Synthesis and Characterization of γ-Alumina-Supported Cobalt and Iron Nanocatalysts

Abstract

The present work deals with the synthesis of cobalt monometallic and bimetallic Co/Fe nanocatalysts supported on alumina. The nanocatalysts were prepared by a wet impregnation method. The samples were characterized in terms of reducibility, dispersion, metal particle size, textural characteristics and crystallinity. These characteristics were revealed using hydrogen temperature-programmed reduction (TPR), CO-chemisorption, transmission electron microscopy (TEM), X-ray diffraction (XRD) and nitrogen adsorption analysis. H2-TPR analysis of Co/Al2O3indicated three temperature regions at 507◦C (low temperature), 650◦C (medium temperature) and 731◦C (high temperature) while characteristic peaks of Fe/ Al2O3appeared at 454◦C, 635◦C and 716◦C, respectively. Bimetallic nanocatalysts exhibited different physicochemical properties than those of the monometallic nanocatalysts. The incorporation of iron into cobalt nanocatalysts up to 50% of the total metal loaded enhanced the reducibility, increased the CO and H2chemisorbed and degree of reduction (DRT) while surface area decreased, further increase in the iron content resulted in a decrease in the crystallinity, increase in the average metal particle size and shift in the reduction towards higher temperatures.