State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, International Joint Laboratory of Catalytic Chemistry, College of Sciences, Shanghai University, Shanghai 200444, China.
Environ Sci Technol. 2023 Sep 26;57(38):14472-14481. doi: 10.1021/acs.est.3c05112. Epub 2023 Sep 11.
Catalyst deactivation caused by alkali metal poisoning has long been a key bottleneck in the application of selective catalytic reduction of NO with NH (NH-SCR), limiting the service life of the catalyst and increasing the cost of environmental protection. Despite great efforts, continuous accumulation of alkali metal deposition makes the resistance capacity of 2 wt % KO difficult to enhance via merely loading acid sites on the surface, resulting in rapid deactivation and frequent replacement of the NH-SCR catalyst. To further improve the resistance of alkali metals, encapsulating alkali metals into the bulk phase could be a promising strategy. The bottleneck of 2 wt % KO tolerance has been solved by virtue of ultrahigh potassium storage capacity in the amorphous FePO bulk phase. Amorphous FePO as a support of the NH-SCR catalyst exhibited a self-adaptive alkali-tolerance mechanism, where potassium ions spontaneously migrated into the bulk phase of amorphous FePO and were anchored by PO with the generation of FeO at the NH-SCR reaction temperature. This ingenious potassium storage mechanism could boost the KO resistance capacity to 6 wt % while maintaining approximately 81% NO conversion. Besides, amorphous FePO also exhibited excellent resistance to individual and coexistence of alkali (KO and NaO), alkali earth (CaO), and heavy metals (PbO and CdO), providing long durability for CePO/FePO catalysts in flue gas with multipollutants. The cheap and accessible amorphous FePO paves the way for the development and implementation of poisoning-resistant NO abatement.
碱金属中毒导致的催化剂失活一直是 NH-SCR 选择性催化还原 NO 的关键瓶颈，限制了催化剂的使用寿命并增加了环保成本。尽管付出了巨大努力，但由于碱金属的不断积累，仅仅通过在表面负载酸性位来提高 2wt%KO 的阻力能力是困难的，这导致 NH-SCR 催化剂迅速失活并需要频繁更换。为了进一步提高对碱金属的抵抗力，将碱金属封装到体相内部可能是一种很有前途的策略。通过将钾储存在非晶态 FePO 体相内，可以极大地提高钾的储存容量，从而解决了 2wt%KO 的耐受性问题。作为 NH-SCR 催化剂的载体，非晶态 FePO 表现出自适应的耐碱机制，其中钾离子自发地迁移到非晶态 FePO 的体相内，并通过 PO 被固定，同时在 NH-SCR 反应温度下生成 FeO。这种巧妙的钾储存机制可以将 KO 的耐受性提高到 6wt%，同时保持大约 81%的 NO 转化率。此外，非晶态 FePO 还表现出对单个和共存的碱（KO 和 NaO）、碱土金属（CaO）和重金属（PbO 和 CdO）的优异耐受性，为 CePO/FePO 催化剂在多污染物烟道气中提供了长寿命。廉价易得的非晶态 FePO 为开发和实施耐中毒的 NO 减排铺平了道路。
