Abstract The Mn supported on Ce substituted hydroxyapatite (HAp) catalyst was prepared by co-precipitation method and investigated for the low-temperature oxidation of toluene as a model component of VOC. The present work demonstrated the substitution of Ce in HAp in place of Ca. Furthermore, the effect of calcination temperature on oxidation activity of the catalyst was examined by calcining the catalyst at 400, 500 and 600 °C. The low-temperature calcination could favour the insertion of Ce in HAp, whereas higher calcination temperature could lead to the formation of separate CeO 2 phase. The catalyst was characterized by using XRD, surface area, XPS, H 2 -TPR, ATR-FTIR techniques. The probable bonding between Ce and hexagonal HAp, which favors the oxidation of toluene at lower temperature has been explained with the calcination effect. The Ce substitution in HAp leads to the decrease in toluene activation energy which consequently increases the toluene conversion rate. The improvement in Mn 2 O 3 /Mn 3 O 4 ↔ MnO 2 redox cycle was observed due to the Ce substitution compared to unsubstituted Mn supported on HAp. The ATR-FTIR toluene adsorption study demonstrated the plausible mechanism of toluene oxidation. The activation of toluene on Ce substituted catalyst surface could proceed through the adsorption of the –CH 3 group, whereas toluene adsorbed on unsubstituted catalyst surface through ortho, meta or para C–H bond. Graphic Abstract

中文翻译：

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Ce 取代羟基磷灰石负载 Mn 用于 VOC 氧化：催化活性和煅烧效果

摘要 采用共沉淀法制备了负载在 Ce 取代的羟基磷灰石 (HAp) 催化剂上的 Mn，并研究了作为 VOC 模型组分的甲苯的低温氧化。目前的工作证明了 HAp 中的 Ce 取代了 Ca。此外，通过在 400、500 和 600 °C 下煅烧催化剂来检查煅烧温度对催化剂氧化活性的影响。低温煅烧可能有利于 Ce 在 HAp 中的插入，而较高的煅烧温度可能导致形成单独的 CeO 2 相。通过使用XRD、表面积、XPS、H 2 -TPR、ATR-FTIR技术对催化剂进行表征。Ce 和六方 HAp 之间可能的键合有利于甲苯在较低温度下的氧化，已用煅烧效应进行了解释。HAp 中的 Ce 取代导致甲苯活化能降低，从而提高甲苯转化率。Mn 2 O 3 /Mn 3 O 4 ↔ MnO 2 氧化还原循环的改进被观察到，由于与HAp上负载的未取代的Mn相比，Ce取代。ATR-FTIR 甲苯吸附研究证明了甲苯氧化的合理机制。Ce取代催化剂表面上甲苯的活化可以通过吸附-CH 3 基团进行，而甲苯通过邻位、间位或对位C-H键吸附在未取代的催化剂表面上。图形摘要 Mn 2 O 3 /Mn 3 O 4 ↔ MnO 2 氧化还原循环的改进被观察到，由于与HAp上负载的未取代的Mn相比，Ce取代。ATR-FTIR 甲苯吸附研究证明了甲苯氧化的合理机制。Ce取代催化剂表面上甲苯的活化可以通过吸附-CH 3 基团进行，而甲苯通过邻位、间位或对位C-H键吸附在未取代的催化剂表面上。图形摘要 Mn 2 O 3 /Mn 3 O 4 ↔ MnO 2 氧化还原循环的改进被观察到，由于与HAp上负载的未取代的Mn相比，Ce取代。ATR-FTIR 甲苯吸附研究证明了甲苯氧化的合理机制。Ce取代催化剂表面上甲苯的活化可以通过吸附-CH 3 基团进行，而甲苯通过邻位、间位或对位C-H键吸附在未取代的催化剂表面上。图形摘要