Method for 2-MF gas phase hydrogenation reaction by using 2-methyltetrahydrofuran catalyst

Abstract

The invention discloses a 2-MF (2-methyltetrahydrofuran) gas phase hydrogenation reaction method using a 2-methyltetrahydrofuran catalyst, and relates to a 2-MF gas phase hydrogenation reaction method, and the catalyst adopts non-noble metal Ni as a catalyst active component and silicon dioxide as a carrier. When the catalyst is applied to a 2-MF gas phase hydrogenation reaction process, H2 / N2 mixed gas is used for reduction at a certain temperature. After reduction is finished, feeding is performed for a period of time with a small H2 / 2-MF ratio, then H2 / 2-MF is increased, gas-phase catalytic hydrogenation reaction is performed, the loading amount of Ni is low, mild gas-phase hydrogenation reaction conditions are adopted, and the catalyst is high in activity, high in selectivity and good in stability. The catalyst is low in cost, resources are saved, and the gas phase hydrogenation process is high in safety, so that better economic benefits are achieved.

Description

Technical Field

[0001] The invention relates to a 2-MF gas phase hydrogenation reaction method, in particular to a 2-methyltetrahydrofuran catalyst used in a 2-MF gas phase hydrogenation reaction method. Background Art

[0002] 2-Methyltetrahydrofuran (hereinafter referred to as 2-MTHF) is an ideal biosolvent with high added value. Compared with traditional solvents such as tetrahydrofuran, 2-MTHF has lower ecological hazards and is a green solvent. It is widely used in biofuels, pharmaceutical industry, organic metal reaction solvents and other fields. As a biofuel, 2-MTHF can be miscible with gasoline in any proportion. When it is used as a gasoline additive, it can not only improve the performance of the fuel, but also reduce exhaust emissions and reduce environmental pollution. As a drug synthesis intermediate, 2-MTHF is a raw material for synthesizing anti-hemorrhoid drugs such as primaquine phosphate and chloroquine phosphate. As a reaction solvent, 2-MTHF is often used as a reaction medium and participates in various organic reactions, such as Grignard reaction, lithiation reaction and coupling reaction. Its stability and solubility enable these reactions to proceed more smoothly.

[0003] Some of the technologies for synthesizing 2-methyltetrahydrofuran by catalytic hydrogenation of 2-methylfuran that have been reported are listed below. Chinese patent CN101492433B, "A green synthesis method of 2-methyltetrahydrofuran", in a reactor, 2-methylfuran and a composite catalyst are subjected to liquid phase hydrogenation reaction at 50-100 ° C and 1.0-4.0 MPa until hydrogen absorption is complete, and the reaction liquid is separated to obtain 2-methyltetrahydrofuran. The composite catalyst used is a precious metal ruthenium and a non-precious metal zinc, copper or iron simultaneously supported on an activated carbon carrier. This invention has the advantages of low reaction pressure and moderate temperature, simple operation and high yield, but the precious metal ruthenium is used in the catalyst, the catalyst cost is relatively high, and the reaction process adopts a liquid phase hydrogenation process, the catalyst needs to be separated and recycled, the separation cost is high and there is catalyst loss.

[0004] Chinese patent CN103977803B, "A method for preparing 2-methyltetrahydrofuran by gas phase hydrogenation of 2-methylfuran", discloses a catalyst NiO / SiO2 catalyst; wherein the mass percentage of NiO is 20%-40%, the mass percentage of carrier SiO2 is 60%-80%, and the mass percentage of alkali metal or alkaline earth metal oxide additive is 2%-10%; the reaction temperature is about 100-180 ° C, the pressure is less than 2 MPa, the 2-methylfuran conversion rate is 100%, the selectivity of 2-methyltetrahydrofuran is above 95%, and the by-products are relatively small, mainly 2-pentanol.

[0005] Chinese patent CN106905269B, "A process for producing 2-methyltetrahydrofuran by continuous hydrogenation in a kettle", adds 2-methylfuran and Raney nickel catalyst to the main reactor, adds 2-methyltetrahydrofuran and palladium carbon catalyst to the sub-reactor, replaces with nitrogen and hydrogen three times respectively, controls the temperature in the main reactor to be 90 ℃, and the pressure to be 5.5-6.0 MPa. After reacting for 3 hours, the sub-reactor is heated to 50 ℃ and the pressure to be 5.0-5.5 MPa. The process includes 2-methylfuran entering the main reactor for hydrogenation reaction, the reaction liquid entering the sub-reactor for hydrogenation reaction, and then separating gas and liquid through a gas-liquid separator, receiving the crude product, and distilling to obtain the finished product. This process uses a continuous kettle liquid phase continuous hydrogenation method to carry out the reaction, eliminating the processing steps before and after each kettle, saving time and improving efficiency. At the same time, since the material does not need to be processed in each kettle, the chance of contact between the material and the catalyst and the air is reduced, which improves the safety of the reaction. The hydrogen in the reaction can be recycled, reducing hydrogen loss and reducing the pollution to the atmosphere caused by the discharge of hydrogen waste gas into the air.

