Mg掺杂对稀土钙钛矿型LaCrO_3催化剂的结构和甲烷催化燃烧性能的影响

Effects of magnesium doping on structure and methane combustion performance of rare-earth perovskite LaCrO_3 catalysts

以柠檬酸为络合剂采用溶胶-凝胶法制备了纯LaCrO3和Mg掺杂型催化剂,以X射线衍射法分析各样品的物相,BET法测定样品的比表面积,TPR技术表征样品的还原性能,以甲烷燃烧为探针反应考察各样品的催化氧化活性。实验结果表明,未掺杂Mg的样品为单一相钙钛矿LaCrO3结构。Mg的掺杂即可破坏单相钙钛矿LaCrO3结构的形成,明显削弱其衍射峰强度,同时产生LaCrO4和La2CrO6及MgO物相,但提高了催化剂的还原能力,改善了催化活性。当加入Mg的质量分数为10%时催化活性最好。

Several chromium-containing rare earth mixed oxides catalysts were synthesized by sol-gel method and characterized by means of XRD, TPR and BET. Catalytic activity of the samples for oxidation reactions were tested using methane combustion as the probe reaction. The results showed that the samples without doping of Mg had a single-phase perovskite LaCrO3 structure; doping of Mg inhibited the formation of perovskite LaCrO3 structure and remarkably weakened the diffraction intensity, leading to formation of mixed phase of LaCrO4, La2CrO6 and MgO, thus enhancing reduction capability and catalytic activity of the samples. Optimum activity was attained at Mg doping quantity of 10%.