Coupling CO_(2)reduction with ethane aromatization for enhancing catalytic stability of iron-modified ZSM-5

The shale gas revolution and the carbon-neutrality goal are motivating the landscape toward the synthesis of value-added chemicals or fuels from underutilized ethane with the assistance of greenhouse gas CO_(2).Combining ethane aromatization with CO_(2)reduction offers an opportunity to directly produce liquid products for facile separation,storage,and transportation.In the present work,Fe/ZSM-5 catalysts showed promise in the simultaneous CO_(2)reduction and ethane aromatization at atmospheric pressure and 873 K.The catalysts were further investigated using X-ray diffraction(XRD)and X-ray absorption fine structure(XAFS)measurements under in-situ conditions,indicating that most of Fe species existed in the form of Fe oxides and a portion of Fe was incorporated into the ZSM-5 framework generating Lewis acid sites.Both types of Fe species remained almost unchanged under reaction conditions,contributing to an enhanced aromatization activity of Fe/ZSM-5.The effects of CO_(2)and steam on the acid sites and in turn aromatization activity were also investigated by transient studies,which exhibited a reversible modification behavior.Moreover,CO_(2)was identified to be critical to enhance coke resistance and in turn catalyst stability.This work highlights the feasibility of using CO_(2)to assist the upgrading of abundant ethane from shale gas to aromatics over non-precious Fe-based zeolite catalysts.