Method for synthesizing fatty alcohol

Abstract

The invention discloses a fatty alcohol synthesis method, which comprises: (1) mixing fatty olefin, alcohol, a catalyst, an optional catalyst auxiliary agent and a ligand in a solvent, adding CO, and carrying out a pressurization heating reaction to obtain fatty acid ester; and (2) carrying out hydrogenation reaction on the fatty acid ester and hydrogen under the action of a hydrogenation catalyst to generate fatty alcohol. According to the method disclosed by the invention, fatty olefin is changed into fatty acid ester through carbonyl esterification reaction, and then fatty alcohol is generated through hydrogenation, so that the problems that in the prior art, a hydroformylation intermediate product aldehyde is unstable and easy to polymerize, and a generated polymer is difficult to separate from a catalyst, so that heavy components in a catalyst solution are accumulated, and the selectivity of a noble metal catalyst is not high are solved; according to the method disclosed by the invention, the reaction selectivity is improved, the material consumption is reduced, and the catalyst for the carbonyl esterification reaction can be circulated for a long time and does not need to be regularly discharged and the like, so that the method has a relatively good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of fatty alcohol synthesis, and more particularly to a method for synthesizing fatty alcohol. Background Art

[0002] Fatty alcohols are aliphatic alcohols with a chain of 3 to 30 carbon atoms. Fatty alcohols were first produced from spermaceti. The resulting mixed fatty alcohols were sulfonated and neutralized to form sulfates, which were the earliest anionic detergents. Coconut oil, palm oil and tallow, which are relatively abundant sources, were subsequently developed and utilized as raw materials. The fatty acids obtained by hydrolysis are then reduced to alcohols. They are collectively referred to as natural fatty alcohols. After the development of the petrochemical industry, the fatty alcohols produced using petroleum products as raw materials are called synthetic fatty alcohols. The methods for producing fatty alcohols include the Ziegler process and the carbonyl synthesis process.

[0003] The Ziegler process uses ethylene as the raw material and trialkylaluminum to produce aluminum alcohol compounds through chain growth and oxidation, and then produces fatty alcohols through hydrolysis, neutralization and fractionation.

[0004] Hydroformylation is the process of synthesizing aldehydes from olefins, carbon monoxide and hydrogen in the presence of a catalyst and under pressure. The number of atoms in the aldehyde is one more carbon than that of the raw olefin. Aldehydes are hydrogenated to produce fatty alcohols.

[0005] Among them, the hydroformylation method is mainly divided into homogeneous method and heterogeneous method. The heterogeneous method uses cobalt catalysts to react olefins with synthesis gas (CO and hydrogen) to generate fatty aldehydes. After the reaction, water is added for extraction. The catalyst is dissolved in the water phase and the product is in the oil phase. The catalyst and the product are separated to obtain fatty aldehydes, which are hydrogenated to obtain fatty alcohols. This technology is mature and reliable and has been used industrially. However, in the carbonyl synthesis section, the reaction pressure reaches more than 200 kg and the reaction temperature exceeds 150 degrees. The project investment is large, the selectivity is low, and the raw material cost is high. The homogeneous method uses, such as rhodium metal, to react long-chain olefins with synthesis gas (CO and hydrogen) to generate fatty aldehydes. After the reaction, they are separated by distillation. The generated fatty aldehydes are evaporated as light components, and the catalyst is recycled back to the reactor as heavy components. Because the fatty aldehydes produced in the reaction process are unstable and easy to polymerize, the generated polymers are difficult to separate from the catalyst, resulting in the accumulation of heavy components in the catalyst solution, and the catalyst solution has to be discharged regularly. This leads to the loss of precious metals, high costs, and regular shutdown treatment.

