Modeling of double-loop fluidized bed solar reactor for efficient thermochemical fuel production

A new model of solar reactor based on a double-loop fluidized bed involving CeO2 nanoparticles and two gas streams, N2 and CO2, for efficient thermochemical fuel production, is presented. The fluidized bed reactors are commonly used to carry out a variety of chemical reactions, due to solid granular materials, which play the fundamental role of catalyst. In the system under investigation, the overall reaction CO2→CO+1⁄2O2 is achieved, by means of a thermochemical two-step cycle, based on CeO2 nanoparticles. The first step (CeO2 thermal reduction) has been implemented with a solar-driven endothermic dissociation of the metal oxide to lower- valence metal-oxide. The second step (CO2 splitting) has been carried out with an exothermic oxidation of the reduced metal-oxide, which is produced in the first step, to form CO. The use of nanoparticles as catalyst allows maximizing the surface area of reaction, and at the same time, the reactor based on double-loop fluidized bed allows continuous operation, without alternating flows of inert sweep gas and CO2. The thermodynamic analysis of the system under investigation showed a calculated maximum ideal efficiency of about 63%.