Insights into the high performance of Mn-Co oxides derived from metal-organic frameworks for total toluene oxidation

Mn-Co mixed metal oxide is considered as efficient catalyst for the total oxidation of volatile organic compounds. In this study, nanocube-like metal-organic frameworks (Mn3[Co(CN)6]2·nH2O) are adopted as the precursor to generate Mn-Co oxides with different Mn/Co molar ratios, which affect little on phase structure and textural properties. The obtained MOF-Mn1Co1 with uniform metal dispersion is rich in high valence of surface Mn4+ and Co3+ species, leading to high low-temperature catalytic activity of total toluene oxidation. The results of toluene-TPD followed by TPO and toluene-TPSR match well with the catalytic performances of MOF-Mn1Co1, MOF-Mn1Co2, and MOF-Mn2Co1, and in situ FITR proves that the benzoate route exists over MOF-Mn1Co1. It is found that a moderate ratio of Mn/Co (1:1) favors good low-temperature reducibility and high Oads/Olatt, resulting in superior oxidation performance. However, the stability in the existence of water for MOF-Mn1Co1 is not satisfied, which should be overcome in the future.