Process for hydrogenating butadiene-acrylonitrile rubber, hydrogenated butadiene-acrylonitrile rubber and use

Abstract

This invention relates to the field of hydrogenation of unsaturated copolymers, and discloses a method for hydrogenating nitrile rubber, hydrogenated nitrile rubber, and its applications. The method includes the following steps: a) Hydrogenation reaction: In the presence of hydrogen, a polyethylene glycol-stabilized rhodium nano-catalyst is contacted with a nitrile rubber solution to carry out a hydrogenation reaction; b) Catalyst recovery: After the hydrogenation reaction is completed, the pressure and temperature are reduced, a first solvent is added, and the mixture is stirred. After further cooling to room temperature, phase separation is performed to obtain the recovered catalyst. The recovered catalyst from step b is recycled back to step a for reuse. The solid content of the nitrile rubber solution is 1-15 wt%. After cooling and adding the first solvent, the system temperature is set to 65-75°C. This method is environmentally friendly. The polyethylene glycol-stabilized rhodium nano-catalyst exhibits high catalytic activity and good recyclability when used in the hydrogenation of nitrile rubber. The catalyst can be separated through a simple phase separation operation.

Description

Technical Field

[0001] This invention relates to the field of hydrogenation of unsaturated copolymers, and more specifically, to a method for hydrogenating nitrile rubber, hydrogenated nitrile rubber, and its applications. Background Technology

[0002] Hydrogenated nitrile rubber possesses excellent properties such as wear resistance, low temperature resistance (-40℃), oxidation resistance, ozone resistance, and thermal stability. It can be used to manufacture components for automotive fuel systems, oilfield blowout preventers, seals for nuclear power plants, and printing and dyeing rollers. Currently, it is mainly produced through hydrogenation modification of nitrile rubber.

[0003] Currently, most hydrogenated nitrile butadiene products on the market are produced using the homogeneous solution hydrogenation method. The catalyst is dispersed in the polymer solution in molecular form, and the degree of hydrogenation is easy to meet. However, this method generally uses expensive noble metal coordination compounds as catalysts. The noble metals leave a large amount of residue in the hydrogenation products, and it is difficult to separate the catalyst from the hydrogenation products. If the catalyst remains in the rubber products, it will seriously affect their aging performance and increase the production cost. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of high catalyst cost, large residual amount, and difficult separation in the existing technology, and to provide a method for hydrogenating nitrile rubber, hydrogenated nitrile rubber and its application. The nitrile rubber hydrogenation uses a nano-rhodium catalyst with high catalytic activity, and the catalyst can be separated and recycled through a simple phase separation operation.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for hydrogenating nitrile rubber, characterized by comprising the following steps:

[0006] a. Hydrogenation reaction: In the presence of hydrogen, a polyethylene glycol-stabilized nano-rhodium catalyst is contacted with a nitrile rubber solution to carry out a hydrogenation reaction;

[0007] b. Catalyst recovery: After the hydrogenation reaction is completed, the pressure and temperature are reduced, the first solvent is added, the mixture is stirred for the first time, and after cooling to room temperature, the phases are separated to obtain the recovered catalyst.

[0008] The recovered catalyst described in step b is recycled back to step a for reuse;

[0009] The solid content of the nitrile rubber solution is 1-15 wt%.

[0010] The cooling process, followed by the addition of the first solvent, resulted in a system temperature of 65-75°C.

[0011] A second aspect of the present invention provides a hydrogenated nitrile butadiene rubber, characterized in that it is prepared by the method provided in the first aspect of the present invention;

[0012] When the polyethylene glycol-stabilized nano-rhodium catalyst is used once, the degree of hydrogenation of the hydrogenated nitrile butadiene rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile butadiene rubber is not greater than 1 ppm.

[0013] According to one embodiment of the present invention, when the polyethylene glycol-stabilized nano-rhodium catalyst is used 5 times, the degree of hydrogenation of the hydrogenated nitrile rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile rubber is not greater than 5 ppm.

[0014] According to one embodiment of the present invention, when the polyethylene glycol-stabilized nano-rhodium catalyst is used 10 times, the degree of hydrogenation of the hydrogenated nitrile butadiene rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile butadiene rubber is not greater than 10 ppm.

