Constructing a high-efficiency iron-based catalyst for carbon dioxide oxidative dehydrogenation of 1-butene: The role of oxygen mobility and proposed reaction mechanism

The utilization of CO₂ as a soft oxidant for the synthesis of 1,3-butadiene (BD) through the oxidative dehydrogenation (ODH) of 1-butene is emerging as a potential technology not only because it can reduce the environmental problems caused by CO₂ but also because of the abundant availability, low cost and mild oxidizing properties of CO₂. However, this technology suffers from low catalytic activities due to the inherent inertness of CO₂. Herein, a high-efficiency iron-based catalyst for the ODH of 1-butene with CO₂ was designed and prepared from the perspective of improving the catalyst oxygen mobility, and the turnover frequency (TOF) has been improved to thrice that of the traditional Fe₂O₃/γ-Al₂O₃ catalyst. Furthermore, the effect of the oxygen mobility in the catalysts on their catalytic activity was determined. The oxygen mobility of the catalysts played a key role in CO₂ activation, which in turn facilitated the ODH reaction. The TOFs of the catalysts increased linearly with increasing oxygen mobility. In addition, the γ-Al₂O₃ support, especially the Lewis acid sites on its surface, was proved to be necessary for the reaction. Both the carrier and active component were required for the reaction to proceed. Based on the above results, the mechanism of the ODH of 1-butene with CO₂ was proposed.