Catalytic and Mechanistic Insights into Side-Chain Alkenylation of Toluene with Methanol for Styrene Formation

The literature on catalytic and mechanistic aspects of the side-chain alkenylation of toluene with methanol for the formation of styrene on solid base catalysts is reviewed. The development of catalysts and catalysis are described mostly on alkali ion exchange zeolite catalysts with fundamental chemistry related to the side-chain alkenylation. Mechanistic studies performed from various viewpoints are described. Methods to elucidate the reaction mechanisms are discussed based on the identification of the adsorbed species of the reactants, use of plausible intermediate compounds as reactant, characterization of surface properties to examine the correlation with reaction results, poisoning of the active sites by certain molecules, and theoretical calculations of the energy profile along with the reaction coordinate. These studies are discussed with critical assessments. The review addresses several challenges that prevent the side-chain alkenylation of toluene with methanol from industrialization which include decomposition of methanol to CO and H_2, and co-production of ethylbenzene. The paper covers mostly literature published during the period from 2000 to early 2021.