Unraveling the Mn-promoted coke elimination mechanism by CO2 over NaFeMn/ZSM-5 catalyst during CO2 hydrogenation

Abstract

Coke deposition and catalyst deactivation are widely viewed as a crucial issue for CO2 hydrogenation performance, however, effective strategy for coke attenuation and the corresponding underlying mechanism are still rarely explored. In this research, we discovered that the reactant CO2 can also play a vital role in diminishing coke deposits during CO2 conversion, and carbon on zeolite can just be eliminated with the assistance of activated iron catalysts. Moreover, Mn promoter can restrict Na migration to zeolite, sustaining zeolite acidity for aromatization. Significantly, the migrating Mn on zeolite from NaFeMn can promote the formation of CO2-oxidizable coke, thus accelerating coke oxidation by CO2. These findings are beneficial for the improvement of catalyst stability and optimization of reaction system.