Vanadium oxides supported on hydrotalcite-type precursors: the effect of acid-base properties on the oxidation of isopropanol

Brazilian Journal of Chemical Engineering

D. M. Meira²  G. G. Cortez²  W. R. Monteiro¹  J. A. J. Rodrigues¹ 

[1] ,Faculdade de Engenharia Química de Lorena Departamento de Engenharia Química Laboratório de Catálise IILorena SP ,Brazil

关键词: Mixed oxides;    Hydrotalcites;    Isopropanol;    V-Mg-Al catalysts;   

DOI  :  10.1590/S0104-66322006000300008

来源: SciELO

【 摘 要 】

Vanadium oxide supported on hydrotalcite-type precursors was studied in the oxidation of isopropanol. Hydrotalcites with different y = Mg/Al ratios were synthesized by the method of coprecipitation nitrates of Mg and Al cations with K2CO3 as precipitant. The decomposition of these hydrotalcite precursors at 450°C yielded homogeneous MgyAlOx mixed oxides that contain the Al+3 cations totally incorporated into the MgO framework. The materials were characterized by chemical analysis, BET superficial area, X-ray diffraction, temperature-programmed reduction (TPR) and the reaction of isopropanol, a probe molecule used to evaluate the acid-base properties. The results of TPR showed that the reducibility of V+5 decreased with the increase in magnesium loading in catalysts. The X-ray diffraction patterns of Al-rich hydrotalcite precursors showed the presence of crystalline phases of brucite and gibbsite. It was shown that chemical composition, texture, acid-base properties of the active sites and also Mg/Al ratio strongly affect the formation of the products in the oxidation of isopropanol. The Al-rich catalysts were much more active than the Mg-rich ones, converting isopropanol mainly to propylene.

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