阅读说明：本技术 一种丁二烯直接氢氰化制备己二腈的方法 (Method for preparing adiponitrile by direct hydrocyanation of butadiene ) 是由 童明全 潘蓉 琚裕波 李健 李超 李振虎 李昊燃 杨璐 张伟 许凯 郭旭青 李 于 2020-08-13 设计创作，主要内容包括：本发明提供了一种丁二烯直接氢氰化制备己二腈的方法,涉及己二腈制备技术领域。本发明以同一零价金属镍单齿有机膦催化剂催化一级氢氰化反应、异构化反应和二级氢氰化反应,零价金属镍单齿有机膦催化剂对于三个反应均具有较好的催化活性和稳定性；以同一路易斯酸作为助催化剂辅助零价金属镍单齿有机膦催化剂催化异构化反应和二级氢氰化反应,所述助催化剂能有效加快异构化和二级氢氰化反应的反应速度。本发明提供的方法中一级氢氰化、异构化、二级氢氰化三步反应耦合连续化进行,不仅成本低,而且己二腈产品选择性较高；此外,还能够减少一级氢氰化和异构化两步反应后的催化剂分离及产品提纯工作,大大缩短了工艺流程,大幅降低了设备投资。(The invention provides a method for preparing adiponitrile by directly hydrocyanating butadiene, and relates to the technical field of adiponitrile preparation. The invention uses the same zero-valent metal nickel monodentate organic phosphine catalyst to catalyze the primary hydrocyanation reaction, the isomerization reaction and the secondary hydrocyanation reaction, and the zero-valent metal nickel monodentate organic phosphine catalyst has better catalytic activity and stability for the three reactions; the same Lewis acid is used as a cocatalyst to assist the zero-valent metal nickel monodentate organophosphine catalyst in catalyzing the isomerization reaction and the secondary hydrocyanation reaction, and the cocatalyst can effectively accelerate the reaction speed of the isomerization reaction and the secondary hydrocyanation reaction. In the method provided by the invention, three reaction coupling continuous processes of primary hydrocyanation, isomerization and secondary hydrocyanation are carried out, so that the cost is low, and the adiponitrile product selectivity is high; in addition, the catalyst separation and product purification work after the two-step reaction of primary hydrocyanation and isomerization can be reduced, the process flow is greatly shortened, and the equipment investment is greatly reduced.)

1. A method for preparing adiponitrile by directly hydrocyanating butadiene, which is characterized by comprising the following steps:

(1) carrying out primary hydrocyanation reaction on excessive butadiene and hydrogen cyanide under the action of a first catalyst to obtain 3-pentenenitrile and 2-methyl-3-butenenitrile;

(2) carrying out isomerization reaction on the 2-methyl-3-butenenitrile under the action of a second catalyst and a first cocatalyst to obtain 3-pentenenitrile;

(3) carrying out secondary hydrocyanation reaction on the 3-pentenenitrile obtained in the step (1) and the hydrogen cyanide obtained in the step (3) under the action of a third catalyst and a second cocatalyst to obtain adiponitrile;

the first catalyst, the second catalyst and the third catalyst are the same and are selected from nickel metal monodentate organic phosphine ligand catalysts; the structure of the nickel metal monodentate organophosphine ligand catalyst comprises zero-valent nickel and a monodentate organophosphine ligand, wherein the monodentate organophosphine ligand comprises one or more of triethyl phosphite, triisopropyl phosphite, triphenyl phosphite, tri-o-tolyl phosphite, tri-p-tolyl phosphite and tri-m-tolyl phosphite, and the molar ratio of the zero-valent nickel to the monodentate organophosphine ligand is 1: 5-20;

the first cocatalyst and the second cocatalyst are the same and are selected from Lewis acid; the Lewis acid comprises one or more of triphenylboron, triphenyl borate, zinc chloride, aluminum chloride, tin chloride and aluminum isopropoxide.

2. The method according to claim 1, wherein the monodentate organophosphine ligand is one or more of tri-o-tolyl phosphite, tri-p-tolyl phosphite, and tri-m-tolyl phosphite.

