Nitrile rubber hydrogenation method

Abstract

The invention discloses a method for hydrogenating nitrile rubber, comprising: adding a ruthenium-based pincer complex catalyst and an additive to a rubber solution containing nitrile rubber and an organic solvent to obtain a hydrogenation reactant system, stirring the hydrogenation reactant system under a hydrogen pressure of 4.0 to 10 MPa and a temperature of 100 to 150° C. for 6 to 12 hours; the ruthenium-based pincer complex catalyst is a ruthenium-based pincer complex catalyst shown in general formula I, the organic solvent is an aromatic hydrocarbon solvent or a ketone solvent, and the additive is a phenol compound. In the method, the hydrogenation degree of nitrile rubber can reach up to 99.6%, has high reaction activity and good stability, and can achieve high selectivity and high conversion rate hydrogenation of nitrile rubber to obtain hydrogenated nitrile rubber on the basis of low catalyst feed.

Description

Technical Field

[0001] The invention belongs to the technical field of nitrile rubber, and in particular relates to a nitrile rubber hydrogenation method. Background Art

[0002] Nitrile rubber (NBR) is a copolymer formed by the polymerization of acrylonitrile and butadiene monomers. It has good oil resistance, wear resistance, heat resistance, and strong adhesion. Its disadvantages are poor low temperature resistance, poor ozone resistance, poor insulation performance, and slightly low elasticity. Hydrogenated nitrile rubber (HNBR) is a highly saturated elastomeric material obtained by selectively hydrogenating nitrile rubber. Compared with nitrile rubber, hydrogenated nitrile rubber has excellent oil resistance and chemical corrosion resistance due to the retention of cyanide. At the same time, due to its highly saturated methylene chain structure, its mechanical strength is significantly improved, and after the carbon-carbon double bond is hydrogenated, its heat resistance and aging resistance are significantly improved, and it has excellent ozone resistance, making it one of the rubbers with better comprehensive performance.

[0003] At present, the main foreign manufacturers of hydrogenated nitrile rubber are Japan's Zeon and Germany's Lanxess, and the domestic ones are mainly Zannan Technology and Dawn Chemical. There are currently three main production technologies for hydrogenated nitrile rubber: ethylene-acrylonitrile copolymerization, NBR emulsion hydrogenation, and NBR solution hydrogenation. Among them, the solution hydrogenation method is the main production method currently used in industrialization. At present, the catalysts used in the NBR solution hydrogenation method mainly include precious metal homogeneous catalysts such as palladium, rhodium, and ruthenium, and heterogeneous carrier catalysts. Japan's Zeon Company uses SiO 2 Pd / SiO as carrier 2 The catalyst, NBR catalyst residues or additives used in the polymerization reaction may adhere to the carrier surface or remain in the micropores, causing the catalyst activity to drop sharply, affecting its reuse. Hydrogenation of nitrile rubber using a new homogeneous palladium catalyst: Synthesis and characterization. J. Appl. Polym. Sci., 1990, 41, 1357 disclosed homogeneous palladium catalyst Pd (OAc) 2 , there are defects of poor activity and selectivity, such as the rhodium-type catalyst RhCl (PPh 3 ) 3It has the highest activity and selectivity, with a hydrogenation rate of >95%, but rhodium metal is expensive and the production cost of the product is too high. Ruthenium catalysts disclosed in patent application documents US4631315, US4673757 and EP0405266A2 have very high activity in NBR hydrogenation reactions and are much cheaper than rhodium catalysts, but they have poor selectivity during hydrogenation, are prone to side reactions, and produce a large amount of gel. At present, this field is still facing problems such as imperfect hydrogenation process, high production cost, unstable catalytic system, and low product quality. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for hydrogenating nitrile rubber in view of the deficiencies of the above-mentioned prior art. The method comprises adding a ruthenium-based pincer complex catalyst and an additive into a rubber solution containing nitrile rubber and an organic solvent to obtain a hydrogenation reactant system, and stirring the hydrogenation reactant system under a hydrogen pressure of 4.0 to 10 MPa and a temperature of 100 to 150° C. for 6 to 12 hours. The method has a maximum degree of hydrogenation of 99.6%, high reaction activity and good stability, and can achieve high selectivity and high conversion rate hydrogenation of nitrile rubber to obtain hydrogenated nitrile rubber on the basis of relatively low catalyst feed.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for hydrogenating nitrile rubber, characterized in that it includes: adding a ruthenium-based pincer complex catalyst and an additive to a rubber solution containing nitrile rubber and an organic solvent to obtain a hydrogenation reactant system, stirring the hydrogenation reactant system under a hydrogen pressure of 4.0 to 10 MPa and a temperature of 100 to 150° C. for 6 to 12 hours; the ruthenium-based pincer complex catalyst is a ruthenium-based pincer complex catalyst shown in general formula I, the organic solvent is an aromatic hydrocarbon solvent or a ketone solvent, and the additive is a phenol compound;

