Zhao Sirui, Bo Longli, Huang Sining, Luo Mengyao, Yuan Hudie
Shaanxi Key Laboratory of Environmental Engineering, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Shaanxi Key Laboratory of Environmental Engineering, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Key Laboratory of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an 710055, China.
J Hazard Mater. 2025 May 5;488:137422. doi: 10.1016/j.jhazmat.2025.137422. Epub 2025 Jan 27.
To verify the feasibility of replacing noble metal catalysts by transition metals-based catalysts, monolithic CuMnO/CeO/cordierite honeycomb (CH) catalysts were prepared by conventional impregnation method and applied in microwave catalytic combustion of toluene. The research suggested that CuMnO/CeO/CH catalysts, demonstrated strong microwave-absorbing ability due to first dielectric loss and secondary magnetic loss, exhibited higher catalytic activities under microwave heating than electric heating. This is probably attributed to high temperature "hot spots" of microwave, the abundant pore structure of active particles of CuMnO/CeO/CH catalyst, and oxygen vacancies and O on the catalysts' surface. The research also suggested that under the conditions of an initial toluene concentration of 1500 mg m, airflow of 0.18 m³ h and gas hourly space velocity of 7000 h, toluene could be completely removed at a relatively low temperature of 276 °C and mineralized at 304 °C by microwave catalytic combustion. Compared with noble metal catalysts, CuMnO/0.03CeO/CH catalyst had a lower light-off temperature and nearly complete combustion temperature for toluene removal and mineralization under microwave heating, which confirms the possibility of replacing noble metal catalysts. Moreover, CuMnO/0.03CeO/CH catalyst exhibited excellent stability at a bed temperature of 300 ℃ after six cycles of a total of 960 min and achieved a 100 % removal and 94 % mineralization of toluene. This study also identified the key mechanism behind which is the electron transfers among Cu/Cu, Mn/Mn/Mn, and Ce/Ce that promoted the adsorption, activation, and transformation of gaseous oxygen. Hence, toluene is firstly adsorbed by active particles and then oxidized onto the hot spots by both O and O which follows the L-H mechanism and the MvK mechanism, respectively. Therefore, this research work provides further technological support for the development of transition metals-based catalysts and the application of microwave catalytic combustion in treating industrial VOCs waste gas.
为验证用过渡金属基催化剂替代贵金属催化剂的可行性，采用传统浸渍法制备了整体式CuMnO/CeO/堇青石蜂窝（CH）催化剂，并将其应用于甲苯的微波催化燃烧。研究表明，CuMnO/CeO/CH催化剂由于具有首次介电损耗和二次磁损耗而表现出较强的微波吸收能力，在微波加热下比电加热表现出更高的催化活性。这可能归因于微波的高温“热点”、CuMnO/CeO/CH催化剂活性颗粒丰富的孔结构以及催化剂表面的氧空位和O。研究还表明，在初始甲苯浓度为1500 mg m、气流为0.18 m³ h和气体时空速为7000 h的条件下，通过微波催化燃烧，甲苯在相对较低的276℃温度下可被完全去除，并在304℃下矿化。与贵金属催化剂相比，CuMnO/0.03CeO/CH催化剂在微波加热下具有更低的甲苯去除和矿化的起燃温度及近乎完全燃烧温度，这证实了替代贵金属催化剂的可能性。此外，CuMnO/0.03CeO/CH催化剂在300℃的床层温度下经过总共960分钟的六个循环后表现出优异的稳定性，实现了甲苯100%的去除率和94%的矿化率。该研究还确定了其背后的关键机制，即Cu/Cu、Mn/Mn/Mn和Ce/Ce之间的电子转移促进了气态氧的吸附、活化和转化。因此，甲苯首先被活性颗粒吸附，然后分别通过O和O在热点上被氧化，这分别遵循L-H机理和MvK机理。因此，这项研究工作为过渡金属基催化剂的开发以及微波催化燃烧在处理工业挥发性有机化合物废气中的应用提供了进一步的技术支持。