[0015] The third aspect of the present invention provides an application of the hydrogenated nitrile butadiene rubber described in the second aspect of the present invention in at least one field, namely aerospace, oil field, transportation and deep sea.

[0016] Through the above technical solutions, the method for hydrogenating nitrile butadiene rubber (NBR), the hydrogenated NBR, and its applications provided by this invention achieve the following beneficial effects: In the method for hydrogenating NBR provided by this invention, by utilizing a nano-rhodium catalyst and using polyethylene glycol as the mobile phase of the catalyst, the active component nano-rhodium is dynamically supported therein, resulting in high hydrogenation catalytic activity. Furthermore, the catalyst has good recyclability and can be stably applied to the NBR hydrogenation reaction. Moreover, the nano-rhodium catalyst can be separated from the hydrogenated NBR solution through simple phase separation, and the catalyst loss rate is low. Detailed Implementation

[0017] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0018] The first aspect of this invention provides a method for hydrogenating nitrile rubber, characterized by comprising the following steps:

[0019] a. Hydrogenation reaction: In the presence of hydrogen, a polyethylene glycol-stabilized nano-rhodium catalyst is contacted with a nitrile rubber solution to carry out a hydrogenation reaction;

[0020] c. Catalyst recovery: After the hydrogenation reaction is completed, the pressure and temperature are reduced, the first solvent is added, the mixture is stirred for the first time, and after cooling to room temperature, the phases are separated to obtain the recovered catalyst.

[0021] The recovered catalyst described in step b is recycled back to step a for reuse;

[0022] The solid content of the nitrile rubber solution is 1-15 wt%.

[0023] The cooling process, followed by the addition of the first solvent, resulted in a system temperature of 65-75°C.

[0024] In this invention, polyethylene glycol is used as the mobile phase of the catalyst, and the active component, nano-rhodium, is dynamically supported therein, resulting in high catalytic activity and good recyclability.

[0025] When the solid content of the nitrile rubber solution meets the above-mentioned range, its viscosity is more suitable for hydrogenation, thereby further increasing the degree of hydrogenation.

[0026] In this invention, the conditions for the first stirring are not particularly limited. For example, in this invention, stirring can be carried out at 70-90°C for 1-12 hours.

[0027] In this invention, the hydrogenation reaction described in step a is preferably carried out under a fourth stirring. In order to obtain better technical results, the stirring speed of the fourth stirring is 20-600 rpm, preferably 50-400 rpm.

[0028] In this invention, the first solvent is selected from at least one of n-heptane, cyclohexane, diethyl ether, and isopropyl ether.

[0029] In this invention, after the first stirring, it is preferable to cool the system to room temperature (20-25°C) before performing phase separation.

[0030] In this invention, during the hydrogenation reaction, the ethylene glycol phase and the nitrile rubber solution are miscible as one phase, and the nano-rhodium catalyst is uniformly dispersed in the system, allowing the hydrogenation reaction to proceed efficiently. After the reaction is completed, a first solvent is added, and the system temperature is controlled so that the polyethylene glycol-stabilized nano-rhodium catalyst and the nitrile rubber solution are separated into two mutually insoluble liquid-liquid phases. The active component, nano-rhodium, returns from the organic solvent phase to the polyethylene glycol phase. After the system is further cooled to room temperature, the catalyst can be separated and recycled through a simple phase separation operation.

[0031] In this invention, the phase separation operation is not particularly limited and can be a conventional phase separation operation in the art. Those skilled in the art can make adjustments as needed, for example, it can be filtration.

[0032] According to the present invention, the number average molecular weight of the polyethylene glycol is 400-10000.

[0033] In this invention, when the number-average molecular weight of the polyethylene glycol meets the above-mentioned range, the viscosity is suitable, which can effectively disperse the active component, nano-rhodium, and further improve the catalytic activity.

[0034] According to the present invention, the number average molecular weight of the polyethylene glycol is 1000-5000.

[0035] According to the present invention, the particle size of the polyethylene glycol-stabilized rhodium nanocatalyst is 1-10 nm.

[0036] In this invention, when the particle size of the polyethylene glycol-stabilized rhodium nanocatalyst meets the above-mentioned range, the catalyst can be uniformly dispersed in the reaction system when applied to the hydrogenation reaction of nitrile rubber, thereby improving catalytic activity and catalytic efficiency.

