High-temperature sorption process for air separation and oxygen removal

This paper describes the concept of a new, efficient high-temperature oxygen sorption process based on a perovskite-type ceramic sorbent for oxygen removal and air separation. The new sorption process takes advantage of the unique properties of certain perovskite-type ceramics that can adsorb a large quantity of oxygen, but not other gases, at high temperatures (300-800 °C). The essential principle of this new sorption process is based on the changing of oxygen nonstoichiometry of the perovskite-type ceramics with temperature and oxygen partial pressure. Two highly oxygen-deficient perovskite oxides, La_0.1Sr_0.9Co_0.5Fe_0.5 O_3-δ, and La_0.1Sr_0.9Co_0.9Fe_0.1 O_3-δ, were examined as candidate materials for the oxygen sorption process. Oxygen sorption equilibrium properties were studied by thermogravimetric analysis (TGA) at 500 and 600 °C and oxygen pressures ranging from 1.3 × 10-4 to 1 atm. The oxygen removal performance at 500 and 600 °C was also investigated in a fixed-bed adsorption column. An infinitely large selectivity, a relatively high oxygen sorption capacity, and fast sorption kinetics are the main characteristics of this new type of sorbent. The process can be used to remove trace oxygen from other gases or to produce high-purity nitrogen and ultrapure oxygen from air.