Method for hydrogenation of nitrile rubber by using two-dimensional layered catalyst

Abstract

The invention relates to a method for applying a two-dimensional layered catalyst to hydrogenation of nitrile rubber, which is characterized in that a two-dimensional layered material is used as a carrier to load noble metal as a hydrogenation catalyst, and hydrogenated nitrile rubber is prepared through hydrogenation reaction of nitrile rubber under a hydrogen condition; the two-dimensional layered material is selected from one of pseudo-boehmite, molybdenum disulfide and graphene. By fully utilizing the characteristics of large specific surface and no pore channel of the two-dimensional material, the noble metal center on the catalyst is fully exposed, and the opportunity of contact with nitrile rubber is increased, so that the hydrogenation reaction efficiency and the noble metal utilization rate are improved, and the high-efficiency catalyst is more suitable for nitrile rubber hydrogenation.

Description

Technical Field

[0001] The present invention relates to the field of modification of polymer materials, and particularly to a method for hydrogenating nitrile rubber using a two-dimensional layered catalyst. Background Art

[0002] Hydrogenated nitrile rubber is a type of high-end rubber with excellent properties such as good oil resistance, heat resistance, chemical corrosion resistance, oxidation resistance, high strength, tear resistance, and wear resistance. Hydrogenated nitrile rubber has excellent comprehensive properties and is processed into seals, pipes, etc. and is widely used in industries such as automotive and petrochemical.

[0003] Currently, hydrogenated nitrile rubber is synthesized by catalytic hydrogenation of nitrile rubber. Nitrile rubber is prepared by copolymerizing 1,3-butadiene and acrylonitrile as monomers in a certain proportion. Since unsaturated carbon-carbon double bonds remain after the polymerization of butadiene, nitrile rubber can undergo cross-linking, oxidation and other reactions, which is not conducive to its use under harsh conditions. By catalytic hydrogenation, the carbon-carbon double bonds in nitrile rubber can be converted into carbon-carbon single bonds, ensuring the chemical stability of hydrogenated nitrile rubber.

[0004] The hydrogenation catalyst is the key to preparing hydrogenated nitrile rubber. The existing catalyst systems can be divided into homogeneous noble metal catalysts represented by RhCl(PPh 3 ) 3 and heterogeneous noble metal catalysts represented by Pd / SiO 2 . The extensive use of noble metals makes the cost of hydrogenated nitrile rubber remain high. Therefore, reducing the catalyst cost is an important direction in the research of hydrogenated nitrile rubber. To reduce costs, Patent CN107308985A discloses a hydrogenation catalyst using silica-supported noble metals, which can achieve the recovery of the catalyst. Patent US Patent 6207795 discloses a method for recovering the catalyst using acid-base precipitation. Patent US Patent6646059 discloses a method for recovering the catalyst using ion exchange resin adsorption.

[0005] It should be noted that since nitrile rubber is a polymer, the physical properties of polymer solutions are significantly different from those of small molecule solutions. The entanglement of polymer chains reduces the chance of carbon-carbon double bonds on the chains contacting heterogeneous catalysts. At the same time, the size of the entangled polymer "coil" is relatively large, on the order of 100 nanometers, and cannot freely diffuse into the catalyst pores. For common heterogeneous catalysts, their specific surface area is mainly provided by the inner surface with a pore structure, and the active metal centers are located inside the pores and cannot contact the carbon-carbon double bonds of nitrile rubber, reducing the utilization rate of noble metal active components. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for hydrogenating nitrile rubber using a two-dimensional layered catalyst that can improve the hydrogenation reaction efficiency and the utilization rate of precious metals.

[0007] To solve the above problems, a method for hydrogenating nitrile rubber using a two-dimensional layered catalyst according to the present invention is characterized in that: this method uses a two-dimensional layered material as a carrier to load precious metals as a hydrogenation catalyst, and under hydrogen conditions, it is used for the hydrogenation reaction of nitrile rubber to prepare hydrogenated nitrile rubber; the two-dimensional layered material is selected from one of pseudoboehmite (Al(O)OH), molybdenum disulfide (MoS 2 ) and graphene (G).

[0008] The precious metal is selected from one of palladium, rhodium, and ruthenium, and its mass content in the catalyst is 0.1 wt% - 5 wt%.

[0009] The mass of the nitrile rubber is 1 - 100 times the mass of the catalyst.