[0006] Therefore, a better method for synthesizing fatty alcohols was developed. Summary of the invention

[0007] In order to solve the problems in the prior art, the present invention proposes a method for synthesizing fatty alcohols. The present invention converts fatty olefins into fatty acid esters through carbonylation reaction, and then hydrogenates to generate fatty alcohols, which overcomes the problems in the prior art that the intermediate product aldehyde of hydroformylation is unstable and easy to polymerize, and the generated polymer is difficult to separate from the catalyst, resulting in the accumulation of heavy components in the catalyst solution, loss of precious metal catalysts and low selectivity. The method of the present invention improves the selectivity of the reaction, reduces material consumption, and the catalyst for the carbonylation reaction used in the present invention can be circulated for a long time without the need for regular discharge, and has good application prospects.

[0008] One of the objects of the present invention is to provide a method for synthesizing fatty alcohols, comprising the following steps:

[0009] (1) mixing a fatty olefin, an alcohol, a catalyst, an optional catalyst promoter, and a ligand in a solvent, adding CO, and reacting under pressure and temperature to obtain a fatty acid ester;

[0010] (2) Fatty acid esters are hydrogenated with hydrogen in the presence of a hydrogenation catalyst to generate fatty alcohols.

[0011] The outstanding feature of the present invention is that the synthesis of fatty alcohol adopts two steps, the first step adopts carbonyl esterification reaction to generate fatty acid ester, and the second step adopts hydrogenation of fatty acid ester to generate fatty alcohol.

[0012] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0013] Fatty olefins and alcohols are added to the reactor in a certain proportion, and then a certain amount of catalyst, catalyst promoter and ligand are added. CO is then blown in to pressurize to the reaction pressure, and the temperature is raised to the reaction temperature. The reaction pressure is maintained by blowing in CO for a certain period of time to produce fatty acid esters, and then the CO is stopped. After the pressure is released, the generated fatty acid esters are separated from the catalyst by distillation. The fatty acid esters are collected and used as raw materials for hydrogenation reaction. The fatty acid esters are pumped into the fixed bed hydrogenation reactor by a metering pump, and hydrogen is also blown into the fixed bed hydrogenation reactor in a certain proportion with the fatty acid esters. The fatty acid esters react with hydrogen to generate fatty alcohols. After hydrogenation, the liquid phase is collected by cooling to obtain crude fatty alcohols, which are then sent to a distillation tower to obtain fatty alcohols by distillation.

[0014] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0015] Step (1),

[0016] The fatty olefin is selected from fatty olefins having 4 to 30 carbon atoms; preferably, the fatty olefin is selected from fatty olefins having 8 to 20 carbon atoms; and / or,

[0017] The alcohol is selected from alcohols having 1 to 6 carbon atoms; preferably, the alcohol is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol or isobutanol; further preferably, the water content of the alcohol is less than 0.25wt%, preferably the water content of the alcohol is less than 0.1wt%.

[0018] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0019] Step (1),

[0020] The solvent is selected from at least one of inert solvents; preferably, the solvent is selected from at least one of toluene, acid esters or alcohols; further preferably, the acid ester is selected from the same substance as the fatty acid ester in the reaction product of step (1); and / or,

[0021] The hydrogen content in the CO is less than 1500 ppm, preferably the hydrogen content is less than 500 ppm, and the oxygen content in the CO is less than 5 ppm, preferably the oxygen content is less than 1 ppm.

[0022] In the technical solution of the present invention, the hydrogen needs to be controlled because when the hydrogen content is high, by-product aldehydes will be produced, which will lead to the accumulation of heavy components in the carbonylation reaction liquid for a long time.

[0023] In the technical solution of the present invention, the content of hydrogen needs to be controlled. When the oxygen content is high, the ligand will be oxidized and inactivated.

[0024] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0025] Step (1),

[0026] The catalyst is a catalyst for carbonyl esterification reaction; in the technical solution of the present invention, the catalyst for carbonyl esterification reaction used is a catalyst commonly used in the prior art; preferably, the catalyst is a catalyst for carbonyl esterification reaction containing an organic metal;

[0027] Further preferably, the catalyst is a catalyst for carbonylation reaction containing at least one organic metal selected from rhodium and palladium;

[0028] More preferably, the catalyst is selected from at least one of rhodium acetate, rhodium acetylacetonate, rhodium acetylacetonate dicarbonyl rhodium, palladium acetate, palladium acetylacetonate, and di(acetylacetonate)palladium.

