A process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile

Abstract

The application provides a method for isomerizing cis-2-pentenenitrile into 3-pentenenitrile, which comprises isomerizing cis-2-pentenenitrile into 3-pentenenitrile in a supercritical fluid under the action of a catalyst and a ligand; wherein the catalyst is a rare earth metal oxide or a rare earth metal halide, and the ligand is a monodentate phosphite or a polydentate phosphite. By selecting a rare earth metal oxide or a rare earth metal halide and combining a specific monodentate phosphite or a polydentate phosphite, cis-2-pentenenitrile is isomerized into 3PN in a supercritical fluid, the catalytic process has high raw material conversion rate and high 3PN selectivity, cis-2-pentenenitrile can be efficiently converted into 3PN in the second hydrocyanation step in the industrialization process of butadiene hydrocyanation to adiponitrile, thereby eliminating the poisoning effect of cis-2-pentenenitrile on the catalyst, improving the process efficiency, saving the cost, and improving the economic benefit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical synthesis, in particular to a method for isomerizing cis-2-pentenenitrile into 3-pentenenitrile. BACKGROUND

[0002] Adiponitrile is an important chemical raw material, and has extremely wide application value in many important fields such as plastics, rubber, fiber, etc., and plays a key role in promoting the development of modern industry. At present, the main production methods of adiponitrile in industry are propylene nitrile electrolysis dimerization method, adipic acid catalytic amination method and butadiene hydrocyanation method. Among them, the butadiene hydrocyanation method has high atom economy, short process route, high yield and small pollution, and has become the mainstream of industrialized preparation method of adiponitrile.

[0003] The reaction process of butadiene hydrocyanation method for preparing adiponitrile mainly includes three parts: (1) one-step hydrocyanation, that is, butadiene and hydrocyanic acid (HCN) generate 3-pentenenitrile (3PN) under the action of catalyst and ligand, and by-product branched 2-methyl-3-butenenitrile (2M3BN) is generated; (2) isomerization reaction, the by-product 2M3BN is isomerized into straight-chain 3PN under the action of catalyst; (3) two-step hydrocyanation, that is, 3PN and HCN react to obtain product adiponitrile under the action of catalyst and Lewis acid. As shown in the following reaction formula:

[0004]

[0005] In the two-step hydrocyanation reaction, cis-2-pentenenitrile is produced as a by-product, which not only means the loss of adiponitrile yield, but also the accumulation of cis-2-pentenenitrile will cause excess of hydrocyanic acid in the reaction system, and the excess of hydrocyanic acid reacts with the catalyst to generate cyanide, which deactivates the catalyst and reduces the production efficiency of adiponitrile.

[0006] The by-product cis-2-pentenenitrile has a boiling point close to that of 3PN, and is difficult to separate by distillation; therefore, cis-2-pentenenitrile is preferably isomerized into 3PN, so as to continue to participate in the two-step hydrocyanation. Patent CN1914164A discloses that alumina extrudate is used as catalyst to isomerize cis-2-pentenenitrile into 3PN through reaction distillation, but the required temperature is high, which is easy to produce oligomers, or the isomerization efficiency is low at low temperature for a long time. Patent USA5070202 uses primary amine and secondary amine and other amine substances to catalyze the isomerization of cis-2-pentenenitrile into 3PN, but there are still problems such as low conversion rate and poor selectivity. SUMMARY

[0007] In view of the deficiencies in the prior art, the application discloses a method for isomerizing cis-2-pentenenitrile into 3-pentenenitrile, which can catalyze cis-2-pentenenitrile to isomerize into 3-pentenenitrile with high efficiency and high selectivity, and the method is highly operable, suitable for isomerization reaction of a mixture containing 3PN and cis-2-pentenenitrile, and has important industrial application value.

[0008] In order to achieve the above technical purposes, the application provides a method for isomerizing cis-2-pentenenitrile into 3-pentenenitrile, which comprises that cis-2-pentenenitrile is subjected to isomerization reaction in a supercritical fluid under the action of a catalyst and a ligand to generate 3-pentenenitrile; wherein the catalyst is a rare earth metal oxide and / or a rare earth metal halide, and the ligand is a monodentate phosphite or a polydentate phosphite.

