Sr_1–xCa_xFeO_3-δ as a New Oxygen Sorbent for the High-Temperature Pressure-Swing Adsorption Process

Abstract

The low-cost and environmentally friendly perovskite-type oxide of Sr 1−x Ca x FeO 3-δ was proposed here as a new oxygen sorbent usable in a high-temperature pressure-swing adsorption (HT-PSA) process for oxygen production (separation) from air. The oxygen sorption/desorption properties of the Sr 1−x Ca x FeO 3-δ samples (x = 0−1.0) were examined at 550 °C by means of thermogravimetric analysis (TGA). Among the examined samples, Sr 0.76 Ca 0.24 FeO 3-δ (x = 0.24) was found to exhibit the largest value (7.8 cm 3 g −1 ) for the amount of reversibly sorbed/desorbed oxygen by the change in oxygen concentration between air (21 vol % O 2 ) and 5 vol % O 2 . For such an excellent oxygen sorption/desorption behavior to be verified, the oxygen content (oxygen nonstoichiometry, 3-δ) in Sr 0.76 Ca 0.24 FeO 3-δ was estimated as a function of ambient oxygen concentration. The oxygen content of Sr 0.76 Ca 0.24 FeO 3-δ was sensitive to the oxygen concentration and varied largely with its change, especially in the range of 5−21 vol % O 2 . Thus, it is expected that the large change in oxygen content can result in the large amount of reversibly sorbed/desorbed oxygen even by a small pressure-swing amplitude. Actually, the Sr 0.76 Ca 0.24 FeO 3-δ pellet sample was evaluated as an oxygen sorbent for the HT-PSA process by using a small-column apparatus. As a result, the amount of oxygen production for the Sr 0.76 Ca 0.24 FeO 3-δ pellet sample indicated 4.9 cm 3 g −1 per cycle at 600 °C. This value was approximately two times larger than that for the benchmark sample of La 0.1 Sr 0.9 Co 0.9 Fe 0.1 O 3-δ (LSCF1991).

Sr1-xCaxFe1-yCoyO3-δ as facile and tunable oxygen sorbents for chemical looping air separation

“…Recently, SrFeO 3 based oxygen sorbents have received many research interests, owing to its large oxygen capacity and low operating temperature [40][41][42]. The versatile structure of SrFeO 3 offers many opportunities to introduce dopants at A and/or B site to further tuning the redox property [43][44][45]. By co-doping of Ca and Co at A and B sites respectively, oxygen partial pressure swing can be operated between 0.05 and 0.2 atm to achieve 1 wt% oxygen capacity at 400 • C-500 • C based on our recent study [46].…”

CaCoxZr1−xO3−δ Perovskites as Oxygen‐Selective Sorbents for Air Separation

“…Oxygen production has many applications in chemical syntheses and manufacturing processes, and more recently in applications involving clean energy production such as solid‐oxide fuel cells (SOFCs) . Air separation is mainly performed by the following three type of unit operations: (1) cryogenic distillation, (2) membrane separation, and (3) O 2 ‐ or N 2 ‐selective gas sorption . Cryogenic distillation is the most developed but energy intensive process and is particularly useful for air separation on a large scale .…”

“…[1][2][3][4][5][6] Air separation is mainly performed by the followingt hree type of unit operations:( 1) cryogenic distillation, (2) membrane separation, and (3)O 2 -o rN 2 -selective gas sorption. [5,7] Cryogenic distillation is the most developed but energy intensivep rocess and is particularly usefulf or air separation on al arge scale. [4] Membrane and sorptionp rocesses are suitable for small-or medium-scale on-site production.…”

Reducing the Cost of Zinc–Oxygen Batteries by Oxygen Recycling

“…Unfortunately, oxygen is too expensive for energy‐storage systems in which cost is a vital factor. The oxygen dosage for a 10 MWh zinc–oxygen energy‐storage system is around 2100 Nm 3 day −1 (1 cycle per day), at which the pressure swing adsorption (PSA) oxygen generator becomes the most efficient oxygen supply method of suitable scale and lowest cost . However, the cost of oxygen still reaches ¢ 30 Nm −3 , which leads to ¢ 6 kWh −1 increment per cycle for the energy‐storage system.…”

“…Theo xygen dosagef or a1 0MWh zinc-oxygen energy-storages ystem is around 2100 Nm 3 day À1 (1 cycle per day), at which the pressures wing adsorption (PSA) oxygen generator becomes the most efficient oxygens upply method of suitable scale and lowest cost. [23,24] However, the cost of oxygens till reaches ¢30Nm À3 , [25][26][27][28] which leads to ¢6 kWh À1 incrementper cycle for the energy-storagesystem.According to ar eview by Yang et al, [4] the cost of electricity storage needs to be comparablet ot hat of traditional electricity generationa tacost as low as ¢8-10 kWh À1 per cycle.T herefore, the cost of oxygen in the zinc-oxygen battery urgently needs to be reduced.Herein, we propose an efficient oxygen recycling strategy in az inc-oxygen battery because the amount of oxygeng eneratedf rom the chargingp rocess is equal to that required for the discharge process,w ith the same charge/discharge capacities.T herefore,t he cost can be reduced substantially for the [a] Z.…”