Alkylation of toluene with methanol over alkali exchanged ZSM-5

The catalytic activity was investigated of a series of alkali exchanged and alkali impregnated ZSM-5 zeolites in the alkylation of toluene with methanol. The variations of the rate of the reaction were concluded to be governed mainly by the concentrations of protonated methanol molecules and of adsorbed toluene. The active sites were concluded to be weak Brønsted acid sites, present as a result of lattice defects. The alkali cations were not active in the alkylation reaction. They do, however, influence the acid strength of the weak acid sites. Because of this influence, the concentration of methoxonium ions and hence the rate of alkylation decreases from LiZSM-5 to CsZSM-5.