[0009] Based on a large number of experiments, the research and development team of the application found that, compared with the oxide catalysts such as alumina and zinc oxide in the prior art, the use of the rare earth metal oxide or the rare earth metal halide as the catalyst in the above technical solution can significantly improve the conversion rate of cis-2-pentenenitrile isomerization and the selectivity of 3PN; further, the use of the monodentate phosphite or the polydentate phosphite as the catalyst ligand in the above technical solution, in combination with the specific catalyst type and the supercritical fluid condition, can further improve the conversion rate of cis-2-pentenenitrile and the selectivity of 3PN through the synergistic effect of the three, and the reaction condition is relatively mild, and the reaction time is also greatly shortened.

[0010] It can be proved by the examples and comparative examples of the application that the above technical solution can achieve high conversion rate and high selectivity, high process efficiency, and is suitable for industrial production.

[0011] In further examples of the application, the type of the catalyst is optimized. Optionally, the rare earth metal oxide includes at least one of lanthanum oxide, actinium oxide, samarium oxide, praseodymium oxide, cerium oxide and neodymium oxide, and is further optionally lanthanum oxide; the rare earth metal halide is optionally chloride, and is further optionally at least one of lanthanum chloride, cerium chloride and europium chloride, and the exploration process is shown in the examples of the application.

[0012] In further examples of the application, the amount of the catalyst is explored. Optionally, the molar ratio of cis-2-pentenenitrile to the catalyst is (10-200):1, and is further optionally (20-100):1, so as to improve the conversion rate of raw materials, save costs and improve product quality.

[0013] In further examples of the application, the type and amount of the supercritical fluid are optimized.

[0014] Optionally, the supercritical fluid comprises at least one of supercritical carbon dioxide, supercritical nitrogen dioxide, supercritical sulfur dioxide, supercritical ammonia, preferably supercritical carbon dioxide. The optimization process is shown in the embodiments of the present application.

[0015] Optionally, the mass ratio of the supercritical fluid to the cis-2-pentenenitrile is (0.2-20):1, preferably (0.5-5):1. By controlling the supercritical fluid, the conversion rate of cis-2-pentenenitrile and the selectivity of 3PN in the overall reaction can be improved.

[0016] The type and amount of ligand are explored in further examples of the present application.

[0017] Optionally, the monodentate phosphite ligand comprises at least one of triethyl phosphite, triphenyl phosphite, tri-p-tolyl phosphite, tri-m-tolyl phosphite, tri-o-tolyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(2-phenylphenyl) phosphite, phenyldiisooctyl phosphite, triisooctyl phosphite, and diisodecyl phosphite, preferably triphenyl phosphite.

[0018] Optionally, the multidentate phosphite ligand is selected from at least one of 2,2'-diphenol bisdiphenyl phosphite, 2,2'-diphenol bistolyl phosphite, 2,2'-diphenol bis(2,2'-diphenol) phosphite, [1,1'-biphenyl]-2,2'-diyltetraphenyl bisphosphite, [1,1'-binaphthalene]-2,2'-diyltetraphenyl bisphosphite, tetraphenyl(3,3',5,5'-tetramethyl-[1,1'-biphenyl]-2,2'-diyl) bisphosphite, [1,1'-biphenyl]-2,2'-diyltetra-o-methyl bisphosphite, 3,3',5-trimethyl-[1,1'-biphenyl]-2,2'-diyl) bis(phosphite), 3,3',5,5'-tetra-tert-butyl-2,2'-diphenol bis(2,2'-diphenol) phosphite, 3,3',-di-tert-butyl-5,5'-dimethoxy-2,2'-diphenol bis(2,2'-diphenol) phosphite; preferably 2,2'-diphenol bisdiphenyl phosphite. The results of the cis-2-pentenenitrile isomerization reaction of different ligand catalysts are shown in the embodiments of the present application.

[0019] Optionally, the molar ratio of the ligand to the catalyst is (1-20):1, preferably (2-10):1. By optimizing the amount of ligand, the catalytic performance of the catalyst can be enhanced.

