期刊
MICROPOROUS AND MESOPOROUS MATERIALS
卷 56, 期 2, 页码 153-162出版社
ELSEVIER
DOI: 10.1016/S1387-1811(02)00481-X
关键词
photocatalysis; polyoxometalate; mixed oxide; layer double hydroxide; pesticide degradation
Zn/Al/W(Mn) mixed oxides were prepared via calcination of the precursors of monovacant and monosubstituted Keggin type polyoxometalate (POM) intercalated layered double hydroxides (LDHs) such as Zn2Al(OH)(6)-[SiW11O39](0.12) . 0.2H(2)O and Zn2Al(OH)(6)[SiW11O39Mn(H2O)](0.16) . 0.3H(2)O at 600-700 degreesC. The physicochemical properties of the products were characterized by the methods of powder X-ray diffraction, elemental analysis, scanning electron microscopy, UV diffusion reflectance spectroscopy, infrared spectroscopy, thermogravimetric analysis, electron spin resonance and N-2 adsorption-desorption measurements. Phase changes during the process of calcination of the POM containing LDH precursors were studied, indicating that the precursors decomposed at 400 degreesC and formed ZnO- and Al2O3-like phases together with an X-ray amorphous phase, and then yielded a mixture of well-crystallized phase of ZnAl2O4 formal spinel and ZnWO4 inverse spinel at 600-700 degreesC. As for the thermally decomposed products, the changes of BET surface areas and pore sizes are related to their crystallinity and structures. Compared with the POM-LDH precursors, the mixed oxides thus obtained exhibited higher photocatalytic activity to degrade aqueous organochlorine pesticides hexachlorocyclohexane. (C) 2002 Elsevier Science Inc. All rights reserved.
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