In-situ FTIR study of hydrogen spillover and reaction kinetics in hybrid catalysts

An attempt is made to demonstrate that in hybrid catalysts there is a rapid molecular transfer between hydrogenation sites (which are the metals loaded on alumina) and the acid sites (zeolite)-the site of catalytic cracking. In this study a series of hybrid catalysts were prepared by loading metals Ni and W on Al 2 O 3 and then physically mixing with H-USY to give the final catalysts. H-D Exchange (-OH+D 2 ) of the Bronsted acid site was carried out, that led to a complete description of interactions between spilt-over hydrogen and acid sites of the zeolite. The hybrid catalysts showed more H-D exchange as compared to USY zeolite alone. This was a clear demonstration of spill over. Amongst the hybrid catalysts, the bi-metallic hybrid catalyst (NiW) showed more exchange as compared to the mono metallic hybrid catalysts. This reflects on greater capacity of the bimetallic catalyst for the hydrogen spill over. The effect of spilt-over hydrogen on the catalytic activity for the hydrocracking of n -heptane was also investigated. n -heptane was cracked to form only two major products: propane and iso -butane. All hybrid catalysts showed high selectivity for the main products. NiW based hybrid catalyst showed excellent performance as a hydrocracking catalyst.