High-entropy Mn-based spinel oxides with enhanced catalytic activity, sulfur resistance, and thermal stability for propane total oxidation.

The catalytic elimination of light alkanes from industrial emissions remains challenging due to their stable molecular structures. Herein, a series of Mn-based spinel oxides with single A-site cations (Mg, Co, Ni, Cu, Zn) and a high-entropy spinel (Mg0.2Co0.2Ni0.2Cu0.2Zn0.2)Mn2O4 (denoted as HEO-5Mn) were synthesized via a sucrose-assisted sol-gel method. Compared to the conventional spinels, HEO-5Mn exhibits superior catalytic activity for propane oxidation (T90 = 260°C), decent sulfur resistance, and good water tolerance. Systematic characterizations (XRD, Raman, FTIR, H2-TPR, O2-TPD, and XPS) reveal that the high-entropy effect induces pronounced lattice distortion, abundant oxygen vacancies, and enhanced low-temperature reducibility, which collectively facilitate the Mars-van Krevelen mechanism. Furthermore, partial substitution of Mn at the B site with a small amount of La further improves the sintering resistance upon high-temperature aging (750°C) while preserving the intrinsic activity. This work demonstrates that high-entropy design combined with rational B-site modification offers a promising strategy for developing durable and efficient non-precious metal catalysts for practical VOC abatement.