Integrating desulfurization with CO2-capture in chemical-looping combustion

Chemical looping combustion (CLC) is an emerging technology for clean combustion. We have previously demonstrated that the embedding of metal nanoparticles into a nanostructured ceramic matrix can result in unusually active and sinter-resistant nanocomposite oxygen carrier materials for CLC which maintain high reactivity and high-temperature stability even when sulfur contaminated fuels are used in CLC. Here, we propose a novel process scheme for in situ desulfurization of syngas with simultaneous CO2-capture in chemical looping combustion by using these robust nanocomposite oxygen carriers simultaneously as sulfur-capture materials. We found that a nanocomposite Cu-BHA carrier can indeed strongly reduce the H2S concentration in the fuel reactor effluent. However, during the process the support matrix is also sulfidized and takes part in the redox process of CLC. This results in SO2 production during the reduction of the oxygen carrier and thus limits the degree of desulfurization attainable with this kind of carrier. Nevertheless, the results suggest that simultaneous desulfurization and CO2 capture in CLC is feasible with Cu as oxygen carrier as long as appropriate carrier support materials are chosen, and could result in a novel, strongly intensified process for low-emission, high efficiency combustion of sulfur contaminated fuel streams.