Characterization of ZnAl2O4 Obtained by Different Methods and Used as Catalytic Support of Pt
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In this work the synthesis of a ZnAl2O4 spinel to be used as a support of metals and its characterization were studied. The methods used for the ZnAl2O4 preparation were: ceramic method (CM), mechanochemical synthesis in humid medium (HMS) and coprecipitation (COPR). ZnAl2O4 CM and ZnAl2O4 HMS showed negligible acidity, but the ZnAl2O4 COPR displayed a low acidity. The spinels obtained by COPR and HMS showed higher specific surface area and pore volumes than that prepared by the ceramic method. In addition the catalytic performance of Pt supported on the prepared spinel was evaluated in the n-butane dehydrogenation reaction. The Pt catalysts prepared with ZnAl2O4 COPR presented better activity and selectivity to olefins than the ones prepared with ZnAl2O4 HMS and ZnAl2O4 CM, which could be correlated with a higher metallic dispersion and lower particle sizes, detected by TEM. The acidity of ZnAl2O4 COPR, observed by isopropanol dehydration and TPD of pyridine, and the sequence of specific surface areas of the different spinels (ZnAl2O4 COPR > ZnAl2O4 HMS > ZnAl2O4 CM) are other important factors to define the final dispersion of the catalysts.
KeywordsSynthesis of ZnAl2O4 support High-energy ball milling Platinum catalysts supported on ZnAl2O4 Catalysts preparation and characterization
Authors thank Miguel A. Torres for the experimental assistance, to Dra. Silvana A. D’Ippolito for TPD of pyridine experiments and to M. J. Yañez (CCT-Bahía Blanca) for TEM measurements. Besides, this work was made with the financial support of Universidad Nacional del Litoral and CONICET—Argentina.
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