[0029] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0030] Step (1),

[0031] The catalyst promoter is selected from at least one of p-toluenesulfonic acid and benzenesulfonic acid; and / or,

[0032] The ligand is selected from organophosphorus ligands;

[0033] Preferably, the ligand is selected from at least one of phosphate ligands, phosphite ligands, phosphorus phosphate ligands, phosphorene ligands, oxalamide phosphorus ligands, trimethoxyphosphine, triphenylphosphine, diphenylphosphine, and tri(2-methoxyphenyl)phosphine.

[0034] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0035] Step (1),

[0036] The molar ratio of the alcohol to the fatty olefin is 1-10:1, preferably 1.03-1.1:1; and / or,

[0037] The concentration of the catalyst in the reaction system is 10-1000 ppm, preferably, the concentration of the catalyst in the reaction system is 50-250 ppm.

[0038] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0039] Step (1),

[0040] The molar ratio of the ligand to the catalyst is 1-50:1, preferably 1.2-10:1; and / or,

[0041] The mass ratio of the solvent to the fatty olefin is 0.1-10:1, preferably 0.2-2:1; and / or,

[0042] When containing the catalyst promoter,

[0043] The concentration of the catalyst promoter in the reaction system is 1000-20000 ppm, preferably 5000-10000 ppm.

[0044] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0045] Step (1),

[0046] The temperature of the pressurized temperature reaction is 60-180°C, preferably 80-120°C; and / or,

[0047] The pressure of the pressurized temperature reaction is 1.0-10.0 MPaG, preferably 2.0-5.0 MPaG; and / or,

[0048] The time of the pressurized temperature-elevated reaction is 0.1-72 hours, preferably 0.5-3 hours.

[0049] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0050] Step (2),

[0051] In the technical solution of the present invention, the hydrogenation catalyst is a catalyst commonly used in the prior art; preferably, the hydrogenation catalyst is selected from at least one of a nickel-based catalyst or a copper-based catalyst; and / or,

[0052] The liquid hourly space velocity of the hydrogenation catalyst is 0.5-5h -1 , preferably 1-2h -1 .

[0053] In the synthesis method of fatty alcohols described in the present invention, preferably,

[0054] Step (2), the hydrogenation reaction is gas phase hydrogenation or liquid phase hydrogenation;

[0055] The temperature of the hydrogenation reaction is 60-280°C, preferably 130-220°C.

[0056] If gas phase hydrogenation is used, the molar ratio of hydrogen to fatty acid ester is 60-1000:1;

[0057] If liquid phase hydrogenation is used, the hydrogenation reaction uses the fatty alcohol corresponding to the product of the hydrogenation reaction as the solvent, and the inlet mass concentration of the fatty acid ester is controlled to be lower than 25%, preferably 5-10%, and the hydrogenation reaction pressure is 1.5-8.0 MPaG, preferably 2.0-6.0 MPaG.

[0058] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0059] Compared with the prior art, the present invention has at least the following advantages:

[0060] The present invention converts fatty olefins into fatty acid esters through a carbonylation reaction, and then hydrogenates them into fatty alcohols, thereby overcoming the problems in the prior art that the intermediate aldehyde of hydroformylation is unstable and easily polymerized, and the generated polymer is difficult to separate from the catalyst, resulting in accumulation of heavy components in the catalyst solution and loss of precious metal catalysts with low selectivity. The method of the present invention improves the selectivity of the reaction and reduces material consumption. In addition, the catalyst for the carbonylation reaction used in the present invention can be circulated for a long time without the need for regular discharge, and has good application prospects.

