Synthesis of
Synthesis of
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DOI：
10.1007/s11356-023-28715-2
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发表时间：
2023-07
影响因子：
5.8
通讯作者：
Zhi Li;Chunjing Su;Yimin Yan;Mingli Fu
中科院分区：
文献类型：
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作者：
Zhi Li;Chunjing Su;Yimin Yan;Mingli Fu
以草酸铵为沉淀剂，采用氧化还原沉淀法和水热合成法合成了一系列xCe-MnO 2（x= 0-1）催化剂。结果表明，0. 25 Ce-MnO 2对甲苯的催化氧化活性最高，T99为240 °C。XRD、拉曼、SEM、TEM、EDS-mapping、BET等表征结果表明，通过调节Ce的引入量，0. 25 Ce-MnO 2催化剂呈现出三维多级层状纳米片结构，具有丰富的活性位，有效形成了Ce-Mn均匀分散。0. 25 Ce-MnO 2催化剂具有较大的孔径和体积，具有良好的甲苯转移性能。与MnO 2相比，0. 25 Ce-MnO 2的晶型向四锰钾矿型α-MnO 2相移动，暴露出更多的有利于催化甲苯的晶面。H2-TPR、O2-TPD和XPS表征进一步证实了Ce和Mn氧化物之间的强相互作用，表现出更好的低温还原性和氧迁移性，同时沿着丰富的Ce 3+和Mn 3+物种，其中晶格氧起主要作用。原位漫反射红外光谱研究表明，0. 25 Ce-MnO 2催化剂对甲苯的吸附和脱附能力均高于MnO 2催化剂，苯甲酸盐物种是催化氧化反应的关键中间体。此外，苯甲酸酯和表面酚类物种是MnO 2催化氧化的关键中间体。由于0. 25 Ce-MnO 2具有较好的甲苯转化为苯甲酸盐的能力，因此具有较好的催化活性。
A series ofxCe-MnO2(x= 0–1) catalysts were synthesized using ammonium oxalate as a precipitator via the redox precipitation method and hydrothermal synthesis method. The results indicate that 0.25Ce-MnO2exhibited the highest catalytic activity for toluene oxidation, with the T99of 240 °C. Characterization results from XRD, Raman, SEM, TEM, EDS-mapping, BET, and other techniques reveal that the 0.25Ce-MnO2catalyst exhibited a three-dimensional multistage ultrathin nanosheet structure by adjusting the introduction amount of Ce, with abundant active sites, and effectively formed Ce-Mn homogeneous dispersion. The larger pore size and volume of 0.25Ce-MnO2catalyst lead to it excellent toluene transfer ability. Furthermore, compared with MnO2, the crystal pattern of 0.25Ce-MnO2shifted to the tetragonal cryptomelane type α-MnO2phase and exposed more crystal planes which are beneficial to catalyze toluene. H2-TPR, O2-TPD, and XPS characterization further confirmed the strong interaction between Ce and Mn oxides, which exhibited better low-temperature reducibility and oxygen migration, along with abundant Ce3+and Mn3+species, where lattice oxygen played a major role. Moreover, in situ DRIFTS revealed that the 0.25Ce-MnO2catalyst showed higher adsorption and desorption capacity for toluene than the MnO2catalyst, and benzoate species were the key intermediates for catalytic oxidation. Additionally, benzoate and surface phenolic species were the key intermediates for catalytic oxidation of MnO2. Because 0.25Ce-MnO2possesses better ability of converting toluene to benzoate species, it exhibits better activity.