Process for making nitriles

摘要

Adiponitrile is made by reacting 3-pentenenitrile with hydrogen cyanide. The 3-pentenenitrile is made by reacting 1,3-butadiene with hydrogen cyanide. The catalyst for the reaction of 1,3-butadiene with hydrogen cyanide to make 3-pentenenitrile is recycled. At least a portion of the recycled catalyst is purified by an extraction process, which separates catalyst degradation products and reaction byproducts, such as mononitriles having 9 carbon atoms, from the catalyst.

主权项

1. 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 a 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 the first catalyst flows through the first reaction zone along with reactants and products, wherein the second catalyst flows through the second reaction zone along with reactants and products, wherein the third catalyst flows through the third reaction zone along with reactants and products, wherein C9 mononitriles are produced as a byproduct in said first reaction zone, wherein first catalyst flowing from the first reaction zone is concentrated in one or more distillation steps and recycled in at least one catalyst recycle stream to the first reaction zone, wherein a portion of the first catalyst recycle stream to the first reaction zone is contacted with an extraction solvent in a liquid/liquid extraction step to produce a solvent phase and a raffinate phase, wherein said solvent phase comprises first catalyst and said raffinate phase comprises C9 mononitriles, wherein the weight ratio of C9 mononitriles to first catalyst in said solvent phase is less than the weight ratio of C9 mononitriles to first catalyst in said first catalyst recycle stream introduced to the liquid/liquid extraction step; and wherein first catalyst from said solvent phase obtained in said liquid/liquid extraction step is recycled to the first reaction zone or the second reaction zone or both the first and second reaction zone.