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STUDIES ON METALLIC CHLORIDES THERMO-CHEMICAL CYCLES USING NUCLEAR ENERGY FOR HYDROGEN PRODUCTION IN ARGENTINA Authors: A.E. Bohé, M. Bosco and H.E. Nassini Comisión Nacional de Energía Atómica, ARGENTINA SUMMARY Based on domestic capabilities developed for more than 50 years in Argentina, related with both nuclear energy and hydrogen production and applications technologies, the production of hydrogen using high-temperature nuclear reactors is being seriously considered as a sustainable and environmentally friendly alternative for the country. Research activities currently underway in Argentine on the water splitting thermo-chemical processes for hydrogen production are focused on the metallic chlorides family of thermo-chemical cycles. Theoretical and experimental investigations are addressed to elucidate the kinetics and mechanisms of thermo-chemical reactions at laboratory scale, in order to find the optimum conditions for increasing the efficiency of these cycles as a previous step for a future scaling up of the experimental facilities. Thermodynamic analyses were carried out on the original Fe-Cl thermo-chemical cycle consisting of four chemical reaction steps. Thermodynamic calculations predicted the formation of hematite during hydrolysis of FeCl2 (instead of magnetite) and a low production of H2 due to an oxidative atmosphere in the reaction site. A feasible way to enhance the H2 production could be by removing the O2 from the reaction site, for example with the presence of an O2 scavenger like metallic Ti. Thermodynamic analysis considering the presence of metallic Ti showed the formation of magnetite during hydrolysis of FeCl2, the presence of ilmenite (TiFeO3) and higher yield efficiency in the production of H2, due to a reducing atmosphere in the reaction site. In order to verify the thermodynamic calculation conclusions, an experimental setup was built and constructed for producing the Fe-Cl cycle chemical reactions in a batch mode. After heating the chemical reactants during 48 hours at 650 C, no significant amount of H2 was produced while the presence of hematite was confirmed by X-Ray diffraction as a solid product of chemical reactions. Adding a Ti sheet in the reactor bed, it was observed that the production of H2 increased significantly, even for shorter reaction times, e.g. 5 hours of heating at 650 C. Experimental results confirmed the previous theoretical calculations and show that, for producing H2 in a efficient way with the original Fe-Cl thermo-chemical cycle, it is necessary to remove as soon as possible the O2 from the reaction site. Based on these promising preliminary results, several research activities were planned to be executed in the near future. They include: (1) design and construction of a laboratory-scale reactor for continuous operation; (2) implementation of separating membrane technology for removing H2 and O2 from the gaseous stream, i.e. separation of H2 and O2 from HCL and Cl2 with a ceramic membrane and further separation of H2 from O2 with a composite membrane consisting of a ceramic support membrane coated by a metallic palladium layer; and (3) development of catalytic surfaces with rare earth and refractory metal oxides in order to make the reactions faster and to improve the efficiency of the process.

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