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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Understanding the mechanochemical synthesis of the perovskite LaMnO3 and its catalytic behaviour
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Understanding the mechanochemical synthesis of the perovskite LaMnO3 and its catalytic behaviour

机译：了解钙钛矿兰诺3的机械化学合成及其催化作用

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Mechanochemistry offers a solventless, 'waste free' route to preparing metal oxide catalysts, however, there is limited information on the chemical steps involved. In this work, the perovskite LaMnO3 has been successfully synthesized via mechanochemistry from metal oxide powders, La2O3 and Mn2O3, at room temperature, using a planetary ball mill. Separate ex situ 'time slices' were taken during the milling procedure to provide insights into the underlying chemistry. The crystalline material was assessed using XRD, which identified 100% perovskite phase after 3 h of milling. Conversely, characterization by X-ray absorption spectroscopy (XAS) at both the Mn K-edge and La L-3-edge provides a very different picture. The XAS data shows that there are significant structural alterations as early as 30 min of milling, with the La precursor dispersed over Mn2O3. Increasing milling time then allows for mechanical activation of both precursors and the formation of powdered LaMnO3, with no calcination step required. The XAS highlights that there is a significant amount of amorphous, oxygen deficient, content even when XRD has identified 100% perovskite phase. The samples were tested for the decomposition of the environmental pollutant N2O; at a milling time of 3 h, the LaMnO3 catalyst displays a much early onset production of N-2 compared to a traditional sol-gel synthesized LaMnO3, resulting from increased oxygen deficiency at the surface, confirmed by XPS and STEM-EELS. This is an encouraging sign that mechanochemical routes can be harnessed to provide a sustainable route to preparing mixed metal oxide catalysts with enhanced catalytic performance.
机译：机械化学技术提供了一种无溶剂的“无浪费”途径来制备金属氧化物催化剂，但是，有关所涉及的化学步骤的信息有限。在这项工作中，使用行星球磨机，通过从金属氧化物粉末，La2O3和Mn2O3的金属氧化物粉末，La2O3和Mn2O3的机械化学成功地合成了Perovskite LAMNO3。在铣削程序期间采取单独的EXITU'时间切片'，以提供对潜在化学的见解。使用XRD评估结晶材料，其在研磨3小时后鉴定了100％钙钛矿相。相反，在Mn K边缘和La L-3边缘的X射线吸收光谱（XAS）的表征提供了截然不同的图像。 XAS数据表明，早期磨削的结构改变有显着的结构改变，LA前体分散在MN2O3上。然后增加研磨时间允许机械激活前体和粉末状兰诺3的形成，无需煅烧步骤。 XAS突出显示，即使XRD鉴定了100％钙钛矿相，也有大量的无定形，缺氧，含量。测试样品以进行环境污染物N2O的分解;在3小时的铣削时间，与传统的溶胶 - 凝胶合成的LAMNO3相比，兰诺3催化剂显示出N-2的许多早期发作产生，由表面上增加的氧缺氧增加，由XPS和茎鳗确认。这是一种令人鼓舞的标志，可以利用机械化学路线以提供一种可持续的途径，以制备具有增强的催化性能的混合金属氧化物催化剂。

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