Oxidative dehydrogenation of 4-vinylcyclohexene and ethylbenzene: current state and future prospects.

The current state of research on the oxidative dehydrogenation of ethylbenzene and 4-vinylcyclohexene to styrene in the presence of dioxygen and carbon dioxide is reviewed. The high efficiency and potential of producing styrene from 4-vinylcyclohexene (a dimerization/condensation adduct of buta-1,3-diene) using carbon dioxide over oxide and zeolite catalysts modified with selected rare-earth metal (REM) oxides are demonstrated. Experimental findings are presented and potential reaction pathways are discussed. Particular emphasis is placed on the redox and acid-base properties of the catalysts and their critical role in catalyst selection for these processes.