1 Development of Cu-based Oxygen Carriers for Chemical-Looping Combustion Luis F. de Diego a,* , Francisco García-Labiano a , Juan Adánez a , Pilar Gayán a , Alberto Abad a , Beatriz M. Corbella b , Jose María Palacios b a Instituto de Carboquímica (CSIC), Department of Energy and Environment, Miguel Luesma Castán 4, 50015 Zaragoza, Spain b Instituto de Catálisis y Petroleoquímica (CSIC), Campus UAM-Cantoblanco, 28049 Madrid, Spain Abstract In a chemical-looping combustion (CLC) process, gas (natural gas, syngas, etc) is burnt in two reactors. In the first one, a metallic oxide that is used as oxygen source is reduced by the feeding gas to a lower oxidation state, being CO 2 and steam the reaction products. In the second reactor, the reduced solid is regenerated with air to the fresh oxide, and the process can be repeated for many successive cycles. CO 2 can be easily recovered from the outlet gas coming from the first reactor by simple steam condensation. Consequently, CLC is a clean process for the combustion of carbon containing fuels preventing the CO 2 emissions to atmosphere. The main drawback of the overall process is that the carriers are subjected to strong chemical and thermal stresses in every cycle and the performance and mechanical strength can decay down to unacceptable levels after enough number of cycles in use. In this paper the behaviour of CuO as an oxygen carrier for a CLC process has been analysed in a thermogravimetric analyser (TGA). The effects of carrier composition and preparation method used have been investigated to develop Cu-based carriers exhibiting high