Efficient carbon integration of CO2 in propane aromatization over acidic zeolites

Abstract

Direct converting carbon dioxide (CO₂) and propane (C₃H₈) into aromatics with high carbon utilization offers a desirable opportunity to simultaneously mitigate CO₂ emission and adequately utilize C₃H₈ in shale gas. Owing to their thermodynamic resistance, converting CO₂ and C₃H₈ respectively remains difficult. Here, we achieve 60.2% aromatics selectivity and 48.8% propane conversion over H-ZSM-5-25 via a zeolite-catalyzing the coupling of CO₂ and C₃H₈. Operando dual-beam FTIR spectroscopy combined with ¹³C-labeled CO₂ tracing experiments revealed that CO₂ is directly involved in the generation of aromatics, with its carbon atoms selectively embedded into the aromatic ring, bypassing the reverse water-gas shift pathway. Accordingly, a cooperative aromatization mechanism is proposed. Thereinto, lactones, produced from CO₂ and olefins, are proven to be the key intermediate. This work not only provides an opportunity for simultaneous conversion of CO₂ and C₃H₈, but also expends coupling strategy designing of CO₂ and alkanes over acidic zeolites.