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/gamma-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 gamma-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.