YBaCo4O7+δ sorbent for oxygen-enriched carbon dioxide stream production at a low-temperature

Oxyfuel combustion, using O-2/CO2 mixed gas as the oxidant, increases CO2 concentration in the flue gas and reduces the cost of CO2 capture. Nevertheless, the cost of oxygen production is a key to make the process a viable future option. In this work, YBaCo4O7+delta (YBC114) sorbent with a layered hexagonal structure was prepared and used to produce the O-2-CO2 gas mixture at a low temperature (200-400 degrees 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 degrees C. The XRD patterns show that YBC114 has a good stability in both the O-2-containing and CO2-containing atmosphere at 200-400 degrees C. Cyclic operation for the low temperature O-2-enriched CO2 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 degrees C to 345 degrees 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 degrees C to 200 degrees C. It has been found that the synthesis method of the YBC114 also has a significant effect on the oxygen absorption/desorption kinetics. (C) 2011 Elsevier Ltd. All rights reserved.