Use of manganese ore in chemical-looping combustion (CLC)-Effect on steam gasification

The chemical-looping combustion (CLC) process is a novel solution for efficient combustion with direct separation of carbon dioxide. The process uses a metal oxide as an oxygen carrier to transfer oxygen from an air to a fuel reactor, where the fuel reacts with the solid oxygen carrier. When solid fuel is used in CLC, the char needs to be gasified by e.g. steam to form H-2 and CO that can be subsequently oxidized to H2O and CO2 by the oxygen carrier. In this work, the influence of the oxygen carrier on the rate of steam gasification is studied, by comparing the conversion of petcoke in the presence of manganese ore to that of ilmenite. The experiments were carried out in a fluidized-bed reactor at 970 degrees C using a fluidization gas of 50% steam in nitrogen. The manganese ore shows an increase by a factor five in the rate of steam gasification of char as compared to ilmenite. The dramatic increase in rate of steam gasification, in combination with potentially low costs of this material suggests that manganese ore could be an interesting material for CLC with solid fuels. (C) 2012 Elsevier Ltd. All rights reserved.