Thermal oxidation of iron nanoparticles and its implication for chemical-looping combustion

BACKGROUND: Chemical looping combustion (CLC) is a promising environmentally friendly technology in which the greenhouse gas CO2 can be readily separated at high-purity, therefore providing an effective method of carbon capture. Its performance, however, is limited by the kinetics of oxidation of the oxygen carrier, whose size is typically in the range of micrometers to millimetres. This paper reports a new idea using metallic nanoparticles as potential oxygen carriers to improve the performance of chemical looping combustion. RESULTS: A detailed experimental study of the heating and oxidation of iron nanoparticles in a simultaneous TGA/DSC system was conducted. Kinetic analysis revealed improved reactivity of iron nanoparticles, as shown by a reduction in the activation energy, which is highly dependent upon the conversion ratio. The implication and potential application of nanoscale metallic nanoparticles as oxygen carriers in CLC are discussed. CONCLUSION: Compared with conventional sized iron particles, the reduction of particle size to nanoscale can offer a number of advantages, such as increased reactivity, reduced mass resistance and enhanced heat transfer, however, a number of practical factors associated with increased specific surface area need to be assessed carefully.