Effect of manganese modification on the low-temperature formaldehyde oxidation performance of ZIF-67 derived Co₃O₄

In consideration of the inferior performance of ZIF-67 derived Co₃O₄ catalyst in the low-temperature formaldehyde oxidation, manganese was utilized to modify Co₃O₄ catalyst. The results showed that the Mn-Co₃O₄ catalyst exhibited the superior HCHO oxidation activity and achieved 90% HCHO conversion at a WHSV of 60000 mL/(g_cat·h) and inlet HCHO concentration of 98.16 mg/m³ at 118 ℃. XRD, Raman and BET results demonstrated that the Mn-Co₃O₄ catalyst possessed lower crystallinity, more defects and specific surface area, which was conducive to the adsorption of reactants and exposure of more active sites. XPS, H₂-TPR and O₂-TPD results indicated that the strong interaction between Mn and Co species prominently improved the low temperature reducibility and O₂ activation performance of Mn-Co₃O₄ catalyst, which endowed it with more abundant Co³⁺ and surface-adsorbed oxygen species. Therefore, the Mn-Co₃O₄ catalyst exhibited superior HCHO oxidation performance. Based on in-situ DRIFTS results, dioxymethylene and formate species were recognized as the main reaction intermediates of HCHO oxidation over the Mn-Co₃O₄ catalyst.