Fe, Co-codoped Mg-Al spinels with dual-function sites for CO2-assisted ethane dehydrogenation

Abstract

CO 2 -assisted ethane dehydrogenation provides an attractive route to realize the comprehensive utilization of light alkanes and CO 2 , yet its practical efficiency is restricted by the thermodynamically stable and kinetically inert reactants. Herein, a series of Fe, Co-codoped Mg-Al spinel-type catalysts were synthesized by a sol-gel method and incipient wetness impregnation, and their catalytic performance for the oxidative dehydrogenation of ethane with CO 2 was evaluated. An initial ethane conversion of 26.2% and ethylene selectivity of 91.4% were achieved at 650°C, with no significant loss of catalytic activity after 32 h of reaction. Through XRD, UV–Vis, H 2 -TPR, XPS characterizations as well as Mössbauer spectroscopy, it was found that the newly introduced cobalt species occupied some tetrahedral sites in the form of Co 2+ , acting as Lewis acid sites and facilitating ethane activation. Meanwhile, partial octahedrally coordinated Fe 3+ can be reduced during the reaction to form tetrahedrally coordinated Fe 2+ ions, which can effectively activate CO 2 . Excellent ethane oxidative dehydrogenation catalysts have been obtained via Fe, Co-codoping by decoupling the competitive activation of ethane and CO 2 at one single active site into the synchronized activation at dual active sites.