Temperature-dependent reaction pathways of CO oxidation and the application as monolithic catalysts for Co3O4 nanorods

Abstract

Via investigating the evolution of carbonate intermediates by in-situ DRIFTS (25 °C–350 °C) analysis, temperature-dependent reaction pathways of CO oxidation over Co3O4 nanorods are successfully proposed. The types of reactive oxygen species participated in CO oxidation may affect the way CO react with neighboring oxygen atoms. Additionally, the negative effect of water and CO2 on the catalytic activity was also studied. Considering the remarkable reactivity towards CO, the Co3O4 catalysts were integrated onto metallic and cordierite monolithic substrates and used for CO conversion as application. SEM examinations show that the catalyst layer was coated on the substrates uniformly with few microcracks, and desirable mechanical shock and thermal shock resistance was observed. The influence of substrate materials, gas hourly space velocity, the existence of water vapor and CO2, and reaction time on the CO oxidation performance of monolithic catalysts was investigated. Metallic monolithic catalysts performed higher CO oxidation activity mainly owing to superior heat conductivity and larger surface area compared with cordierite monolithic catalysts. It is noticeable that superior activity was also achieved under high gas flow with the existence of H2O (5.6 vol.%) and CO2 (7 vol.%) at 220 °C, suggesting great promise for practical application.