Hydrocyanation process with reduced yield losses
A hydrocyanation process produces adiponitrile and other dinitriles having six carbon atoms. The process involves forming a reaction mixture in the presence of at least one Lewis acid. The reaction mixture includes ethylenically unsaturated nitrites having five carbon atoms, hydrogen cyanide, and a catalyst precursor compositions. The reaction mixture is continuously fed while controlling the overall feed molar ratio of 2-pentenenitriles to all unsaturated nitriles and the overall feed molar ratio of hydrogen cyanide to all unsaturated nitrites. In the reaction product mixture, including adiponitrile, the ratio of the concentration of 2-pentenenitriles to the concentration of 3-pentenenitriles from about 0.2/1 to about 10/1. Included in the catalyst precursor composition is a zero-valent nickel and at least one multidentate phosphorus-containing ligand. The multidentate phosphorus-containing ligand may be a phosphite, a phosphonite, a phosphinite, a phosphine, and a mixed phosphorus-containing ligand or a combination of such members.
1. A hydrocyanation process to produce adiponitrile and other dinitriles having six carbon atoms, the process comprising:
a) forming a reaction mixture in the presence of at least one Lewis acid, said reaction mixture comprising ethylenically unsaturated nitriles having five carbon atoms, hydrogen cyanide, and a catalyst precursor composition, by continuously feeding the ethylenically unsaturated nitriles, the hydrogen cyanide, and the catalyst precursor composition;
b) controlling X and Z,
wherein X is the overall feed molar ratio of 2-pentenenitriles to all unsaturated nitriles; and
Z is the overall feed molar ratio of hydrogen cyanide to all unsaturated nitriles;
by selecting
a value for X in the range of 0.001 to 0.5; and
a value for Z in the range of 0.5 to 0.99;
such that the value of quotient Q, wherein
Q
=
X
[
(
moles
3
PN
+
4
PN
in
the
feed
)
/
(
moles
all
unsaturated
nitriles
in
the
feed
)
]
-
Z
is in the range from 0.2 to 10, wherein 3PN is 3-pentenenitriles and 4PN is 4-pentenenitrile; and
c) withdrawing a reaction product mixture comprising adiponitrile;
wherein the ratio of the concentration of 2-pentenenitriles to the concentration of 3-pentenenitriles in the reaction mixture is in the range from 0.2/1 to 10/1;
wherein the catalyst precursor composition comprises a zero-valent nickel and at least one multidentate phosphorus-containing ligand;
wherein the multidentate phosphorus-containing ligand is selected from the group consisting of a phosphite, a phosphonite, a phosphinite, a phosphine, and a mixed phosphorus-containing ligand or a combination of such members; and
wherein the multidentate phosphorus-containing ligand gives acceptable results according to at least one protocol of the 2-Pentenenitrile Hydrocyanation Test Method.
2. The process of claim 1 ,
wherein the selected value for X is in the range from 0.01 to 0.25 and the selected value for Z is in the range from 0.70 to 0.99; and wherein the value of 0 is in the range from 1 to 5; and
wherein the ratio of the concentration of 2-pentenenitriles to the concentration of 3-pentenenitriles in the reaction mixture is in the range from 1/1 to 5/1.
3. The process of claim 2 , wherein the multidentate phosphorus-containing ligand is a phosphite.
4. The process of claim 2 , wherein the multidentate phosphorus-containing ligand is a phosphonite.
5. The process of claim 2 , wherein the multidentate phosphorus-containing ligand is a phosphinite.
6. The process of claim 2 , wherein the multidentate phosphorus-containing ligand is a phosphine.
7. The process of claim 2 , wherein the multidentate phosphorus-containing ligand is a mixed phosphorus-containing ligand comprising at least one combination selected from the group consisting of a phosphite-phosphonite, a phosphite phosphinite, a phosphite-phosphine, a phosphonite-phosphinite, a phosphonite-phosphine, and a phosphinite-phosphine or a combination of such members.
8. The process of claim 1 wherein the overall feed molar ratio of 2-pentenenitriles to all unsaturated nitriles is controlled by addition of 2-pentenenitriles produced in an independent process or by direct recycle of the 2-pentenenitriles from the reaction product mixture within the process.
9. The process of claim 1 wherein the Lewis acid promoter comprises at least one compound selected from the group consisting of zinc chloride, iron (II) chloride, manganese (II) chloride, and mixtures thereof.
10. The process of claim 1 wherein the temperature of the reaction mixture is maintained from 20° C. to 90° C.
11. The process of claim 1 wherein the temperature of the reaction mixture is maintained from 35° C. to 70° C.
12. The process of claim 1 wherein the 2-pentenenitriles originate from a pentenenitrile hydrocyanation process.
13. The process of claim 1 wherein the 3-pentenenitriles originate from a 1,3-butadiene hydrocyanation process.
14. The process of claim 1 wherein the catalyst precursor composition further comprises at least one monodentate phosphorus-containing ligand selected from the group consisting of a phosphite, a phosphonite, a phosphinite, and a phosphine or a combination of such members.
15. The process according to claim 1 , wherein the multidentate phosphorus-containing ligand is a bidentate phosphite.
16. The process according to claim 1 , wherein the multidentate phosphorus-containing ligand is a bidentate phosphonite.
17. The process according to claim 1 , wherein the multidentate phosphorus-containing ligand is a bidentate phosphinite.
18. The process according to claim 1 , wherein the multidentate phosphorus-containing ligand is a bidentate phosphine.
19. The process according to claim 1 , wherein the multidentate phosphorus-containing ligand is a bidentate mixed phosphorus-containing ligand selected from the group consisting of a phosphite-phosphonite, a phosphite-phosphinite, a phosphite-phosphine, a phosphonite-phosphinite, a phosphonite-phosphine, and a phosphinite-phosphine or a combination of such members.