[0061] The synthesis of the fatty alcohol of the present invention adopts two steps, the first step adopts carbonyl esterification reaction to generate fatty acid ester, and the second step adopts fatty acid ester hydrogenation to generate fatty alcohol. The selectivity of fatty acid ester in the first step of the present invention can reach more than 98%, and can reach up to 99.9%. The selectivity of fatty acid ester hydrogenation can reach more than 97.5%. The final yield of fatty alcohol can reach 95%. The yield of fatty alcohol prepared by hydroformylation is higher than that of the prior art. DETAILED DESCRIPTION

[0062] The present invention is described in detail below in conjunction with specific examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0063] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0064] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0065] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0066] Example 1

[0067] (1) 168 g of carbon dodecene was added to the reactor, followed by 46 g of solvent methyl tridecanoate, 35 g of methanol (industrial high-quality methanol), 56 mg of palladium acetate, 0.85 g of trimethoxyphosphorus ligand, and 5 g of p-toluenesulfonic acid. CO (the hydrogen content in CO was less than 1500 ppm, and the oxygen content was less than 5 ppm) was blown in and the pressure was increased. When the pressure reached 4.0 MPaG, the heater of the reactor was slowly turned on and the temperature was slowly raised to 85°C to start the reaction. The heating of the reactor was turned off and the hot water was removed from the reactor. The temperature was raised to 90°C using the reaction heat. The reaction pressure was maintained by blowing in CO. The reaction temperature was maintained for 3 h. Carbon dodecene reacted with CO and methanol to generate fatty acid methyl esters. Stop the CO from entering, release the pressure to 10 kPaG, open the condenser and vacuum pump connected to the gas phase pipeline of the reactor, evacuate to 2 mmHg, distill out the generated methyl tridecanoate and unreacted carbon dodecene, and then further separate the tridecanoic acid ester and carbon dodecene by distillation to obtain about 260 g of tridecanoic acid ester as a raw material for hydrogenation reaction. The overall conversion rate of carbonylation reaction is about 95%, and the selectivity is 99.9%.

[0068] (2) 400 g / h of 5 wt% tridecanoate tridecanol solution was pumped into a single tube reactor after being pressurized to 6.0 MPaG by a metering pump. The temperature of the single tube reactor was maintained at 190° C. At the same time, hydrogen was blown into the reactor inlet at a hydrogen flow rate of 30 g / h. The single tube reactor was filled with Raney nickel catalyst at a liquid hourly space velocity of 0.75 h -1 The tridecanoic acid ester reacts with hydrogen to generate tridecanol, which enters the gas-liquid separation tank after the reaction, and the gas phase is discharged as the discharge gas, and the liquid phase is collected to obtain 397.5g of tridecanol. The conversion rate of the hydrogenation reaction is about 99.9%, and the selectivity is 99.5%.

[0069] Example 2

[0070] The preparation method is basically the same as that in Example 1, except that:

[0071] Using carbonyl nonadecene, the concentration of the catalyst metal rhodium acetate is 1000ppm, the molar ratio of the ligand to the rhodium metal catalyst is controlled at 50:1, the carbonyl esterification reaction time is adjusted to 24h, the reaction temperature is adjusted to 180°C, the carbonyl esterification conversion rate can reach 92%, and the selectivity is about 99.9%.

[0072] During the hydrogenation reaction, the reaction temperature was raised to 280°C and the liquid hourly space velocity of the hydrogenation catalyst was 0.5h -1 The hydrogenation catalyst uses copper chromite catalyst, and the conversion rate of the hydrogenation reaction at the reactor outlet is about 99.9%, and the selectivity is 99.5%.

[0073] Embodiment 3-6

[0074] 604g of fatty olefin and alcohol (water content is less than 0.25wt%) are added to the reactor in a certain proportion, and then a certain amount of catalyst, catalyst promoter and ligand are added, and then CO (hydrogen content is less than 1500ppm, and the oxygen content in the CO is less than 5ppm) is blasted into the reactor to pressurize to the reaction pressure, and then the temperature is raised to the reaction temperature, the reaction temperature is 60-180°C, and the reaction pressure is maintained by blasting CO, the reaction pressure is 1.0-10.0MPaG, the reaction time is 0.1-72h, and fatty acid esters are produced. Then the CO is stopped, and after the pressure is released, the generated fatty acid esters are separated from the catalyst by distillation. The fatty acid esters are collected and used as raw materials for hydrogenation reaction; specific reaction raw materials and reaction conditions are shown in Table 1, Table 2, and Table 3.

