Advances and mechanistic insights in the catalytic semi-hydrogenation of acetylene over non-metallic catalysts

Acetylene semi-hydrogenation reaction is a critical transformation process for removing trace levels of acetylene from industrial ethylene streams. Noble metal catalysts are commonly used for this process; however, their high cost and limited availability hinder large-scale and long-term applications. Non-metallic catalysts, on the contrary, exhibit multiple benefits in acetylene hydrogenation, including higher activity, greater selectivity, and environmental friendliness. This review primarily discusses the use of non-metallic catalysts in acetylene hydrogenation, such as metal oxides, nitrides, and carbon compounds. The emphasis is on the catalytic mechanism and critical steps of non-metallic catalysts based on frustrated Lewis pairs (FLP), including the adsorption and activation of hydrogen and acetylene, as well as ethylene production. In addition, research work on catalyst design and reaction condition modification to improve conversion rate and product selectivity is discussed. Finally, the future development directions of non-metallic catalyzed acetylene hydrogenation are reviewed, including further mechanistic investigations, the study of novel catalytic systems, and the implementation of environmentally friendly chemical processes. It is envisaged that non-metallic catalyzed acetylene hydrogenation would play a key role in energy conversion and the chemical sector, contributing to long-term sustainability.