[0010] The hydrogenation reaction temperature of the nitrile rubber is 80 - 140 °C, and the reaction time is 1 - 24 hours.

[0011] In the hydrogenation reaction of the nitrile rubber, the organic solvent is selected from one of acetone, methyl isobutyl ketone, cyclohexanone, toluene, and benzene.

[0012] The pressure of the hydrogen is 1 - 8 MPa.

[0013] The present invention has the following advantages compared with the prior art: The present invention uses a two-dimensional material as the carrier of the catalyst to load precious metals, and fully utilizes the characteristics of the large specific surface area and no pores of the two-dimensional material, so that the precious metal centers on the catalyst are fully exposed, increasing the chance of contact with nitrile rubber, thereby improving the hydrogenation reaction efficiency and the utilization rate of precious metals, and being more suitable for high-efficiency catalysts for nitrile rubber hydrogenation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following further details the specific embodiments of the present invention with reference to the accompanying drawings.

[0015] Figure 1 1H NMR spectrum of the product of Example 1 of the present invention.

[0016] Figure 2 Transmission electron microscope photograph of the catalyst of Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] A method for hydrogenating nitrile rubber using a two-dimensional layered catalyst, which uses a two-dimensional layered material as a carrier to support a noble metal as a hydrogenation catalyst, and is used for the hydrogenation reaction of nitrile rubber under the condition of hydrogen with a pressure of 1-8 MPa, a reaction temperature of 80-140 °C, and a reaction time of 1-24 hours to prepare hydrogenated nitrile rubber; the two-dimensional layered material is selected from one of pseudoboehmite (Al(O)OH), molybdenum disulfide (MoS 2 ), graphene (G).

[0018] Among them: the noble metal is selected from one of palladium, rhodium, and ruthenium, and its mass content in the catalyst is 0.1 wt% - 5 wt%.

[0019] The mass of the nitrile rubber is 1-100 times the mass of the catalyst.

[0020] In the hydrogenation reaction of nitrile rubber, the organic solvent is selected from one of acetone, methyl isobutyl ketone, cyclohexanone, toluene, and benzene.

[0021] The specific process of this method is as follows: By mass (g), 1-100 parts of nitrile rubber are dissolved in an organic solvent to form a nitrile rubber solution, and 1 part of the noble metal catalyst supported on the two-dimensional material is added. The air in the reaction kettle is replaced with hydrogen, repeated 3 times, hydrogen with a pressure of 1-8 MPa is charged, and the temperature is raised to 80-140 °C under stirring, and the reaction is carried out for 1-24 hours. Then, it is cooled to room temperature, the pressure is reduced to atmospheric pressure, and the reaction kettle is opened. The catalyst and the hydrogenated nitrile rubber solution are separated by centrifugation. Methanol is added to the hydrogenated nitrile rubber solution to precipitate a white hydrogenated nitrile rubber precipitate. The solvent is removed and dried to obtain the product hydrogenated nitrile rubber.

[0022] Example 1 1 gram of nitrile rubber was dissolved in 100 milliliters of acetone and stirred evenly to obtain a nitrile rubber solution. 0.1 gram of the noble metal catalyst supported on the two-dimensional material, 1wt% Pd / Al(O)OH, was added to the nitrile rubber solution. The air in the reaction kettle was replaced with hydrogen, repeated 3 times, 4 MPa of hydrogen was charged, and the temperature was raised to 100 °C under stirring. After reacting for 2 hours, it was cooled to room temperature, the pressure was reduced to atmospheric pressure, and the reaction kettle was opened. The catalyst and the hydrogenated nitrile rubber solution were separated by centrifugation. 100 milliliters of methanol was added to the hydrogenated nitrile rubber solution to precipitate a white hydrogenated nitrile rubber precipitate. The solvent was removed and dried to obtain the product hydrogenated nitrile rubber.

[0023] Sampling was carried out, and the obtained product was 1 analyzed by 1H NMR, as Figure 1 shown: According to the peak area ratio of the alkyl and alkenyl signals, the hydrogenation degree was found to be 98%.

[0024] The catalyst used was scanned by transmission electron microscopy, as Figure 2As shown, noble metal palladium is uniformly dispersed in layered pseudo-boehmite (Al(O)OH), and the catalyst has the characteristics of typical two-dimensional layered materials.