[0020] In further examples of the present application, the control conditions of the isomerization reaction are optimized. Optionally, the temperature of the isomerization reaction is 20-200 DEG C, preferably 40-80 DEG C; optionally, the pressure of the isomerization reaction is 2-30 MPa, preferably 5-20 MPa, the control conditions of the isomerization reaction segment of the present application are relatively mild, and the operability is strong; optionally, the time of the isomerization reaction is 0.5-20 h, preferably 2-10 h, the technical solution of the present application can shorten the reaction time, thereby significantly improving the production efficiency.

[0021] It is worth noting that the research and development team further found through a large number of experiments that the present application is also applicable to the isomerization process of a mixture containing cis-2-pentenenitrile and 3PN, and the conversion rate of cis-2-pentenenitrile and the product selectivity are both better, so the technical solution of the present application has important industrial application value. The experimental results of the isomerization of a mixture containing cis-2-pentenenitrile and 3PN are shown in the examples of the present application.

[0022] Compared with the prior art, the present application has the following beneficial effects: by selecting rare earth metal oxides or rare earth metal halides, combined with specific monodentate phosphites or polydentate phosphites, the present application catalyzes the isomerization of cis-2-pentenenitrile to generate 3PN in a supercritical fluid, the conversion rate of the raw material is high, the selectivity of 3PN is high, cis-2-pentenenitrile can be efficiently converted to 3PN in the industrialization process of butadiene hydrocyanation to adiponitrile, in the two-step hydrocyanation link, thereby eliminating its poisoning effect on the catalyst, improving the process efficiency, saving the cost, and improving the economic benefit. BRIEF DESCRIPTION OF DRAWINGS

[0023] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the present application, and together with the description of the exemplary embodiments of the present application and the explanation thereof serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0024] Figure 1 The gas chromatography results of the reaction material in Example 1 of the present application are shown.

[0025] Figure 2 The gas chromatography results of the reaction material in Comparative Example 3.1 of the present application are shown. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present application, the present application will be described more fully below, and the preferred embodiments of the present application are given. However, it should be understood that these embodiments are only used for more detailed description, and should not be understood as limiting the present application in any form, i.e. not intended to limit the protection scope of the present application.

[0027] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. The test reagents used in the following examples are all conventional biochemical reagents unless otherwise specified; the experimental methods used are all conventional methods unless otherwise specified.

[0028] It should be noted that the embodiments in the present invention and the features in the embodiments can be combined with each other without conflict.

[0029] In the following examples, the catalyst used needs to be calcined at high temperature before use to remove moisture, and is transferred to the reaction kettle in an inert gas atmosphere; then the ligand, cis-2-pentenenitrile is added in turn, and then the reaction kettle is sealed, vacuumed and then carbon dioxide gas (or nitrogen dioxide, sulfur dioxide gas, etc.) is introduced; by controlling the temperature and pressure of the reaction kettle, the gas reaches the supercritical state for reaction; after the reaction is completed, the temperature is lowered and the pressure is reduced; then gas chromatography is used for analysis. The inert gas refers to a gas that does not chemically interact with the reactants, for example: nitrogen and group zero elements in the periodic table (such as argon).

[0030] The monodentate phosphite and polydentate phosphite used in the embodiments of the present invention can be obtained by commercial purchase or by existing published technology.

[0031] In the following examples, the conversion rate is based on the reactant cis-2-pentenenitrile, that is, the proportion of cis-2-pentenenitrile reacted out of the initial charge; the selectivity indicates the proportion of the target product 3-pentenenitrile in the amount of reactant reduced.

[0032] Example 1

[0033] A method for isomerizing cis-2-pentenenitrile to 3-pentenenitrile, specifically, in an inert gas atmosphere, 1 mol of lanthanum oxide catalyst, 5 mol of triphenyl phosphite as a ligand, and 100 mol of cis-2-pentenenitrile are sequentially added to the reaction kettle; then the reaction kettle is sealed, vacuumed, and then carbon dioxide gas is introduced, the temperature of the reaction kettle is controlled at 40°C, the pressure is 10 MPa, and the reaction time is 3h. After the reaction, quantitative analysis is performed using gas chromatography (such as Figure 1 ), the conversion rate is based on the reactant cis-2-pentenenitrile, that is, the proportion of cis-2-pentenenitrile reacted out of the initial charge; the selectivity indicates the proportion of the target product 3-pentenenitrile in the amount of reactant reduced. The results are shown in Table 1.

