Direct CO₂ Methylation to Value-Added Aromatics Through Tandem Catalysis

The direct CO₂ methylation, coupling CO₂ hydrogenation with benzene ring methylation, provides a promising strategy to synthesize value-added aromatics using green hydrogen and CO₂ as C1 source. The tandem reaction promotes the conversion of CO₂ due to the consumption of in situ formed methoxy or methanol over the tandem catalyst of metal oxide and acid zeolite. This review aims to present the thermodynamics advantage and mechanistic insights of direct CO₂ methylation process. In practice, catalytic conversion and selectivity for typical tandem catalysts are still far below the thermodynamic equilibrium. The detail roles and proximity effects for metal oxide and acid zeolite are covered in order to give directions to the catalyst design and reaction condition optimization, which has been proposed to overcome the kinetic limitation for the direct CO₂ methylation development in future.