Physical mixtures as simple and efficient alternative to alloy carriers in chemical looping processes

Chemical looping combustion is a clean combustion technology for fossil or renewable fuels. In a previous demonstration, chemical looping was applied to CO2 activation via reduction to CO with concurrent production of synthesis gas (CO + H-2) from CH4 via rationally designed Fe-Ni alloys. Here, it is demonstrated that that a simple physical mixture can even outperform the equivalent alloy based on an intricate gas phase mediated coupling between the two metals: Ni cracks methane to carbon and H-2. The latter then reduces iron oxide carrier, forming steam, which gasifies the carbon deposits on Ni to produce a mixture of CO+H-2, thus regenerating the active Ni surface. It was suggested that the principle demonstrated herethe gas phase-mediated coupling of two solid reactants with distinct functionalitiesshould be applicable broadly toward oxidation reactions and hence opens a new avenue for rational design of chemical looping processes. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 51-59, 2017