AuPd/Co3O4/3DOM MnCo2O4: Highly active catalysts for methane combustion

Abstract

Three-dimensionally ordered macroporous (3DOM) MnCo2O4-supported Co3O4 and AuPd (xAuPdz/yCo3O4/3DOM MnCo2O4; x = 0.56–1.98 wt%, z = 1.9–2.1, and y = 4.80–24.36 wt%) catalysts were prepared using polymethyl methacrylate (PMMA) microsphere-templating, incipient wetness impregnation, and polyvinyl alcohol (PVA)-protected reduction methods. Physicochemical properties of the materials were characterized by means of numerous techniques, and their catalytic activities were evaluated for methane combustion. It is found that the xAuPdz/yCo3O4/3DOM MnCo2O4 samples with a surface area of 26.5–53.1 m2/g possessed a high-quality 3DOM architecture, in which the AuPd nanoparticles (NPs) with a size of 4.6–5.8 nm were highly dispersed on the surface of the macropore framework. Among all of the samples, 1.98AuPd2.1/18.20Co3O4/3DOM MnCo2O4 exhibited the highest catalytic activity: the T10%, T50%, and T90% (temperatures required for achieving methane conversions of 10, 50, and 90 %, respectively) were 262, 340, and 408 °C at a space velocity of 40,000 mL/(g h). Partial deactivation of the 1.98AuPd2.1/18.20Co3O4/3DOM MnCo2O4 sample due to introduction of water vapor or carbon dioxide was reversible. It is concluded that the good catalytic performance of 1.98AuPd2.1/18.20Co3O4/3DOM MnCo2O4 was associated with its high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Co3O4 or AuPd2.1 NPs and 3DOM MnCo2O4.