A catalytic process for dehydration of an aliphatic C2-C6 alcohol to its corresponding olefin is disclosed. The process continuously flows through a reaction zone a liquid phase containing an aliphatic C2-C6 alcohol to contact a non-volatile acid catalyst at a reaction temperature and pressure to at least partially convert the aliphatic C2-C6 alcohol in the liquid phase to its corresponding olefin. The reaction pressure is greater than atmospheric pressure and the reaction temperature is above the boiling point of the olefin at reaction pressure, but below the critical temperature of the alcohol, and the olefin product is substantially in the gaseous phase. After the contacting step, the olefin containing gaseous phase is separated from the liquid phase. The invention also relates to catalytic processes such as a hydrolysis of an olefin to an alcohol, an esterification, a transesterification, a polymerization, an aldol condensation or an ester hydrolysis.