Understanding the Influence of Acidity on the Diffusion of Water in Zeolites

The conversion of methanol to hydrocarbons over ZSM-5 zeolite catalysts exists within the framework of obtaining gasoline fuel and high-value petrochemicals such as propylene sustainably from bio-feedstock. The initial steps of the reaction are highly debated as methanol and its derivative, dimethyl ether, and water compete for ZSM-5 catalytic active sites. Also, water reduces the reaction rate and increases ZSM-5 lifetime. This work aims to understand how the movement of water affects this competitive bonding process and catalyst stability. We aim to quantify and compare the mobility of water in ZSM-5 with different acidic site densities (Si/Al = 25, 36 and 135). The experimental data obtained will further be quantitatively analysed to decouple the processes of bonding and release from the active sites. This is required to understand and predict the behaviour of ZSM-5 zeolite catalysts.