Tandem Reactions of CO₂ Reduction and Ethane Aromatization

Aromatization of light alkanes is of great interest because this can expand the raw materials used to produce aromatics to include fractions of natural gas that are readily available and inexpensive. Combining CO₂ reduction with ethane dehydrogenation and aromatization can also mitigate CO₂ emissions. A one-step process that can produce liquid aromatics from the reactions of CO₂ and ethane using phosphorus (P)- and gallium (Ga)-modified ZSM-5 has been evaluated at 873 K and atmospheric pressure. The addition of P improves the hydrothermal stability of Ga/ZSM-5, reduces coke formation on the catalyst surface, and allows the formation of more liquid aromatics through the tandem reactions of CO₂-assisted oxidative dehydrogenation of ethane and subsequent aromatization. Density functional theory calculations provide insights into the effect of Ga- and P- modification on ethane dehydrogenation to ethylene as well as the role of CO₂ on the production of aromatics.