A method for preparing adiponitrile by electrolyzing acrylonitrile based on an anodic sacrificial agent

Abstract

The present invention discloses a method for preparing adiponitrile by electrolyzing acrylonitrile based on an anodic sacrificial agent, which relates to the technical field of electrochemical synthesis. Through the electrolytic dimerization of acrylonitrile coupled with the oxidation reaction of the sacrificial agent, the conversion rate of acrylonitrile can be increased, and the electrical energy generated by the electrode reaction can be mutually supplemented to improve the energy utilization efficiency of the entire system. The challenge of this coupling reaction lies in the need to precisely control the electrolysis conditions to ensure that both reactions can proceed efficiently while avoiding the occurrence of side reactions. The difficulty lies in the preparation of the catalyst and the regulation of the electrolysis system environment. The method of the present invention can effectively achieve the regulation of the electrolysis system environment. Compared with the current industrial method for synthesizing adiponitrile by electrolyzing acrylonitrile, it can effectively control the generation of oxygen, the entire electrolysis process is safe, the conversion rate of acrylonitrile is not less than 82%, and the selectivity of the obtained adiponitrile is not less than 85%.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical synthesis, and particularly relates to a method for preparing adiponitrile by electrolyzing acrylonitrile based on an anodic sacrificial agent. Background Art

[0002] As an important organic chemical raw material, traditional preparation methods of adiponitrile have problems such as high energy consumption and large pollution. Existing technologies usually prepare adiponitrile by the dimerization reaction of acrylonitrile on the cathode. This process can be completed in one step, avoiding the use of harmful chemical catalysts and reducing the generation of by-products, having advantages such as simple process and mild reaction conditions.

[0003] However, existing technologies usually adopt the diaphragmless method, and a mixture of organic vapor, hydrogen and oxygen will exist simultaneously in the whole reaction equipment, bringing safety problems in industrial production. Therefore, it is particularly important to develop a safe technology for preparing adiponitrile by electrolyzing acrylonitrile. Summary of the Invention

[0004] Aiming at the above deficiencies of the existing technology, the present invention provides a method for preparing adiponitrile by electrolyzing acrylonitrile based on an anodic sacrificial agent, which uses a sacrificial agent to improve the safety performance.

[0005] To achieve the above invention purpose, the technical solution adopted by the present invention is as follows:

[0006] Provide a method for preparing adiponitrile by electrolyzing acrylonitrile based on an anodic sacrificial agent, which comprises the following steps:

[0007] S1: Use the hydrothermal method to attach a multi-metal catalyst on a metal substrate to obtain an electrolytic anode;

[0008] S2: Configure an electrolyte solution with a pH value of 7-11; the electrolyte solution includes a quaternary ammonium salt, a phosphate, acrylonitrile and a sacrificial agent, and the sacrificial agent is urea, a lower alcohol, a lower aldehyde or a hydrazine compound;

[0009] S3: Set metal lead or metal cadmium as the electrolytic cathode, and adopt the diaphragmless method to carry out constant current electrolysis;

[0010] S4: Take the electrolyzed liquid phase and extract it with dichloromethane to obtain adiponitrile.

[0011] Further, the metal substrate is nickel, iron or titanium.

[0012] Further, the multi-metal catalyst is obtained by generating metal clusters on the metal substrate through one or more hydrothermal reactions and then through a thermal reaction; the metal clusters are a combination of two or three of nickel, iron, cobalt, molybdenum, manganese, chromium, cerium, praseodymium, neodymium or samarium.

[0013] Further, the phosphate is disodium hydrogen phosphate or trisodium phosphate.

