Simultaneous Removal of Multipollutants (VOCs/NO/SO2) by Catalytic Ozonation Coupled with Wet Scrubbing Technology: From the Laboratory to Industrial Testing

The simultaneous removal of multi-VOCs (C3H6O/C6H6/C7H8/C8H10) and NO/SO2 by catalytic ozonation on the CoOx-CrOx/γ-Al2O3 (SCC) catalyst was studied on a laboratory scale and in industrial field testing, respectively. It was discovered that the removal efficiencies of aromatic VOCs gradually increased as the excess ozone ratio (λ), the ratio of the actual number of moles of ozone to the theoretical number, increased. With the help of a wet scrubbing system, multi-VOCs and SO2 can be completely removed. The removal efficiency of NO remained above 95%, and the NO2 selectivity was only 2%. The applicability of the SCC catalyst at lower temperatures was verified by achieving conversion efficiencies of multiple pollutants of more than 80% at 50 °C, with the scrubbing system. In an industrial field-scale test performed in a textile mill in Anhui Province, China, it was proven that in the absence of catalyst assistance, VOCs with high molecular weight were gradually degraded and small molecules such as methanol, formaldehyde, and formic acid were generated more. Coupled with the SCC catalyst, at λ = 3, the concentrations of almost all major VOC pollutants could be degraded to <3 ppm. Analyzed by XRD, O2-TPD, H2-TPR, XPS, and ICP-OES characterizations, the excellent activity and stability of the SCC catalysts are attributed to the good dispersion of metal oxides, strong intermetallic interactions, excellent reducibility, rapid redox cycles of Cr3+/Cr6+ and Co2+/Co3+, and abundant chemisorbed oxygen. The slight deactivation of the SCC catalysts utilized continuously in the textile mill may be related to the loss of active Cr6+ and Co2+. The results show that the combination of catalytic ozonation technology and the wet scrubbing system can realize the efficient and simultaneous removal of multiple pollutants, providing an experimental and practical basis for further industrial application.