Insight into CO selective chemisorption from syngas mixtures through Li2MnO3; a new H2 enrichment material

Abstract

Carbon oxides separation from a hydrogen stream is essential to achieve ideal energy systems. In this context, lithium manganate (Li₂MnO₃) is the first alkaline ceramic reported for the selective chemisorption of CO under non-oxidative conditions. The Li₂MnO₃ was synthesized, characterized, and dynamically and isothermally tested for selective CO chemisorption from syngas mixtures (H₂ + CO) by thermogravimetry, GC and DRIFTS techniques, using different H₂, CO, and CO₂ flow compositions. Afterwards, the kinetic parameters were determined by fitting the isothermal data to the modified Jander–Zhang model to CO capture. All results showed that addition of H₂ shifted the CO capture to lower temperatures and highly increased its kinetics and its efficiency. Moreover, it was elucidated that the presence of carbon oxides has a “shielding effect” over the surface of the Li₂MnO₃, minimizing or inhibiting the reaction between the Li₂MnO₃ and H₂. Finally, cyclic CO capture and desorption, using syngas flows, presented good efficiencies and stability, although the CO capture efficiency slightly diminished over 10 cycles. Therefore, Li₂MnO₃ is a promising material for H₂ purification systems.