[0014] Further, when the phosphate is disodium hydrogen phosphate, the components of the electrolyte are as follows:

[0015] 10 wt% - 20 wt% of disodium hydrogen phosphate, 0.5 wt% - 2 wt% of quaternary ammonium salt, 10 wt% - 20 wt% of acrylonitrile, and 2.5 wt% - 10 wt% of sacrificial agent;

[0016] When the phosphate is trisodium phosphate, the components of the electrolyte are as follows:

[0017] 5 wt% - 15 wt% of trisodium phosphate, 0.5 wt% - 5 wt% of quaternary ammonium salt, 10 wt% - 20 wt% of acrylonitrile, and 2.5 wt% - 10 wt% of sacrificial agent.

[0018] Further, in the step S3, during the constant current electrolysis, the current density is less than or equal to 200 mA·cm -2 , and the voltage is less than or equal to 5 V.

[0019] Further, the quaternary ammonium salt is an alkane structure asymmetric or asymmetric short-chain quaternary ammonium salt.

[0020] Further, the quaternary ammonium salt is tetrabutylammonium hydrogen phosphate, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, or benzyltriethylammonium bromide.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention can improve the conversion rate of acrylonitrile through the electrolytic dimerization of acrylonitrile coupled with the oxidation reaction of the sacrificial agent, and can also supplement the electric energy generated by the electrode reaction with each other to improve the energy utilization efficiency of the whole system. The challenge of this coupling reaction lies in the need to precisely control the electrolysis conditions to ensure that both reactions can proceed efficiently while avoiding the occurrence of side reactions. The difficulty lies in the preparation of the catalyst and the regulation of the electrolysis system environment. The method of the present invention can effectively regulate the electrolysis system environment. Compared with the method of electrolyzing acrylonitrile to synthesize adiponitrile currently used in industry, it can effectively control the generation of oxygen, the whole electrolysis process is safe, the conversion rate of acrylonitrile is not less than 82%, and the selectivity of the obtained adiponitrile is not less than 85%. Specific Embodiments

[0023] The specific embodiments of the present invention will be described below to facilitate the understanding of those skilled in the art of the present technology. It should be clear, however, that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions made using the inventive concept of the present invention are within the scope of protection.

[0024] The description of raw materials and equipment in the embodiments of the present invention is as follows:

[0025] Acrylonitrile: 99% containing inhibitor MEHQ, Shanghai Macklin Biochemical Co., Ltd.; Disodium hydrogen phosphate dodecahydrate: analytical pure, Chengdu Kelong Chemical Co., Ltd.; Trisodium phosphate: analytical pure, Chengdu Kelong Chemical Co., Ltd.; Tetramethylammonium hydroxide, 25% aqueous solution: analytical pure, Shanghai Titan Scientific Co., Ltd.; Tetraethylammonium hydroxide, 25% aqueous solution: analytical pure, Shanghai Titan Scientific Co., Ltd.; Tetrapropylammonium hydroxide, 25% aqueous solution: analytical pure, Shanghai Titan Scientific Co., Ltd.; Tetrabutylammonium hydroxide, 25% aqueous solution: analytical pure, Shanghai Titan Scientific Co., Ltd.; Tetrabutylammonium hydrogen phosphate: 97% +, Shanghai Titan Scientific Co., Ltd.; Urea: 99% +, Chengdu Kelong Chemical Co., Ltd.; Ethanol: 99% +, Chengdu Kelong Chemical Co., Ltd.; Hydrazine hydrate: 99% +, Chengdu Kelong Chemical Co., Ltd.; High-purity cadmium sheet: 99.999%, Huiji Metal Materials Sales; Dichloromethane: analytical pure, Chengdu Kelong Chemical Co., Ltd.; Benzyltriethylammonium hydroxide: analytical pure, Shanghai Merck Chemical Technology Co., Ltd.; Foam nickel: 99.9%, Cyber Electrochemical Materials Co., Ltd.; Sodium molybdate: analytical pure, Chongqing Chuandong Chemical (Group) Co., Ltd.; Nickel nitrate: analytical pure, Chongqing Chuandong Chemical (Group) Co., Ltd.; Cobalt nitrate: analytical pure, Chongqing Chuandong Chemical (Group) Co., Ltd.; Ammonium fluoride: analytical pure, Chongqing Chuandong Chemical (Group) Co., Ltd.; Iron nitrate: analytical pure, Shanghai Merck Chemical Technology Co., Ltd.; Cerium nitrate: analytical pure, Shanghai Merck Chemical Technology Co., Ltd.

