Adsorption and desorption characteristics of barium oxide at high temperature

Oxygen-selective adsorbents were prepared by two different methods, hydrothermal and sol–gel methods. The adsorption and desorption characteristics of these adsorbents were compared in terms of stability and sorption capacity. The sorbents prepared by the sol–gel method showed better cyclic stability and higher adsorption capacity than that prepared by the hydrothermal method because the sol–gel method entrapped well the barium peroxide. Relaxation time for adsorption ranged from 4 to 9 min depending on the preparation methods and that for desorption was 6 min regardless of the preparation methods. Breakthrough experiment with the sorbent prepared by the sol–gel method was performed. The adsorption breakthrough curves at 600 °C showed two plateau regions. One was at about 3.5%, and the other was 20%. The first plateau region is related to the sharp transition point of the oxygen adsorption isotherm. Though the relaxation time for adsorption was 6 min, the time required from the end of the first plateau to the beginning of the second plateau was just 2 min. During the desorption, a plateau region at 3.5% of oxygen concentration was observed regardless of the desorption flow rate.