Direct aromatization of CO₂ via combined CO₂ hydrogenation and zeolite-based acid catalysis

Abstract

Aromatics, including benzene, toluene, and xylenes (BTX), are essential chemical building blocks and are widely used as solvents, fuel additives, and polymers. With the recent development in CO₂ capture technologies and the progress made in producing H₂ using renewable energy, direct hydrogenation of CO₂ to aromatics via heterogeneous catalysis has emerged as a promising pathway to accomplish the production of aromatics with simultaneous utilization of waste CO₂. In this review, we focus on recent advances in the nascent field of direct CO₂ aromatization, whereby tandem catalysts composed of CO₂ hydrogenation and aromatization functionalities are designed and deployed. We review two categories of tandem catalysts: catalysts integrating Fe-based/H-ZSM-5 components following RWGS (reverse water-gas shift of CO₂ to CO)-FT (Fischer-Tropsch synthesis of lower olefins)-aromatization pathways, and catalysts combining metal oxide/H-ZSM-5 domains following CO₂ to methanol-aromatization pathways. The key parameters that determine the catalytic performance, such as the composition and structure of the Fe-based or metal oxide-based CO₂ conversion catalysts, the properties of H-ZSM-5, and the synergy between the two components, are analyzed to provide insights for the design of efficient tandem catalysts for CO₂ aromatization. In parallel, thermodynamic analyses, mechanistic studies, and density functional theory (DFT) computations for the relevant reaction routes and pathways are discussed to offer improved understanding of CO₂ activation, reaction intermediates, and product formation. Finally, the challenges and prospects for these tandem reactions are addressed to provide suggested paths forward for future research.

Abstract source: Published article, Journal of CO₂ Utilization.