CHARACTERIZATION OF SILICA SUPPORTED IRON-COBALT CATALYSTS FOR FISCHER-TROPSCH SYNTHESIS
Abstract
To investigate the influence of composition on the kinetics of Fischer-Tropsch synthesis, well characterized silica supported Fe-Co alloy catalysts were prepared and studied. The influence of temperature and particle size of the metallic crystallites on the carburization processes which occur on Fe catalysts during the synthesis reaction was also investigated using silica supported Fe and an unsupported Fe powder. Three major conclusions were derived from these investigations: (1) The pore structure of the support and the drying procedure used to remove the excess water and decompose the metallic salts following the incipient wetness preparation for the supported Fe-Co catalysts significantly influences the distribution of the metals on the support. (2) The hydrocarbon selectivities of the bimetallic catalysts were unlike simple physical mixtures of Fe and Co catalysts, but were intermediate to those of Fe and Co. Initial rates showed a strong iron influence. (3) The carbides which form during the synthesis reaction are dependent on the particle size of the metallic crystallites and the temperature of the synthesis reaction. The techniques used to characterize the catalysts in this investigation include Mossbauer spectroscopy, X-ray diffraction, differential kinetic analysis, transient drying studies, and N(,2) adsorption studies. Mossbauer spectroscopy was the primary investigative tool used, and most of the analysis was done at atmospheric pressure utilizing a reactor/absorption cell which allowed in situ analysis.
Degree
Ph.D.
Subject Area
Chemical engineering
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