One-pot synthesis process of fatty alcohol

Abstract

The invention discloses a one-pot synthesis process of fatty alcohol, and belongs to the technical field of chemical synthesis. The specific process is as follows: fatty acid is taken as a raw material, CnZnOZrOx loaded by a C-N carrier is taken as a catalyst, mixed gas of hydrogen and carbon dioxide is introduced, and the fatty alcohol is prepared through reaction. The invention provides a rapid and green one-pot reaction process for realizing CO2 hydrogenation, fatty acid methyl esterification and fatty acid methyl ester hydrogenation in the same reactor under the action of a copper-based catalyst. Carbon dioxide is used as a raw material, so that the yield and process efficiency of the target product fatty alcohol can be improved under mild conditions, the concentration of CO2 in the atmosphere can be reduced, the CO2 is converted into valuable chemicals, and sustainable utilization of resources is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and particularly relates to a one-pot synthesis process for fatty alcohol. Background Art

[0002] As the world's dependence on fossil fuels and carbon emissions become increasingly serious, biomass, as the only renewable carbon source, is seen as a potential energy alternative to reduce carbon emissions and achieve carbon neutrality. Biomass conversion is an important research direction in the current energy field, aiming to effectively convert biomass resources into clean energy and high value-added chemicals. Therefore, the development of more efficient biomass conversion technology is crucial to promoting the development of sustainable energy. In addition, carbon dioxide (CO 2 ) is a greenhouse gas and is gradually being regarded as a potential carbon source. 2 Used to synthesize high value-added chemicals, it can not only reduce greenhouse gas emissions but also improve resource utilization efficiency.

[0003] Oils, fatty acids and fatty acid methyl esters are common biomass energy sources. Fatty alcohols produced by hydrogenation are important chemical raw materials and are widely used in lubricants, food additives, surfactants, polymers, cosmetics and medicines. They play an important role in the development of the national economy. The global demand for fatty alcohols continues to grow, and the consumption of fatty alcohols is also gradually increasing.

[0004] Under the existing technology, there are three main process routes for preparing natural fatty alcohols, namely direct hydrogenation of oils and fats, hydrogenation after oil hydrolysis, and hydrogenation after oil alcoholysis. In industry, the method of hydrogenation after oil alcoholysis is usually used. First, oils and methanol are transesterified to obtain fatty acid methyl esters, and then hydrogenated to obtain fatty alcohols. Since the reaction conditions are not as harsh as direct hydrogenation of oils and fats, and there is no acid corrosion problem, glycerol can be recovered, and the selectivity of fatty alcohols is high, it is widely used. However, this process needs to be carried out in at least two steps, and each step requires specific reaction conditions and catalysts. This multi-step reaction increases the complexity of the process, requires precise control of reaction conditions such as temperature, pressure and catalyst active sites, and may also lead to additional steps for product separation and purification, further increasing the time and cost of the entire process.

[0005] In addition, the addition of methanol increases energy consumption. In the transesterification reaction, methanol is used as a reactant to react with oil to produce fatty acid methyl esters. In order to ensure a high conversion rate of the reaction, an excess of methanol is usually required, which not only increases the cost of raw materials, but also increases energy consumption. In addition, the production of methanol itself is also a process with high energy consumption. During the entire reaction process, the use of methanol will have a negative impact on energy efficiency and reduce the economic efficiency of the process. For example: Patent CN112661608A discloses a method for preparing natural fatty alcohols, in which natural oils and methanol are subjected to transesterification reaction under the action of a copper-based catalyst to produce fatty acid methyl esters; the obtained fatty acid methyl esters are atomized and passed into a reactor assembly to react with hydrogen to obtain a crude natural fatty alcohol; then the crude natural fatty alcohol is passed into an evaporator for dealcoholization treatment, and finally the natural fatty alcohol is obtained by vacuum distillation; but the reaction process is complicated, requires multiple steps of reaction, and increases the consumption of methanol.

[0006] Patent CN116621676A discloses a Ni / Mo 2 A method for selective hydrogenation / hydrodeoxygenation of fatty acid methyl esters catalyzed by C@CQDs. 2 C-based materials, nano-Ni and Mo 2 C chemically coupled to achieve Ni-Mo 2 Due to the strong metallic force between C, the hydrogenation catalyst prepared can obtain a higher selectivity for stearyl alcohol when used for the hydrogenation of methyl stearate to prepare stearyl alcohol. However, the preparation of the catalyst is complicated, the reaction requires a high pressure (4 MPa), and the reaction time is long (18h).

