Production of butylamine in the gas phase hydrogenation of butyronitrile over Pd/SiO2 and Ba-Pd/SiO2

The gas phase (1 atm, 473-563 K) hydrogenation of butyronitrile has been studied over Pd/SiO2 and Ba-Pd/SiO2. Catalysts characterization involved temperature-programmed reduction (TPR), H-2/NH3 chemisorption/temperature programmed desorption (TPD), X-ray diffraction (XRD), and TEM measurements. The incorporation of Ba with Pd resulted in the formation of smaller metal nano-particles (7 vs 28 nm) with a resultant (seven-fold) higher H-2 chemisorption and decreased total surface acidity (from NH3 chemisorption/TPD). Temperature-related activity maxima were observed for both catalysts and are associated with thermal desorption of the nitrile reactant. Exclusivity to the target butylamine was achieved at T >= 543 K where Ba-Pd/SiO2 delivered higher selective hydrogenation rate (91 mol h(-1) mol(Pd)(-1)) than Pd/SiO2 (54 mol h(-1) mol(Pd)(-1)), attributed to greater availability of surface-reactive hydrogen. Lower surface acidity served to minimize condensation to higher amines. The rate and selectivity to butylamine exceed those previously reported for gas phase operation.