NH3选择性还原NOx技术在重型柴油车尾气净化中的应用

基于实验室对柴油车用V₂O₅-WO₃/TiO₂催化剂配方以及涂覆成型技术的大量研究，设计了一条产量为6000只/月的NH₃选择性催化还原NO_x （NH₃-SCR）催化剂中试生产线，并对生产的催化剂产品进行了发动机台架测试. 结果表明，实验室制备的V₂O₅-WO₃/TiO₂粉体催化剂和生产线产品，在空速为50000 h^-1和200-450 ℃条件下NO_x转化率均可达80%以上；采用大尺寸堇青石载体涂覆后制备的V₂O₅-WO₃/TiO₂整体催化剂经实验室小样测试，在空速为10000-30000 h^-1和250-450 ℃条件下NO_x转化率也为80%以上. 发动机台架测试结果表明，该催化剂产品可使重型柴油机NO_x排放达到国IV标准中欧洲稳态循环（ESC）和欧洲瞬态循环（ETC）排放限值的要求. 该生产线经适当调整后也可用于生产非钒基NH₃-SCR整体催化剂，以满足未来钒基NH₃-SCR催化剂更新换代的需求.

Selective catalytic reduction of NOx by NH3 for heavy-duty diesel vehicles

A catalyst production line with a production capacity of 6000 catalyst monoliths per month for the selective catalytic reduction of NO_x by NH₃ (NH₃-SCR) for NO_x abatement in diesel vehicle exhaust was set up based on a detailed laboratory study of the catalyst formulation and washcoating technology for V₂O₅-WO₃/TiO₂ catalyst. The catalyst produced by this line was tested on a bench scale diesel engine. The V₂O₅-WO₃/TiO₂ powder catalyst prepared in the laboratory and production line both achieved >80% NO_x conversion at 200-450 ℃ and a GHSV of 50000 h^-1. The washcoated catalyst used a large cordierite support and gave >80% NO_x conversion at 250-450 ℃ and GHSVs of 10000-30000 h^-1. The engine bench tests showed that after treatment by the catalyst, the NO_x emission met the European steady-state cycle (ESC) and European transient cycle (ETC) limits of the China IV standard. The production line can also be used for the production of vanadium-free NH₃-SCR catalysts to meet the required replacement of the present vanadium-based NH₃-SCR catalyst in the future.