Chemical Looping Combustion in a Bed of Iron Loaded Geopolymers

The chemical looping combustion allows for inherent CO2 separation when burning fossil fuels in presence of a suitable oxygen carrier. The choice of the material to be used should take into account not only chemical/physical properties but also economical, environmental, and safety concerns, addressing for more common materials, like Fe oxides. In this research a geopolymeric oxygen carrier, based on Fe2O3, was tested for the first time in a laboratory CLC plant operated at high temperature for the combustion of a CO rich gas from char gasification in CO2. The CLC plant reliably performed in repeated cycles without decay of the CO conversion during the chemical looping combustion. The maximum CO content in the flue gas was around 1% vol. and carbon monoxide conversion achieved 97%. The calculated oxygen transport capacity was 0.66%. The plant results were confirmed by the XRD analysis that proved the presence of reduced phases in samples after chemical looping stage and by significant peaks obtained during H2 reduction in TPR equipment.