[0026] Electrochemical workstation: CHI660D, Shanghai Chenhua Instrument Co., Ltd.; Electronic balance: FA1104N, Shanghai Precision Scientific Instrument Co., Ltd.; Electrothermal blast drying oven: 101A - 1E, Shanghai Experimental Instrument Factory Co., Ltd.; Ultra-pure water purifier: PW, Shanghai Meilei Environmental Technology Co., Ltd.; Diaphragmless three-electrode electrolytic cell: Gaoshi Ruilian; Electronic constant temperature water bath: KC - 11 - CR2, Shanghai Jinqiao Instrument Factory; Gas chromatograph: GC7980, Shanghai Tianmei Scientific Instrument Co., Ltd.; Microsyringe: 10 μL, Shanghai Tianmei Scientific Instrument Co., Ltd.

[0027] Example 1

[0028] Using nickel foam as the metal substrate, the nickel foam was pretreated. Specifically, the nickel foam was cut into 1*6*0.2 cm, ultrasonically cleaned with ethanol for 15 min, and then ultrasonically cleaned with 3M hydrochloric acid for 15 min;

[0029] In this example, the catalyst is FeCo(OH) x / CeO 2 , and the preparation and loading process of the catalyst is as follows:

[0030] Take Ce(NO 3 ) 3 ·6H 2 O (1.129 g, 40 mM), CO(NH 2 ) 2 (0.781 g, 200 mM), NH 4 F (0.452 g, 200 mM) and stir in a reaction kettle at room temperature until completely dissolved. Put the pretreated nickel foam NF into the reaction kettle, carry out hydrothermal reaction at 150 °C for 6 h, repeatedly rinse with ultrapure water, and obtain CeO 2 / NF after drying.

[0031] Take Fe(NO 3 ) 3 ·9H 2 O (0.251 g, 16 mM), Co(NO 3 ) 2 ·6H 2 O (0.454 g, 24 mM), CO(NH 2 ) 2 (0.781 g, 200 mM), NH 4 F (0.452 g, 200 mM) and stir in a reaction kettle at room temperature until completely dissolved. Put CeO 2 / NF into the reaction kettle, carry out hydrothermal reaction at 150 °C for 6 h, repeatedly rinse with ultrapure water, and obtain nickel foam loaded with the catalyst FeCo(OH) x / CeO 2 / NF after drying.

[0032] Prepare the electrolyte: disodium hydrogen phosphate (40 g, 10 wt%), tetrabutylammonium hydrogen phosphate (2 g, 0.5 wt%), acrylonitrile (32 g, 8 wt%), urea (10 g, 2.5 wt%), and the rest is ultrapure water; Specifically, when implementing, the quaternary ammonium salt can also be a modified or chiral quaternary ammonium salt such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, benzyltriethylammonium bromide, etc.; Then, an inert gas is introduced in a sealed environment, and FeCo(OH) x / CeO2 / NF was used as the electrolytic anode, and a cadmium sheet was set as the electrolytic cathode, and an electrolytic reaction was carried out at a constant current of 50 mA·cm -2 for 10 h.

[0033] After the reaction was completed, the content of O 2 in the system was detected to be 1% by on-line TCD of gas chromatography, and the content of N 2 was 20%, and the content of H 2 was less than 0.5%. The liquid phase after the reaction was extracted with dichloromethane and then detected by gas chromatography, and the conversion rate of acrylonitrile was calculated to be 85%, and the Faraday efficiency and selectivity of adiponitrile were 82% and 95% respectively.

