then washed with distilled water until the pH stabilized, dried overnight at 90°C, and calcined at 500°C for 4 h (heating rate 2°C / min). The final white solid obtained was the supported ZnO.

[0059] The obtained ZnO support was analyzed by SEM, as shown in the attached figure. Figure 1 .

[0060] Example 2

[0061] Ni 1.5 In 1.5 Synthesis of ZnO catalysts

[0062] An equal-volume impregnation method was used, with deionized water as the solvent. 1 g of ZnO support absorbs approximately 1.3 mL of water. A mixed solution of Ni(NO3)2·6H2O and InCl3·4H2O (Ni(NO3)2·6H2O concentration: 0.058 g / mL, InCl3·4H2O concentration: 0.029 g / mL) was pipetted onto the 1 g ZnO support and uniformly impregnated. The solution was allowed to stand at room temperature for 9 h, dried at 90 °C, and calcined at 650 °C for 4 h (heating rate: 2.5 °C / min). Finally, it was reduced with hydrogen at 650 °C for 3 h (heating rate: 3.5 °C / min).

[0063] Example 3

[0064] Ni 1.5 Cu 1.5 Synthesis of ZnO catalysts

[0065] An equal-volume impregnation method was used, with deionized water as the solvent. 1 g of ZnO support absorbs approximately 1.3 mL of water. A mixed solution of Ni(NO3)2·6H2O and Cu(NO3)2·3H2O (Ni(NO3)2·6H2O concentration: 0.058 g / mL, Cu(NO3)2·3H2O concentration: 0.044 g / mL) was pipetted onto the 1 g ZnO support and uniformly impregnated. The solution was allowed to stand at room temperature for 9 h, dried at 90 °C, and calcined at 650 °C for 4 h (heating rate: 2.5 °C / min). Finally, it was reduced with hydrogen at 650 °C for 3 h (heating rate: 3.5 °C / min).

[0066] Example 4

[0067] Ni 1.5 Mn 1.5 Synthesis of ZnO catalysts

[0068] An equal-volume impregnation method was used, with deionized water as the solvent. 1 g of ZnO support absorbs approximately 1.3 mL of water. 1.3 mL of a mixed solution of Ni(NO3)2·6H2O and Mn(NO3)2·4H2O (Ni(NO3)2·6H2O concentration: 0.058 g / mL, Mn(NO3)2·4H2O concentration: 0.052 g / mL) was pipetted onto the 1 g ZnO support and uniformly impregnated. The solution was allowed to stand at room temperature for 9 h, dried at 90 °C, and calcined at 650 °C for 4 h (heating rate: 2.5 °C / min). Finally, it was reduced with hydrogen at 650 °C for 3 h (heating rate: 3.5 °C / min).

[0069] Example 5

[0070] Ni 1.5 Fe 1.5 Synthesis of ZnO catalysts

[0071] An equal-volume impregnation method was used, with deionized water as the solvent. 1 g of ZnO support absorbs approximately 1.3 mL of water. A mixed solution of Ni(NO3)2·6H2O and Fe(NO3)3·9H2O (Ni(NO3)2·6H2O concentration: 0.058 g / mL, Fe(NO3)3·9H2O concentration: 0.085 g / mL) was pipetted onto the 1 g ZnO support and uniformly impregnated. The solution was allowed to stand at room temperature for 9 h, dried at 90 °C, and calcined at 650 °C for 4 h (heating rate: 2.5 °C / min). Finally, it was reduced with hydrogen at 650 °C for 3 h (heating rate: 3.5 °C / min).

[0072] The obtained catalyst Ni 1.5 Fe 1.5 / ZnO was subjected to HRTEM analysis, as shown in the appendix. Figure 2 and attached Figure 3 .

[0073] Example 6

[0074] Synthesis of Ni1Fe2 / ZnO catalyst

[0075] An equal-volume impregnation method was used, with deionized water as the solvent. 1 g of ZnO support absorbs approximately 1.3 mL of water. A mixed solution of Ni(NO3)2·6H2O and Fe(NO3)3·9H2O (Ni(NO3)2·6H2O concentration: 0.038 g / mL, Fe(NO3)3·9H2O concentration: 0.112 g / mL) was pipetted onto the 1 g ZnO support and uniformly impregnated. The solution was allowed to stand at room temperature for 9 h, dried at 90 °C, and calcined at 650 °C for 4 h (heating rate: 2.5 °C / min). Finally, it was reduced with hydrogen at 650 °C for 3 h (heating rate: 3.5 °C / min).

[0076] The obtained catalyst Ni1Fe2 / ZnO was analyzed by HRTEM, as shown in the attached figure. Figure 4 .