[0006] In the ruthenium pincer complex catalyst represented by the general formula I, M is metal ruthenium or osmium;

[0007] When M is metal ruthenium, A is carbon, nitrogen, silicon or phosphorus; B 1 or B 2 are independently C, CH, CH 2 or NH; X or Y is independently NR 2 , PR 2 、SiR 3 or SR, R is C1-C6 alkyl, cycloalkyl or aryl; L is halogen, carbonyl, hydrogen or PR 3 One or more of;

[0008] When M is metal osmium, A is a nitrogen atom; B 1 or B 2 CH 2; X or Y is PR 2 , R is a C1-C6 alkyl, cycloalkyl or aryl group; L is one or more of halogen or hydrogen;

[0009]

[0010] The above-mentioned nitrile rubber hydrogenation method is characterized in that the molecular weight range of the nitrile rubber is 200,000 to 500,000, the mass percentage of the nitrile rubber in the rubber solution containing nitrile rubber and organic solvent is 5% to 10%, and the nitrile rubber is a copolymer formed by polymerization of acrylonitrile and butadiene monomers, and the acrylonitrile content is 25% to 45%.

[0011] The above-mentioned nitrile rubber hydrogenation method is characterized in that the ruthenium-based pincer complex catalyst is one or more of the general formulas I-1 to I-16.

[0012]

[0013] The above-mentioned nitrile rubber hydrogenation method is characterized in that the ruthenium-based pincer complex catalyst is of general formula I-4, I-14 or I-15.

[0014] The above-mentioned nitrile rubber hydrogenation method is characterized in that the mass of the ruthenium-based pincer complex catalyst is 0.1‰ to 1‰ of the mass of the nitrile rubber.

[0015] The above-mentioned nitrile rubber hydrogenation method is characterized in that the mass of the ruthenium-based pincer complex catalyst is 0.2‰ to 0.5‰ of the mass of the nitrile rubber.

[0016] The above-mentioned nitrile rubber hydrogenation method is characterized in that the aromatic hydrocarbon solvent is benzene, toluene, chlorobenzene or xylene, and the ketone solvent is one or more of acetone, butanone, cyclohexanone and methyl isopropyl ketone.

[0017] The above-mentioned nitrile rubber hydrogenation method is characterized in that the organic solvent is chlorobenzene or butanone.

[0018] The above-mentioned nitrile rubber hydrogenation method is characterized in that the mass of the additive is 0.2‰ to 0.4‰ of the mass of the nitrile rubber; the additive is phenol, hydroquinone, 2,6-di-tert-butyl-p-cresol, propofol, p-methylphenol or p-tert-butylphenol.

[0019] The above-mentioned nitrile rubber hydrogenation method is characterized in that the additive is 2,6-di-tert-butyl-p-cresol or propofol.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The method for hydrogenating nitrile rubber of the present invention comprises adding a ruthenium-based pincer complex catalyst and an additive to a rubber solution containing nitrile rubber and an organic solvent to obtain a hydrogenation reactant system, and stirring the hydrogenation reactant system under a hydrogen pressure of 4.0 to 10 MPa and a temperature of 100 to 150° C. for 6 to 12 hours. The method has a hydrogenation degree of up to 99.6%, high reaction activity and good stability, and can achieve high selectivity and high conversion rate hydrogenation of nitrile rubber to obtain hydrogenated nitrile rubber on the basis of low catalyst feed.