[0007] Patent CN111701591A discloses a hydrogenation catalyst and a preparation method thereof and a method for preparing fatty alcohols by hydrogenating fatty acid esters. When a copper source is added to a titanium dioxide dispersion to prepare a hydrogenation catalyst for preparing fatty alcohols by hydrogenating fatty acid esters, a higher selectivity for fatty alcohols can be obtained, but the catalyst has a single active component, low catalytic activity, and a harsh reaction process (240 °C, 5 MPa, 23 h).

[0008] Therefore, there is an urgent need to provide a process for preparing fatty alcohols under mild conditions, and in particular, to develop a green one-pot process for synthesizing fatty alcohols. Summary of the invention

[0009] In view of the above-mentioned deficiencies in the prior art, the present invention provides a one-pot synthesis process for fatty alcohols. The present invention can prepare fatty alcohols under low temperature and low pressure conditions, has mild reaction conditions, simple process and high yield of fatty alcohols.

[0010] To achieve the above purpose, the technical solution adopted by the present invention to solve the technical problem is: using fatty acid as raw material, CN carrier loaded CnZnOZrO x As a catalyst, a mixed gas of hydrogen and carbon dioxide is introduced to react to produce fatty alcohols.

[0011] Furthermore, the reaction pressure is 0.5~3.5 MPa.

[0012] Furthermore, the reaction pressure is 2.4~3.0 MPa.

[0013] Furthermore, the reaction temperature is 120-180 °C.

[0014] Furthermore, the reaction temperature is 120-150 °C.

[0015] Furthermore, the reaction time is 1 to 10 h.

[0016] Further, the fatty acid includes, but is not limited to, lauric acid, myristic acid, palmitic acid, stearic acid or erucic acid.

[0017] Furthermore, a reaction solvent is also required in the preparation process, and the reaction solvent is an organic solvent.

[0018] Furthermore, the organic solvent includes, but is not limited to, dodecane, n-hexane or n-heptane.

[0019] Furthermore, the amount of carbon dioxide added is 1 / 5 to 1 / 2 of the volume of hydrogen.

[0020] Furthermore, the molar ratio of the catalyst to the fatty acid is 1:1 to 1:3.

[0021] Furthermore, the molar ratio of the catalyst to the fatty acid is 1:1.

[0022] Furthermore, CN-supported CnZnOZrO x The catalyst was prepared as follows: The metal precursor Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 6H 2 O, ZrO(NO 3 ) 2 ·xH 2O was dissolved to obtain a 1-2 M transparent solution, and alkali solution was added dropwise under continuous stirring to control the pH value to 7-8, and aged at room temperature for 1 h. Then, the CN carrier was poured into the suspension, placed in a 80-100 °C water bath, sealed and stirred for 2 h, filtered, and the filter cake was dried under vacuum. Finally, the dried filter cake was crushed and calcined at 400-450 °C for 3-5 h to obtain CuZnZrO x / CN catalyst.

[0023] Furthermore, CuZnZrO x The molar ratio of Cu:Zn:Zr in the / CN catalyst is 5:2:1~4.

[0024] Furthermore, the alkali solution is a 5 wt.% ammonia solution.

[0025] Beneficial effects of the present invention: The present invention proposes to realize CO in the same reactor under the action of copper-based catalyst. 2 A green one-pot reaction process for hydrogenation, fatty acid methylation and fatty acid methyl ester hydrogenation. Using carbon dioxide as a raw material can not only improve the yield and process efficiency of the target product fatty alcohol under mild conditions, but also reduce CO in the atmosphere. 2 concentration, converting them into valuable chemicals and achieving sustainable utilization of resources.

[0026] The present invention proposes to use methanol generated in situ to replace methanol introduced from the outside, CO 2 The methanol produced in situ by hydrogenation is immediately used in the fatty acid methylation reaction. While promoting the in situ production of methanol, it eliminates the effect of the external diffusion of additional methanol on the methylation reaction rate. The fatty acid methyl ester produced in situ immediately participates in the hydrogenation reaction, eliminating the effect of the external diffusion of methyl ester on the hydrodeoxygenation reaction rate and accelerating the reaction rate of methyl ester hydrogenation. DETAILED DESCRIPTION