[0006] The literature (Li Zengjie, Journal of Fuel Chemistry, 2018, 46 (1) 54-58) reported an impregnation method to prepare Ni / Al2O3 catalyst for 2-MF hydrogenation to 2-MTHF. The effects of different NiO loadings on 2-MF conversion and 2-MTHF selectivity were studied. The results showed that with the increase of nickel oxide loading, its selectivity showed a trend of first increasing and then decreasing. When the NiO loading was 25%, the selectivity of 2-methyltetrahydrofuran was as high as 97.1%, and the conversion of 2-methylfuran reached 99.4%.

[0007] The literature (X. Jia, Catalysis Letters (2024) 154: 4955-4969) reported an eggshell-type Pd-Ni bimetallic catalyst (Pd-Ni / Al2O3) with different Pd-Ni ratios prepared by deposition precipitation method with spherical Al2O3 as the carrier, and applied it to 2-MF hydrogenation to 2-MTHF for the first time. The effect of Ni loading on the Pd-Ni bimetallic interaction was explored in the reaction. By introducing the Ni component, the use of precious metal Pd was reduced and the activity of the catalyst was improved. Studies have shown that the Pd-Ni / Al2O3 catalyst has the highest activity when the molar ratio of Pd and Ni components is 1.5, the reaction temperature is 90 ℃, and the reaction pressure is 1.5MPa. The 2-MF conversion rate and 2-MTHF selectivity reach 99.6% and 99.5%, respectively. The catalyst also has high stability. After 7 cycles, the conversion rate only decreases by 1%, and the activity is restored after calcination. Summary of the invention

[0008] The purpose of the present invention is to provide a 2-methyltetrahydrofuran catalyst for a 2-MF gas phase hydrogenation reaction method. The method adopts non-precious metal Ni as a catalyst active component, and improves the activity of the catalyst by adding a complexing agent. The catalyst is applied to the 2-MF gas phase hydrogenation reaction, and is reduced by a H2 / N2 mixed gas before the reaction, and then the H2 / 2-MF is increased to carry out a gas phase catalytic hydrogenation reaction. The catalyst of the present invention has low cost, saves resources, and has high gas phase hydrogenation process safety, thereby achieving better economic benefits.

[0009] The objective of the present invention is achieved through the following technical solutions: A 2-methyltetrahydrofuran catalyst is used for a 2-MF gas phase hydrogenation reaction method, the method comprising the following steps: (1) Weigh the Ni salt and the complexing agent, add deionized water to prepare a solution, and completely dissolve them by ultrasonic treatment at room temperature; (2) Add carrier SiO2 to the above solution and immerse at room temperature for 24 h; (3) Evaporate the sample to dryness and then dry overnight; (4) calcining the dried sample in an inert gas to obtain a Ni / SiO2 catalyst; (5) The catalyst was applied to the gas-phase hydrogenation reaction of 2-MF.

[0010] The 2-methyltetrahydrofuran catalyst is used in a 2-MF gas phase hydrogenation reaction method, the soluble Ni salt is nitrate, the molar ratio of the complexing agent to NiO is in the range of 0-2, and the complexing agent is glycine or citric acid.

[0011] The 2-methyltetrahydrofuran catalyst is used for the 2-MF gas phase hydrogenation reaction method, wherein the mass percentage of NiO is 5%-25%, and the mass percentage of the carrier SiO2 is 95%-75%. The 2-methyltetrahydrofuran catalyst is used in the 2-MF gas phase hydrogenation reaction method, the impregnation time is 12-36 h, and the evaporation temperature is 60-90 ° C The 2-methyltetrahydrofuran catalyst is used in the 2-MF gas phase hydrogenation reaction method, and the drying method is drying in air, the drying temperature is 70-130° C., and the drying time is 6-12 h.

[0012] The 2-methyltetrahydrofuran catalyst is used in a 2-MF gas phase hydrogenation reaction method, the calcination method is inert gas calcination, the inert gas is argon or nitrogen, the calcination temperature is 300-600° C., and the calcination time is 2-6 h.

[0013] The 2-methyltetrahydrofuran catalyst is used for a 2-MF gas phase hydrogenation reaction method. The 2-MF gas phase hydrogenation reaction is preceded by reduction with a H2 / N2 mixed gas. After the reduction is completed, a small amount of H2 / 2-MF is first tried as feed, and then the H2 / 2-MF ratio is increased to carry out a gas phase catalytic hydrogenation reaction.