[0022] 2. The method for hydrogenating nitrile rubber of the present invention creatively uses a ruthenium-based pincer complex as a catalyst and a phenol compound as an additive to hydrogenate the nitrile rubber, and has the characteristics of high conversion rate and high selectivity.

[0023] 3. The nitrile rubber hydrogenation method of the present invention has the characteristics of high stability, can effectively avoid the influence of external conditions such as air and humidity, does not require inert atmosphere protection, and is easy to operate.

[0024] 4. The hydrogenation method of the present invention has low feed amount and can effectively reduce production costs.

[0025] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0026] Instruction Manual

[0027] Figure 1 This is a schematic diagram of the infrared spectrum of the nitrile rubber after the hydrogenation reaction in Example 1.

[0028] Figure 2 Schematic diagram of the H NMR spectrum of the nitrile rubber after hydrogenation reaction in Example 1. DETAILED DESCRIPTION

[0029] The invention provides a method for hydrogenating nitrile rubber, comprising: adding a ruthenium-based pincer complex catalyst and an additive to a rubber solution containing nitrile rubber and an organic solvent to obtain a hydrogenation reactant system, and stirring the hydrogenation reactant system for reaction for 6 to 12 hours under the conditions of a hydrogen pressure of 4.0 to 10 MPa and a temperature of 100 to 150° C.; the ruthenium-based pincer complex catalyst is a ruthenium-based pincer complex catalyst shown in general formula I, the organic solvent is an aromatic hydrocarbon solvent or a ketone solvent, and the additive is a phenol compound; the hydrogen pressure may be, for example, 4.0 MPa, 8.0 MPa or 10 MPa, the temperature may be, for example, 100° C., 130° C. and 150° C., and the reaction time may be, for example, 6 hours, 8 hours or 12 hours;

[0030] In the ruthenium pincer complex catalyst represented by the general formula I, M is metal ruthenium or osmium;

[0031] When M is metal ruthenium, A is carbon, nitrogen, silicon or phosphorus; B 1 or B 2 are independently C, CH, CH 2 or NH; X or Y is independently NR 2 , PR 2 、SiR 3 or SR, R is C1-C6 alkyl, cycloalkyl or aryl; L is halogen, carbonyl, hydrogen or PR 3 One or more of; wherein NR 2 , PR 2 、SiR 3 or R in SR 2 or R 3 Represents the number of substituents R, such as NR 2、 PR 2 The structural formulas of SR are as follows:

[0032]

[0033] When M is metal osmium, A is a nitrogen atom; B 1 or B 2 CH 2 ; X or Y is PR 2 , R is a C1-C6 alkyl, cycloalkyl or aryl group; L is one or more of halogen or hydrogen;

[0034]

[0035] The molecular weight of the nitrile rubber is in the range of 200,000 to 500,000, and the mass percentage of the nitrile rubber in the rubber solution containing the nitrile rubber and the organic solvent is 5 to 10%; the nitrile rubber is a copolymer formed by polymerization of acrylonitrile and butadiene monomers, and the acrylonitrile content is 25 to 45%; the molecular weight of the nitrile rubber can be, for example, 200,000, 300,000 or 500,000, the mass percentage of the nitrile rubber can be, for example, 5%, 8% or 10%, and the acrylonitrile content can be, for example, 25%, 30% or 45%;

[0036] The ruthenium pincer complex catalyst is one or more of the general formulas I-1 to I-16. Preferably, the ruthenium pincer complex catalyst is the general formula I-4, I-14 or I-15;

[0037]

[0038] In addition, the mass of the ruthenium-based pincer complex catalyst is 0.1% to 1% of the mass of the nitrile rubber, such as 0.1%, 0.8% or 1%. Preferably, the mass of the ruthenium-based pincer complex catalyst is 0.2% to 0.5% of the mass of the nitrile rubber, such as 0.2% or 0.5%.

