The improvement of catalytic efficiency is of great significance to the removal of volatile organic compounds (VOCs), a class of key air pollutants leading to ground-level ozone pollution. Herein, a series of micro-spherical Ca-Mn mixed oxides (CaMnO), namely CaMnO, CaMnO and CaMnO, were prepared by a two-step precipitation method, and defects were constructed on which by selective dissolution to enhance the low-temperature catalytic performance in the oxidation of propane (CH) as a representative short-chain alkane VOCs. The synthesized CaMnO oxides demonstrated drastically different response to the dissolution modification initiated by acid treatment. Specifically, after acid dissolution, while CaMnO and CaMnO maintained largely their original structures, the perovskite-type CaMnO underwent lattice rearrangement and was transformed into γ-MnO-like product with only a tiny amount of Ca. In CH oxidation, the catalytic performance of CaMnO was significantly improved after selective dissolution, as indicated by a significant decrease of T, the temperature to achieve 90% CH conversion, from 455 °C to 240 °C. Mechanistic investigation by in-depth X-ray photoelectron spectroscopy studies revealed that selective dissolution led to higher Mn concentrations and more oxygen vacancies on the oxide surfaces, thus facilitated electron transfer and O activation in CH oxidation reactions. This study paves a new path for the design of cost-effective oxide catalysts toward the abatement of short-chain alkane VOCs.

中文翻译：

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选择性溶解微球形钙锰混合氧化物以实现丙烷的高效氧化

催化效率的提高对于挥发性有机化合物（VOC）这一导致地面臭氧污染的关键空气污染物的去除具有重要意义。本文通过两步沉淀法制备了一系列微球形钙锰混合氧化物（CaMnO），即CaMnO、CaMnO和CaMnO，并通过选择性溶解在其上构造缺陷以增强低温催化性能。丙烷（CH）作为代表性短链烷烃VOC的氧化性能。合成的 CaMnO 氧化物对酸处理引发的溶解改性表现出截然不同的反应。具体来说，酸溶解后，虽然CaMnO和CaMnO基本保持其原始结构，但钙钛矿型CaMnO发生晶格重排，转变为仅含有少量Ca的γ-MnO类产物。在CH氧化中，选择性溶解后CaMnO的催化性能显着提高，T（CH转化率达到90%的温度）显着降低，从455℃降至240℃。通过深入的X射线光电子能谱研究进行的机理研究表明，选择性溶解导致氧化物表面上更高的Mn浓度和更多的氧空位，从而促进CH氧化反应中的电子转移和O活化。这项研究为设计具有成本效益的氧化物催化剂以减少短链烷烃挥发性有机化合物铺平了新的道路。