[0014] The 2-methyltetrahydrofuran catalyst is used in a 2-MF gas phase hydrogenation reaction method, and the H2 / N2 mixed gas is a 25-75% N2 / H2 mixed gas.

[0015] The 2-methyltetrahydrofuran catalyst is used in a 2-MF gas phase hydrogenation reaction method, the reduction temperature is 300-600° C., and the reduction time is 2-6 h.

[0016] The 2-methyltetrahydrofuran catalyst is used in a 2-MF gas phase hydrogenation reaction method. The initial H2 / 2-MF is 0.2-1. After the reaction is run for 5-10 hours, the H2 / 2-MF ratio is increased to 3-7 for reaction. The reaction temperature is 60-120° C. and the reaction pressure is 1-4 MPa.

[0017] The salient features of the present invention are: The impregnation method for preparing catalysts does not require complicated equipment and experimental conditions, is simple and easy, and can be mass-produced.

[0018] The non-precious metal Ni is used as the active component, which is rich in resources and low in cost.

[0019] By adding complexing agents, the catalyst can have higher activity at lower active metal loading. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with specific implementation examples: According to the present invention, a certain amount of Ni salt and complexing agent are weighed to prepare a solution according to the loading amount of different active components of the catalyst and the molar ratio of complexing agent / NiO, a certain amount of spherical SiO2 is added to the solution, and the solution is immersed at room temperature for 24 hours, and then the water is evaporated at 80°C. Then the obtained sample is dried at 120°C for 12 hours, and roasted at 500°C in an inert gas for 4 hours to obtain a catalyst. Before use, the catalyst needs to be reduced for 4 hours at a gas flow ratio of H2 / N2 of 25-75%. The complexing agent can be glycine or citric acid, and the inert gas is argon or nitrogen.

[0021] Example 1 2.05 g of hydrated nickel nitrate and 0.63 g of glycine were added to 15 ml of deionized water and ultrasonicated at room temperature for 30 min to fully dissolve them. Then 10 g of spherical SiO2 was added to the solution and immersed at room temperature for 24 h, and then the water was evaporated at 80 °C. The obtained sample was dried at 120 °C for 12 h and then calcined at 500 °C in an argon atmosphere for 4 h to obtain a Ni / SiO2 catalyst.

[0022] Example 2 4.32 g of hydrated nickel nitrate and 1.34 g of glycine were added to 15 ml of deionized water and ultrasonicated at room temperature for 30 min to fully dissolve them. Then 10 g of spherical SiO2 was added to the solution and immersed at room temperature for 24 h, and then the water was evaporated at 80 °C. The obtained sample was dried at 120 °C for 12 h and then calcined at 500 °C in an argon atmosphere for 4 h to obtain a Ni / SiO2 catalyst.

[0023] Example 3 6.89 g of hydrated nickel nitrate and 2.13 g of glycine were added to 15 ml of deionized water and ultrasonicated at room temperature for 30 min to fully dissolve them. Then 10 g of spherical SiO2 was added to the solution and immersed at room temperature for 24 h, and then the water was evaporated at 80 °C. The obtained sample was dried at 120 °C for 12 h and then calcined at 500 °C in an argon atmosphere for 4 h to obtain a Ni / SiO2 catalyst.

[0024] Example 4 9.73 g of hydrated nickel nitrate and 3.01 g of glycine were added to 15 ml of deionized water and ultrasonicated at room temperature for 30 min to fully dissolve them. Then 10 g of spherical SiO2 was added to the solution and immersed at room temperature for 24 h, and then the water was evaporated at 80 °C. The obtained sample was dried at 120 °C for 12 h and then calcined at 500 °C in an argon atmosphere for 4 h to obtain a Ni / SiO2 catalyst.

[0025] Example 5 12.97 g of hydrated nickel nitrate and 4.02 g of glycine were added to 15 ml of deionized water and ultrasonicated at room temperature for 30 min to fully dissolve them. Then 10 g of spherical SiO2 was added to the solution and impregnated at room temperature for 24 h, and then the water was evaporated at 80 °C. The obtained sample was dried at 120 °C for 12 h and then calcined at 500 °C in an argon atmosphere for 4 h to obtain a Ni / SiO2 catalyst.

[0026] Example 6 3.38 g of hydrated nickel nitrate and 2.68 g of citric acid were added to 15 ml of deionized water and ultrasonicated at room temperature for 30 min to fully dissolve them. Then 10 g of spherical SiO2 was added to the solution and immersed at room temperature for 24 h, and then the water was evaporated at 80 °C. The obtained sample was dried at 120 °C for 12 h and then calcined at 500 °C in an argon atmosphere for 4 h to obtain a Ni / SiO2 catalyst.