[0075] Table 1

[0076]

[0077] Table 2

[0078]

[0079] Table 3

[0080] Overall carbonylation reaction conversion Overall carbonylation selectivity Example 3 98％ 99.9％ Example 4 97.5％ 99.9％ Example 5 97％ 99.9％ Example 6 96.8％ 99.9％

[0081] The fatty acid ester solution prepared in the above embodiment (the hydrogenation reaction uses the fatty alcohol corresponding to the product after the hydrogenation reaction as a solvent, and the inlet mass concentration of the fatty acid ester is controlled to be 10%) is pumped into a fixed bed hydrogenation reactor via a metering pump, and hydrogen is also blown into the fixed bed hydrogenation reactor at the same time according to a certain ratio with the fatty acid ester, and the fatty acid ester reacts with the hydrogen to generate fatty alcohol, and the liquid phase is collected after cooling after hydrogenation to obtain crude fatty alcohol, which is then sent to a distillation tower to obtain fatty alcohol through distillation. Different reaction conditions and reaction yields are shown in Table 4.

[0082] Table 4

[0083]

[0084] Comparative Example 1

[0085] 168g of carbon dodecene was added to the reactor, 100mg of rhodium acetate was added, and then 0.35g of trimethoxyphosphorus ligand was added, and then the temperature was raised to 90°C, and synthesis gas with a molar ratio of 1:1 was blown in, and the reaction pressure was maintained at 1.6MPaG. After 5 hours, the reaction was stopped, and sampling was performed to determine that the conversion rate of carbon dodecene was 96% and the selectivity was 93%. After the unreacted carbon dodecene was distilled out by vacuum distillation, carbon tridecaldehyde was collected.

[0086] 100 g / h of tridecanol solution of carbonyl tridecaldehyde (concentration of carbonyl tridecaldehyde 5%) was pumped to a pressure of 2.5 MPaG and fed into a single tube reactor filled with Raney nickel catalyst at a temperature of 160 °C and a liquid space velocity of 0.75 h -1 The carbon tridecanal reacts with hydrogen to generate tridecanol, and the reactor outlet enters the gas-liquid separation tank, and the gas phase is discharged. The liquid phase is collected and sent for sample testing. The conversion rate of carbon tridecanal is 99.9%, and the selectivity is 98.2%.

[0087] From the comparison of the results of Comparative Example 1 and Example 1, it can be seen that the aldehyde generated by carbonyl synthesis in Comparative Example 1 is unstable and easily polymerized, and the generated polymer is difficult to separate from the catalyst, resulting in the accumulation of heavy components in the catalyst solution, the loss of precious metal catalyst selectivity is not high, and the selectivity of the hydrogenation section of Comparative Example 1 is also low. Compared with the fatty acid ester generated by carbonyl esterification of the present invention, the fatty acid ester prepared by the present invention is more stable and has higher selectivity.

[0088] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0089] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0090] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0091] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

Claims

1. A method for synthesizing fatty alcohols, characterized in that: The following steps are involved: (1) mixing a fatty olefin, an alcohol, a catalyst, an optional catalyst promoter, and a ligand in a solvent, adding CO, and reacting under pressure and at elevated temperature to obtain a fatty acid ester; (2) Fatty acid esters are hydrogenated with hydrogen in the presence of a hydrogenation catalyst to generate fatty alcohols.

2. The synthetic method of fatty alcohol according to claim 1, characterized in that: Step (1), The fatty olefin is selected from fatty olefins having 4 to 30 carbon atoms; preferably, the fatty olefin is selected from fatty olefins having 8 to 20 carbon atoms; and / or, The alcohol is selected from alcohols having 1 to 6 carbon atoms; preferably, the alcohol is selected from at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol or isobutanol; further preferably, the water content of the alcohol is less than 0.25wt%, preferably the water content of the alcohol is less than 0.1wt%.