[0037] According to the present invention, the particle size of the polyethylene glycol-stabilized rhodium nanocatalyst is 1-5 nm.

[0038] According to the present invention, the content of rhodium element is 10-280 ppm, based on the total amount of the polyethylene glycol-stabilized nano-rhodium catalyst.

[0039] In this invention, when the content of the rhodium element meets the above-mentioned range, the cost can be reduced while ensuring catalytic activity.

[0040] According to the present invention, the rhodium content is 25-160 ppm, based on the total amount of the polyethylene glycol-stabilized nano-rhodium catalyst.

[0041] In this invention, the method further includes: after the fourth stirring is completed, cooling and depressurization are carried out so that the temperature of the system is room temperature (20-25℃) and the pressure is atmospheric pressure.

[0042] According to the present invention, the nitrile rubber solution contains a second solvent and nitrile rubber.

[0043] In this invention, the nitrile rubber solution is obtained by dissolving nitrile rubber in a second solvent.

[0044] Further, the second solvent is an organic solvent selected from at least one of aromatic hydrocarbons, derivatives of aromatic hydrocarbons substituted with alkyl or halogens, haloalkanes, ethers, ketones, and amides, preferably at least one of benzene, toluene, xylene, chlorobenzene, dichlorobenzene, trichlorobenzene, dichloromethane, chloroform, 1,2-dichloroethane, tetrahydrofuran, acetone, butanone, and N,N-dimethylformamide.

[0045] In this invention, the preparation of the nitrile rubber solution is preferably carried out in the presence of a protective gas.

[0046] According to the present invention, the solid content of the nitrile rubber solution is 3-10 wt%.

[0047] According to the present invention, the content of rhodium in the polyethylene glycol-stabilized nano-rhodium catalyst is 0.01-0.5 wt% of nitrile rubber.

[0048] In this invention, the rhodium content in the polyethylene glycol-stabilized nano-rhodium catalyst is 0.01-0.5 wt% of the nitrile rubber, which enables the hydrogenation reaction of nitrile rubber to be efficient and economical.

[0049] According to the present invention, the content of rhodium in the polyethylene glycol-stabilized nano-rhodium catalyst is 0.03-0.1 wt% of nitrile rubber.

[0050] According to the present invention, the conditions for the hydrogenation reaction include: pressure 1-10 MPa, temperature 70-150°C, and time 1-18 h.

[0051] In this invention, when the conditions for the hydrogenation reaction meet the above-mentioned range, the hydrogenation reaction of nitrile rubber is stable and efficient under the action of a polyethylene glycol-stabilized nano-rhodium catalyst.

[0052] According to the present invention, the conditions for the hydrogenation reaction include: pressure 3-8 MPa, temperature 80-150°C, and time 4-12 h.

[0053] According to the present invention, the conditions for the first stirring include: stirring time of 1-3 hours and stirring temperature of 65-75°C.

[0054] In this invention, there is no particular limitation on the stirring rate of the first stirring, as long as the particle size of the rhodium salt meets the requirements. For example, the stirring rate in this invention can be 50-400 rpm.

[0055] In this invention, when the system temperature meets the above-mentioned range during the first stirring, the organic solvent phase and the ethylene glycol phase can be efficiently separated, thereby efficiently separating the polyethylene glycol-stabilized nano-rhodium catalyst, resulting in low residual rhodium catalyst in the hydrogenated nitrile rubber.

[0056] According to the present invention, the mass ratio of the first solvent, polyethylene glycol and the second solvent is 1:0.4-3:1-7.

[0057] In this invention, the inventors discovered that the types of the first solvent and the second solvent have a significant impact on the temperature at which the second solvent and the ethylene glycol phase achieve liquid-liquid separation, and it is necessary to ensure that the temperature at which the second solvent and the polyethylene glycol phase achieve liquid-liquid separation is not lower than 75°C.

[0058] According to the present invention, the method for preparing the polyethylene glycol-stabilized rhodium nanocatalyst includes the following steps:

[0059] S1. Rhodium salt and polyethylene glycol are stirred a second time to obtain a mixture;

[0060] S2. Under anaerobic conditions, hydrogen gas is introduced into the above mixture for pressurization, and a third stirring is performed to obtain a polyethylene glycol-stabilized rhodium nanocatalyst.

