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 and by isomerizing 2-methyl-3-butenenitrile. Phenolic compounds, such as phenol and cresols, are present as a catalyst impurity or as a catalyst degradation product. Phenolic compounds are removed during the nitrile manufacturing process.

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 first reaction zone effluent 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 second reaction zone effluent 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 third reaction zone effluent 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 the first reaction zone effluent of step (a) comprises one or more phenolic compounds of the formulawhere R1 is H or an alkyl group having 1 to 4 carbon atoms, and n is 0 to 4, provided that when the phenolic compound of formula (II) has more than one alkyl group, these alkyl groups may be the same or different,
wherein first catalyst in the first reaction zone effluent 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 at least a portion of the 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 said phenolic compound of formula (II), and wherein the weight ratio of said phenolic compound of formula (II) to first catalyst in said solvent phase is less than the weight ratio of said phenolic compound of formula (II) to first catalyst in said catalyst recycle stream introduced to the liquid/liquid extraction step; and wherein the 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.