3. The synthetic method of fatty alcohol according to claim 1, characterized in that: Step (1), The solvent is selected from at least one of inert solvents; preferably, the solvent is selected from at least one of toluene, acid esters or alcohols; further preferably, the acid ester is selected from the same substance as the fatty acid ester in the reaction product of step (1); and / or, The hydrogen content in the CO is less than 1500 ppm, preferably the hydrogen content is less than 500 ppm, and the oxygen content in the CO is less than 5 ppm, preferably the oxygen content is less than 1 ppm.

4. The synthetic method of fatty alcohol according to claim 1, characterized in that: Step (1), The catalyst is a catalyst for carbonyl esterification reaction; Preferably, the catalyst is an organic metal-containing catalyst for carbonylation reaction; Further preferably, the catalyst is a catalyst for carbonylation reaction containing at least one organic metal selected from rhodium and palladium; More preferably, the catalyst is selected from at least one of rhodium acetate, rhodium acetylacetonate, rhodium acetylacetonate dicarbonyl rhodium, palladium acetate, palladium acetylacetonate, and di(acetylacetonate)palladium.

5. The method for synthesizing fatty alcohols according to claim 1, wherein: Step (1), The catalyst promoter is selected from at least one of p-toluenesulfonic acid and benzenesulfonic acid; and / or, The ligand is selected from organophosphorus ligands; Preferably, the ligand is selected from at least one of phosphate ligands, phosphite ligands, phosphorus phosphate ligands, phosphorene ligands, oxalamide phosphorus ligands, trimethoxyphosphine, triphenylphosphine, diphenylphosphine, and tri(2-methoxyphenyl)phosphine.

6. The method for synthesizing fatty alcohols according to claim 1, wherein: Step (1), The molar ratio of the alcohol to the fatty olefin is 1-10:1, preferably 1.03-1.1:1; and / or, The concentration of the catalyst in the reaction system is 10-1000 ppm, preferably, the concentration of the catalyst in the reaction system is 50-250 ppm.

7. The method for synthesizing fatty alcohols according to claim 1, wherein: Step (1), The molar ratio of the ligand to the catalyst is 1-50:1, preferably 1.2-10:1; and / or, The mass ratio of the solvent to the fatty olefin is 0.1-10:1, preferably 0.2-2:1; and / or, When containing the catalyst promoter, The concentration of the catalyst promoter in the reaction system is 1000-20000 ppm, preferably 5000-10000 ppm.

8. The method for synthesizing fatty alcohols according to claim 1, wherein: Step (1), The temperature of the pressurized temperature reaction is 60-180°C, preferably 80-120°C; and / or, The pressure of the pressurized temperature reaction is 1.0-10.0 MPaG, preferably 2.0-5.0 MPaG; and / or, The time of the pressurized temperature-elevated reaction is 0.1-72 hours, preferably 0.5-3 hours.

9. The method for synthesizing fatty alcohols according to claim 1, wherein: Step (2), The hydrogenation catalyst is selected from at least one of a nickel-based catalyst and a copper-based catalyst; and / or, The liquid hourly space velocity of the hydrogenation catalyst is 0.5-5h -1 , preferably 1-2h -1 .

10. The method for synthesizing fatty alcohols according to claim 1, characterized in that: Step (2), the hydrogenation reaction is gas phase hydrogenation or liquid phase hydrogenation; The temperature of the hydrogenation reaction is 60-280°C, preferably 130-220°C; If gas phase hydrogenation is used, the molar ratio of hydrogen to fatty acid ester is 60-1000:1; If liquid phase hydrogenation is used, the hydrogenation reaction uses the fatty alcohol corresponding to the product of the hydrogenation reaction as the solvent, and the inlet mass concentration of the fatty acid ester is controlled to be lower than 25%, preferably 5-10%, and the hydrogenation reaction pressure is 1.5-8.0 MPaG, preferably 2.0-6.0 MPaG.

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