Experimental Study of Cement-Supported CuO Oxygen Carriers in Chemical Looping with Oxygen Uncoupling (CLOU)

Abstract

Chemical looping with oxygen uncoupling (CLOU) provides a possible process that could be used for combustion of solid fuels with easy separation of CO2. Cu-based oxygen carriers are among the most promising metal oxide oxygen carriers for CLOU, because CuO has a very high oxygen transport capability and high reaction rates. However, Cu-based oxygen carriers always suffer from the problem of agglomeration, which would result in defluidization. Inhibiting the agglomeration using methods as simple as possible becomes a key issue for the use of Cu-based oxygen carriers in CLOU. This study prepared four types of oxygen carriers with different CuO contents as the active component and cement as the support material by mechanical mixing. The oxygen release and uptake rates were determined by successive cycling tests in a TGA. The fluidization behavior against agglomeration during cyclic oxygen release/uptake reactions were tested in a batch-scale fluidized bed. Experimental results showed that the addition of cement can effectively inhibit the agglomeration of Cu-based oxygen carriers and this type of oxygen carrier could have potential use in the CLOU process. A theoretical equation based on the concept of Zener pinning force was developed to understand the effect of various support materials on the agglomeration limit.