Effect of Barium Content and Sample Size of BaO₂−MgO Oxygen Acceptor on Reaction Rate

Abstract

The BaO-BaO 2 reaction cycle was investigated in a range of temperatures from 973 to 1123 K and oxygen pressures from 0 to 0.2 MPa using the BaO 2 -MgO oxygen acceptor of different barium content and sample size prepared with barium peroxide and magnesium oxide. The rates of the oxidation of barium oxide and the reduction of barium peroxide by the BaO 2 -MgO oxygen acceptor during repeated cycling were little influenced by pellet sizes smaller than 16 mm in diameter, and an increase in the barium content of the sample led to a decrease in the reaction rate, while oxygen loading of the oxygen acceptor increased. In addition, fairly high reaction rates were obtained for the BaO 2 /MgO at ratios up to 1:1.4 (mol). The application of the BaO-BaO 2 reaction cycle to oxygen production or enrichment with regard to operation mode and conditions was also investigated using the BaO 2 -MgO oxygen acceptor.

Preparation of single-phase three-component alkaline earth oxide of (BaSrMg)O: a high capacity and thermally stable chemisorbent for oxygen separation

“…In addition, the sorption isotherm also revealed that the sorption capacity (2.02 mmol-O 2 g À1 ) of (BaSrMg)O was much higher than that (1.75 mmol-O 2 g À1 ) of (BaMg)O, as previously reported by Jin et al and his co-workers. 1,33 The chemisorption and desorption cycle is shown in Fig. 7b.…”

“…14,15 As a result, a new method using alkaline earth oxides has been commercialized for air separation based on the BaO-BaO 2 redox reaction cycle: BaO + 1/2O 2 4 BaO 2 . 1,10 In this method, BaO exhibits a high oxygen selectivity and sorption capacity. However, since BaO is very reactive, it reacts easily with its surroundings and is also sintered at an elevated temperature in the BaO-BaO 2 redox reaction, resulting in a poor thermal stability and poor productivity for a multi-cyclic operation.…”

“…However, since BaO is very reactive, it reacts easily with its surroundings and is also sintered at an elevated temperature in the BaO-BaO 2 redox reaction, resulting in a poor thermal stability and poor productivity for a multi-cyclic operation. 1 Furthermore, the transition of the BaO-BaO 2 redox reaction occurs at a low oxygen pressure, which requires a high operating cost. Thus, various attempts have already been made to overcome these drawbacks using additives as a promoter or stabilizer for the BaO-BaO 2 redox reaction.…”

“…Thus, various attempts have already been made to overcome these drawbacks using additives as a promoter or stabilizer for the BaO-BaO 2 redox reaction. [16][17][18] For example, Jin et al 1 used MgO powders to improve the thermal stability of the BaO-BaO 2 redox reaction, while Park et al 10 showed that the reaction rate and thermal stability of the BaO-BaO 2 redox reaction were both enhanced by coating the BaO particles with MgO. Notwithstanding, the requirement of a low transition oxygen pressure for the BaO-BaO 2 redox reaction remains an issue.…”

Preparation of Tunable (BaSrMg)O for Oxygen Chemisorption: Formation Mechanism and Characterization

“…Yet, while cryogenic distillation is advantageous for a large-scale air separation process, it involves high energy consumption, capital, and operating costs . Similarly, while physisorption is easily commercialized, it has a poor selectivity for air separation as the physisorption enthalpies of oxygen and nitrogen are very similar. − As an alternative, oxygen-selective chemisorption has been attracting attention in recent studies, where chemisorbents, such as Co-based metal–organic host materials − and BaO-based alkaline earth oxides, − are used for the selective lattice binding of oxygen by sorption and then the reversible release of oxygen by desorption. For practical applications, BaO-based alkaline earth oxides are favored, as Co-based metal–organic frameworks include the toxic cobalt element and require a large amount of organic material, making them environmentally unfriendly.…”