3. The method of claim 1 or 2, wherein the molar ratio of zero-valent nickel to monodentate organophosphorus ligand is from 1:7 to 10.

4. The method according to claim 1, wherein the molar ratio of butadiene to zero-valent nickel in the nickel metal monodentate organophosphine ligand catalyst in step (1) is 30-60: 1.

5. the method according to claim 1, wherein the Lewis acid is a mixture of triphenylboron and zinc chloride, and the molar content of the triphenylboron in the mixture is 9-30%.

6. The method as claimed in claim 1 or 5, wherein in the step (2) and the step (3), the molar ratio of the Lewis acid to the zero-valent nickel in the nickel metal monodentate organophosphine ligand catalyst is independently 1: 0.6-1.

7. The method of claim 1, wherein the first catalyst, the second catalyst, the third catalyst, the first cocatalyst and the second cocatalyst are dispersed with the same solvent, and are used in the form of a catalyst dispersion, wherein the solvent is an aromatic hydrocarbon, an alkane, a nitrogen-containing organic compound or an oxygen-containing organic compound; the mass of the first catalyst, the second catalyst and the third catalyst is respectively 1.0-3.0 times of that of the respective solvent for dispersion; the mass of the first cocatalyst and the mass of the second cocatalyst are respectively 8-20% of the mass of the respective solvent for dispersion.

8. The process according to claim 1, characterized in that the ratio of the amount of species of butadiene to hydrogen cyanide in step (1) is greater than 1.2; the temperature of the primary hydrocyanation reaction is 60-130 ℃, and the pressure is 0.5-2.0 MPa.

9. The method according to claim 1, wherein the isomerization reaction in step (2) is carried out at a temperature of 60 to 130 ℃ and a pressure of 0.1 to 2.0 MPa.

10. The process according to claim 1, wherein the molar ratio of 3-pentenenitrile to hydrogen cyanide in step (3) is 1.2-3: 1; the temperature of the secondary hydrocyanation reaction is 30-130 ℃, and the pressure is 0.1-2.0 MPa.

Technical Field

The invention relates to the technical field of adiponitrile preparation, in particular to a method for preparing adiponitrile by directly hydrocyanating butadiene.

Background

Adiponitrile is an important organic chemical raw material, which is mainly reduced into hexamethylene diamine through hydrogenation, and the hexamethylene diamine is used for producing chemical products such as nylon-66, Hexamethylene Diisocyanate (HDI), nylon-610, polyurethane foam, adhesives, other auxiliaries and the like.

The industrial production process of adiponitrile mainly includes butadiene cyaniding process, acrylonitrile electrolyzing process, adipic acid ammoniating process and caprolactam process. Adiponitrile is currently produced primarily by two processes, the cyanidation of butadiene and the electrolysis of acrylonitrile. Among them, the butadiene cyanidation process was first developed by dupont in the beginning of the 60 th century. An early process was the chlorocyanation process, butadiene with Cl₂The addition reaction is carried out to generate 1, 4-dichloro-2-butene, the 1, 4-dichloro-2-butene and sodium cyanide are subjected to substitution reaction to generate 1, 4-dicyanobutene, and the 1, 4-dicyanobutene is subjected to hydrogenation reaction to generate adiponitrile. In the early 70 s of the 20 th century, the dupont company improved the butadiene cyanidation method, developed the direct cyanidation process of butadiene, and butadiene directly reacted with hydrocyanic acid under the action of catalyst, and produced adiponitrile by three steps of first-stage hydrocyanation addition, isomerization and second-stage hydrocyanation addition, wherein the chemical reaction formulas of the three steps are respectively shown as formulas (1) to (3):

firstly, butadiene and hydrocyanic acid (HCN) undergo a primary hydrocyanation reaction under the action of a catalyst to generate linear 3-pentenenitrile (3PN) and branched 2-methyl-3-butenenitrile (2M3BN), namely a reaction formula (1). Since the main product obtained by hydrocyanation addition reaction of the branched 2M3BN and hydrocyanic acid is 2-methylglutaronitrile, the yield of the target product Adiponitrile (ADN) is reduced, and thus the branched 2M3BN needs to be converted into linear 3 PN. Under the action of a catalyst and a Lewis acid assistant, 2M3BN can generate an isomerization reaction to generate a 3PN product, namely a reaction formula (2); and finally, carrying out secondary hydrocyanation on the purified 3PN and hydrocyanic acid under the action of a catalyst and a Lewis acid assistant to obtain a target product Adiponitrile (ADN), namely a reaction formula (3).

