Zhang Pan, Wang Penglu, Impeng Sarawoot, Lan Tianwei, Liu Xiangyu, Zhang Dengsong
State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, International Joint Laboratory of Catalytic Chemistry, College of Sciences, Shanghai University, No. 99 Shangda Road, Shanghai 200444, P. R. China.
National Nanotechnology Center, National Science and Technology Development Agency, Pathum Thani 12120, Thailand.
Environ Sci Technol. 2022 Sep 6;56(17):12553-12562. doi: 10.1021/acs.est.2c02255. Epub 2022 Aug 12.
Selective catalytic reduction (SCR) of NO from the flue gas is still a grand challenge due to the easy deactivation of catalysts. The copoisoning mechanisms and multipoisoning-resistant strategies for SCR catalysts in the coexistence of heavy metals and phosphorus are barely explored. Herein, we unexpectedly found unique compensation effects of heavy metals and phosphorus copoisoning over NO reduction catalysts and the introduction of heavy metals results in a dramatic recovery of NO reduction activity for the P-poisoned CeO/TiO catalysts. P preferentially combines with Ce as a phosphate species to reduce the redox capacity and inhibit NO adsorption. Heavy metals preferentially reduced the Brønsted acid sites of the catalyst and inhibited NH adsorption. It has been demonstrated that heavy metal phosphate species generated over the copoisoned catalyst, which boosted the activation of NH and NO, subsequently bringing about more active nitrate species to relieve the severe impact by phosphorus and maintain the NO reduction over CeO/TiO catalysts. The heavy metals and P copoisoned catalysts also possessed more acidic sites, redox sites, and surface adsorbed oxygen species, which thus contributed to the highly efficient NO reduction. This work elaborates the unique compensation effects of heavy metals and phosphorus copoisoning over CeO/TiO catalysts for NO reduction and provides a perspective for further designing multipoisoning-resistant CeO-based catalysts to efficiently control NO emissions in stationary sources.
由于催化剂容易失活，从烟道气中选择性催化还原（SCR）NO仍然是一个巨大的挑战。对于在重金属和磷共存情况下SCR催化剂的共中毒机制和抗多重中毒策略，人们几乎没有进行过探索。在此，我们意外地发现了重金属和磷对NO还原催化剂共中毒的独特补偿效应，并且引入重金属会使P中毒的CeO/TiO催化剂的NO还原活性显著恢复。P优先与Ce结合形成磷酸盐物种，从而降低氧化还原能力并抑制NO吸附。重金属优先减少催化剂的布朗斯特酸位点并抑制NH吸附。已经证明，在共中毒催化剂上生成的重金属磷酸盐物种促进了NH和NO的活化，随后产生了更多活性硝酸盐物种，以减轻磷的严重影响并维持CeO/TiO催化剂上的NO还原。重金属和P共中毒的催化剂还具有更多的酸性位点、氧化还原位点和表面吸附氧物种，因此有助于高效的NO还原。这项工作阐述了重金属和磷对CeO/TiO催化剂共中毒在NO还原方面的独特补偿效应，并为进一步设计抗多重中毒的CeO基催化剂以有效控制固定源中的NO排放提供了一个视角。