[0061] In the mixture, the mass ratio of the rhodium salt to the polyethylene glycol is 0.00001-0.00028:1, calculated as rhodium.

[0062] In this invention, the preparation method is simple to operate, environmentally friendly, and the prepared polyethylene glycol-stabilized rhodium nanocatalyst has a small particle size and good repeatability.

[0063] In this invention, the introduction of hydrogen gas and pressurization to the above-mentioned range can efficiently reduce rhodium ions to zero-valent rhodium, thereby obtaining a polyethylene glycol-stabilized nano-rhodium catalyst with high catalytic efficiency.

[0064] In this invention, there are no special requirements or limitations on the conditions and methods for creating an oxygen-free environment in step S2. For example, in this invention, a protective gas can be used to replace the system. Preferably, the protective gas can be nitrogen and / or an inert gas.

[0065] Furthermore, in the mixture, when the mass ratio of the rhodium salt to the polyethylene glycol, calculated as rhodium, meets the above-mentioned range, the rhodium salt exhibits good dispersibility and high catalytic activity in the polyethylene glycol.

[0066] Furthermore, in order to achieve better technical results, after the system is replaced with a protective gas, hydrogen gas can be introduced for another replacement.

[0067] In this invention, the inventors discovered that when the rhodium salt is selected from rhodium chloride, the resulting catalyst exhibits stable performance, which is beneficial for improving hydrogenation efficiency.

[0068] Furthermore, in this invention, the rhodium salt is preferably added in the form of an aqueous solution of rhodium salt.

[0069] According to the present invention, the conditions for the second stirring include stirring at 70-90°C for 1-3 hours.

[0070] In this invention, the conditions for the second stirring satisfy the above-mentioned range, which enables the rhodium salt to be better dispersed in polyethylene glycol, thereby improving its dispersibility and thus improving the hydrogenation efficiency.

[0071] In this invention, there is no particular limitation on the stirring rate of the second stirring, as long as the rhodium salt is uniformly dispersed in polyethylene glycol. For example, in this invention, the stirring rate of the second stirring is 200-500 rpm.

[0072] According to the present invention, the conditions for the third stirring include stirring at 70-90°C for 4-10 hours.

[0073] In this invention, there is no particular limitation on the stirring rate of the third stirring, as long as it enables the rhodium ions to be efficiently reduced. For example, in this invention, the stirring rate of the third stirring is 200-500 rpm.

[0074] According to the present invention, in the mixture, the mass ratio of the rhodium salt to the polyethylene glycol is 0.000025-0.00016:1, calculated as rhodium.

[0075] In this invention, in step S2, the pressurization makes the system pressure 3-6 MPa.

[0076] A second aspect of the present invention provides a hydrogenated nitrile butadiene rubber, characterized in that it is prepared by the method provided in the first aspect of the present invention;

[0077] Wherein, when the polyethylene glycol-stabilized nano-rhodium catalyst is used once, the degree of hydrogenation of the hydrogenated nitrile butadiene rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile butadiene rubber is not greater than 1 ppm.

[0078] Alternatively, when the polyethylene glycol-stabilized nano-rhodium catalyst is used 5 times, the degree of hydrogenation of the hydrogenated nitrile butadiene rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile butadiene rubber is not greater than 5 ppm.

[0079] Alternatively, when the polyethylene glycol-stabilized nano-rhodium catalyst is used 10 times, the degree of hydrogenation of the hydrogenated nitrile butadiene rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile butadiene rubber is not greater than 10 ppm.

[0080] The third aspect of the present invention provides an application of the hydrogenated nitrile butadiene rubber described in the second aspect of the present invention in at least one field, namely aerospace, oil field, transportation and deep sea.

[0081] The present invention will be described in detail below through preparation examples and embodiments.

[0082] In the following examples, the degree of hydrogenation was measured by HNMR;

[0083] The residual rhodium content in hydrogenated nitrile butadiene rubber was determined by inductively coupled plasma atomic emission spectrometry (ICP-OES).

[0084] The particle size of the polyethylene glycol-stabilized rhodium nanocatalyst was measured by TEM.

