An improved multi-reaction zone process provides for improved nitrile product quality and yield. In a first reaction zone, 1,3-butadiene is reacted with hydrogen cyanide in the presence of a catalyst to produce pentenenitriles comprising 3- pentenenitrile and 2-methyl-3-butenenitrile. In a second reaction zone, 2-methyl-3- butenenitrile, recovered from the first reaction zone, is isomerized to 3-pentenenitrile. In an optional third reaction zone, 3-pentenenitrile recovered from the first and second reaction zones is reacted with hydrogen cyanide in the presence of a catalyst and a Lewis acid to produce adiponitrile. A portion of the first catalyst is purified and recycled. Zero valent nickel is added to the purified first catalyst before it is recycled.