Behavior of a manganese-iron mixed oxide doped with titanium in reducing the oxygen demand for CLC of biomass

7 figures, 5 tables.-- © 2021. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Chemical Looping Combustion (CLC) is a promising carbon capture technology to contribute to the development of BioEnergy with Carbon Capture and Storage (BECCS) technologies. In CLC, the oxygen needed for combustion is supplied by a solid oxygen carrier. During the last years, intensive research has been conducted to identify potential oxygen carriers. Iron and manganese-based minerals allowed obtaining high CO2 capture efficiencies, but lower values for the combustion efficiency, that is, high oxygen demand values, due to the high content of volatiles in biomass. Manganese-iron mixed oxides doped with titanium possess the capability of releasing molecular oxygen under specific conditions which would enhance volatile conversion. The objective of the present work was to evaluate the potential of one of these materials ((Mn66Fe)-Ti7) to improve the combustion efficiency of CLC with biomass in a 0.5 kWth continuous CLC unit. Almost 100% of CO2 capture efficiency was obtained in all the experiments. Once the operational conditions for the synthetic material (Mn66Fe)-Ti7 were optimized, it was possible to reach oxygen demand values about 10% with the advantage that the (Mn66Fe)-Ti7 oxygen carrier presented magnetic properties that would facilitate its separation from biomass ashes in the fuel reactor.
This work was supported by ENE2017-89473-R AEI/FEDER, UE. A. Pérez-Astray thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for the BES-2015-074651 pre-doctoral fellowship co-financed by the European Social Fund. T. Mendiara thanks for the “Ramón y Cajal” post-doctoral contract awarded by MINECO.