The selection of the catalytic system is the key in the process of producing adiponitrile by three steps of primary hydrocyanation addition, isomerization and secondary hydrocyanation addition of butadiene and hydrocyanic acid. In order to improve the selectivity of the target product and reduce the production cost, researchers have been devoted to the selection or development of catalysts. Professor dieter vogt, university of urtecht, the netherlands in 2007 developed a bidentate organophosphine ligand catalyst which can improve the selectivity of 3PN in the primary hydrocyanation reaction to 97.6% (j.am. chem. soc.2007,129, 12622-12623). In 2012, the university of qinghua and the company of amqing eosin photochemical adopted a bidentate phosphite ligand and monodentate ligand mixed catalyst system to increase the selectivity of primary hydrocyanation 3PN to 96% (CN201210553219.5), thereby avoiding the use of an isomerization reaction step. However, the bidentate ligand has a complex structure, raw materials are not easily available, the number of synthesis and preparation steps is large, and the yield is low, so that the bidentate ligand catalyst is high in price, and the investment cost for omitting an isomerization reaction part cannot always offset the cost of the catalyst.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for preparing adiponitrile by direct hydrocyanation of butadiene. The method selects the metal nickel monodentate organic phosphine catalyst system for the primary hydrocyanation, isomerization and secondary hydrocyanation reactions, and has low cost and high adiponitrile product selectivity.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for preparing adiponitrile by directly hydrocyanating butadiene, which comprises the following steps:

(1) carrying out primary hydrocyanation reaction on excessive butadiene and hydrogen cyanide under the action of a first catalyst to obtain 3-pentenenitrile and 2-methyl-3-butenenitrile;

(2) carrying out isomerization reaction on the 2-methyl-3-butenenitrile under the action of a second catalyst and a first cocatalyst to obtain 3-pentenenitrile;

(3) carrying out secondary hydrocyanation reaction on the 3-pentenenitrile obtained in the step (1) and the hydrogen cyanide obtained in the step (3) under the action of a third catalyst and a second cocatalyst to obtain adiponitrile;

the first catalyst, the second catalyst and the third catalyst are the same and are selected from nickel metal monodentate organic phosphine ligand catalysts; the structure of the nickel metal monodentate organophosphine ligand catalyst comprises zero-valent nickel and a monodentate organophosphine ligand, wherein the monodentate organophosphine ligand comprises one or more of triethyl phosphite, triisopropyl phosphite, triphenyl phosphite, tri-o-tolyl phosphite, tri-p-tolyl phosphite and tri-m-tolyl phosphite, and the molar ratio of the zero-valent nickel to the monodentate organophosphine ligand is 1: 5-20;

the first cocatalyst and the second cocatalyst are the same and are selected from Lewis acid; the Lewis acid comprises one or more of triphenylboron, triphenyl borate, zinc chloride, aluminum chloride, tin chloride and aluminum isopropoxide.

Preferably, the monodentate organophosphine ligand is one or more of tri-o-tolyl phosphite, tri-p-tolyl phosphite and tri-m-tolyl phosphite.

Preferably, the molar ratio of the zero-valent nickel to the monodentate organophosphorus ligand is 1: 7-10.

Preferably, in the step (1), the molar ratio of butadiene to zero-valent nickel in the nickel metal monodentate organophosphine ligand catalyst is 30-60: 1.

preferably, the Lewis acid is a mixture of triphenylboron and zinc chloride, and the molar content of the triphenylboron in the mixture is 9-30%.

Preferably, in the step (2) and the step (3), the molar ratio of the Lewis acid to the zero-valent nickel in the nickel metal monodentate organophosphine ligand catalyst is independently 1: 0.6-1.

