Interaction in LaOx-Co3O4 for highly efficient purification of toluene: Insight into LaOx content and synergistic effect contribution

Abstract

Catalytic combustion is an effective and economic technology to remove volatile organic compounds (VOCs). The La2O3, Co3O4, 90Co-10La, 80Co-20La and 70Co-30La samples were prepared via traditional precipitation means, and employed for the catalytic oxidation of toluene. Coupled with XRD, SEM, BET, Ranman, XPS, O2-TPD and H2-TPR analyses, it were found that the addition of LaOx could change the microstructure and redox ability of catalyst, resulting in the formation of LaCoO3 perovskite and the increase in the concentrations of Co2+ and Oads. The 80Co-20La sample exhibited the best toluene conversion (T90 = 242 °C), CO2 selectivity, stability, the optimal specific reaction rates (Rs = 2.0 × 10−3 mmol h−1m−2) and Ea (17.4 kJ/mol). The high catalytic efficiency could be explained by the enhanced synergistic effect between LaOx and CoOx due to the appropriate incorporation of LaOx, and the formed more LaCoO3 perovskite. It was related to the concentrations of Co2+ and Oads, which was beneficial to the low-temperature reducibility, and thus catalytic performance at low temperature was improved. The present work provids a useful idea for the rational design of the removal of VOCs for using transition/rare earth bimetallic oxides efficient to replace the noble metal catalysts.