Reed Corey, Lee Yong-Kul, Oyama S Ted
Environmental Catalysis and Nanomaterials Laboratory, Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0211, USA.
J Phys Chem B. 2006 Mar 9;110(9):4207-16. doi: 10.1021/jp054288w.
Silica-supported manganese oxide catalysts with loadings of 3, 10, 15, and 20 wt % (as MnO2) were characterized with use of X-ray absorption spectroscopy and X-ray diffraction (XRD). The edge positions in the X-ray absorption spectra indicated that the oxidation state for the manganese decreased with increasing metal oxide loading from a value close to that of Mn2O3 (+3) to a value close to that of Mn3O4 (+2(2)/3). The XRD was consistent with these results as the diffractograms for the supported catalysts of higher manganese oxide loading matched those of a Mn3O4 reference. The reactivity of the silica-supported manganese oxide catalysts in acetone oxidation with ozone as an oxidant was studied over the temperature range of 300 to 600 K. Both oxygen and ozone produced mainly CO2 as the product of oxidation, but in the case of ozone the reaction temperature and activation energy were significantly reduced. The effect of metal oxide loading was investigated, and the activity for acetone oxidation was greater for a 10 wt % MnOx/SiO2 catalyst sample compared to a 3 wt % MnOx/SiO2 sample.
采用X射线吸收光谱和X射线衍射（XRD）对负载量分别为3、10、15和20 wt%（以MnO₂计）的二氧化硅负载氧化锰催化剂进行了表征。X射线吸收光谱中的边缘位置表明，随着金属氧化物负载量的增加，锰的氧化态从接近Mn₂O₃（+3）的值降低到接近Mn₃O₄（+2(2)/3）的值。XRD与这些结果一致，因为较高氧化锰负载量的负载型催化剂的衍射图与Mn₃O₄参比物的衍射图相匹配。在300至600 K的温度范围内研究了二氧化硅负载氧化锰催化剂在以臭氧为氧化剂的丙酮氧化反应中的反应活性。氧气和臭氧作为氧化剂时，氧化产物主要都是CO₂，但在臭氧的情况下，反应温度和活化能显著降低。研究了金属氧化物负载量的影响，与3 wt% MnOx/SiO₂样品相比，10 wt% MnOx/SiO₂催化剂样品对丙酮氧化的活性更高。
