Thermochemical assessment of chemical looping assisted by oxygen uncoupling with a MnFe-based oxygen carrier

• Published in: Applied energy 2019-10, Vol.251, p.113340, Article 113340
• Main Authors: Abad, A., Pérez-Vega, R., de Diego, L.F., Gayán, P., Izquierdo, M.T., García-Labiano, F., Adánez, J.
• Format: Article
• Language: English
• Subjects: Chemical Looping Combustion; CO2 capture; Iron; Manganese; Oxygen carrier; Oxygen uncoupling
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2019.113340

[Display omitted] •Suitable operating conditions for chemical looping with Mn-Fe mixed oxides.•Exploitation of oxygen uncoupling capability of Mn-Fe material is possible.•Thermochemical properties for a Mn-Fe mixed oxide for mass and enthalpy balances.•Improvement of combustion efficiency can offset the use of a high air excess ratio. A previously developed manganese-iron mixed oxide doped with TiO2 shows promising properties for the combustion of solid fuels with intrinsic CO2 capture by Chemical Lopping assisted by Oxygen Uncoupling (CLaOU) owing to its oxygen uncoupling capability, i.e. ability to generate gaseous oxygen at high temperature, and to oxidize gaseous fuels such as H2, CO or CH4 by reacting with lattice oxygen. In this work, a window of suitable operating conditions was determined to facilitate the use of this material in a CLaOU unit. For this purpose, mass and enthalpy balances were performed for the whole CLaOU unit considering theoretical values of thermochemical parameters, such as the equilibrium constant of relevant reactions in CLaOU and the formation enthalpies of reacting solids. An air reactor temperature of 1148 K and a high air excess ratio are suggested in order to promote the transfer of oxygen via the oxygen uncoupling mechanism, which would be preferable for the combustion of solid fuels. Auto-thermal operation of the CLaOU unit is guaranteed for air excess ratio values λ