[0025] Comparative example Dissolve 1 g of nitrile rubber in 100 mL of acetone, stir evenly to obtain a nitrile rubber solution. Add 0.1 g of commercially available noble metal catalyst 1 wt% Pd / Al 2 O 3 to the nitrile rubber solution. Replace the air in the reaction kettle with hydrogen, repeat 3 times, charge 4 MPa of hydrogen, heat up to 100 °C under stirring, react for 2 hours, then cool to room temperature, reduce the pressure to atmospheric pressure, and open the reaction kettle. Centrifuge to separate the catalyst and the hydrogenated nitrile rubber solution. Add 100 mL of methanol to the hydrogenated nitrile rubber solution to precipitate white hydrogenated nitrile rubber. Remove the solvent and dry to obtain the product hydrogenated nitrile rubber. Take a sample and perform 1 1H NMR analysis, and the hydrogenation degree is 62%.

[0026] Example 2 Dissolve 1 g of nitrile rubber in 100 mL of acetone, stir evenly to obtain a nitrile rubber solution. Add 0.1 g of noble metal catalyst supported on two-dimensional material 5 wt% Ru / Al(O)OH to the nitrile rubber solution. Replace the air in the reaction kettle with hydrogen, repeat 3 times, charge 8 MPa of hydrogen, heat up to 120 °C under stirring, react for 1 hour, then cool to room temperature, reduce the pressure to atmospheric pressure, and open the reaction kettle. Centrifuge to separate the catalyst and the hydrogenated nitrile rubber solution. Add 100 mL of methanol to the hydrogenated nitrile rubber solution to precipitate white hydrogenated nitrile rubber. Remove the solvent and dry to obtain the product hydrogenated nitrile rubber. Take a sample and perform 1 1H NMR analysis, and the hydrogenation degree is 85%.

[0027] Example 3 Dissolve 1 g of nitrile rubber in 50 mL of methyl isobutyl ketone, stir evenly to obtain a nitrile rubber solution. Add 1 g of noble metal catalyst supported on two-dimensional material 0.1 wt% Pd / Al(O)OH to the nitrile rubber solution. Replace the air in the reaction kettle with hydrogen, repeat 3 times, charge 1 MPa of hydrogen, heat up to 80 °C under stirring, react for 24 hours, then cool to room temperature, reduce the pressure to atmospheric pressure, and open the reaction kettle. Centrifuge to separate the catalyst and the hydrogenated nitrile rubber solution. Add 100 mL of methanol to the hydrogenated nitrile rubber solution to precipitate white hydrogenated nitrile rubber. Remove the solvent and dry to obtain the product hydrogenated nitrile rubber. Take a sample and perform 1 1H NMR analysis, and the hydrogenation degree is 99%.

[0028] Example 4 Dissolve 1 g of nitrile rubber in 200 mL of cyclohexanone, stir evenly to obtain a nitrile rubber solution. Add 0.01 g of 5wt% Rh / Al(O)OH noble metal catalyst supported on two-dimensional material to the nitrile rubber solution, displace the air in the reaction kettle with hydrogen, repeat 3 times, charge 4 MPa of hydrogen, heat to 140 °C with stirring, after reacting for 12 hours, cool to room temperature, reduce the pressure to atmospheric pressure, and open the reaction kettle. Centrifuge to separate the catalyst and the hydrogenated nitrile rubber solution. Add 100 mL of methanol to the hydrogenated nitrile rubber solution to precipitate white hydrogenated nitrile rubber. Remove the solvent and dry to obtain the product hydrogenated nitrile rubber. Take samples and perform 1 1H NMR analysis, with a hydrogenation degree of 90%.

[0029] Example 5 Dissolve 1 g of nitrile rubber in 100 mL of toluene, stir evenly to obtain a nitrile rubber solution. Add 1 g of 1wt% Pd / MoS supported on two-dimensional material noble metal catalyst to the nitrile rubber solution 2 , displace the air in the reaction kettle with hydrogen, repeat 3 times, charge 4 MPa of hydrogen, heat to 100 °C with stirring, after reacting for 6 hours, cool to room temperature, reduce the pressure to atmospheric pressure, and open the reaction kettle. Centrifuge to separate the catalyst and the hydrogenated nitrile rubber solution. Add 100 mL of methanol to the hydrogenated nitrile rubber solution to precipitate white hydrogenated nitrile rubber. Remove the solvent and dry to obtain the product hydrogenated nitrile rubber. Take samples and perform 1 1H NMR analysis, with a hydrogenation degree of 76%.

