State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources, Xinjiang University, Xinjiang 830017, China; Xinjiang Key Laboratory of Coal Clean Conversion & Chemical Engineering Process, Xinjiang University, Xinjiang 830017, China; School of Chemical Engineering and Technology, Xinjiang University, Xinjiang 830017, China.
State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources, Xinjiang University, Xinjiang 830017, China; Xinjiang Key Laboratory of Coal Clean Conversion & Chemical Engineering Process, Xinjiang University, Xinjiang 830017, China; School of Chemical Engineering and Technology, Xinjiang University, Xinjiang 830017, China.
J Environ Sci (China). 2024 Sep;143:201-212. doi: 10.1016/j.jes.2023.08.019. Epub 2023 Aug 24.
Silver (9 wt.%) was loaded on CoO-nanofiber using reduction and impregnation methods, respectively. Due to the stronger electronegativity of silver, the ratios of surface Co/Co on Ag/CoO were higher than on CoO, which further led to more adsorbed oxygen species as a result of the charge compensation. Moreover, the introducing of silver also obviously improved the reducibility of CoO. Hence the Ag/CoO showed better catalytic performance than CoO in benzene oxidation. Compared with the Ag/CoO synthesized via impregnation method, the one prepared using reduction method (named as AgCo-R) exhibited higher contents of surface Co and adsorbed oxygen species, stronger reducibility, as well as more active surface lattice oxygen species. Consequently, AgCo-R showed lowest T value of 183°C, admirable catalytic stability, largest normalized reaction rate of 1.36 × 10 mol/(h·m) (150°C), and lowest apparent activation energy (E) of 63.2 kJ/mol. The analyzing of in-situ DRIFTS indicated benzene molecules were successively oxidized to phenol, o-benzoquinone, small molecular intermediates, and finally to CO and water on the surface of AgCo-R. At last, potential reaction pathways including five detailed steps were proposed.
采用还原法和浸渍法分别将银（9wt%）负载到 CoO 纳米纤维上。由于银的电负性更强，Ag/CoO 上的表面 Co/Co 比值高于 CoO，这进一步导致更多的吸附氧物种，从而实现电荷补偿。此外，引入银还明显提高了 CoO 的还原性能。因此，Ag/CoO 在苯氧化中表现出比 CoO 更好的催化性能。与浸渍法合成的 Ag/CoO 相比，通过还原法制备的 Ag/CoO（命名为 AgCo-R）具有更高的表面 Co 和吸附氧物种含量、更强的还原能力以及更多的活性表面晶格氧物种。因此，AgCo-R 表现出最低的 T 值 183°C、令人钦佩的催化稳定性、归一化反应速率最大为 1.36×10 mol/(h·m)（150°C）以及最低的表观活化能（E）63.2 kJ/mol。原位 DRIFTS 分析表明，苯分子在 AgCo-R 表面上依次被氧化为苯酚、邻苯醌、小分子中间体，最终生成 CO 和水。最后，提出了包括五个详细步骤的潜在反应途径。
