ABSTRACT
Some of the largest commercially produced primary amines are manufactured by catalytic hydrogenation of nitrites using sponge metal catalysts. The larger the market volume for the amine, the more important the technology used to control selectivity becomes to remain a viable producer. We've found that controlling the selectivity to the primary amine using lithium hydroxide modified sponge cobalt in backrnix reactors, batch, semi-batch or continuous, at moderate pressures and temperatures provides an excellent means of minimizing byproducts without sacrificing productivity. LiOH modified sponge cobalt was found to recycle in batch processing without loss of selectivity for primary amines. In continuous backrnix processing LiOH modified sponge cobalt catalyst retained selectivity through numerous reactor turnovers compared to LiOH modified sponge nickel. NaOH and KOH modified catalysts tended to agglomerate under similar conditions. Procedures using a semi-batch system are provided for selecting optimum catalysts for nitrile hydrogenation, measuring the catalysts activity and its ability to resist poisoning by nitrites. This paper presents a practical approach to selecting the best selectivity control for the commercial production of primary amines and demonstrates that chemical additives alone are not enough to allow one to obtain the best possible control over selectivity and in fact, the mode of operation and reaction conditions are also important in the optimization process.
