A new reversible chemical system for efficient utilization of carbonaceous compounds

An endothermic chemical system composed of pulverized iron-based oxide and carbon powder has been investigated by using the temperature swing method (TSM) at 700–800 °C. Ferrites of Zn, Mn, and Ni, and magnetite were studied. The magnetite showed the most promising result. In the TSM, magnetite as the working material was reduced to wüstite and carbon was concurrently oxidized to CO in a flow of N2 at 800 °C; this process is referred to as an activation step of the metal oxide. In the reverse process, in a flow of CO2, the wüstite was oxidized to magnetite and the injected CO2 was reduced to CO at 700 °C. The total amount of oxygen donated to carbon during the activation step was the same as that taken from the magnetite during the reduction step. In this system, the following net reaction is realized at temperatures of 700–800 °C: C + CO2 → 2CO. The process will therefore serve for the utilization of coal and other carbonaceous compounds at much lower temperatures than are employed in the traditional water-gas and producer-gas reactions.