[0085] In the preparation example, the nitrile rubber was purchased from Lanzhou Petrochemical Company of China National Petroleum Corporation, grade 4105;

[0086] Polyethylene glycol with molecular weights of 1000, 2000, 4000, 10000, and 20000 was purchased from Alfa Aesar.

[0087] RhCl3·3H2O was purchased from Kunming Platinum Metal Materials Co., Ltd.

[0088] Polyvinyl alcohol, molecular weight 20,000, purchased from Alfa Aesar;

[0089] Na2PdCl4·xH2O (containing 30wt% Pd), 99% pure, purchased from Alfa Aesar.

[0090] All other reagents were commercially available analytical grade pharmaceuticals.

[0091] The following preparation examples describe the preparation of polyethylene glycol-stabilized rhodium nanocatalysts.

[0092] Preparation Example 1

[0093] S1. 0.7g of RhCl3 aqueous solution (containing 0.24mmol of RhCl3·3H2O) and 263g of polyethylene glycol 4000 were added to a reaction vessel and stirred at 90℃ and a stirring rate of 300r / min for 2h to obtain a mixture. The mass ratio of rhodium salt to polyethylene glycol 4000, calculated as rhodium, was 0.000095:1.

[0094] S2. After replacing the mixture in the reactor with nitrogen and hydrogen respectively, the reactor is pressurized to 4 MPa with hydrogen and stirred at 70°C and 300 r / min for 2 h. The temperature is then reduced to 20°C and the pressure is reduced to atmospheric pressure to obtain polyethylene glycol-stabilized rhodium nanocatalyst A1.

[0095] The particle size and rhodium content of the polyethylene glycol-stabilized nano-rhodium catalyst A1 are shown in Table 1.

[0096] Preparation Example 2

[0097] S1. 1.4 g of RhCl3 aqueous solution (containing 0.49 mmol of RhCl3·3H2O) and 2000 g of polyethylene glycol 2000 were added to a reaction vessel and stirred at 70 °C and a stirring rate of 300 r / min for 4 h to obtain a mixture. The mass ratio of rhodium to polyethylene glycol 2000 was 0.000025:1, calculated as rhodium.

[0098] S2. After replacing the mixture in the reactor with nitrogen and hydrogen respectively, the reactor is pressurized to 4 MPa with hydrogen and stirred at 90°C and 300 r / min for 2 h. The temperature is then reduced to 20°C and the pressure is reduced to atmospheric pressure to obtain polyethylene glycol-stabilized rhodium nanocatalyst A2.

[0099] The particle size and rhodium content of the polyethylene glycol-stabilized nano-rhodium catalyst A2 are shown in Table 1.

[0100] Preparation Example 3

[0101] S1. Add 0.4g of RhCl3 aqueous solution (containing 0.15mmol of RhCl3·3H2O) and 94g of polyethylene glycol 1000 to a reaction vessel. Stir at 70℃ and 300r / min for 4h to obtain a mixture. The mass ratio of rhodium to polyethylene glycol 1000 is 0.00016:1, calculated as rhodium.

[0102] S2. After replacing the mixture in the reactor with nitrogen and hydrogen respectively, pressurize the reactor with hydrogen to 2MPa, stir at 90℃ and stirring rate of 300r / min for 4h, cool down to 20℃, and reduce the pressure to atmospheric pressure to obtain polyethylene glycol-stabilized rhodium nanocatalyst A3.

[0103] The particle size and rhodium content of the polyethylene glycol-stabilized nano-rhodium catalyst A3 are shown in Table 1.

[0104] Preparation Example 4

[0105] The method was consistent with that of Example 1, except that the amount of polyethylene glycol 4000 used was 118 g, and the mass ratio of rhodium to polyethylene glycol 4000 in the resulting mixture was 0.000212:1 (calculated as rhodium).

[0106] The particle size and rhodium content of the polyethylene glycol-stabilized nano-rhodium catalyst A4 are shown in Table 1.

[0107] Preparation Example 5

[0108] The method was consistent with that of Example 1, except that the amount of polyethylene glycol 4000 used was 60 g, and the mass ratio of rhodium to polyethylene glycol 4000 in the resulting mixture was 0.000411:1 (calculated as rhodium).

