International Joint Laboratory of Catalytic Chemistry, State Key Laboratory of Advanced Special Steel, Department of Chemistry, Research Center of Nano Science and Technology, College of Sciences, Shanghai University, Shanghai 200444, China.
Environ Sci Technol. 2022 Feb 15;56(4):2647-2655. doi: 10.1021/acs.est.1c06932. Epub 2022 Feb 2.
The presence of alkali metals in flue gas is still an obstacle to the practical application of catalysts for selective catalytic reduction (SCR) of NO by NH. Polymeric vanadyl species play an essential role in ensuring the effective NO abatement for NH-SCR. However, polymeric vanadyl would be conventionally deactivated by the poison of alkali metals such as potassium, and it still remains a great challenge to construct robust and stable vanadyl species. Here, it was demonstrated that a more durable dimeric VO active site could be constructed with the assistance of triethylamine, thereby achieving alkali-resistant NO abatement. Due to the rational construction of polymerization structures, the obtained TiO-supported cerium vanadate catalyst featured more stable dimeric VO species and the active sites could survive even after the poisoning of alkali metal. Moreover, the depolymerization of VO was suppressed endowing the catalysts with more Brønsted and Lewis acid sites after the poisoning of alkali metal, which ensured the efficient NO reduction. This work unraveled the effects of alkali metal on the polymerization state of active species and opens up a way to develop low-temperature alkali-resistant catalysts for NO abatement.
碱金属在烟道气中的存在仍然是 NH 选择性催化还原 (SCR) 催化剂实际应用的障碍。聚合钒物种在确保 NH-SCR 有效去除 NO 方面起着至关重要的作用。然而，聚合钒通常会被钾等碱金属毒物失活，因此构建稳健和稳定的钒物种仍然是一个巨大的挑战。在这里，证明了在三乙胺的协助下可以构建更耐用的二聚 VO 活性位，从而实现耐碱的 NO 去除。由于聚合结构的合理构建，所获得的 TiO 负载的铈钒酸盐催化剂具有更稳定的二聚 VO 物种，即使在碱金属中毒后，活性位也能存活。此外，在碱金属中毒后，VO 的解聚受到抑制，赋予催化剂更多的 Brønsted 和 Lewis 酸位，从而确保了高效的 NO 还原。这项工作揭示了碱金属对活性物种聚合状态的影响，为开发用于 NO 去除的低温耐碱催化剂开辟了道路。
