Sorptive and activity behavior of iron minerals for hydrocarbon synthesis

Abstract

The sorptive behavior of hydrogen and of carbon monoxide and of their mixtures on a low grade iron ore, magnetite, hematite and a commercial synthetic NH 3—iron catalyst was studied in an attempt to describe their catalytic properties for Fischer-Tropsch hydrocarbon synthesis. In comparison to hydrogen and carbon monoxide adsorbed individually, the adsorption of both the gases is enhanced invariably when adsorbed simultaneously from the mixture. Sorption of hydrogen is enhanced by the presorption of carbon monoxide on the catalyst surface while a small amount of presorbed hydrogen hardly enhances the carbon monoxide adsorption. Initial rates of carbon monoxide hydrogenation, which are most representative of clean surfaces, measured over the temperature range 250–360°C, are in the order hematite > magnetite > synthetic-NH 3-iron > iron ore. From the initial rates, the selectivity for methane formation at 250°C for all the four catalysts is about 20 percent.