[0039] The aromatic hydrocarbon solvent is benzene, toluene, chlorobenzene or xylene, and the ketone solvent is one or more of acetone, butanone, cyclohexanone and methyl isopropyl ketone. Preferably, the organic solvent is chlorobenzene or butanone.

[0040] The mass of the additive is 0.2-0.4‰ of the mass of the nitrile rubber, for example, it can be 0.2‰ or 0.4‰; the additive is phenol, hydroquinone, 2,6-di-tert-butyl-p-cresol, propofol, p-methylphenol or p-tert-butylphenol, and preferably, the additive is 2,6-di-tert-butyl-p-cresol or propofol.

[0041] In the following examples, catalysts I-1 to I-16 were purchased from Umicore, Strem or Sigma.

[0042] Example 1

[0043] This embodiment provides a method for hydrogenating nitrile rubber, comprising:

[0044] Step 1, dissolving 25g of nitrile rubber in 500mL of an organic solvent to obtain a rubber solution; the organic solvent is chlorobenzene; the nitrile rubber is a copolymer formed by polymerization of acrylonitrile and butadiene monomers, and the acrylonitrile content is 30%; the molecular weight range of the nitrile rubber is 300,000;

[0045] Step 2: Place the glue solution in a 1L high-pressure hydrogenation reactor, add 25mg of catalyst I-1 and 10mg of additive 2,6-di-tert-butyl-p-cresol, replace the air with nitrogen, introduce hydrogen and pressurize to 6.0MPa, heat to 120°C and stir to react for 10h;

[0046] Step 3: The hydrogenation degree of the nitrile rubber was determined by infrared chromatography and nuclear magnetic resonance after the reaction. The hydrogenation results are shown in Table 1.

[0047] In Examples 2 to 16, the catalyst I-1 in step 2 of Example 1 is replaced by I2 to 16 in sequence, and other conditions are the same as those of Example 1. The hydrogenation degrees of Examples 2 to 16 are listed in Table 1.

[0048] Embodiment 17

[0049] This embodiment provides a method for hydrogenating nitrile rubber, comprising:

[0050] Step 1, dissolving 50g of nitrile rubber in 500mL of an organic solvent to obtain a rubber solution; the organic solvent is chlorobenzene; the nitrile rubber is a copolymer formed by polymerization of acrylonitrile and butadiene monomers, and the acrylonitrile content is 30%; the molecular weight range of the nitrile rubber is 300,000;

[0051] Step 2: Place the glue solution in a 1L high-pressure hydrogenation reactor, add 25mg of catalyst I-4 and 10mg of additive 2,6-di-tert-butyl-p-cresol, replace the air with nitrogen, introduce hydrogen and pressurize to 6.0MPa, heat to 120°C and stir to react for 10h;

[0052] Step 3: The hydrogenation degree of the nitrile rubber was determined by infrared chromatography and nuclear magnetic resonance after the reaction. The hydrogenation results are shown in Table 1.

[0053] Embodiment 18

[0054] This embodiment provides a method for hydrogenating nitrile rubber, comprising:

[0055] Step 1, dissolving 25g of nitrile rubber in 500mL of an organic solvent to obtain a rubber solution; the organic solvent is butanone; the nitrile rubber is a copolymer formed by polymerization of acrylonitrile and butadiene monomers, and the acrylonitrile content is 30%; the molecular weight range of the nitrile rubber is 300,000;

[0056] Step 2: Place the glue solution in a 1L high-pressure hydrogenation reactor, add 25mg of catalyst I-4 and 10mg of additive 2,6-di-tert-butyl-p-cresol, replace the air with nitrogen, introduce hydrogen and pressurize to 6.0MPa, heat to 120°C and stir to react for 10h;

[0057] Step 3: The hydrogenation degree of the nitrile rubber was determined by infrared chromatography and nuclear magnetic resonance after the reaction. The hydrogenation results are shown in Table 1.

