Process for making nitriles

A process for making 3-pentenenitrile, said process comprising the steps of:

• (a) reacting in a first reaction zone a mixture comprising 1,3-butadiene (BD) and hydrogen cyanide (HCN) in the presence of a first catalyst comprising zero-valent Ni and a first phosphorus-containing ligand to produce a reaction product comprising 3-pentenenitrile (3PN) and 2-methyl-3-butenenitrile (2M3BN);
• (b) isomerizing at least a portion of the 2M3BN of step (a) in a second reaction zone in the presence of a second catalyst comprising zero-valent Ni and a second phosphorus-containing ligand to produce reaction product comprising 3PN;
• wherein first catalyst flows through the first reaction zones along with reactants and products,
• wherein second catalyst flows through the second reaction zones along with reactants and products,
• wherein the zero valent nickel content of the first catalyst is reduced and catalyst degradation byproducts are produced during the process,
• wherein first catalyst flowing from the first reaction zone is concentrated in one or more distillation steps to form a concentrated first catalyst and recycled to the first reaction zone,
• wherein a portion of the concentrated first catalyst is purified by removing catalyst degradation products in a liquid/liquid extraction step to form a purified catalyst,
• wherein the purified first catalyst is recycled to the first reaction zone or the second reaction zone or both the first and second reaction zone,
• wherein zero valent nickel is added to the purified catalyst from the liquid/liquid extraction step after the catalyst is purified in the liquid/liquid extraction step and before the purified catalyst is recycled to the first reaction zone or the second reaction zone or both the first and second reaction zone, and
• wherein the zero valent nickel added to the purified catalyst replenishes first catalyst which has been lost by degradation during the process.