[0109] The particle size and rhodium content of the polyethylene glycol-stabilized nano-rhodium catalyst A5 are shown in Table 1.

[0110] Preparation Example 6

[0111] The method was the same as that used in Preparation Example 1, except that the mixture was stirred at 25°C for 10 hours.

[0112] The particle size and rhodium content of the polyethylene glycol-stabilized nano-rhodium catalyst A6 are shown in Table 1.

[0113] Preparation Example 7

[0114] The method is the same as that used in Preparation Example 1, except that polyethylene glycol 4000 is replaced with polyethylene glycol 10000.

[0115] The particle size and rhodium content of the obtained polyethylene glycol-stabilized nano-rhodium catalyst A7 are shown in Table 1.

[0116] Preparation Example 8

[0117] The method is the same as that used in Preparation Example 1, except that polyethylene glycol 4000 is replaced with polyethylene glycol 20000;

[0118] The particle size and rhodium content of the obtained polyethylene glycol-stabilized nano-rhodium catalyst A8 are shown in Table 1.

[0119] Comparative Preparation Example 1

[0120] The method is the same as that used in Example 1, except that polyethylene glycol 4000 is replaced with polyvinyl alcohol (molecular weight 20000);

[0121] The particle size and rhodium content of the obtained polyvinyl alcohol-stabilized nano-rhodium catalyst D1 are shown in Table 1.

[0122] Comparative Preparation Example 2

[0123] The method is the same as that used in preparation 1, except that the aqueous solution of RhCl3 is replaced with an aqueous solution of Na2PdCl4.

[0124] The particle size and palladium content of the obtained polyethylene glycol-stabilized nano-palladium catalyst D2 are shown in Table 1.

[0125] Comparative preparation example 3

[0126] The method was consistent with that of Preparation Example 1, except that the nano-sized rhodium metal particles obtained by physical grinding were dispersed in polyethylene glycol-4000. The particle size and rhodium content of the obtained polyethylene glycol-stabilized nano-rhodium catalyst D3 are shown in Table 1.

[0127] Table 1

[0128] catalyst Average particle size / nm Rhodium / Palladium content / ppm A1 2.2 95 A2 1.3 25 A3 3.5 160 A4 5.4 212 A5 9.2 275 A6 8.6 94 A7 5.9 95 A8 9.8 93 D1 15 5 D2 25 94 D3 58.9 94

[0129] As shown in Table 1, the average particle size of preparation examples 1-8 is between 1-10 nm, and the rhodium content is between 10-280 ppm. Among them, the preferred examples 1-3 have an average particle size in the range of 1-5 nm, and the rhodium content is in the range of 25-160 ppm.

[0130] The following examples and comparative examples describe the method for hydrogenating nitrile rubber and recovering the catalyst. Wherein, the solid content of the nitrile rubber solution refers to the percentage of the mass of nitrile rubber to the mass of the nitrile rubber solution; the amount of rhodium nanocatalyst used refers to the percentage of the mass of rhodium in the catalyst to the mass of nitrile rubber; and the residual rhodium in the hydrogenated nitrile rubber refers to the percentage of the mass of rhodium in the hydrogenated nitrile rubber to the mass of the nitrile rubber.

[0131] Example 1

[0132] a. Hydrogenation reaction: Under nitrogen protection, 50g of nitrile rubber was dissolved in 950g of toluene solution to obtain nitrile rubber solution. Polyethylene glycol-stabilized nano-rhodium catalyst A1 was added to the solution. The reaction was carried out for 12h at a hydrogen pressure of 8MPa, a system temperature of 80℃, and a stirring rate of 100rpm to obtain hydrogenated nitrile rubber solution.

[0133] b. After the pressure is reduced to atmospheric pressure, 315g of n-heptane (50℃) is added to the reactor. At this point, the system temperature is 70℃. The mixture is stirred at 100rpm and 70℃ for 2 hours (first stirring). After cooling to room temperature, catalyst A1 is recovered by phase separation. The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2.

[0134] The mass ratio of n-heptane, polyethylene glycol, and toluene was 1:0.8:3. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium in the hydrogenated nitrile rubber are shown in Table 3.

[0135] Example 2

[0136] The method is consistent with that in Example 1, except that:

[0137] (1) Replace A1 with A2;

[0138] (2) The conditions for the hydrogenation reaction are: 130℃, 3MPa, 100rpm for 7h.

