Li Ning, Zhang Tiantian, Wu Zuliang, Li Jing, Wang Wei, Zhu Jiali, Yao Shuiliang, Gao Erhao
School of Petrochemical Engineering, Changzhou University Jiangsu 213164 China.
School of Environmental Science and Engineering, Changzhou University Jiangsu 213164 China
RSC Adv. 2023 Jan 11;13(3):1738-1750. doi: 10.1039/d2ra07316a. eCollection 2023 Jan 6.
The development of excellent selective catalytic reduction (SCR) catalysts with hydrocarbons for lean-burn diesel engines is of great significance, and a range of novel catalysts loaded with Sn and Ag were studied in this work. It was found that the synergistic effects of Sn and Ag enabled the 1Sn5Ag/γ-AlO (1 wt% Sn and 5wt% Ag) to exhibit superior CH-SCR performance. The de-NO efficiency was maintained above 80% between 336 and 448 °C. The characterization results showed that the presence of AgCl crystallites in the 1Sn5Ag/γ-AlO catalyst helped its redox ability maintain an appropriate level, which suppressed the over-oxidation of CH. Besides, the number of surface adsorbed oxygen (O) and hydroxyl groups (O) were enriched, and their reactivity was greatly enhanced due to the coexistence of Ag and Sn. The ratio of Ag/Ag was increased to 3.68 due to the electron transfer effects, much higher than that of Ag/γ-AlO (2.15). Lewis acid sites dominated the CH-SCR reaction over the 1Sn5Ag/γ-AlO catalyst. The synergistic effects of Sn and Ag facilitated the formation of intermediates such as acetates, enolic species, and nitrates, and inhibited the deep oxidation of CH into CO, and the CH-SCR mechanism was carefully proposed.
开发用于稀燃柴油发动机的具有烃类选择性催化还原（SCR）性能的优异催化剂具有重要意义，本文研究了一系列负载Sn和Ag的新型催化剂。结果发现，Sn和Ag的协同作用使1Sn5Ag/γ-AlO（1 wt% Sn和5wt% Ag）表现出优异的CH-SCR性能。在336至448℃之间，脱硝效率保持在80%以上。表征结果表明，1Sn5Ag/γ-AlO催化剂中AgCl微晶的存在有助于其氧化还原能力维持在适当水平，从而抑制了CH的过度氧化。此外，由于Ag和Sn的共存，表面吸附氧（O）和羟基（O）的数量增加，其反应活性大大增强。由于电子转移效应，Ag/Ag的比例增加到3.68，远高于Ag/γ-AlO（2.15）。在1Sn5Ag/γ-AlO催化剂上，Lewis酸位点主导了CH-SCR反应。Sn和Ag的协同作用促进了乙酸盐、烯醇类和硝酸盐等中间体的形成，抑制了CH深度氧化为CO，并详细提出了CH-SCR机理。