[0034] Comparative Example 1

[0035] The comparative example 1 includes comparative example 1.1, comparative example 1.2, comparative example 1.3, comparative example 1.4, and the operation process and control conditions are the same as those of example 1, except that the catalysts used are alumina, zinc oxide and tin oxide respectively, and the reaction results are shown in Table 1.

[0036] Comparative example 2

[0037] The operation process of the comparative example is as follows: under a nitrogen atmosphere, 1 mol of lanthanum oxide catalyst, 5 mol of triphenyl phosphite as ligand, 100 mol of cis-2-pentenenitrile, and 100 mol of organic solvent as solvent are sequentially added to the reaction kettle, and then the reaction kettle is sealed, nitrogen is replaced, the temperature of the reaction kettle is controlled at 80°C, the pressure is 1 MPa, and the reaction time is 3 h. After the reaction, gas chromatography is used for quantitative analysis. The comparative example includes comparative example 2.1, comparative example 2.2, except that the solvents used are toluene and cyclohexane respectively, and the reaction results are shown in Table 1.

[0038] Comparative example 3

[0039] The comparative example 1 includes comparative example 3.1, comparative example 3.2, and the operation process and control conditions are the same as those of example 1, except that the ligand used in comparative example 3.1 is triphenylphosphine, and no ligand is added in comparative example 3.2; the reaction results are shown in Table 1, and the gas chromatogram of comparative example 3.1 is as follows: Figure 2 .

[0040] Table 1

[0041]

[0042] As can be verified from Table 1, in the prior art, oxides such as alumina and zinc oxide are used as catalysts to catalyze the isomerization of cis-2-pentenenitrile, but the isomerization effect is not obvious (such as comparative example 3.3), which shows that the conversion rate of cis-2-pentenenitrile is low, and the selectivity of 3PN is also low; after the introduction of supercritical fluid, the conversion rate of cis-2-pentenenitrile and the selectivity of 3PN are improved (such as comparative examples 1.1-1.4), but the reaction time is still long. In example 1 of the present application, by optimizing the types of catalysts and ligands under supercritical fluid conditions, the conversion rate of cis-2-pentenenitrile and the selectivity of 3PN are greatly improved, and the reaction time is also shortened.

[0043] Example 2

[0044] Based on the method of isomerizing cis-2-pentenenitrile to 3-pentenenitrile shown in example 1, the types of catalysts used in this example are explored. Specifically, the parameters and control conditions of this example are the same as those of example 1, except that the types of catalysts used are different, and the control conditions and reaction results are shown in Table 2.

[0045] Table 2

[0046]

[0047]

[0048] As can be verified from Table 2, the catalyst described in the present application is a rare earth metal oxide or a rare earth metal halide, wherein the rare earth metal oxide can be at least one of lanthanum oxide, actinium oxide, samarium oxide, praseodymium oxide, cerium oxide, neodymium oxide, and further can be lanthanum oxide; the rare earth metal halide can be at least one of chloride, and further can be at least one of lanthanum chloride, cerium chloride and europium chloride.

[0049] Example 3

[0050] Based on the method of isomerization of cis-2-pentenenitrile into 3-pentenenitrile shown in Example 1, this example explores the type of supercritical fluid used. Specifically, the parameters and control conditions of this example are the same as those of Example 1, except that the type of supercritical fluid used is different. The control conditions and reaction results are shown in Table 3.

[0051] Table 3

[0052] Number Catalyst type Conversion of cis-2-pentenenitrile / % Selectivity of 3-pentenenitrile / % Example 1 Supercritical carbon dioxide 98.8 98.0 Example 3.1 Supercritical nitrogen dioxide 97.2 97.4 Example 3.2 Supercritical sulfur dioxide 98.5 98.1 Example 3.3 Supercritical ammonia 97.8 97.3

[0053] As can be verified from Table 3, the supercritical fluid described in the technical solution of the present application can be at least one of supercritical carbon dioxide, supercritical nitrogen dioxide, supercritical sulfur dioxide and supercritical ammonia, and further can be supercritical carbon dioxide.

