High entropy oxide catalysts with SO2 resistance in RWGS reaction

Ubiquitous presence of SO2 usually shows adverse effects on industrial catalysis. Herein, a concept of engineering entropy to design SO2 resistance oxide catalysts is proposed. (Ni0.2Mg0.2Cu0.2Zn0.2Co0.2)Fe2O4 showed excellent performance (the CO2 conv. = 41.4%, CO selec. = 99.6% at 400 degrees C) compared to the control samples in the reverse water-gas shift (RWGS). In addition, (Ni0.2Mg0.2Cu0.2Zn0.2Co0.2)Fe2O4 had the SO2-tolerant ability (the CO2 conv. = 38.5%, CO selec. = 99.2% at 400 degrees C) after being poisoned with 1000 ppm SO2 at 400 degrees C for 1 h. In sharp contrast, the control samples NiFe2O4, MgFe2O4, CuFe2O4 and CoFe2O4 lost their activity. O-1S XPS indicated that (Ni0.2Mg0.2Cu0.2Zn0.2Co0.2)Fe2O4 had higher oxygen vacancy concentrations. SO2 resistance mechanism was studied by infrared spectroscopy, SO2-TPD, in situ S 2p XPS and the DFT results, confirming that the low SO2 adsorption energy of (Ni0.2Mg0.2Cu0.2Zn0.2Co0.2)Fe2O4, which was attributed to the lower Gibbs free energy. This work may inspire the rational design of SO2-resistant catalysts.