[0027] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0028] Example 1 A one-pot synthesis process for fatty alcohols comprises the following steps: (1) Preparation of CuZnZrO x / CN Catalyst The metal precursor Cu(NO 3 )2 ·3H 2 O, Zn(NO 3 ) 2 6H 2 O, ZrO(NO 3 ) 2 ·xH 2 O was dissolved in 20 mL of ultrapure water to obtain a 1 M transparent solution. Ammonia solution (5 wt.%) was added dropwise under continuous stirring, the pH value was controlled to 7-8, and the solution was aged at room temperature for 1 h. Subsequently, the CN carrier was poured into the suspension, placed in an 80 °C water bath, sealed and stirred for 2 h, and washed and filtered to obtain a black-blue filter cake. The filter cake was dried at 60 °C overnight under vacuum. The dried solid was ground into fine powder and calcined at 450 °C for 3 h under Ar atmosphere to obtain a calcined sample. Before use, the CN carrier was heated to 5% H 2 / Ar atmosphere, and then reduced at 300 °C for 3 h to obtain CuZnZrO x / CN catalyst sample, CuZnZrO x The molar ratio of Cu:Zn:Zr in the / CN catalyst is 5:2:2.

[0029] (2) Synthetic fatty alcohol Dissolve 60 mg of stearic acid in dodecane to form a transparent solution, and then add 60 mg of CuZnZrO x / CN catalyst, a mixed gas of hydrogen and carbon dioxide with a volume ratio of 5:1 was introduced, and the reaction was carried out at 2.4 MPa and 150 ℃ for 3 h to obtain fatty alcohol.

[0030] Example 2 A one-pot synthesis process for fatty alcohols comprises the following steps: (1) Preparation of CuZnZrO x / CN Catalyst The metal precursor Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 6H 2 O, ZrO(NO 3 ) 2 ·xH 2O was dissolved in 20 mL of ultrapure water to obtain a 1 M transparent solution. Ammonia solution (5 wt.%) was added dropwise under continuous stirring, the pH value was controlled to 7-8, and the solution was aged at room temperature for 1 h. Subsequently, the CN carrier was poured into the suspension, placed in an 80 °C water bath, sealed and stirred for 2 h, and washed and filtered to obtain a black-blue filter cake. The filter cake was dried at 60 °C overnight under vacuum. The dried solid was ground into fine powder and calcined at 450 °C for 3 h under Ar atmosphere to obtain a calcined sample. Before use, the CN carrier was heated to 5% H 2 / Ar atmosphere, and then reduced at 300 °C for 3 h to obtain CuZnZrO x / CN catalyst sample, CuZnZrO x The molar ratio of Cu:Zn:Zr in the / CN catalyst is 5:2:1.

[0031] (2) Synthetic fatty alcohol Dissolve 240 mg of lauric acid in n-hexane to form a transparent solution, and then add 80 mg of CuZnZrO x / CN catalyst, a mixed gas of hydrogen and carbon dioxide with a volume ratio of 3:1 was introduced, and the reaction was carried out at 2.4 MPa and 180 ℃ for 5 h to obtain fatty alcohol.

[0032] Example 3 A one-pot synthesis process for fatty alcohols comprises the following steps: (1) Preparation of CuZnZrO x / CN Catalyst The metal precursor Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 6H 2 O, ZrO(NO 3 ) 2 ·xH 2 O was dissolved in 20 mL of ultrapure water to obtain a 1 M transparent solution. Ammonia solution (5 wt.%) was added dropwise under continuous stirring, the pH value was controlled to 7-8, and the solution was aged at room temperature for 1 h. Subsequently, the CN carrier was poured into the suspension, placed in an 80 °C water bath, sealed and stirred for 2 h, and washed and filtered to obtain a black-blue filter cake. The filter cake was dried at 60 °C overnight under vacuum. The dried solid was ground into fine powder and calcined at 450 °C for 3 h under Ar atmosphere to obtain a calcined sample. Before use, the CN carrier was heated to 5% H 2 / Ar atmosphere, and then reduced at 300 °C for 3 h to obtain CuZnZrO x / CN catalyst sample, CuZnZrO xThe molar ratio of Cu:Zn:Zr in the / CN catalyst is 5:2:4.

[0033] (2) Synthetic fatty alcohol 60 mg of palmitic acid was dissolved in dodecane to form a transparent solution, and then 20 mg of CuZnZrO was added during stirring. x / CN catalyst, a mixed gas of hydrogen and carbon dioxide with a volume ratio of 2:1 was introduced, and the reaction was carried out at 3.5 MPa and 180 ℃ for 10 h to obtain fatty alcohol.