[0054] Example 4

[0055] Based on the method of isomerization of cis-2-pentenenitrile into 3-pentenenitrile shown in Example 1, this example explores the type of monodentate or polydentate ligand used. Specifically, the parameters and control conditions of this example are the same as those of Example 1, except that the type of ligand used is different. The control conditions and reaction results are shown in Table 4.

[0056] Table 4

[0057]

[0058]

[0059] As can be verified from Table 4, the monodentate phosphite ligand used in the technical scheme of the present application can be at least one of triethyl phosphite, triphenyl phosphite, tri-p-tolyl phosphite, tri-m-tolyl phosphite, tri-o-tolyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(2-phenylphenyl) phosphite, phenyl diisooctyl phosphite, triisooctyl phosphite and diisodecyl phosphite, and further can be triphenyl phosphite. The polydentate phosphite ligand can be at least one of 2,2'-biphenol bis(diphenyl) phosphite, 2,2'-biphenol bis(dimethylphenyl) phosphite, 2,2'-biphenol bis(di(2,2'-biphenol) phosphite), [1,1'-biphenyl]-2,2'-diyltetraphenyl bis(phosphite), [1,1'-binaphthalen]-2,2'-diyltetraphenyl bis(phosphite), tetraphenyl(3,3',5,5'-tetramethyl-[1,1'-biphenyl]-2,2'-diyl) bis(phosphite), [1,1'-biphenyl]-2,2'-diyltetra-o-methyl bis(phosphite), 3,3',5-trimethyl-[1,1'-biphenyl]-2,2'-diyl) bis(phosphite), 3,3',5,5'-tetra-tert-butyl-2,2'-biphenol bis(di(2,2'-biphenol) phosphite), 3,3',-di-tert-butyl-5,5'-dimethoxy-2,2'-biphenol bis(di(2,2'-biphenol) phosphite), and further can be 2,2'-biphenol bis(diphenyl) phosphite.

[0060] Example 5

[0061] Based on the method of isomerization of cis-2-pentenenitrile into 3-pentenenitrile shown in Example 1, this embodiment explores the control conditions of the isomerization reaction, and the control conditions and reaction results are shown in Table 5.

[0062] Table 5

[0063]

[0064] As can be verified from Table 5, the molar ratio of cis-2-pentenenitrile to catalyst is (10-200):1, and further can be (20-100):1; the mass ratio of supercritical fluid to cis-2-pentenenitrile is (0.2-20):1, and preferably (0.5-5):1; the molar ratio of ligand to catalyst is (1-20):1, and preferably (2-10):1.

[0065] In addition, the temperature of the isomerization reaction in the technical scheme of the present application can be 20-200℃, and further can be 40-80℃; the pressure of the isomerization reaction can be 2-30 MPa, and further can be 5-20 MPa; alternatively, the time of the isomerization reaction is 0.5-20 h, and preferably 2-10 h.

[0066] Example 6

[0067] A method for isomerization of cis-2-pentenenitrile into 3-pentenenitrile, specifically, in an inert gas atmosphere, 1 mol of lanthanum oxide catalyst, 5 mol of triphenyl phosphite as ligand, and 100 mol of cis-2-pentenenitrile material (containing 20% of 3PN) are sequentially added into a reaction kettle; then the reaction kettle is sealed, vacuumized, and then carbon dioxide gas is introduced, the temperature of the reaction kettle is controlled at 40 DEG C, the pressure is 10 MPa, and the reaction time is 4 h. After the reaction, gas chromatography is used for quantitative analysis, wherein the conversion rate of cis-2-pentenenitrile is still 100%, and the selectivity of 3-pentenenitrile is 99.5%, which verifies that the present application can be used for catalyzing cis-2-pentenenitrile isomerization to generate 3PN in a mixture system containing cis-2-pentenenitrile and 3PN. Therefore, the technical scheme of the present application can be applied to the isomerization process of a mixture of cis-2-pentenenitrile containing 3PN, and has important industrial application value.

