New aspects for heterogeneous cobalt-catalyzed hydroamination of ethanol

Gas-phase hydroamination of ethanol and ammonia over supported cobalt on silica catalysts was investigated at 103 kPa. Besides the desired products, mono-, di- and triethylamine, acetonitrile, diethylimine, and hydrocarbons (methane, ethene, ethane, propane, and propene) were identified as byproducts. The formation of hydrocarbons was found to depend on the cobalt loading of the catalyst and on the pretreatment of the catalyst. Guaranteeing a sufficient reduction of the cobalt catalyst allows a reduction in the selectivity of hydrocarbons from 25 to 10 mol% at a constant conversion of 90%. In addition, rapid deactivation of the catalyst was observed in the absence of hydrogen. The deactivation was ascribed to the interaction of ammonia with the catalyst and is largely reversible. Carbonaceous species are present on the spent catalyst, as shown by temperature-programmed reduction. These species are thought to be responsible for a slow deactivation in the presence of hydrogen.