Materials for chemical-looping combustion

Book chapter, 2011

Chemical-looping combustion (CLC) is a combustion technology with inherent separation of the greenhouse gas CO2. Two inter-connected fluidized beds, a fuel reactor and an air reactor, are used. The fuel is oxidized by the metal oxide in the fuel reactor, and the metal oxide is regenerated in the air reactor. The outlet gas from the fuel reactor consists of CO2 and H2O, easily separated by condensation. Oxides of Ni, Co, Fe, Cu and Mn are used as oxygen-carrier materials. More than 900 materials have been investigated and some have been used in actual operation in chemical-looping combustors in the size range 0.3 – 140 kW. The total time of operational experience is more than 4000 hours. The work indicates that almost complete conversion of the fuel can be obtained and 100% CO2 capture is possible. Most work so far has been focused on gaseous fuels, but the direct application to solid fuels is also rapidly advancing. Moreover, chemical-looping technologies to produce hydrogen with inherent CO2 capture are being developed. This paper presents an overview of the current status of the technology with focus on materials.