Effect of zeolite acidity and structure on ozone oxidation of toluene using Ru-Mn loaded zeolites at ambient temperature

Five different Ru-Mn/zeolites were used to investigate their catalytic efficiencies for removing toluene (100 ppm) with ozone (1000 ppm) at room temperature. In general, most of metal oxide catalysts for removal of organic compounds need higher temperature than the ambient temperature, but Mn-based catalysts shows activity for prevalent organic pollutants even at room temperature with ozone. For the removal of toluene at room temperature without further heating, bimetallic Ru added Mn catalysts were applied in combination with different zeolite supports. The catalytic activity of the Ru-Mn catalysts strongly depended on the zeolite, of which the characteristics such as acidity and adsorption degree of toluene are dependent on the ratio of SiO₂/Al₂O₃. Among the five Ru-Mn catalysts used, Ru-Mn/HY (SiO₂/Al₂O₃ ratio: 80) and Ru-Mn/ZSM-5 (SiO₂/Al₂O₃ ratio: 80) had higher toluene and ozone removal efficiencies. The toluene removal efficiency of Ru-Mn/zeolites was proportional to the pore volume and surface area. In terms of ozone degradation, Ru-Mn/HY(80) and Ru-Mn/HZSM-5(80) had the highest removal efficiencies. Overall, the catalytic ozone oxidation of toluene using Ru-Mn/zeolites seemed to be affected by a combination of the acidic properties of zeolites, Mn³⁺/Mn⁴⁺ ratio, and concentration ratio of oxygen vacancies to oxygen lattices on the catalyst surface.