[0058] Embodiment 19

[0059] This embodiment provides a method for hydrogenating nitrile rubber, comprising:

[0060] Step 1, dissolving 25g of nitrile rubber in 500mL of an organic solvent to obtain a rubber solution; the organic solvent is butanone; the nitrile rubber is a copolymer formed by polymerization of acrylonitrile and butadiene monomers, and the acrylonitrile content is 30%; the molecular weight range of the nitrile rubber is 300,000;

[0061] Step 2: Place the glue solution in a 1L high-pressure hydrogenation reactor, add 25mg of catalyst I-4 and 10mg of propofol, replace the air with nitrogen, introduce hydrogen and pressurize to 6.0MPa, heat to 120°C and stir for 10h;

[0062] Step 3: The hydrogenation degree of the nitrile rubber was determined by infrared chromatography and nuclear magnetic resonance after the reaction. The hydrogenation results are shown in Table 1.

[0063] In Examples 20 to 22, the reaction pressure in step 2 of Example 18 is replaced with 4.0 MPa, 8.0 MPa and 10.0 MPa respectively, and other conditions are the same as those of Example 18. The degree of hydrogenation is listed in Table 1.

[0064] In Examples 23 to 25, the reaction temperature in step 2 of Example 18 is replaced with 100°C, 130°C and 150°C respectively, and other conditions are the same as those of Example 18. The degree of hydrogenation is listed in Table 1.

[0065] In Examples 26 to 28, the reaction time in step 2 of Example 18 is replaced with 6 h, 8 h and 12 h respectively. Other conditions are the same as those of Example 18. The degree of hydrogenation is listed in Table 1.

[0066] Embodiment 29

[0067] This embodiment is the same as Embodiment 18, except that in step 2, the mass of the catalyst is 3 mg, and the mass of the additive is 5 mg.

[0068] Embodiment 30

[0069] This embodiment is the same as Embodiment 19, except that in step 2, the mass of the catalyst is 20 mg, and the mass of the additive is 8 mg.

[0070] Embodiment 31

[0071] This embodiment is the same as Example 17, except that in step 1, the organic solvent is acetone and cyclohexanone, the volume ratio of acetone and cyclohexanone is 1:1, the acrylonitrile content is 25%, and the molecular weight range of nitrile rubber is 200,000; in step 2, the additive is phenol, the catalyst is I-1 and I-2, the mass ratio of I-1 and I-2 is 1:1, and the mass of the catalyst is 10 mg.

[0072] Embodiment 32

[0073] This embodiment is the same as Example 17, except that in step one, the organic solvent is benzene; in step one, the acrylonitrile content is 45%, and the molecular weight of the nitrile rubber is 500,000; in step two, the additive is hydroquinone, and the catalysts are I-5, I-6, I-7 and I-8, and the mass ratio of I-5, I-6, I-7 and I-8 is 1:1:2:1.

[0074] Embodiment 33

[0075] This embodiment is the same as Example 17, except that in step 1, the organic solvent is toluene, the acrylonitrile content is 45%, and the molecular weight of the nitrile rubber is 500,000; in step 2, the additive is p-methylphenol, and the catalysts are I-6, I-7, I-9, I-10 and I-12, and the mass ratio of I-6, I-7, I-9, I-10 and I-12 is 1:1:1:2:1.

[0076] Embodiment 34

[0077] This embodiment is the same as Embodiment 17, except that in step 1, the organic solvent is xylene, the acrylonitrile content is 25%, and the molecular weight of the nitrile rubber is 200,000; and in step 2, the additive is p-tert-butylphenol.

[0078] Embodiment 35

[0079] This embodiment is the same as Embodiment 34, except that the organic solvent in step 1 is acetone.

[0080] Embodiment 36

[0081] This embodiment is the same as Embodiment 34, except that the organic solvent in step 1 is cyclohexanone.

[0082] Embodiment 37

[0083] This embodiment is the same as Embodiment 34, except that the organic solvent in step 1 is methyl isopropyl ketone.

