Performance and mechanism analysis of MnO_<i>x</i>/HZSM-5 catalytic oxidation of formaldehyde at room temperature

Abstract

Using HZSM-5 zeolite, potassium permanganate and methanol as raw materials, MnOx/HZSM-5 catalyst was prepared to oxidize formaldehyde at room temperature. X-ray diffraction (XRD), Raman spectroscopy (Raman), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoelectron spectroscopy (XPS) and other characterization methods were used to analyze the morphology, structure and chemical composition of the catalyst. The catalytic activity and regeneration performance of MnOx/HZSM-5 on formaldehyde were studied, and the mechanism of formaldehyde catalytic oxidation was discussed. The results show that the formaldehyde removal rate of MnOx/HZSM-5 remains at 90% after 1020 minutes of dynamic testing. After five regeneration tests, the removal rate of formaldehyde by MnOx/HZSM-5 remains at 91%. In the static test, the formaldehyde removal rate reaches 97% and the conversion rate of formaldehyde reaches 92%. After analyzing the mechanism of oxidizing formaldehyde with MnOx/HZSM-5, it is found that formaldehyde is first adsorbed by the catalyst to the active site of MnOx. Then it is preliminarily oxidized to intermediate products such as formates or carbonates. Finally, it is deeply oxidized with carbon dioxide and water.

Keywords

• zeolite
• manganese oxide
• catalytic oxidation
• formaldehyde
• room temperature