Process for making nitriles

A process for making adiponitrile, 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;
• and
• (c) reacting in a third reaction zone a mixture comprising 3PN from step (b) and hydrogen cyanide (HCN) in the presence of a third catalyst comprising zero-valent Ni and a third phosphorus-containing ligand and in the presence of Lewis acid promoter to produce a reaction product comprising adiponitrile,
• wherein catalyst flows through the first, second and third reaction zones along with reactants and products,
• wherein the first catalyst is recycled to the first reaction zone through a first catalyst recycle loop,
• wherein the third catalyst is recycled to the third reaction zone through a separate catalyst recycle loop,
• wherein the catalyst recycle loops for recycling the first and third catalysts are different,
• wherein a portion of the first catalyst concentrated in the first recycle loop of the first stage is purified by a liquid/liquid extraction step, and
• wherein purified first catalyst is returned to the first reaction zone.