Effects of binary Co–Mn oxides promoters on low-temperature catalytic performance of Pd/Al2O3 for methane combustion

Aiming at fabricating high-activity and stable methane combustion catalysts in the dry/wet conditions, Co–Mn binary oxides were employed as promoters to Pd/Al2O3 system herein. The introduction of appropriate amount of manganese made Mn3+ maximally enter into the Co3O4 spinel structure, conducive to the conversion of Co3+ to Co2+ by Mn3+ and then the enhancement of lattice distortion. Therefore, abundant oxygen vacancies were produced, which enhanced the surface-concentrations of active Pd2+ and Oads species, together with the exchange of oxygen species. The resulting catalyst with a molar Mn/Co ratio of 0.20 performed superior low-temperature activity and durability. Moreover, the synergy of Mn and Co could accelerate the removal process of accumulated OH/H2O from the active sites, thereby promoting the regeneration of PdO and oxygen vacancies. This endowed the tailored catalyst with remarkable moisture-tolerance and hydrothermal stability, and inspiring enhanced activity (T90 = 350 °C) after removing water vapor.