Title Pt-Sn catalysts supported on highly-dispersed ceria on carbon - Application to citral hydrogenation
Authors SERRANO RUIZ, JUAN CARLOS, Sepulveda-Escribano, A. , Rodriguez-Reinoso, F. , Duprez, D.
External publication Si
Means J. Mol. Catal. A-Chem.
Scope Article
Nature Científica
JCR Quartile 2
JCR Impact 2.70700
Publication date 01/05/2007
ISI 000245897100034
DOI 10.1016/j.molcata.2006.12.031
Abstract A novel kind of bimetallic Pt-Sn catalysts supported on carbon and promoted with highly-dispersed ceria were prepared by a co-impregnation method and tested in the liquid phase hydrogenation of citral after reduction at low (473 K) and high (773 K) temperatures. They were characterized by N-2 adsorption at 77 K, X-ray diffraction, temperature-programmed reduction (TPR), transmission electron microscopy (TEM) and CO chemisorption at room temperature. Results from N-2 adsorption, XRD and TEM indicated that impregnation method used here led to a highly-dispersed ceria on carbon. Conversely to massive CeO2, TPR profile of CeO2/C showed two broad overlapped peaks at low temperatures (803 and 903 K), which are indicative of the easier reduction of the supported promoter. Addition of platinum partially promotes the reductions of surface ceria, this indicating a close metal-promoter interaction. Ceria reducibility was increased with tin addition. The reduction treatment at 773 K produced a strong decrease in the CO adsorption capacity in all cases, although this loss was more relevant for the monometallic catalyst. After reduction at low temperature (473 K), the monometallic Pt/CeO2/C was the most active catalyst, while the presence of tin reduced the catalytic activity. Reduction at high temperature (773 K) produced the decrease of activity in the case of monometallic sample while bimetallic catalysts, specially the one with Sn/Pt=0.25, increased the citral conversion values. Reduction treatment at 773 K also increased selectivity to unsaturated alcohols (geraniol and nerol) of bimetallic samples, which presented in all cases higher values than their monometallic counterpart. The onset of new Pt-CeOx and Pt-SnOx sites after the reduction process is proposed to explain the increase in activity and selectivity of bimetallic catalysts. (c) 2006 Elsevier B.V. All rights reserved.
Keywords ceria; carbon; citral hydrogenation; SMSI; platinum; tin
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