[0034] Example 4 A one-pot synthesis process for fatty alcohols comprises the following steps: (1) Preparation of CuZnZrO x / CN Catalyst The metal precursor Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 6H 2 O, ZrO(NO 3 ) 2 ·xH 2 O was dissolved in 20 mL of ultrapure water to obtain a 1 M transparent solution. Ammonia solution (5 wt.%) was added dropwise under continuous stirring, the pH value was controlled to 7-8, and the solution was aged at room temperature for 1 h. Subsequently, the CN carrier was poured into the suspension, placed in an 80 °C water bath, sealed and stirred for 2 h, and washed and filtered to obtain a black-blue filter cake. The filter cake was dried at 60 °C overnight under vacuum. The dried solid was ground into fine powder and calcined at 450 °C for 3 h under Ar atmosphere to obtain a calcined sample. Before use, the CN carrier was heated to 5% H 2 / Ar atmosphere, and then reduced at 300 °C for 3 h to obtain CuZnZrO x / CN catalyst sample, CuZnZrO x The molar ratio of Cu:Zn:Zr in the / CN catalyst is 5:2:1.

[0035] (2) Synthetic fatty alcohol Dissolve 300 mg of erucic acid in n-hexane to form a transparent solution, and then add 100 mg of CuZnZrO x / CN catalyst, a mixed gas of hydrogen and carbon dioxide with a volume ratio of 3:1 was introduced, and the reaction was carried out at 2.6MPa and 180℃ for 6h to obtain fatty alcohol.

[0036] Example 5 A one-pot synthesis process for fatty alcohols comprises the following steps: (1) Preparation of CuZnZrO x / CN Catalyst The metal precursor Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 6H 2 O, ZrO(NO 3 ) 2 ·xH 2 O was dissolved in 20 mL of ultrapure water to obtain a 1 M transparent solution. Ammonia solution (5 wt.%) was added dropwise under continuous stirring, the pH value was controlled to 7-8, and the solution was aged at room temperature for 1 h. Subsequently, the CN carrier was poured into the suspension, placed in an 80 °C water bath, sealed and stirred for 2 h, and washed and filtered to obtain a black-blue filter cake. The filter cake was dried at 60 °C overnight under vacuum. The dried solid was ground into fine powder and calcined at 450 °C for 3 h under Ar atmosphere to obtain a calcined sample. Before use, the CN carrier was heated to 5% H 2 / Ar atmosphere, and then reduced at 300 °C for 3 h to obtain CuZnZrO x / CN catalyst sample, CuZnZrO x The molar ratio of Cu:Zn:Zr in the / CN catalyst is 5:2:4.

[0037] (2) Synthetic fatty alcohol 90 mg of myristic acid was dissolved in dodecane to form a transparent solution, and then 30 mg of CuZnZrO was added during stirring. x / CN catalyst, a mixed gas of hydrogen and carbon dioxide with a volume ratio of 2:1 was introduced, and the reaction was carried out at 2.8 MPa and 160°C for 8 h to obtain fatty alcohol.

[0038] Comparative Example 1 Compared with Example 1, the difference is that CuZn is used as the catalyst, and the rest of the process is the same as Example 1.

[0039] Comparative Example 2 Compared with Example 1, the difference is that Cu / m-ZrO 2 As catalyst, the rest of the process is the same as in Example 1.

[0040] Comparative Example 3 Compared with Example 1, the difference is that CuZn x / CN was used as the catalyst, and the rest of the process was the same as in Example 1.

[0041] Comparative Example 4 Compared with Example 1, the difference is that Cu-NbOx / SBA-15 was used as the catalyst, the pressure was 4.0 MPa, and the rest of the process was the same as in Example 1.

[0042] Comparative Example 5 Compared with Example 1, the difference is that CuCo / C is used as the catalyst, and the rest of the process is the same as Example 1.