[0034] Example 2

[0035] Prepare the electrolyte: trisodium phosphate (20 g, 5 wt%), tetrabutylammonium hydrogen phosphate (2 g, 0.5 wt%), acrylonitrile (40 g, 10 wt%), urea (20 g, 5 wt%), and the rest is ultrapure water; specifically, when implemented, the quaternary ammonium salt can also be a modified or chiral quaternary ammonium salt such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, benzyltriethylammonium bromide, etc.; then an inert gas was introduced into the sealed environment, and the FeCo(OH) x / CeO 2 / NF prepared by the method of Example 1 was used as the electrolytic anode, and a cadmium sheet was set as the electrolytic cathode, and an electrolytic reaction was carried out at a constant current of 50 mA·cm -2 for 10 h.

[0036] After the reaction was completed, the content of O 2 in the system was detected to be 1% by on-line TCD of gas chromatography, and the content of O 2 in the system was detected to be 1% by on-line TCD of gas chromatography. The liquid phase after the reaction was extracted with dichloromethane and then detected by gas chromatography, and the conversion rate of acrylonitrile was calculated to be 80%, and the Faraday efficiency and selectivity of adiponitrile were 74% and 85% respectively.

[0037] Example 3

[0038] The nickel foam was pretreated according to the method of Example 1. In this example, the catalyst used was NiMo(OH) x , and the preparation and loading process of the catalyst was as follows:

[0039] Take Ni(NO 3 ) 2 ·6H 2 O (0.453 g, 24 mM), MoNa 2 O 4 ·2H2 O(0.252 g, 16 mM), CO(NH 2 ) 2 (0.781 g, 200 mM), NH 4 F(0.452 g, 200 mM) were stirred in a reaction kettle at room temperature until completely dissolved. The pretreated nickel foam NF was put into the reaction kettle, and hydrothermal reaction was carried out at 150 °C for 6 h. After being repeatedly rinsed with ultrapure water and dried, nickel foam NiMo(OH) x / NF loaded with catalyst was obtained;

[0040] Prepare the electrolyte: disodium hydrogen phosphate (80 g, 20 wt%), tetrabutylammonium hydrogen phosphate (20 g, 5 wt%), acrylonitrile (80 g, 20 wt%), ethanol (40 g, 10 wt%), and the rest is ultrapure water; In specific implementation, the quaternary ammonium salt can also be modified or chiral quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, benzyltriethylammonium bromide, etc.; Then, an inert gas was introduced in a sealed environment, and NiMo(OH) x / NF was used as the electrolytic anode, a cadmium sheet was set as the electrolytic cathode, and an 8 h electrolytic reaction was carried out at a constant current of 50 mA·cm -2 .

[0041] After the reaction was completed, the content of O 2 in the system was detected to be 2% by on-line TCD using gas chromatography, the content of N 2 was 25%, and the content of H 2 was less than 0.5%. The liquid phase after the reaction was extracted with dichloromethane and then detected by gas chromatography. The conversion rate of acrylonitrile was calculated to be 89%, and the Faraday efficiency and selectivity of adiponitrile were 80% and 85% respectively.

[0042] Example 4

[0043] The nickel foam was pretreated according to the method of Example 1. In this example, the catalyst was MoNi(OH) x S y , and the preparation and loading process of the catalyst was as follows:

[0044] Take Ni(NO 3 ) 2 ·6H 2 O(0.453 g, 24 mM), MoNa 2 O 4 ·2H 2 O(0.252 g, 16 mM), CO(NH 2 ) 2 (0.781 g, 200 mM), NH 4F(0.452 g, 200 mM) was stirred in a reaction kettle at room temperature until completely dissolved. The pretreated nickel foam NF was put into the reaction kettle, and hydrothermal reaction was carried out at 120 °C for 6 h. After being repeatedly rinsed with ultrapure water and dried, NiMo(OH) x / NF was obtained;

[0045] Take Na 2 S·9H 2 O(1.171 g, 15 mM), CO(NH 2 ) 2 (0.781 g, 200 mM), NH 4 F(0.452 g, 200 mM) was stirred in a reaction kettle at room temperature until completely dissolved. NiMo(OH) x / NF was put into the reaction kettle, and hydrothermal reaction was carried out at 150 °C for 6 h. After being repeatedly rinsed with ultrapure water and dried, the nickel foam loaded with the catalyst MoNi(OH) x S y / NF was obtained.

