Co-Containing Catalysts for Fischer-Tropsch Synthesis, Prepared by Decomposition of Co-Al Hydroxycarbonate-Nitrate
Co-based catalysts are the most widely used for Fischer-Tropsch synthesis (FTS) from hydrogen-rich syngas. The size of metallic cobalt crystallites and the extent of its interaction with the oxide support are main factors, which determine the activity and selectivity of the catalyst. The challenge is balancing the extent of interaction in order to ensure high dispersion of metallic cobalt, however preventing formation of hard-reducible mixed oxides. Two precursors: nitrate salts (impregnated catalysts) and hydroxycarbonates (precipitated catalysts) produce the two extreme cases of low interaction and deep interaction of cobalt with the support. In many publications, promotion with noble metals was reported as an efficient method to control the cobalt dispersion. Recently, NO-moderated calcination of Co-containing catalysts was shown to be effective for preparing highly dispersed Co/Al2O3 and Co/SiO2 catalysts from nitrate precursor, since NO acts as “oxygen scavenger” and regulates oxidation potential of gas [1,2]. In this paper we present another approach to regulate the extent of interaction of cobalt to alumina by using mixed hydroxycarbonate-nitrates of Co as precursors.