[0043] Comparative Example 6 Compared with Example 1, the difference is that the reaction process is carried out in two steps, as follows: A synthetic process for fatty alcohols comprises the following steps: (1) Preparation of CuZnZrO x / CN Catalyst The metal precursor Cu(NO 3 ) 2 ·3H 2 O, Zn(NO 3 ) 2 6H 2 O, ZrO(NO 3 ) 2 ·xH 2 O was dissolved in 20 mL of ultrapure water to obtain a 1 M transparent solution. Ammonia solution (5 wt.%) was added dropwise under continuous stirring, the pH value was controlled to 7-8, and the solution was aged at room temperature for 1 h. Subsequently, the CN carrier was poured into the suspension, placed in an 80 °C water bath, sealed and stirred for 2 h, and washed and filtered to obtain a black-blue filter cake. The filter cake was dried at 60 °C overnight under vacuum. The dried solid was ground into fine powder and calcined at 450 °C for 3 h under Ar atmosphere to obtain a calcined sample. Before use, the CN carrier was heated to 5% H 2 / Ar atmosphere, and then reduced at 300 °C for 3 h to obtain CuZnZrO x / CN catalyst sample, CuZnZrO x The molar ratio of Cu:Zn:Zr in the / CN catalyst is 5:2:2.

[0044] (2) Dissolve 30 mg of stearic acid in dodecane to form a transparent solution, and then add 30 mg of CuZnZrO x / CN catalyst, methanol was added and the reaction was carried out at 0.5 MPa and 120 °C for 1 h; (3) After the reaction is completed, hydrogen is introduced to continue the reaction for 2 h to obtain fatty alcohol.

[0045] Comparative Example 7 The preparation process is consistent with that of Comparative Example 6, and the fatty alcohol is synthesized by a two-step method. The difference is that the reaction temperature in step (2) is 220°C and the pressure is 4.2 MPa. The rest of the process is consistent with that of Comparative Example 6.

[0046] Comparative Example 8 Compared with Example 1, the difference is that the reaction temperature is 240°C, and the rest of the process is the same as Example 1.

[0047] The catalytic efficiency and yield of the fatty alcohols prepared in Examples 1 to 5 and Comparative Examples 1 to 8 were tested. The results are shown in Table 1.

[0048] Table 1 Catalytic efficiency and yield of fatty alcohols prepared by different processes

[0049] According to the test results in Table 1, the technical solutions described in Examples 1 to 5 of the present invention have the highest catalytic efficiency and yield when synthesizing fatty alcohols, which are significantly better than Comparative Examples 1 to 8. Although the catalytic efficiency of the catalyst used in Comparative Example 4 is similar to that of the technical solutions of Examples 1 to 5 of the present application, its yield is far less than that of Examples 1 to 5.

[0050] Although Comparative Example 6 is basically the same as the process of the technical solution of the present application, and the reaction principle used is consistent, it is not a one-pot synthesis process, but first reacts stearic acid and methanol to generate methyl stearate, and then introduces hydrogen to continue to react to generate stearyl alcohol, which leads to a significant reduction in its catalytic efficiency and yield. Comparative Example 7 adjusts the reaction parameters on the basis of Comparative Example 6. After improving its reaction temperature and pressure, it can be seen that the catalytic efficiency and yield are further improved compared to Comparative Example 6, but it is still not comparable to the effect of this solution.

[0051] Therefore, according to the test results in Table 1, it can be seen that only according to the technical solution described in the present invention can the advantages of high catalytic efficiency and high yield be achieved when synthesizing fatty alcohols.

[0052] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A one-pot synthesis process for fatty alcohols, characterized in that: Using fatty acids as raw materials, CN carrier-loaded CnZnOZrO x As a catalyst, a mixed gas of hydrogen and carbon dioxide is introduced to react to produce fatty alcohols.

2. The one-pot synthesis process according to claim 1, characterized in that: The reaction pressure is 0.5~3.5 MPa.

3. The one-pot synthesis process according to claim 2, characterized in that: The reaction pressure is 2.4~3.0 MPa.

4. The one-pot synthesis process according to claim 1, characterized in that: The reaction temperature is 120~180 ℃.

5. The one-pot synthesis process according to claim 4, characterized in that: The reaction temperature is 120~150 ℃.

6. The one-pot synthesis process according to claim 1, characterized in that: The reaction time is 1~10 h.

7. The one-pot synthesis process according to claim 1, characterized in that: The fatty acid is lauric acid, myristic acid, palmitic acid, stearic acid or erucic acid.

8. The one-pot synthesis process according to claim 1, characterized in that: A reaction solvent is also required in the preparation process, and the reaction solvent is an organic solvent.

9. The one-pot synthesis process according to claim 1, characterized in that: The amount of carbon dioxide added is 1 / 5~1 / 2 of the volume of hydrogen.

10. The one-pot synthesis process according to claim 1, characterized in that: The molar ratio of the catalyst to the fatty acid is 1:1 to 1:3.

Images