Side-chain alkylation of toluene with methanol to produce styrene: an overview
Styrene is a key building-block chemical for the production of polymers with significant application value. Producing styrene by toluene side-chain alkylation with methanol has been deemed as a potential one-step alternative to the conventional two-step route via the alkylation of benzene with ethylene and sequential hydrogenation of ethylbenzene. In recent decades, a lot of research has been conducted in order to understand the reaction mechanism of toluene side-chain alkylation. Based on the discussion of the reaction mechanism, we focused on the recent progress on catalysts and evaluated the catalytic performance in toluene side-chain alkylation. A variety of side-chain alkylation catalysts can be divided into five categories: modified X zeolite catalysts, composite zeolite catalysts, carbon-based catalysts, metal oxide catalysts and N-doped catalysts. Also, the effect of reaction conditions and catalyst deactivation were emphasized. Finally, the perspective and the future direction of toluene side-chain alkylation were presented.