Preferably, the first catalyst, the second catalyst, the third catalyst, the first cocatalyst and the second cocatalyst are dispersed by using the same solvent, and the solvent is used in the form of a catalyst dispersion liquid, and the solvent is aromatic hydrocarbon, alkane, nitrogen-containing organic matter or oxygen-containing organic matter; the mass of the first catalyst, the second catalyst and the third catalyst is respectively 1.0-3.0 times of that of the respective solvent for dispersion; the mass of the first cocatalyst and the mass of the second cocatalyst are respectively 8-20% of the mass of the respective solvent for dispersion.

Preferably, the ratio of the amount of species of butadiene to hydrogen cyanide in step (1) is greater than 1.2; the temperature of the primary hydrocyanation reaction is 60-130 ℃, and the pressure is 0.5-2.0 MPa.

Preferably, the temperature of the isomerization reaction in the step (2) is 60-130 ℃, and the pressure is 0.1-2.0 MPa.

Preferably, the molar ratio of the 3-pentenenitrile to the hydrogen cyanide in the step (3) is 1.2-3: 1; the temperature of the secondary hydrocyanation reaction is 30-130 ℃, and the pressure is 0.1-2.0 MPa.

The invention provides a method for preparing adiponitrile by directly hydrocyanating butadiene, which comprises the following steps: (1) carrying out primary hydrocyanation reaction on excessive butadiene and hydrogen cyanide under the action of a first catalyst to obtain 3-pentenenitrile and 2-methyl-3-butenenitrile; (2) carrying out isomerization reaction on the 2-methyl-3-butenenitrile under the action of a second catalyst and a first cocatalyst to obtain 3-pentenenitrile; (3) carrying out secondary hydrocyanation reaction on the 3-pentenenitrile obtained in the step (1) and the hydrogen cyanide obtained in the step (3) under the action of a third catalyst and a second cocatalyst to obtain adiponitrile; the first catalyst, the second catalyst and the third catalyst are the same and are nickel metal monodentate organic phosphine ligand catalysts; the first cocatalyst and the second cocatalyst are the same and are Lewis acids. The invention optimizes the technical process of preparing adiponitrile by direct hydrocyanation of butadiene, adopts a metallic nickel monodentate organic phosphine ligand catalyst system to catalyze the reaction process, and has the monodentate ligand catalyst cost which is obviously lower than that of a bidentate ligand catalyst, thereby obviously reducing the catalyst investment cost in the reaction process; moreover, the metal nickel monodentate organic phosphine ligand catalyst selected by the invention has better catalytic activity and stability for three reactions of primary hydrocyanation, isomerization and secondary hydrocyanation, and can ensure that an adiponitrile product has higher selectivity by matching with a Lewis acid cocatalyst capable of effectively accelerating the reaction speed of isomerization and secondary hydrocyanation. In addition, the same zero-valent metal nickel monodentate organophosphine catalyst is used for catalyzing the primary hydrocyanation reaction, the isomerization reaction and the secondary hydrocyanation reaction, the same Lewis acid is used as a cocatalyst for assisting the zero-valent metal nickel monodentate organophosphine catalyst in catalyzing the isomerization reaction and the secondary hydrocyanation reaction, and the primary hydrocyanation reaction, the isomerization reaction and the secondary hydrocyanation reaction are coupled and continuously carried out, so that the catalyst separation and product purification work after the primary hydrocyanation and isomerization two-step reaction can be reduced, the process flow is further shortened, and the equipment investment and the production cost are reduced.

Drawings

FIG. 1 is a flow diagram of a process for the direct hydrocyanation of butadiene to adiponitrile in an embodiment of the present invention; in fig. 1, first to ninthly are reaction kettles, namely a first reaction kettle, a second reaction kettle, a third reaction kettle, a fourth reaction kettle, a fifth reaction kettle, a sixth reaction kettle, a seventh reaction kettle, an eighth reaction kettle and a ninth reaction kettle, and the third reaction kettle is a flash evaporation device.

The results of the examples show that the method for preparing adiponitrile by directly hydrocyanating butadiene provided by the invention has a single-pass yield of 36-59% of adiponitrile relative to butadiene and a product selectivity of 81-87% of adiponitrile.