Degradation of gaseous unsymmetrical dimethylhydrazine by vacuum ultraviolet coupled with MnO2

In this study, α-, β-, and δ-MnO2 were prepared by a uniform hydrothermal method and then coupled with vacuum ultraviolet (VUV) for the degradation of gaseous unsymmetrical dimethylhydrazine (UDMH). The performance in the remove of UDMH, by-products distribution and mechanistic insights were systematically investigated. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption/desorption, Field Emission Scanning Electron Microscopy (FE-SEM), Raman, thermal gravimetric (TG), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) to investigate the factors affecting the catalytic activity. The results showed that O2 and H2O were essential for the remove of UDMH . The integrated process considerably improved the remove and mineralization of UDMH by ozone catalytic oxidation . There were more reactive oxygen species generated in the integrated process. The catalytic activity of the prepared catalysts following the order: δ-MnO2 >α-MnO2 >β-MnO2. δ-MnO2 displayed the highest remove rate of 100% and CO2 concentration of 42 ppmv. The good performance of δ-MnO2 was attributed to high specific surface area and surface oxygen vacancies.