CO2 Assisted Oxidative Dehydrogenation of Light Alkanes: A Spectroscopic Perspective

Carbon dioxide has been highlighted in recent years as a promising mild oxidant in the oxidative dehydrogenation (ODH) of low molecular weight alkanes over different metal oxide-based catalysts. Using CO₂ as an alternative oxidizing agent has been shown to effectively suppress the undesirable combustion of the alkane under ODH conditions. In addition, its potential benefit for in-situ removal of carbon deposits via the reverse Boudouard reaction has been also underscored in the open literature. While oxygen assisted ODH involves a Mars van Krevelen mechanism, in ODH with CO₂ it is shown that usually, olefin formation occurs mainly through a tandem scheme where direct alkane dehydrogenation is coupled with the reverse water gas shift (RWGS) reaction. However, the role of CO₂ on the mechanism for the formation of olefins is still in question as different reaction pathways involving CO₂ participation over supported metal oxide catalysts may occur. Since these pathways affect catalyst reactivity, we will discuss a combined approach where vibrational spectroscopy is coupled with catalytic measurements to provide insights into the role of CO₂ on metal oxide stability.