[0027] Example 7 5.31 g of hydrated nickel nitrate and 4.21 g of citric acid were added to 15 ml of deionized water and ultrasonicated at room temperature for 30 min to fully dissolve them. Then 10 g of spherical SiO2 was added to the solution and immersed at room temperature for 24 h, and then the water was evaporated at 80 °C. The obtained sample was dried at 120 °C for 12 h and then calcined at 500 °C in an argon atmosphere for 4 h to obtain a Ni / SiO2 catalyst.

[0028] Catalyst performance test 1.0 g of the prepared spherical catalyst was loaded into the reactor and reduced in a mixture of N2:H2=3:1 at 500°C for 4 h. After the temperature of the reactor dropped to the reaction temperature, N2 was turned off and the H2 flow rate was adjusted to 80 mL / min. The raw material 2-MF was transported to the evaporator through an infusion pump and entered the reactor together with H2 for reaction. The obtained product was analyzed by gas chromatography.

[0029] At a reaction pressure of 2 MPa, a reaction temperature of 90 °C and a liquid hourly space velocity of 2.4 h -1 The performance evaluation results of the catalyst are shown in Table 1.

[0030] Table 1 Catalyst performance evaluation results Examples 2-Methyltetrahydrofuran conversion rate (100%) 2-Methyltetrahydrofuran selectivity (100%) 1 97.3 95.5 2 98.5 95.8 3 98.5 96.5 4 98.6 96.3 5 98.7 96.7 6 98.5 96.3 7 98.6 96.5 .

Claims

1. A 2-methyltetrahydrofuran catalyst is used for a 2-MF gas phase hydrogenation reaction method, characterized in that: The method comprises the following steps: (1) Weigh the Ni salt and the complexing agent, add deionized water to prepare a solution, and completely dissolve them by ultrasonic treatment at room temperature; (2) Add carrier SiO2 to the above solution and immerse at room temperature for 24 h; (3) Evaporate the sample to dryness and then dry overnight; (4) calcining the dried sample in an inert gas to obtain a Ni / SiO2 catalyst; (5) The catalyst was applied to the gas-phase hydrogenation reaction of 2-MF.

2. A 2-methyltetrahydrofuran catalyst according to claim 1 is used for a 2-MF gas phase hydrogenation reaction method, characterized in that: The soluble Ni salt is nitrate, the molar ratio of complexing agent to NiO is in the range of 0-2, and the complexing agent is glycine or citric acid.

3. A 2-methyltetrahydrofuran catalyst according to claim 1 is used for a 2-MF gas phase hydrogenation reaction method, characterized in that: The mass percentage of NiO is 5%-25%, and the mass percentage of carrier SiO2 is 95%-75%.

4. A 2-methyltetrahydrofuran catalyst according to claim 1 is used for a 2-MF gas phase hydrogenation reaction method, characterized in that: The immersion time is 12-36 hours, and the evaporation temperature is 60-90°C.

5. A 2-methyltetrahydrofuran catalyst according to claim 1 is used for a 2-MF gas phase hydrogenation reaction method, characterized in that: The drying method is drying in air, the drying temperature is 70-130°C, and the drying time is 6-12 hours.

6. A 2-methyltetrahydrofuran catalyst according to claim 1 is used for a 2-MF gas phase hydrogenation reaction method, characterized in that: The calcination method is inert gas calcination, the inert gas is argon or nitrogen, the calcination temperature is 300-600° C., and the calcination time is 2-6 h.

7. A 2-methyltetrahydrofuran catalyst for 2-MF gas phase hydrogenation reaction method according to claim 1, characterized in that: The 2-MF is reduced with H2 / N2 mixed gas before the gas phase hydrogenation reaction. After the reduction is completed, a small amount of H2 / 2-MF is first fed and then the H2 / 2-MF ratio is increased to carry out the gas phase catalytic hydrogenation reaction.

8. A 2-methyltetrahydrofuran catalyst for 2-MF gas phase hydrogenation reaction method according to claim 1, characterized in that: The H2 / N2 mixed gas is 25-75% N2 / H2 mixed gas.

9. A 2-methyltetrahydrofuran catalyst for 2-MF gas phase hydrogenation reaction method according to claim 1, characterized in that: The reduction temperature is 300-600° C., and the reduction time is 2-6 h.

10. A 2-methyltetrahydrofuran catalyst for 2-MF gas phase hydrogenation reaction method according to claim 1, characterized in that: The initial H2 / 2-MF ratio is 0.2-1. After the reaction is run for 5-10 hours, the H2 / 2-MF ratio is increased to 3-7 for reaction. The reaction temperature is 60-120°C; the reaction pressure is 1-4 MPa.