Stabilized ε-Fe₂C catalyst with Mn tuning to suppress C1 byproduct selectivity for high-temperature olefin synthesis.

Abstract

Accurately controlling the product selectivity in syngas conversion, especially increasing the olefin selectivity while minimizing C1 byproducts, remains a significant challenge. Epsilon Fe₂C is deemed a promising candidate catalyst due to its inherently low CO₂ selectivity, but its use is hindered by its poor high-temperature stability. Herein, we report the successful synthesis of highly stable ε-Fe₂C through a N-induced strategy utilizing pyrolysis of Prussian blue analogs (PBAs). This catalyst, with precisely controlled Mn promoter, not only achieved an olefin selectivity of up to 70.2% but also minimized the selectivity of C1 byproducts to 19.0%, including 11.9% CO₂ and 7.1% CH₄. The superior performance of our ε-Fe₂C-xMn catalysts, particularly in minimizing CO₂ formation, is largely attributed to the interface of dispersed MnO cluster and ε-Fe₂C, which crucially limits CO to CO₂ conversion. Here, we enhance the carbon efficiency and economic viability of the olefin production process while maintaining high catalytic activity.