[0084] In the above examples, the structural formulas of catalysts I-1 to I-16 are as follows

[0085]

[0086] Table 1 Hydrogenation degree results

[0087]

[0088]

[0089] As can be seen from Table 1, the hydrogenation degree of nitrile rubber in the hydrogenation method of the present invention can reach up to 99.6%, and the method has high reaction activity and good stability. The method can achieve high selectivity and high conversion rate hydrogenation of nitrile rubber to obtain hydrogenated nitrile rubber on the basis of relatively low catalyst feed.

[0090] according to Figure 1-2 It can be seen that the obtained hydrogenated nitrile rubber has a high degree of hydrogenation and good selectivity, and the degree of hydrogenation can reach more than 99%.

[0091] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for hydrogenating nitrile rubber, It is characterized in that include: A pincer complex catalyst and an additive are added to a rubber solution containing nitrile rubber and an organic solvent to obtain a hydrogenation reactant system, and the hydrogenation reactant system is stirred and reacted for 6 to 12 hours under the conditions of a hydrogen pressure of 4.0 to 10 MPa and a temperature of 100 to 150° C.; the pincer complex catalyst is a pincer complex catalyst shown in general formula I, the organic solvent is an aromatic hydrocarbon solvent or a ketone solvent, and the additive is a phenol compound; In the pincer complex catalyst shown in the general formula I, M is metal ruthenium or osmium; When M is metal ruthenium, A is carbon, nitrogen, silicon or phosphorus; B 1 or B 2 are independently C, CH, CH 2 or NH; X or Y is independently NR 2 , PR 2 、SiR 3 or SR, R is C1-C6 alkyl, cycloalkyl or aryl; L is halogen, carbonyl, hydrogen or PR 3 One or more of; When M is metal osmium, A is a nitrogen atom; B 1 or B 2 CH 2 ; X or Y is PR 2 , R is C1-C6 alkyl, cycloalkyl or aryl; L is one or more of halogen or hydrogen 。 2. A method for hydrogenating nitrile rubber according to claim 1, It is characterized in that The molecular weight of the nitrile rubber is in the range of 200,000 to 500,000. In the rubber solution containing nitrile rubber and organic solvent, the mass percentage of nitrile rubber is 5% to 10%. The nitrile rubber is a copolymer formed by polymerization of acrylonitrile and butadiene monomers, and the acrylonitrile content is 25% to 45%.

3. A method for hydrogenating nitrile rubber according to claim 1, It is characterized in that The pincer complex catalyst is one or more of the general formulas I-1 to I-16 。 4. A method for hydrogenating nitrile rubber according to claim 3, It is characterized in that The pincer complex catalyst is of general formula I-4, I-14 or I-15.

5. A method for hydrogenating nitrile rubber according to claim 1, It is characterized in that The mass of the pincer complex catalyst is 0.1‰ to 1‰ of the mass of the nitrile rubber.

6. A method for hydrogenating nitrile rubber according to claim 5, It is characterized in that The mass of the pincer complex catalyst is 0.2‰ to 0.5‰ of the mass of the nitrile rubber.

7. A method for hydrogenating nitrile rubber according to claim 1, It is characterized in that The aromatic hydrocarbon solvent is benzene, toluene, chlorobenzene or xylene, and the ketone solvent is one or more of acetone, butanone, cyclohexanone and methyl isopropyl ketone.

8. A method for hydrogenating nitrile rubber according to claim 7, It is characterized in that The organic solvent is chlorobenzene or butanone.

9. A method for hydrogenating nitrile rubber according to claim 1, It is characterized in that The mass of the additive is 0.2‰ to 0.4‰ of the mass of the nitrile rubber; the additive is phenol, hydroquinone, 2,6-di-tert-butyl-p-cresol, propofol, p-methylphenol or p-tert-butylphenol.

10. A method for hydrogenating nitrile rubber according to claim 9, It is characterized in that The additive is 2,6-di-tert-butyl-p-cresol or propofol.

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