Synthesis and characterization of TiO2-MgO mixed oxides prepared by the sol-gel method

被引:47
作者
Lopez, T
Hernández, J
Gómez, R
Bokhimi, X
Boldú, JL
Muñoz, E
Novaro, O
García-Ruiz, A
机构
[1] Univ Autonoma Metropolitana Iztapalapa, Dept Chem, Mexico City 09340, DF, Mexico
[2] Natl Autonomous Univ Mexico, Inst Phys, Mexico City 01000, DF, Mexico
[3] Natl Polytech Inst, COFAA, UPIICSA, Mexico City 08400, DF, Mexico
关键词
D O I
10.1021/la9812931
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Titania-magnesia mixed oxides, with magnesia concentrations between 10 and 90 wt %, were prepared by using the sol-gel method with titanium n-butoxide and magnesium ethoxide as precursors. The mixed oxides were characterized with X-ray powder diffraction, BET nitrogen adsorption isotherms, electron spin resonance (ESR), and by testing their catalytic activity for 2-propanol and a-butanol. dehydration. Samples contained periclase, anatase, karooite (MgTi2O5), geikielite (MgTiO3), and qandilite (Mg2TiO4) The BET specific surface area varied with magnesia concentration; the samples with 50 wt % MgO had the highest area, 211 m(2)/g. Samples had paramagnetic centers that produced complex ESR spectra when many crystalline phases coexisted. For 2-propanol and 2-butanol decomposition, the activity and selectivity patterns of the mixed oxides were substantially different to those observed in pure TiO2 and pure MgO. This singular behavior should be a result of the structural defects created by the substitution of Mg2+ ions by Ti4+ cations in titania lattice, as well as by the interfaces created when several crystalline phases coexisted.
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收藏
页码:5689 / 5693
页数:5
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