Mesoporous Co3O4 Derived from Facile Calcination of Octahedral Co-MOFs for Toluene Catalytic Oxidation

Abstract

In the present work, mesoporous Co3O4 catalysts were derived from Co-MOFs. The octahedral morphology of the parent Co-MOFs was integrally preserved after calcination. By controlling the calcination temperature, we effectively regulated the physicochemical properties of the obtained samples. The M-Co3O4-350 catalyst exposed plentiful {110} planes with the highest Co3+/Co2+ and Oads/Olatt ratios and the largest specific surface area compared with those of other samples, which are crucial to toluene oxidation. Additionally, smaller nanosized crystals, more defect sites, higher average pore size, and better low-temperature reducibility are also beneficial for toluene degradation. Thus, as a matter of course, M-Co3O4-350 exhibited excellent performance in the catalytic activity test. T90% of toluene conversion over the M-Co3O4-350 catalyst is 239 °C (at SV = 20 000 mL g–1 h–1 and toluene concentration = 1000 ppm). Furthermore, favorable stability of the M-Co3O4-350 catalyst was certified by the 48 h endurance at SV = 20 000 mL g–1 h–1 with no sign of slacking at the setting temperatures. According to in situ diffusion reflectance infrared Fourier transform spectrophotometry (DRIFTS), toluene was decomposed successively to benzyl alcohol, benzoic acid, and maleate species and finally to CO2 and H2O during the process of catalytic oxidation.