Kinetics of carbon dioxide sorption on perovskite-type metal oxides

Kinetics of carbon dioxide sorption on perovskite-type metal oxides is important to the use of these materials as sorbents or membranes for air separation and methane conversion reaction. This paper reports an experimental and modeling study of the kinetics of carbon dioxide sorption on La0.1Sr0.9Co0.5Fe0.5O3-delta particulates in 700-900 degrees C. It was found that the perovskite-type metal oxide samples prepared from corresponding powders sintered at 900 and 1200 degrees C exhibit different sorption kinetics, due to different microstructures of the metal oxide samples. The samples sintered at the higher temperature have a denser structure with slow sorption kinetics, and those sintered at the lower temperature possess a porous structure with fast sorption kinetics. The fast carbon dioxide sorption process on the porous metal oxide samples can be well described by a homogeneous carbonation reaction model. For the dense metal oxide samples, the carbon dioxide sorption is accompanied with oxygen desorption at a similar rate for dense metal oxide particles of different size. The carbon dioxide sorption rate decreases with increasing particle size. The sorption process for the dense samples can be described by a shrinking-core model considering the carbonation reaction on the shrinking-core surface and oxygen desorption from the shrinking core.