Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, School of Environmental and Chemical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China.
Key Laboratory of Beijing on Regional Air Pollution Control, Department of Environmental Science, School of Environmental and Chemical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China; R&D Department of Atmospheric Prevention and Control Technology, Guangdong Suncere Technology Co., Ltd., Guangzhou 510220, China.
J Environ Sci (China). 2023 Apr;126:263-274. doi: 10.1016/j.jes.2022.03.024. Epub 2022 Mar 23.
The cryptomelane-type manganese oxide (OMS-2)-supported Co (xCo/OMS-2; x = 5, 10, and 15 wt.%) catalysts were prepared via a pre-incorporation route. The as-prepared materials were used as catalysts for catalytic oxidation of toluene (2000 ppmV). Physical and chemical properties of the catalysts were measured using the X-ray diffraction (XRD), Fourier transform infrared spectroscopic (FT-IR), scanning electron microscopic (SEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature-programmed reduction (H-TPR) techniques. Among all of the catalysts, 10Co/OMS-2 performed the best, with the T, specific reaction rate at 245°C, and turnover frequency at 245°C (TOF) being 245°C, 1.23 × 10 mol/(g·sec), and 11.58 × 10 sec for toluene oxidation at a space velocity of 60,000 mL/(g·hr), respectively. The excellent catalytic performance of 10Co/OMS-2 were due to more oxygen vacancies, enhanced redox ability and oxygen mobility, and strong synergistic effect between Co species and OMS-2 support. Moreover, in the presence of poisoning gases CO, SO or NH, the activity of 10Co/OMS-2 decreased for the carbonate, sulfate and ammonia species covered the active sites and oxygen vacancies, respectively. After the activation treatment, the catalytic activity was partly recovered. The good low-temperature reducibility of 10Co/OMS-2 could also facilitate the redox process accompanied by the consecutive electron transfer between the adsorbed O and the cobalt or manganese ions. In the oxidation process of toluene, the benzoic and aldehydic intermediates were first generated, which were further oxidized to the benzoate intermediate that were eventually converted into HO and CO.
通过预嵌入法制备了OMS-2 负载的 Co（xCo/OMS-2；x=5、10 和 15wt.%）催化剂。使用 X 射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、扫描电子显微镜（SEM）、X 射线光电子能谱（XPS）和氢气程序升温还原（H-TPR）技术测量了催化剂的物理化学性质。在所有催化剂中，10Co/OMS-2 的性能最佳，在 245°C 时 T、245°C 时的特定反应速率和 245°C 时的周转率频率（TOF）分别为 245°C、1.23×10-3mol/（g·sec）和 11.58×10-3sec-1，在空速为 60,000mL/（g·hr）时用于甲苯氧化。10Co/OMS-2 的优异催化性能归因于更多的氧空位、增强的氧化还原能力和氧迁移率，以及 Co 物种和 OMS-2 载体之间的强协同作用。此外，在存在 CO、SO 或 NH 等中毒气体的情况下，10Co/OMS-2 的活性降低，因为碳酸根、硫酸根和氨物种分别覆盖了活性位点和氧空位。经过活化处理后，部分恢复了催化活性。10Co/OMS-2 的低温还原性好，也有利于氧化还原过程，伴随着吸附氧与钴或锰离子之间的连续电子转移。在甲苯氧化过程中，首先生成苯甲酸和醛中间产物，然后进一步氧化为苯甲酸盐中间产物，最终转化为 HO 和 CO。
