UC Irvine

Chemical looping with oxygen uncoupling (CLOU) is a variant of chemical looping combustion (CLC), which is one of the promising carbon capture and storage technologies. In CLOU, the fuel reacts with gaseous oxygen released by a metal oxide, called the oxygen carrier, at suitable temperatures and oxygen partial pressures, unlike the CLC, where only the lattice oxygen reacts with the fuel. Since solid fuel oxidation with gas phase oxygen is kinetically favorable compared to oxidation on a solid metal oxide, CLOU is considered more effective than CLC for solid fuels like coal and biomass. As a CLOU oxygen carrier, bi-metallic Cu-Mn oxide oxygen carrier demonstrates high combustion efficiency for both solid and gaseous fuels. However, the effects of the fluidizing gas and the pollutant species, such as fuel-sulfur and fuel-nitrogen species, on the performance of this oxide are not well-understood. The objective of this dissertation is to investigate how the type of the fluidizing gas and the presence of SO2 and NO affect the reactivity of Cu-Mn oxygen carrier at CLOU conditions. To achieve this goal, a combination of experiments and density functional theory (DFT) calculations were performed. A lab-scale fluidized bed reactor was designed and built to conduct the experiments. A series of experiments were carried out to determine the effects of various parameters, such as the reduction cycle duration, reactor temperature, and concentration of the pollutants, on the performance of the oxygen carrier. Cu-Mn oxide particles were characterized before and after combustion using a combination of techniques to determine their structural and chemical properties’ change. Additionally, DFT simulations were performed concurrently to obtain a fundamental understanding of the interaction of SO2 with pure CuO, and Cu2O surface. This comprehensive study will be valuable in further development of this oxygen carrier in the CLOU process.