Effect of alkali and transition metal cations-modified-ZSM-5 catalysts in oxidative dehydrogenation of propane to propylene

In this work, ZSM-5 modified with lithium, potassium, caesium, chromium and molybdenum were produced by solid state reaction and their respective catalytic properties were investigated using a laboratory fixed bed reactor in oxidative dehydrogenation of propane to propylene. The results showed that the incorporation of the metals influenced the conversion of propane and the selectivity to propylene due to their adjustments of the catalyst's acidity and led to a reduction in average pore diameter and pore volume. However, the crystalline structure of the original parent zeolite was not strongly affected by the presence of the metals as observed from the XRD and FTIR analyses. Li-ZSM-5 showed the highest selectivity to propylene and low conversion of propane. Mo-ZSM-5 showed good activity and reasonable selectivity at both low and high temperatures of the reaction (70 % selectivity and 43 % conversion). All the catalysts tested showed good activity and reasonable selectivity at the highest temperature of the reaction.