[0139] (3) When recovering the catalyst, after the system temperature is reduced to 105℃, 539g of n-heptane (25℃) is added to the reactor. At this time, the system temperature is 70℃. Stir at 200rpm and 70℃ for 1h.

[0140] The mass ratio of n-heptane, polyethylene glycol, and toluene is 1:0.48:1.76.

[0141] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0142] Example 3

[0143] The method is consistent with that in Example 1, except that:

[0144] (1) Replace A1 with A3;

[0145] (2) The conditions for the hydrogenation reaction are: 120℃, 5MPa, 300rpm for 7h.

[0146] (3) When recovering the catalyst, after the system temperature is reduced to 80°C, 150g of n-heptane (25°C) is added to the reactor. At this time, the system temperature is 70°C. Stir at 400rpm and 70°C for 1h. The mass ratio of n-heptane, polyethylene glycol and toluene is 1:1.75:6.3.

[0147] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0148] Examples 4-8

[0149] Similar to Example 1, except that A1 is replaced with A4-A9.

[0150] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0151] Example 9

[0152] Similar to Example 1, except that the hydrogenation reaction conditions were: 75°C for 24 hours at a hydrogen pressure of 8 MPa.

[0153] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0154] Example 10

[0155] The method is consistent with that in Example 1, except that A1 is reused 5 times.

[0156] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0157] Example 11

[0158] The method is consistent with that in Example 1, except that A1 is reused 10 times.

[0159] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0160] Example 12

[0161] The method is the same as in Example 2, except that A2 is reused 5 times.

[0162] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0163] Example 13

[0164] The method is the same as in Example 2, except that A2 is reused 10 times.

[0165] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0166] Example 14

[0167] The method is the same as in Example 3, except that A3 is reused 5 times.

[0168] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0169] Example 15

[0170] The method is consistent with that in Example 3, except that A3 is reused 10 times.

[0171] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0172] Comparative Examples 1-3

[0173] The method is consistent with that in Example 1, except that A1 is replaced with D1-D3.

[0174] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0175] Comparative Example 4

[0176] Similar to Example 1, except that the amount of nitrile rubber used is 5g and the amount of toluene used is 950g.

[0177] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0178] Comparative Example 5

[0179] Similar to Example 1, except that when recovering the catalyst, after the system temperature was lowered to 60°C, 315g of n-heptane (25°C) was added to the reactor, at which point the system temperature was 50°C, and the mixture was stirred at 100rpm and 50°C (first stirring) for 2 hours.

[0180] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0181] Comparative Example 6

[0182] Similar to Example 1, except that when recovering the catalyst, no n-heptane was added. Instead, the system temperature was directly lowered to room temperature (25°C) and then stirred at 100 rpm and 25°C for 2 hours (first stirring).

[0183] The hydrogenation conditions and the conditions for the first stirring are detailed in Table 2. The solid content of the nitrile rubber solution, the amount of rhodium nanocatalyst, the degree of hydrogenation, and the residual rhodium content in the hydrogenated nitrile rubber are shown in Table 3.

[0184] Table 2

[0185]

[0186]

[0187] *Refers to the first stirring step b.

[0188] Table 3

[0189]

[0190]

[0191] The results above show that Examples 1-15 of the present invention have good effects, wherein the degree of hydrogenation is above 50% and the residual rhodium content does not exceed 60 ppm.

[0192] Examples 1-4, 7, 9 and 11 have further effects, with hydrogenation degree all above 70% and rhodium residue not exceeding 13 ppm.

[0193] Furthermore, Examples 1-3, which conform to the preferred technical solutions of the present invention, have significantly better effects, with hydrogenation degree all above 82% and rhodium residue not exceeding 0.5 ppm.

