Mechanochemical redox synthesis of interstitial mesoporous CoxFe1‐xOy catalyst for CO2 hydrogenation

The study on CoOx‐FeOx catalysts gives a profound insight into the synthesis and the application of multitransition metal oxide catalysts. A facile and solid‐state mechanochemical redox strategy was developed to obtain CoxFe1‐xOy from CoCl2·6H2O and KMnO4 with simply two‐round of ball milling (BM) operation. The process was witnessed by the Brunauer—Emmett—Teller (BET), X‐ray diffraction (XRD), scanning transmission electron microscope (STEM), inductively coupled plasma emission spectrometry (ICP), and X‐ray photoelectron spectroscopy (XPS) characterization, confirming the contribution of the mechanical force and frictional heating in the occurrence of redox reaction, the dispersion of metal species, and the generation of interstitial pores. Importantly, as‐made CoxFe1‐xOy‐BM sample possessed abundant porosity, and the specific surface area of it (131 m2 g−1) was much higher than that of coprecipitation route (49 m2 g−1) and sol‐gel route (33 m2 g−1). The as‐prepared catalysts CoxFe1‐xOy‐BM exhibited excellent performance in reverse water gas shift reaction, reaching 43% of CO2 conversion rate at 500°C with high selectivity (over 80%) during the whole temperature range, while the conversion for both control samples were below 20%. Moreover, continuous 120 hr CO2 hydrogenation at 500°C presented the enhancement of thermal stability and the possible change of active sites. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.