Catalytic Oxidation Mechanism of Toluene over Ce_xMn_1–xO₂: The Role of Oxygen Vacancies in Adsorption and Activation of Toluene

Abstract

Catalytic oxidation has been extensively studied as a promising technology for the removal of toluene from industrial waste gases and indoor air. However, the debate regarding the oxidation mechanism is far from resolved. Ce x Mn1–x O2 catalysts with different mixing ratios are prepared by the sol–gel method and found to exhibit better catalytic activities for toluene oxidation than a single oxide. Characterizations and theoretical calculations reveal that the doped Mn increases the number of oxygen vacancies and the ability of oxygen vacancies to activate aromatic rings, which promotes the rate-determining step of toluene oxidation, i.e., ring-opening reactions. The oxidation products detected by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and Vocus proton transfer reaction mass spectrometry (Vocus-PTR-MS) show that the doped Mn significantly improves the ring-opening efficiency and subsequently yields more short-chain products, such as pyruvic acid and acetic acid. A comprehensive oxidation pathway of toluene is refined in this work.

Materials Enabling Methane and Toluene Gas Treatment

“…Due to its readily available nature and low energy usage, photocatalytic technology has garnered significant attention for the removal of toluene. However, heat is produced by light, and when temperature rises, pollutants may desorb from the catalyst, making deterioration less likely [61]. Accordingly, Yu et al conducted a detailed analysis of toluene adsorption on UiO-66 (Zr) and postulated a synergistic interaction between heat-induced adsorption and photocatalysis.…”

Catalytic Oxidation of Toluene over Pt/CeO2 Catalysts: A Double-Edged Sword Effect of Strong Metal–Support Interaction

“…The elimination and degradation of volatile organic compounds (VOCs), which is known as a significant precursor of O 3 pollution, is very critical to improving air quality. The thermal catalytic oxidation method is considered as one of the most widely used technologies to eliminate VOCs, attributing to benefits of high efficiency and low-level byproduct. − One key point of this technology is further development of higher activity catalysts that could operate at lower temperature.…”