[0194] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for hydrogenating nitrile rubber, characterized in that, Includes the following steps: a. Hydrogenation reaction: In the presence of hydrogen, a polyethylene glycol-stabilized nano-rhodium catalyst is contacted with a nitrile rubber solution to carry out a hydrogenation reaction; b. Catalyst recovery: After the hydrogenation reaction is completed, the pressure and temperature are reduced, the first solvent is added, the mixture is stirred for the first time, and after cooling to room temperature, the phases are separated to obtain the recovered catalyst. The recovered catalyst described in step b is recycled back to step a for reuse; The solid content of the nitrile rubber solution is 1-15 wt%. The cooling process and the addition of the first solvent resulted in a system temperature of 65-75°C. The preparation method of the polyethylene glycol-stabilized rhodium nanocatalyst includes the following steps: S1. Rhodium salt and polyethylene glycol are stirred a second time to obtain a mixture; S2. Under anaerobic conditions, hydrogen gas is introduced into the above mixture for pressurization, and a third stirring is performed to obtain a polyethylene glycol-stabilized rhodium nanocatalyst. In the mixture, the mass ratio of the rhodium salt to the polyethylene glycol is 0.00001-0.00028:1, calculated as rhodium.

2. The method for hydrogenating nitrile rubber according to claim 1, wherein, The number average molecular weight of the polyethylene glycol is 400-10000.

3. The method for hydrogenating nitrile rubber according to claim 2, wherein, The number average molecular weight of the polyethylene glycol is 1000-5000.

4. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, The polyethylene glycol-stabilized rhodium nanocatalyst has a particle size of 1-10 nm.

5. The method for hydrogenating nitrile rubber according to claim 4, wherein, The polyethylene glycol-stabilized rhodium nanocatalyst has a particle size of 1-5 nm.

6. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, Based on the total amount of the polyethylene glycol-stabilized nano-rhodium catalyst, the rhodium content is 10-280 ppm.

7. The method for hydrogenating nitrile rubber according to claim 6, wherein, Based on the total amount of the polyethylene glycol-stabilized nano-rhodium catalyst, the rhodium content is 25-160 ppm.

8. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, The nitrile rubber solution contains a second solvent and nitrile rubber.

9. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, The solid content of the nitrile rubber solution is 3-10 wt%.

10. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, The amount of the polyethylene glycol-stabilized nano-rhodium catalyst and the nitrile rubber solution used is such that the rhodium content is 0.01-0.5 wt% of the nitrile rubber.

11. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, The amount of the polyethylene glycol-stabilized nano-rhodium catalyst and the nitrile rubber solution used is such that the rhodium content is 0.03-0.1 wt% of the nitrile rubber.

12. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, The conditions for the hydrogenation reaction include: pressure 1-10 MPa, temperature 75-150℃, and time 1-18 h.

13. The method for hydrogenating nitrile rubber according to claim 12, wherein, The conditions for the hydrogenation reaction include: pressure 3-8 MPa, temperature 80-130℃, and time 4-12 h.

14. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, The pressure reduction brings the system pressure to atmospheric pressure.

15. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, The conditions for the first stirring include: stirring time of 1-3 hours and stirring temperature of 65-75℃.

16. The method for hydrogenating nitrile rubber according to claim 8, wherein, The mass ratio of the first solvent, the polyethylene glycol, and the second solvent is 1:0.4-3:1-7.

17. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, In the mixture, the mass ratio of the rhodium salt to the polyethylene glycol is 0.000025-0.00016:1, calculated as rhodium.

18. The method for hydrogenating nitrile rubber according to claim 1 or 2, wherein, In step S2, the pressurization makes the system pressure 3-6 MPa.

19. A hydrogenated nitrile butadiene rubber, characterized in that, Prepared by the method according to any one of claims 1-18; Wherein, when the polyethylene glycol-stabilized nano-rhodium catalyst is used once, the degree of hydrogenation of the hydrogenated nitrile butadiene rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile butadiene rubber is not greater than 1 ppm. Alternatively, when the polyethylene glycol-stabilized nano-rhodium catalyst is used 5 times, the degree of hydrogenation of the hydrogenated nitrile butadiene rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile butadiene rubber is not greater than 5 ppm. Alternatively, when the polyethylene glycol-stabilized nano-rhodium catalyst is used 10 times, the degree of hydrogenation of the hydrogenated nitrile butadiene rubber is not less than 82%, and the residual rhodium content in the hydrogenated nitrile butadiene rubber is not greater than 10 ppm.

20. The application of the hydrogenated nitrile butadiene rubber of claim 19 in at least one of the fields of aerospace, oilfield, transportation and deep sea.

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