[0077] Example 7

[0078] Synthesis of Ni2Fe1 / ZnO catalyst

[0079] An equal-volume impregnation method was used, with deionized water as the solvent. 1 g of ZnO support absorbs approximately 1.3 mL of water. A mixed solution of Ni(NO3)2·6H2O and Fe(NO3)3·9H2O (Ni(NO3)2·6H2O concentration: 0.077 g / mL, Fe(NO3)3·9H2O concentration: 0.056 g / mL) was pipetted onto the 1 g ZnO support and allowed to stand at room temperature for 9 h. The solution was then dried at 90 °C and calcined at 650 °C for 4 h (heating rate: 2.5 °C / min). Finally, the solution was reduced with hydrogen at 650 °C for 3 h (heating rate: 3.5 °C / min).

[0080] The obtained catalyst Ni2Fe1 / ZnO was analyzed by HRTEM, as shown in the attached figure. Figure 5 .

[0081] Comparative Example 1

[0082] Ni 1.5 Fe 1.5 Synthesis of SiO2 catalyst

[0083] An equal-volume impregnation method was used, with deionized water as the solvent. 1 g of SiO2 support absorbs approximately 4.0 mL of water. A mixed solution of Ni(NO3)2·6H2O and Fe(NO3)3·9H2O (Ni(NO3)2·6H2O concentration: 0.058 g / mL, Fe(NO3)3·9H2O concentration: 0.085 g / mL) was pipetted onto 1 g of SiO2 support and uniformly impregnated. The solution was allowed to stand at room temperature for 9 h, dried at 90 °C, and calcined at 650 °C for 4 h (heating rate: 2.5 °C / min). Finally, it was reduced with hydrogen at 650 °C for 3 h (heating rate: 3.5 °C / min).

[0084] The obtained catalyst Ni 1.5 Fe 1.5 / SiO2 was analyzed by HRTEM, see attached Figure 6 .

[0085] In this invention, the physical structures of the NiFe catalysts in Examples 5-7 and Comparative Example 1 were analyzed using HRTEM. Figure 2-5 As shown, all NiFe / ZnO catalysts possess a ZnO coating structure. And as... Figure 6 As shown, the NiFe / SiO2 catalyst, as a comparison, exhibits a fully exposed NiFe alloy. Therefore, the formation of the NiFe-ZnO interface is one of the reasons for the high activity of fatty acid methyl ester hydrogenation.

[0086] The structural characteristics and elemental contents of the catalysts in Examples 1, 5-7, and Comparative Example 1 are shown in Table 1 below. The specific surface area of ​​the catalysts was determined using the BET surface area assay, and the size distribution of the metal nanoparticles on the catalysts was determined using HRTEM.

[0087] Table 1. Structural characteristics and elemental content of the catalysts in Examples 1, 5-7 and Comparative Example 1.

[0088]

[0089] Experimental Example 1

[0090] 20 mL of methyl stearate-hexane solution (hexane as solvent, concentration 0.05 mol / L) and 0.3 g of the catalyst from Example 2 were added to the reactor. After sealing the reactor, the air inside was replaced with H2 several times. Then, H2 was added until the pressure inside the reactor reached 4 MPa, and the temperature was raised to 220 °C for 6 h.

[0091] Experimental Example 2

[0092] Similar to Experimental Example 1, the catalyst was changed to the catalyst of Example 3.

[0093] Experimental Example 3

[0094] Similar to Experimental Example 1, the catalyst was changed to the catalyst of Example 4.

[0095] Experiment Example 4

[0096] Similar to Experimental Example 1, the catalyst was changed to the catalyst of Example 5.

[0097] Experimental Example 5

[0098] Similar to Experimental Example 1, the catalyst was changed to the catalyst of Comparative Example 1.

[0099] Experimental Example 6

[0100] Similar to Experimental Example 1, the catalyst was changed to the catalyst of Example 6.

[0101] Experimental Example 7

[0102] Similar to Experimental Example 1, the catalyst was changed to the catalyst of Example 7.

[0103] Experimental Example 8

[0104] Similar to Experimental Example 1, the reaction time was extended to 10 hours, and the catalyst was changed to the catalyst of Example 5.

[0105] The methods for detecting conversion rate, selectivity, and yield are as follows:

[0106] Analysis was performed using an Agilent 7820A gas chromatograph equipped with an FID and HP-5 column. The internal standard method was used, with eicosane selected as the internal standard. The conversion, selectivity for different products, and yield of methyl stearate were calculated using the following formulas:

[0107]

[0108]

[0109]

[0110] In the formula, X represents the conversion rate of methyl stearate, S and Y represent the selectivity and yield of each component in the product, n0 is the initial amount of methyl stearate, n0' is the molar amount of methyl stearate remaining in the solution after the reaction, and n i It represents the molar amount of a certain component in the product.

[0111] Table 2 Product distribution of Experiments 1-8

[0112]

[0113]

[0114] The results in Table 2 show that:

[0115] 1. In the methods for preparing higher fatty alcohols in Experiments 1-4, the catalysts of Examples 2-5 were used respectively, and the types of the second metal active component were different. Among them, Experiment 4 showed higher conversion rate and selectivity, indicating that selecting Fe as the second metal yielded the best results.

