Characterization of Ni-K catalysts supported on γ-alumina and reactivity for the hydrogenation of 1,3-butadiene

A series of gamma -Al2O3 supported K added Ni catalysts were prepared in order to investigate the effect of K on the selective hydrogenation of 1,3-butadiene. The catalysts were prepared by impregnation, with loadings of 15 wt% Ni and varying amounts of K [(K/Ni+K)(atomic) = 0.2-0.6] followed by calcinations at 400degreesC. Reduction was performed at 450degreesC for 5h. They were characterized by temperature-programmed reduction (TPR), 1,3-butadiene-temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and X-ray absorbance near edge structure (XANES) spectroscopy. Activity and product selectivities were tested for hydrogenation of 1,3-butadiene in the temperature range of 100-300degreesC. The set of data indicate that the addition of K modified the electron density of Ni metal and weakened the adsorption strength of butadiene. It has been established by a shift of the Ni 2p(3/2) binding energy in XPS measurement, Ni absorption edge in XANES spectroscopy and 1,3-butadiene-TPD measurements. The catalysts exhibited a high activity and selectivity for 1-butene particularly the K added Ni catalysts due to the promotion of K for Ni based catalysts.