Tandem catalysts of metal-modified ZSM-5 with Na-promoted zinc ferrite for CO2 hydrogenation to aromatics

The CO 2 hydrogenation to aromatics reaction is a promising route to mitigate greenhouse gas emissions while producing basic petrochemical feedstocks. Herein, we demonstrate a tandem catalyst system combining iron- and phosphorus- modified ZSM-5 zeolite (Fe-P-ZSM-5) with sodium-promoted zinc ferrite (NaFeZn) to obtain a catalyst for the reaction to directly convert CO 2 into aromatics in a single reactor. The NaFeZn catalyst selectively converted CO 2 into long-chain olefins as primary products. These olefins were subsequently transformed into aromatics by ZSM-5 zeolites, while paraffins were formed as by-products from the olefin hydrogenation reaction. Compared to ZSM-5, Fe-P-ZSM-5 exhibits enhanced selectivity for aromatics production due to iron and phosphorus modifications that promote aromatization while suppressing hydrogenation. This catalytic enhancement arises from the synergistic interaction between phosphorus and iron. Phosphorus weakens acid strength through its interaction with aluminum, thereby suppressing olefin hydrogenation. Additionally, phosphorus stabilizes iron as an isolated species, which in turn provides distinctive active sites favoring aromatization. • NaFeZn was combined with ZSM-5 zeolites as tandem catalysts for CO 2 -to-aromatics. • Fe-P-ZSM-5 showed improved catalytic performance than H-ZSM-5. • Phosphorus interacts with aluminium, and helps iron to be stable as isolated state. • Fe & P can decrease BAS for hydrogenation while increase LAS for aromatization.