[0116] 2. Experimental Example 4 uses Ni 1.5 Fe 1.5 / ZnO catalyst, Experimental Example 5 uses Ni 1.5 Fe 1.5 Compared with Experimental Example 5, Experimental Example 4 showed a significant increase in conversion rate using SiO2 catalyst, indicating that the formation of the NiFe-ZnO interface greatly improved the activity of fatty acid methyl ester hydrogenation.

[0117] 3. In the methods for preparing higher fatty alcohols in Experiments 4, 6, and 7, the catalysts of Examples 5, 7, and 8 were used respectively, with different Ni and Fe contents. Among them, Experiment 5 showed higher conversion and selectivity, indicating that the effect was best when the weight ratio of Ni to Fe was 1:1. When the Fe content was too high, both the conversion and selectivity decreased, and when the Ni content was too high, the conversion decreased.

[0118] 4. Compared with Experimental Example 8, Experimental Example 4 used the same catalyst, but the reaction time of Experimental Example 8 was extended from 6 hours to 10 hours. Compared with Experimental Example 4, the conversion rate and selectivity of Experimental Example 8 were improved, indicating that the catalyst has good stability and the conversion rate can reach 100%.

[0119] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A catalyst for the hydrogenation of supported fatty acid methyl esters to prepare higher fatty alcohols, characterized in that, The invention includes a carrier and an active component loaded on the carrier, wherein the carrier is zinc oxide, and the active component includes a first metal and a second metal, wherein the first metal is selected from Ni, the second metal is selected from Fe, and the mass ratio of Ni to Fe is 1:

1. The support accounts for 96-98% of the total weight of the catalyst, and the active component accounts for 2-4% of the total weight of the catalyst; the catalyst is a NiFe / ZnO catalyst with a ZnO coating structure, forming a metal-support interface.

2. The catalyst for the hydrogenation of supported fatty acid methyl esters to higher fatty alcohols according to claim 1, characterized in that, The support accounts for 96-97% of the total weight of the catalyst.

3. The catalyst for the hydrogenation of supported fatty acid methyl esters to higher fatty alcohols according to claim 1, characterized in that, The active component accounts for 3-4% of the total weight of the catalyst.

4. A method for preparing a catalyst for the hydrogenation of supported fatty acid methyl esters to higher fatty alcohols as described in any one of claims 1-3, characterized in that, include: (1) Preparation of zinc oxide carrier; (2) Prepare a mixture of Ni salt and salt of the second metal; (3) The mixture is evenly impregnated onto the zinc oxide support, left to stand at room temperature, dried, calcined, and reduced with hydrogen to obtain the catalyst.

5. The preparation method according to claim 4, characterized in that, In step (1), the preparation of the zinc oxide support includes: Zn(NO3)2 was dissolved in deionized water, and the resulting solution was rapidly stirred in a water bath at 60-80°C. Then, a certain amount of Na2CO3 solution was added dropwise to the above solution. The resulting white suspension was stirred at 60-80°C for 0.5-1.5 h, cooled to room temperature, filtered, washed with distilled water until the pH was stable, dried, and calcined to obtain a white solid as the carrier ZnO.

6. The preparation method according to claim 5, characterized in that, In step (1), the roasting temperature is 300-700℃ and the roasting time is 3-5h.

7. The preparation method according to claim 6, characterized in that, In step (1), the roasting temperature is 400-600℃ and the roasting time is 4-5h.

8. The preparation method according to claim 4, characterized in that, In step (3), the calcination temperature is 500-800℃, the calcination time is 3-5h, and the heating rate during calcination is 1-4℃ / min.

9. The preparation method according to claim 8, characterized in that, In step (3), the roasting temperature is 600-700℃ and the roasting time is 4-5h.

10. The preparation method according to claim 4, characterized in that, In step (3), the hydrogen reduction temperature is 500-800℃, the hydrogen reduction time is 2-4h, and the heating rate is 3-5℃ / min.

11. The preparation method according to claim 10, characterized in that, In step (3), the hydrogen reduction temperature is 600-700℃, the hydrogen reduction time is 2-3h, and the heating rate is 3-4℃ / min.

12. A method for preparing higher fatty alcohols, characterized in that, include: Fatty acid methyl ester, organic solvent and catalyst as described in any one of claims 1-3 are added to a batch reactor, and hydrogen gas at a certain pressure is introduced to carry out the reaction; the product after the reaction is separated by distillation to obtain fatty alcohol product.

13. The method according to claim 12, characterized in that, The organic solvent should be a C5-C8 alkane.

14. The method according to claim 13, characterized in that, The organic solvent is n-hexane.

15. The method according to claim 12, characterized in that, The hydrogen gas is introduced at a controlled pressure of 3-5 MPa, the reaction temperature is controlled at 200-240 ℃, and the reaction time is 6-10 h.

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