Experimental and kinetic analysis for particle scale modeling of a CuO-Fe2O3-Al2O3 oxygen carrier during reduction with H2 in chemical looping combustion applications

A kinetic analysis of the H2 reduction of a CuO-Fe2O3-Al2O3 oxygen carrier in gas phase fueled Chemical Looping Combustion of synthesis gas was utilized to derive particle scale representation. An experimentally driven study was carried out to provide an array of operational data sets for kinetic modelling approaches. The impact of key operational variables on the kinetics of the novel oxygen carrier were examined, with emphasis on the application of reliable phenomena driven particle scale models to describe the reduction behavior. Due to the novel nature of the material, a series of experimental studies were carried out to provide a fundamental understanding of how the material changed as oxygen was depleted from the structure due to reduction with H2. This include quantification of the complex mixed metal oxide phase and changes due to lattice oxygen depletion. It was found that H2 reduction occurs in a multistep process where CuFeAlO4 → Cu0+ + FeAl2O4 → Cu0+ + Fe0+ + Al2O3 as oxygen is depleted from the structure. This multistep process was successfully emulated through the use of a two interface Grainy pellet model in which reaction (kinetic) control was the main rate limiting step. This is validated through the examination of other potential rate limiting resistances. The model emulates changes in key operation variables with good accuracy.