Measurement and modeling of decomposition kinetics for copper oxide-based chemical looping with oxygen uncoupling

Abstract

Chemical looping combustion with oxygen uncoupling (CLOU) is a promising CO2-capture ready energy technology that employs oxygen carriers with thermodynamic properties that cause oxygen to be spontaneously liberated as gaseous O2 in the fuel reactor, where it can react directly with solid fuels. One of the promising CLOU carrier metals is copper, cycling between CuO and Cu2O. Experimentally-determined rate expressions for these reactions are needed for proper development, modeling and scale-up of CLOU technology. The CuO–Cu2O system presents an interesting challenge in that the rate of decomposition depends on the thermodynamic driving force imparted by the difference between equilibrium and actual partial pressures of oxygen, and the equilibrium partial pressure is strongly temperature dependent in the range useful for combustion. This study investigates decomposition of two different copper-based oxygen carriers, from CuO to Cu2O oxidation states, to develop a universal kinetic expression to describe the observed rate of reaction as a function of temperature, conversion and gas environment. The kinetic model developed is compared to results of a third support type (silica) using two different CuOwt% loadings (64wt% CuO and 16wt% CuO) to demonstrate applicability to other support types and copper oxide loadings.