High temperature sorption separation of air for producing oxygen‐enriched CO2 stream

Abstract

AbstractA new high temperature sorption process for production of oxygen‐enriched carbon dioxide stream through air separation with carbon dioxide as the purge gas is reported. The process is based on a fixed‐bed packed with a perovskite‐type strontium‐iron doped lanthanum cobaltite, as the sorbent, operated in 500–900°C. Oxygen is adsorbed by the perovskite‐type sorbent with air being fed. An oxygen‐enriched carbon dioxide stream is obtained when the fixed‐bed is regenerated with carbon dioxide as the desorption gas. A specific carbonation‐reaction mechanism for the O2‐desorption process and a complete reverse reaction during the O2‐sorption process are identified with the evidences of XRD and TGA analysis. A study of the sorption process kinetics over a temperature range of 600–800°C was conducted by fixed‐bed sorption/desorption and TGA experiments. Both desorption and sorption processes exhibit a high reaction rate in an initial stage followed by a slower rate in a second stage. A remarkable separation efficiency was observed at 800°C. The new process offers potential for applications in a number of processes including in the efficient and environmentally benign oxyfuel coal combustion process for power generation. © 2005 American Institute of Chemical Engineers AIChE J, 2006