A stable Pt modified cobalt tungstate catalyst for CO2-assisted oxidative dehydrogenation of ethane

Abstract

CO₂-assisted oxidative dehydrogenation (CO₂-ODH) of ethane provides an opportunity to diminish the atmospheric CO₂ level and utilize shale gas effectively to produce ethylene. However, the stability at high temperature of existing catalysts is limited. In this study, CoWO₄ supported Pt metal catalysts with different contents were prepared and examined in CO₂-ODH of ethane, which exhibited excellent stability during continuous operations. From various characterizations such as XRD, SEM, HRTEM, XPS, in situ DRIFTS, TG-DTA and Raman, it is found that the introduction of CO₂ plays a key role in inhibiting the complete reduction of Co species, as well as inhibiting the migration of Pt species and coke deposition, which can be ascribed to the introduced CO₂ combining with reductive H atoms and thus forming the formic acid intermediate, which effectively avoids over-reduction of metal species. However, for the ethane dehydrogenation (EDH) reaction without CO₂ cofed, the Pt species suffer from sintering, and the Co species undergo complete reduction into metallic ones. Moreover, a large amount of coke deposits on the metal particles and support which leads to deactivation. The current work sheds lights on the design of innovative and stable catalysts for light alkane oxidative dehydrogenations.