Selective synthesis of dimethylamine over small-pore zeolites: catalytic selectivity and sorption behavior

Abstract Sorption measurements of alcohols were used to rationalize the performance of zeolites used as catalysts for the synthesis of methylamines via the sequential reaction of methanol and ammonia. Low methanol absorption corresponds to low catalytic activity while high isopropanol absorption corresponds to zeolites producing an equilibrium distribution of methylamines. Generally, zeolites, with sorption values for methanol (or ethanol) of 10–30 w o and little or no isopropanol sorption, selectively produce mono- and dimethylamines versus trimethylamine. Mineral chabazites, while having similar activities, surprisingly provide a wide range of product selectivities. The Geometric Selectivity Index, GSI, denned as the ratio of methanol sorption to the sorption of n -propanol, was found to correspond to the observed catalytic selectivity of the mineral chabazites.