Experimental comparison of two different ilmenites in fluidized bed and fixed bed chemical-looping combustion

Carbon capture for storage or reuse is seen as one possibility to lower the emissions of anthropogenic CO2. Chemical-looping combustion (CLC) is a promising second generation technique to capture CO2 from thermochemical fuel conversion processes, such as combustion for power generation. The technical implementation of CLC can be conducted using different arrangement approaches based on fluidized or fixed bed reactor designs. When it comes to conversion of solid fuels, the lifetime of an oxygen carrier in a CLC system may be limited by side reactions with fuel ash, or by carryover losses. Therefore, low cost oxygen carriers are preferred. In that context, ilmenite, an iron titanium oxide has been the subject of a number of studies. Here, two ilmenite samples from the Lac Tio mine, Quebec, Canada, extracted from different preparation states were evaluated during activation at 900 °C using a CO–CH4–H2 gas mixture diluted in N2. The experiments were carried out both under fluidized bed and fixed bed conditions to point out qualitative differences. Generally fixed bed reduction indicated higher gas conversion although coarser particles were used. However, if oxidation is carried out in a fixed bed, particle sintering may be a substantial problem.