(513bp) Research on Catalysts for the Hydrocyanation of 1,3-Butadiene to Adiponitrile

The most successful application in the synthesis of adiponitrile (AdN) is the hydrocyanation of 1,3-butadiene. This process uses 1,3-butadiene (BD) and HCN as the main raw materials, and employs nickel-phosphorus complex (NiL₄) as catalyst and Lewis acid (LA) as co-catalyst. Usually, three step reactions are included in this process: the hydrocyanation reaction of BD, the isomerization reaction of 2-methyl-3-butenenitrile (2M3BN), the isomerization reaction of 3-pentenenitrile (3PN) to 4-pentenenitrile (4PN) and its hydrocyanation reaction (Figure 1). This process is short route, low cost, high yield, low pollution, and showing green competitiveness. The isomerization reaction of 2M3BN was used as a model reaction to conduct a comprehensive and in-depth study on the catalyst and reaction mechanism, mainly including the kinetic and reaction mechanism research, the deactivation products and deactivation mechanisms, and the design of highly active phosphorus ligands. Based on the characteristics of phosphorus ligands (electronic effect and steric effect) and the mechanism of isomerization reaction, the structure-activity relationship in the isomerization reaction was successfully obtained. A suitable catalyst structure could be conducive to exerting the catalytic activity and ensure the selectivity to 3PN in the isomerization reaction. Finally, phosphorus ligands with high activity and high 3-pentenenitrile selectivity (greater than 99%) were selected based on the structure-activity relationship.