Effect of polyethylene glycol addition on Cu-Mn-Ce-Ox/TiO2/CH catalyst in microwave catalytic combustion of toluene
Adding polyethylene glycol (PEG) can lessen the shedding of coating and improve the dispersion of active particles for monolithic catalysts. In this study, a series of Cu-Mn-Ce-O x (P x )/TiO 2 (P x )/CH catalysts were prepared with different PEG molecular weights (P x , x = 200, 1000, and 2000) to explore the effect of P x addition on the structure and activity of the catalysts in microwave catalytic combustion of toluene. The research showed that P x addition (1 wt% dosage to titanium sol) to coating reduced the particle size of titanium sol and decreased the shedding rate of TiO 2 coating 0.9–0.93 %, and P x addition (3 wt% dosage to CH's water absorption) to active components further lessened the shedding rate of the catalysts 1.93–2.04 %. Under an initial toluene concentration of 1500 mg/m 3 and a gas hourly space velocity of 2260 h −1 , Cu-Mn-Ce-O x (P 1000 )/TiO 2 (P 1000 )/CH owned the highest catalytic activity and its complete removal temperature (T R100 ) and mineralization temperature (T M100 ) to toluene were 180℃ and 218℃, respectively, which were lower 33℃ and 16℃, 56℃ and 58℃ than Cu-Mn-Ce-O x /TiO 2 (P 1000 )/CH and Cu-Mn-Ce-O x /TiO 2 /CH catalysts separately, and its activity maintained steadily with toluene removal efficiencies of 99–91 % over 12 h. The improved activity is attributed to the uniform dispersion of active particles, larger specific surface area, and increased adsorbed oxygen, facilitated by pore-forming and steric-hindrance effects of P x . Electron transfer among Mn 4+ /Mn 3+ /Mn 2+ , Cu 2+ /Cu + , and Ce 4+ /Ce 3+ promoted the oxidation of toluene under microwave irradiation. Therefore, the research provides technological support for developing transition metals-based catalysts for industrial VOC waste gas treatment.
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