Outstanding performance of a Cu-based oxygen carrier impregnated on alumina in chemical looping combustion

Chemical looping combustion (CLC) allows the combustion of a fuel with inherent CO2 capture by using an oxygen carrier to transfer the oxygen from the air to the fuel. Previously to the CLC scale-up, tests should be done in lab-scale CLC units to determine the combustion performance of promising oxygen carriers and, at the same time, to evaluate the durability of these materials. For that, the effect of operating conditions on the oxygen carrier ageing should be considered, which is often disregarded. In this work, tests were done burning a simu-lated biogas stream in a continuous 500 Wth CLC unit with a promising Cu-based oxygen carrier (Cu14Al_ICB). Operating conditions were carefully selected to maximize the durability of this oxygen carrier while complete CH4 combustion was achieved. These operating conditions were based on limiting both the variation of solids conversion by choosing suitable solids circulation rates and the oxidation degree of the particles in the air reactor by minimizing the air excess. Thus, the Cu14Al_ICB material exhibited an excellent mechanical resistance, estimating a particle lifetime of 20,000 h at 900 degrees C. In addition, copper migration to the surface of the particles and loss of copper were not relevant. This is the first time that under certain operating conditions, a Cu-based oxygen carrier can exhibit outstanding mechanical properties during continuous CLC operation at 900 degrees C.