[0068] It should be noted that the above is a further detailed description of the present application in combination with specific embodiments, and the specific implementation of the present application cannot be limited to these descriptions; the size data of the present embodiment does not limit the technical scheme, but only shows one specific working condition. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple improvements and refinements can be made, which should be regarded as falling within the scope of protection of the present application.

Claims

1. A process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile, characterized in that The method comprises isomerization of cis-2-pentene nitrile in a supercritical fluid to generate 3-pentene nitrile under the action of a catalyst and a ligand; wherein the catalyst is at least one of lanthanum oxide, actinium oxide, samarium oxide, praseodymium oxide, cerium oxide, neodymium oxide and / or rare earth metal halide, and the ligand is a monodentate phosphite or a polydentate phosphite. The rare earth metal halide is at least one of lanthanum chloride, cerium chloride and europium chloride. The supercritical fluid is at least one of supercritical carbon dioxide, supercritical nitrogen dioxide, supercritical sulfur dioxide and supercritical ammonia.

2. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that The catalyst is lanthanum oxide and / or rare earth metal halide.

3. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that, The molar ratio of cis-2-pentene nitrile to the catalyst is (10-200):

1.

4. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 3, characterized in that, The molar ratio of cis-2-pentene nitrile to the catalyst is (20-100):

1.

5. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that, The supercritical fluid is supercritical carbon dioxide.

6. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that, The mass ratio of the supercritical fluid to cis-2-pentene nitrile is (0.2-20):

1.

7. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 6, characterized in that, The mass ratio of the supercritical fluid to cis-2-pentene nitrile is (0.5-5):

1.

8. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that, The monodentate phosphite ligand is at least one of triethyl phosphite, triphenyl phosphite, tri-p-tolyl phosphite, tri-m-tolyl phosphite, tri-o-tolyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(2-phenylphenyl) phosphite, phenyldiisooctyl phosphite, triisooctyl phosphite and diisodecyl phosphite.

9. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 8, characterized in that, The monodentate phosphite ligand is triphenyl phosphite.

10. The process for the isomerization of cis-2-pentenoic acid to 3-pentenoic acid according to claim 1, characterized in that, The polydentate phosphite ligand is at least one of 2,2'-diphenylolphosphine bis(diphenyl phosphate), 2,2'-diphenylolphosphine bis(dimethylphenyl phosphate), 2,2'-diphenylolphosphine bis(2,2'-diphenylolphosphine) phosphate, [1,1'-biphenyl]-2,2'-diyltetraphenyl bis(phosphate), [1,1'-binaphthalene]-2,2'-diyltetraphenyl bis(phosphate), tetraphenyl(3,3',5,5'-tetramethyl-[1,1'-biphenyl]-2,2'-diyl) bis(phosphate), [1,1'-biphenyl]-2,2'-diyltetra-o-methyl bis(phosphate), 3,3',5-trimethyl-[1,1'-biphenyl]-2,2'-diyl) bis(phosphate), 3,3',5,5'-tetra-tert-butyl-2,2'-diphenylolphosphine bis(2,2'-diphenylolphosphine) phosphate, 3,3',-di-tert-butyl-5,5'-dimethoxy-2,2'-diphenylolphosphine bis(2,2'-diphenylolphosphine) phosphate.

11. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 10, characterized in that, The polydentate phosphite ligand is 2,2'-diphenylolphosphine bis(diphenyl phosphate).

12. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that, The molar ratio of the ligand to the catalyst is (1-20):

1.

13. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 12, characterized in that, The molar ratio of the ligand to the catalyst is (2-10):

1.

14. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that, The temperature of the isomerization reaction is 20-200℃.

15. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 14, characterized in that, The temperature of the isomerization reaction is 40-80℃.

16. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that, The pressure of the isomerization reaction is 2-30 MPa.

17. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 16, characterized in that, The pressure of the isomerization reaction is 5-20 MPa.

18. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 1, characterized in that, The time of the isomerization reaction is 0.5-20 h.

19. The process for the isomerization of cis-2-pentenenitrile to 3-pentenenitrile according to claim 18, characterized in that, The time of the isomerization reaction is 2-10 h.

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