[0046] Prepare the electrolyte: trisodium phosphate (60 g, 15 wt%), tetrabutylammonium hydrogen phosphate (20 g, 5 wt%), acrylonitrile (80 g, 20 wt%), ethanol (40 g, 10 wt%), and the rest is ultrapure water; specifically, when implemented, the quaternary ammonium salt can also be a modified or chiral quaternary ammonium salt such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, benzyltriethylammonium bromide, etc.; then an inert gas was introduced in a sealed environment, and MoNi(OH) x S y / NF was used as the electrolytic anode, a cadmium sheet was set as the electrolytic cathode, and an electrolytic reaction was carried out at a constant current of 50 mA·cm -2 for 8 h.

[0047] After the reaction was completed, the content of O 2 in the system was detected by on-line TCD of gas chromatography to be 1.5%. The liquid phase after the reaction was extracted with dichloromethane and then detected by gas chromatography. The conversion rate of acrylonitrile was calculated to be 93%, and the Faraday efficiency and selectivity of adiponitrile were 77% and 88% respectively.

[0048] Example 5

[0049] According to the method of Example 1, the nickel foam was pretreated. In this example, the catalyst was CrMoCo(OH) x , and the preparation and loading process of the catalyst were as follows:

[0050] Take Cr(NO 3 ) 3 ·9H 2O(0.52 g, 20 mM), MoNa 2 O 4 ·2H 2 O(0.252 g, 16 mM), Co(NO 3 ) 2 ·6H 2 O(0.454 g, 24 mM), CO(NH 2 ) 2 (0.781 g, 200 mM), NH 4 F(0.452 g, 200 mM) were stirred in a reaction kettle at room temperature until completely dissolved. The pretreated nickel foam NF was put into the reaction kettle, and hydrothermal reaction was carried out at 150 °C for 6 h. After being repeatedly rinsed with ultrapure water and dried, nickel foam CrMoCo(OH) x / NF loaded with catalyst was obtained.

[0051] Prepare the electrolyte: disodium hydrogen phosphate (60 g, 15 wt%), tetrabutylammonium hydrogen phosphate (8 g, 2 wt%), acrylonitrile (52 g, 13 wt%), hydrazine hydrate (40 g, 10 wt%), and the rest is ultrapure water; specifically in implementation, the quaternary ammonium salt can also be modified or chiral quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, benzyltriethylammonium bromide, etc.; then an inert gas was introduced in a sealed environment, and CrMoCo(OH) x / NF was used as the electrolytic anode, a cadmium sheet was set as the electrolytic cathode, and an electrolytic reaction was carried out at a constant current of 50 mA·cm -2 for 12 h.

[0052] After the reaction was completed, the content of O 2 in the system was detected to be 1.5% by on-line TCD using gas chromatography, the content of N 2 was 30%, and the content of H 2 was less than 1%. The liquid phase after the reaction was extracted with dichloromethane and then detected by gas chromatography, and the conversion rate of acrylonitrile was calculated to be 82%, and the Faraday efficiency and selectivity of adiponitrile were 82% and 96% respectively.

