Abstract:

Catalysts of La_1-xLi_xMnO₃(x=0, 0.05, 0.15, 0.25) perovskite-type complex metal oxide were prepared by solvothermal method. The catalysts were characterized by XRD, FT-IR, XPS, H₂-TPR and NO-TPD. The catalytic performance of the catalysts for eliminating nitric oxide (NO) and diesel particulate matter （soot） simultaneously was evaluated in a fixed micro reactor. The results showed that La_1-xLi_xMnO₃ catalysts had single perovskite structure and Mn species existed in the form of Mn³⁺ and Mn⁴⁺. When La³⁺ is partially substituted by Li⁺ in LaMnO₃, there were more Mn⁴⁺ and oxygen vacancies in the La_1-xLi_xMnO₃ catalysts, which can promote the adsorption and activation of oxygen species and nitrogen oxides, thus increase the redox properties and improve the catalytic activity. The La_0.85Li_0.15MnO₃ catalyst had better performance, where the doping amount of Li⁺ was 0.15, the temperature of the maximum combustion rate (T_max) and the ignition temperature (T_ig) was 463℃ and 327℃, respectively, the maximum conversion of NO ($X_{\mathrm{N}\mathrm{O}}^{\mathrm{m}\mathrm{a}\mathrm{x}}$) was 42.1%, reaction temperature ($T_{\mathrm{N}\mathrm{O}}^{\mathrm{m}\mathrm{a}\mathrm{x}}$) was 383℃.

Key words: Mn-based perovskite, NO, soot, catalyst, chemical reaction, fixed-bed

摘要：

采用溶剂热法制备La_1-xLi_xMnO₃ (x=0,0.05,0.15,0.25) 钙钛矿型复合金属氧化物催化剂。通过XRD、FT-IR、XPS、H₂-TPR和NO-TPD等手段对催化剂进行表征，在固定床微型反应器中评价催化剂同时消除NO和碳烟催化性能。结果表明，溶剂热法制备的La_1-xLi_xMnO₃催化剂具有单一的钙钛矿结构，催化剂中Mn物种以Mn³⁺和Mn⁴⁺的形式存在。Li⁺部分取代LaMnO₃中La³⁺后，La_1-xLi_xMnO₃催化剂上Mn⁴⁺数量和氧空位增加，促进更多活性氧物种和氮氧化物的吸附与活化，提高氧化还原性能，改善催化活性。Li⁺取代量为0.15，即La_0.85Li_0.15MnO₃催化剂催化活性较好，T_max和T_ig分别为463℃和327℃，NO最大转化率$X_{\mathrm{N}\mathrm{O}}^{\mathrm{m}\mathrm{a}\mathrm{x}}$为42.1%，反应温度$T_{\mathrm{N}\mathrm{O}}^{\mathrm{m}\mathrm{a}\mathrm{x}}$为383℃。

关键词: 锰基钙钛矿, 一氧化氮, 碳烟, 催化剂, 化学反应, 固定床