[0030] Example 6 Dissolve 1 g of nitrile rubber in 100 mL of toluene, stir evenly to obtain a nitrile rubber solution. Add 1 g of 1wt% Rh / MoS supported on two-dimensional material noble metal catalyst to the nitrile rubber solution 2 , displace the air in the reaction kettle with hydrogen, repeat 3 times, charge 4 MPa of hydrogen, heat to 120 °C with stirring, after reacting for 6 hours, cool to room temperature, reduce the pressure to atmospheric pressure, and open the reaction kettle. Centrifuge to separate the catalyst and the hydrogenated nitrile rubber solution. Add 100 mL of methanol to the hydrogenated nitrile rubber solution to precipitate white hydrogenated nitrile rubber. Remove the solvent and dry to obtain the product hydrogenated nitrile rubber. Take samples and perform 1 1H NMR analysis, with a hydrogenation degree of 88%.

[0031] Example 7 Dissolve 1 g of nitrile rubber in 100 mL of benzene, stir evenly to obtain a nitrile rubber solution. Add 1 g of 1 wt% Ru / G noble metal catalyst supported on two-dimensional material to the nitrile rubber solution, displace the air in the reaction kettle with hydrogen, repeat 3 times, charge 6 MPa of hydrogen, heat up to 100 °C with stirring, after reacting for 12 hours, cool to room temperature, reduce the pressure to atmospheric pressure, and open the reaction kettle. Centrifuge to separate the catalyst and the hydrogenated nitrile rubber solution. Add 100 mL of methanol to the hydrogenated nitrile rubber solution to precipitate white hydrogenated nitrile rubber. Remove the solvent and dry to obtain the product hydrogenated nitrile rubber. Take samples and perform 1 1H NMR analysis, with a hydrogenation degree of 92%.

[0032] Example 8 Dissolve 1 g of nitrile rubber in 100 mL of benzene, stir evenly to obtain a nitrile rubber solution. Add 0.5 g of 0.5 wt% Pd / G noble metal catalyst supported on two-dimensional material to the nitrile rubber solution, displace the air in the reaction kettle with hydrogen, repeat 3 times, charge 8 MPa of hydrogen, heat up to 80 °C with stirring, after reacting for 12 hours, cool to room temperature, reduce the pressure to atmospheric pressure, and open the reaction kettle. Centrifuge to separate the catalyst and the hydrogenated nitrile rubber solution. Add 100 mL of methanol to the hydrogenated nitrile rubber solution to precipitate white hydrogenated nitrile rubber. Remove the solvent and dry to obtain the product hydrogenated nitrile rubber. Take samples and perform 1 1H NMR analysis, with a hydrogenation degree of 89%.

Claims

1. A method for hydrogenating nitrile rubber using a two-dimensional layered catalyst, characterized in that: The method uses a two-dimensional layered material as a carrier to load a precious metal as a hydrogenation catalyst, and is used for the hydrogenation reaction of nitrile rubber under hydrogen conditions to prepare hydrogenated nitrile rubber; the two-dimensional layered material is selected from one of pseudo-boehmite, molybdenum disulfide, and graphene.

2. A method for hydrogenating nitrile rubber using a two-dimensional layered catalyst as claimed in claim 1, characterized in that: The noble metal is selected from one of palladium, rhodium and ruthenium, and accounts for 0.1 wt% to 5 wt% of the mass content of the catalyst.

3. A method for hydrogenating nitrile rubber using a two-dimensional layered catalyst as claimed in claim 1, characterized in that: The mass of the nitrile rubber is 1 to 100 times the mass of the catalyst.

4. A method for hydrogenating nitrile rubber using a two-dimensional layered catalyst as claimed in claim 1, characterized in that: The hydrogenation reaction temperature of the nitrile rubber is 80-140° C., and the reaction time is 1-24 hours.

5. A method for hydrogenating nitrile rubber using a two-dimensional layered catalyst as claimed in claim 1, characterized in that: The organic solvent in the hydrogenation reaction of the nitrile rubber is selected from one of acetone, methyl isobutyl ketone, cyclohexanone, toluene and benzene.

6. A method for hydrogenating nitrile rubber using a two-dimensional layered catalyst as claimed in claim 1, characterized in that: The pressure of the hydrogen is 1-8 MPa.

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