[0053] Example 6

[0054] The nickel foam was pretreated according to the method of Example 1. In this example, the catalyst was MoNi(OH) x S y , and the preparation and loading process of the catalyst were as follows:

[0055] Take Ni(NO 3 ) 2 ·6H 2 O(0.453 g, 24 mM), MoNa2 O 4 ·2H 2 O (0.252 g, 16 mM), CO(NH 2 ) 2 (0.781 g, 200 mM), NH 4 F (0.452 g, 200 mM) were stirred in a reaction kettle at room temperature until completely dissolved. The pretreated nickel foam NF was put into the reaction kettle, and hydrothermal reaction was carried out at 120 °C for 6 h. After being repeatedly rinsed with ultrapure water and dried, NiMo(OH) x / NF was obtained;

[0056] Take Na 2 S·9H 2 O (2.342 g, 30 mM), CO(NH 2 ) 2 (0.781 g, 200 mM), NH 4 F (0.452 g, 200 mM) were stirred in a reaction kettle at room temperature until completely dissolved. NiMo(OH) x / NF was put into the reaction kettle, and hydrothermal reaction was carried out at 150 °C for 6 h. After being repeatedly rinsed with ultrapure water and dried, the nickel foam loaded with the catalyst MoNi(OH) x S y was obtained.

[0057] Prepare the electrolyte: trisodium phosphate (48 g, 12 wt%), tetrabutylammonium hydrogen phosphate (8 g, 2 wt%), acrylonitrile (64 g, 16 wt%), hydrazine hydrate (32 g, 8 wt%), and the rest is ultrapure water; specifically in implementation, the quaternary ammonium salt can also be a modified or chiral quaternary ammonium salt such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltriethylammonium hydroxide, benzyltriethylammonium bromide, etc.; then an inert gas was introduced in a sealed environment, and the target catalyst MoNi(OH) x S y was used as the electrolytic anode, a cadmium sheet was set as the electrolytic cathode, and an electrolytic reaction was carried out at a constant current of 50 mA·cm -2 for 12 h.

[0058] After the reaction was completed, the content of O 2 in the system was detected by on-line TCD of gas chromatography to be 1.5%. The liquid phase after the reaction was extracted with dichloromethane and then detected by gas chromatography, and the conversion rate of acrylonitrile was calculated to be 88%, and the Faraday efficiency and selectivity of adiponitrile were 89% and 97% respectively.

Claims

1. A method for preparing adiponitrile by electrolyzing acrylonitrile based on an anode sacrificial agent, characterized in that: The steps include: S1: Using a hydrothermal method to attach a multi-metal catalyst to a metal substrate to obtain an electrolytic anode; The metal substrate is nickel foam, and the multi-metal catalyst is prepared by generating metal clusters on the metal substrate through one or more hydrothermal reactions and then undergoing thermal reactions; the metal clusters are FeCo(OH) x / CeO2; S2: preparing an electrolyte, wherein the pH value of the electrolyte is 7-11; the electrolyte comprises tetrabutylammonium hydrogen phosphate, phosphate, acrylonitrile and a sacrificial agent, wherein the sacrificial agent is urea, low-carbon alcohol or hydrazine compound; and the phosphate is disodium hydrogen phosphate or trisodium phosphate; S3: Setting metal lead or metal cadmium as the electrolysis cathode and adopting a diaphragm-free method to perform constant current electrolysis; The current density during constant current electrolysis is less than or equal to 200mA∙cm -2 , voltage is less than or equal to 5V; S4: extracting the liquid phase after electrolysis with dichloromethane to obtain adiponitrile.

2. The method for preparing adiponitrile by electrolyzing acrylonitrile based on an anode sacrificial agent according to claim 1, characterized in that: When the phosphate is disodium hydrogen phosphate, the components of the electrolyte are: 10wt%~20wt% of disodium hydrogen phosphate, 0.5wt%~2wt% of tetrabutylammonium hydrogen phosphate, 10wt%~20wt% of acrylonitrile and 2.5wt%~10wt% of a sacrificial agent; When the phosphate is trisodium phosphate, the components of the electrolyte are: 5wt%~15wt% of trisodium phosphate, 0.5wt%~5wt% of tetrabutylammonium hydrogen phosphate, 10wt%~20wt% of acrylonitrile and 2.5wt%~10wt% of sacrificial agent.