Oxygen separation via chemical looping of the perovskite oxide Sr0.8Ca0.2FeO3 in packed bed reactors for the production of nitrogen from air

Abstract

A redox chemical looping process is investigated as an add-on deoxygenation unit for the production of high-purity nitrogen from air using pressure swing adsorption systems. A material screening study indicated the non-stoichiometric perovskite oxide Sr0.8Ca0.2FeO3−δ as a promising candidate redox material with fast kinetics and a 75% greater gravimetric oxygen capacity compared to state-of-the-art SrFeO3 at the desired process conditions. Granules of Sr0.8Ca0.2FeO3 were manufactured and characterised according to their thermodynamic and kinetic redox properties. A lab scale packed-bed reactor was experimentally tested as proof-of-concept and used to validate a convection–diffusion model of mass transfer within the reactor. The model was further applied for scaling up to a production of 1000 Nm3h−1 of high-purity nitrogen. The results indicate good performance of the packed-bed configuration and a favourable energy demand compared with existing nitrogen production technologies. The proposed technology could greatly extend the useable oxygen impurity range of pressure swing adsorption systems for nitrogen production.