YBaCo ₄O _7+δ sorbent for oxygen-enriched carbon dioxide stream production at a low-temperature

Oxyfuel combustion, using O ₂/CO ₂ mixed gas as the oxidant, increases CO ₂ concentration in the flue gas and reduces the cost of CO ₂ capture. Nevertheless, the cost of oxygen production is a key to make the process a viable future option. In this work, YBaCo ₄O _7+δ (YBC114) sorbent with a layered hexagonal structure was prepared and used to produce the O ₂-CO ₂ gas mixture at a low temperature (200-400°C). YBC114 has both the ability of temperature swinging oxygen absorption/desorption (TSA) and the property of pressure swinging oxygen absorption/desorption (PSA) in the temperature range of 200-400°C. The XRD patterns show that YBC114 has a good stability in both the O ₂-containing and CO ₂-containing atmosphere at 200-400°C. Cyclic operation for the low temperature O ₂-enriched CO ₂ stream production indicates that YBC114 has high cyclic stability. The absorption/desorption kinetics can be improved by combining PSA with TSA at no cost of the O ₂ absorption capacity. For such a design, oxygen is absorbed when YBC114 is heated from 200°C to 345°C with a slow ramping rate in an air stream. Oxygen is desorbed and an oxygen-enriched carbon dioxide stream is obtained when YBC114 is exposed in a carbon dioxide stream and cooled from 345°C to 200°C. It has been found that the synthesis method of the YBC114 also has a significant effect on the oxygen absorption/desorption kinetics.