High entropy oxide catalysts with SO2 resistance in RWGS reaction

Ubiquitous presence of SO 2 usually shows adverse effects on industrial catalysis. Herein, a concept of engineering entropy to design SO 2 resistance oxide catalysts is proposed. (Ni 0.2 Mg 0.2 Cu 0.2 Zn 0.2 Co 0.2 )Fe 2 O 4 showed excellent performance (the CO 2 conv. = 41.4%, CO selec. = 99.6% at 400°C) compared to the control samples in the reverse water–gas shift (RWGS). In addition, (Ni 0.2 Mg 0.2 Cu 0.2 Zn 0.2 Co 0.2 )Fe 2 O 4 had the SO 2 -tolerant ability (the CO 2 conv. = 38.5%, CO selec. = 99.2% at 400°C) after being poisoned with 1000 ppm SO 2 at 400°C for 1 h. In sharp contrast, the control samples NiFe 2 O 4, MgFe 2 O 4, CuFe 2 O 4 and CoFe 2 O 4 lost their activity. O 1S XPS indicated that (Ni 0.2 Mg 0.2 Cu 0.2 Zn 0.2 Co 0.2 )Fe 2 O 4 had higher oxygen vacancy concentrations. SO 2 resistance mechanism was studied by infrared spectroscopy, SO 2 -TPD, in situ S 2p XPS and the DFT results, confirming that the low SO 2 adsorption energy of (Ni 0.2 Mg 0.2 Cu 0.2 Zn 0.2 Co 0.2 )Fe 2 O 4 , which was attributed to the lower Gibbs free energy. This work may inspire the rational design of SO 2 -resistant catalysts.