To verify the catalytic activity of La_mMn_nO_x (m,n = 1,2; x = 2.5 ∼ 5.5) catalyst in microwave catalytic combustion of volatile organic compounds (VOCs), monolithic La_mMn_nO_x catalysts were prepared and applied in toluene oxidation in this study. The research demonstrated that the La_mMn_nO_x catalysts had strong microwave-absorbing properties due to first dielectric loss and secondary magnetic loss. The bed temperature rose rapidly due to the formation of hotspots under microwave irradiation. Furthermore, La_mMn_nO_x catalysts chiefly adsorbed toluene by chemical adsorption, and the adsorption capacity of Mn was much stronger than that of La. Based on the activity tests, La₁Mn₁O_x (x = 2.5 ∼ 3.5) catalyst exhibited the highest catalytic activity among the four catalysts, and toluene was converted and mineralized completely at 259 ℃ and 315 ℃, respectively, under the conditions of an initial toluene concentration of 1000 mg/m³, bed height of 150 mm, and gas velocity of 2.5 L/min. Highly active LaMnO₃ perovskite, uniform distribution of active particles, and abundant oxygen vacancies ensured the high activity of the La₁Mn₁O_x catalyst. Hence, the La₁Mn₁O_x catalyst was stable after a total of 600 min of activity test. According to electron transfers on the active Mn surface, the adsorption and activation of gaseous oxygen, and the transformation of O_ads to O_latt on the oxygen vacancies, toluene oxidation speculates to follow the Langmuir-Hinshelwood and the Mars-van Krevelen mechanisms simultaneously. Therefore, this work provides further technological support for applying La_mMn_nO_x catalysts in microwave catalytic combustion of industrial VOCs waste gas.

中文翻译：

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整体式 LamMnnOx 催化剂在甲苯微波催化燃烧中的微波吸收性能、化学吸附及催化活性


为验证 La_mMn_nO_x （m，n = 1,2; x = 2.5 ∼ 5.5） 催化剂在挥发性有机化合物 （VOCs） 微波催化燃烧中的催化活性，本研究制备了整体式 La_mMn_nO_x 催化剂，并将其应用于甲苯氧化。研究表明，由于第一介电损耗和二次磁损耗，La_mMn_nO_x 催化剂具有很强的微波吸收性能。微波照射下热点的形成导致河床温度迅速升高。此外，La_mMn_nO_x催化剂主要通过化学吸附吸附甲苯，Mn的吸附能力远强于La。根据活性测试，La₁Mn₁O_x （x = 2.5 ∼ 3.5）催化剂在四种催化剂中表现出最高的催化活性，甲苯在259 °C和315 °C时被转化并完全矿化， 分别在初始甲苯浓度为 1000 mg/m³、柱床高度为 150 mm、气体速度为 2.5 L/min 的条件下。高活性 LaMnO₃ 钙钛矿、活性颗粒的均匀分布和丰富的氧空位确保了 La₁Mn₁O_x 催化剂的高活性。因此，La₁Mn₁O_x 催化剂在总共 600 min 的活性测试后保持稳定。根据活性 Mn 表面的电子转移、气态氧的吸附和活化以及氧空位上 O_ads 向 O_latt 的转变，甲苯氧化推测同时遵循 Langmuir-Hinshelwood 和 Mars-van Krevelen 机制。 因此，本工作为La_mMn_{n Ox}催化剂在工业VOCs废气微波催化燃烧中的应用提供了进一步的技术支持。