School of Environmental and Chemical Engineering, College of Sciences, Shanghai University, Shanghai 200444, People's Republic of China.
International Joint Laboratory of Catalytic Chemistry, College of Sciences, Shanghai University, Shanghai 200444, People's Republic of China.
Environ Sci Technol. 2020 Jun 16;54(12):7697-7705. doi: 10.1021/acs.est.0c01749. Epub 2020 Jun 4.
It is challenging for selective catalytic reduction (SCR) of NO by NH due to the coexistence of heavy metal and SO in the flue gas. A thorough probe into deactivation mechanisms is imperative but still lacking. This study unravels unexpected offset effects of Cd and SO deactivation over CeO-WO/TiO catalysts, potential candidates for commercial SCR catalysts. Cd- and SO-copoisoned catalysts demonstrated higher activity for NO reduction than a Cd-poisoned catalyst but lower than that for an SO-poisoned catalyst. In comparison to SO, Cd had more severe effects on acidic and redox properties, distinctly decreasing the SCR activity. After sulfation of Cd-poisoned catalysts, SO preferentially bonded with the surface CdO and released CeO active sites poisoned by CdO, thus reserving the highly active CeO-WO sites and maintaining a high activity. The sulfation of Cd-poisoned catalysts also provided more strong acidic sites, and the synergistic effects between the formed cerium sulfate and CeO contributed to the high-temperature SCR performance. This work sheds light on the deactivation mechanism of heavy metals and SO over CeO-WO/TiO catalysts and provides an innovative pathway for inventing high-performance SCR catalysts, which have great resistance to heavy metals and SO simultaneously. This will be favorable to academic and practical applications in the future.
由于烟道气中存在重金属和 SO，NH 选择性催化还原（SCR）NO 具有挑战性。深入探究失活动力学至关重要，但仍存在不足。本研究揭示了 Cd 和 SO 对 CeO-WO/TiO 催化剂失活的意外补偿效应，CeO-WO/TiO 催化剂是商业 SCR 催化剂的潜在候选物。Cd 和 SO 共中毒催化剂的 NO 还原活性高于 Cd 中毒催化剂，但低于 SO 中毒催化剂。与 SO 相比，Cd 对酸性和氧化还原性质的影响更为严重，明显降低了 SCR 活性。Cd 中毒催化剂在硫酸盐化后，SO 优先与表面 CdO 键合，并释放出被 CdO 毒化的 CeO 活性位，从而保留了高活性的 CeO-WO 位并保持高活性。Cd 中毒催化剂的硫酸盐化还提供了更多的强酸性位，形成的硫酸铈与 CeO 之间的协同作用有助于提高高温 SCR 性能。这项工作阐明了 CeO-WO/TiO 催化剂上重金属和 SO 的失活动力学，并为发明同时具有高抗重金属和 SO 性能的高性能 SCR 催化剂提供了一条创新途径。这将有利于未来在学术和实际应用中的发展。
