Methoxy-bridged tandem CO2 hydrogenation and ethylbenzene alkylation for selective synthesis of para-ethyl-toluene

The synthesis of value-added aromatic products, such as para-ethyl-toluene (PetT), from the greenhouse gas carbon dioxide (CO2) and renewable hydrogen (H2) is greatly desired. However, considerable challenges arise due to complex kinetics and difficulties in arranging multiple active components. Herein, we present a strategy for the selective synthesis of PetT via CO2 hydrogenation in the presence of ethylbenzene via tandem reactions over a composite catalyst comprising Zn-Zr binary oxide and a modified crystal-stacking HZSM-5 zeolite, achieving over 70% PetT selectivity in the ethyl-toluene (ET) isomers (∼80% in the C5+ hydrocarbons). State-of-the-art (quasi) in situ characterizations and corresponding theoretical calculations confirmed the designed reaction route involving stepwise activation of CO2 to methoxy species and enhanced aromatic cycles for the formation of C–C bonds. And precisely controlled transfer and transformation of intermediate methoxy species contribute to the promoted performance in the selective synthesis of PetT.