Patent ID: 7528275

Claim:
A process for preparing adiponitrile comprising the steps of (a) hydrocyanating 1 ,3-butadiene over at least one nickel(0) catalyst, resulting in a hydrocyanation stream 1 which comprises 3-pentenenitrile, 2-pentenenitrile, 2-methyl-2-butenenitrile, C 9 nitriles, 2-methyl-3 -butenenitrile, methyiglutaronitrile, the at least one nickel(0) catalyst, unconverted 1 ,3-butadiene and residues of unconverted hydrogen cyanide, (b) removing the at least one nickel(0) catalyst from the hydrocyanation stream 1 to obtain a catalyst stream 1 which comprises the at least one nickel(0) catalyst, and a hydrocyanation stream 2 which comprises 3-pentenenitrile, 2-pentenenitrile, 2-methyl-2-butenenitrile, C 9 nitriles and 2-methyl-3 -butenenitrile, (c) regenerating the at least one nickel(0) catalyst in the catalyst stream 1 by reductive nickel catalyst synthesis with addition of fresh ligand to obtain a catalyst stream 2, (d) hydrocyanating 3-pentenenitrile over at least one nickel(0) catalyst and in the presence of at least one Lewis acid, the nickel(0) catalyst and the Lewis acid from at least partly from catalyst stream 2, resulting in a hydrocyanation stream 3 which comprises the at least one nickel(0) catalyst, adiponitrile and the at least one Lewis acid, (e) removing the at least one nickel(0) catalyst from the hydrocyanation stream 3 by extraction with an organic solvent to obtain a catalyst stream 3 which comprises the at least one nickel(0) catalyst, and a product stream which comprises adiponitrile, and the catalyst stream 3 can be recycled at least partly into process step (a).