New Oxygen-Deficient PerovSkite Nanomaterial for reversible CO2 Capture at room temperature

CO2 is the principle ingredient of green house gases and a good indicator of air pollution in the atmosphere. Hence, it is necessary to reduce the amount of  CO2 before it is exhausted in the atmosphere. CO2 capture by certain compounds finds application at fossil fuel power plants, fuel processing plants as well as various industrial plants. When the CO2 containing gas comes in contact with solid sorbant that is capable of capturing the CO2 it is easily sorbed by the material.

Rapid CO2 capture in nanostructured Brownmillerite CaFeO2.5 with no decay in capture capacity even after multiple cycles of carbonation and calcination. Industrial exhaust CO2 gas causes global warming as a greenhouse gas and there is an ever increasing need to develop materials for direct capture of CO2. In this work, CO2 capture effect in an oxygen-deficient perovskite CaFeO2.5 with Brownmillerite structure by first is demonstrated, exposing the compounds (bulk- and nano-CaFeO2.5) to ambient air for different durations and later, by studying fast carbonation–calcination cycles using thermogravimetry. We found that, while the physical properties of bulk-CaFeO2.5 remain unaltered; nano-CaFeO2.5 shows spontaneous capture of CO2 upon exposure to ambient air. Moreover, nano-CaFeO2.5 can be recovered completely by heating in air, showing that the capture of CO2 is reversible. Investigation of bulk and nano-CaFeO2.5 in a 2-min cycle of carbonation and calcination (regeneration) at 500 °C revealed that the nano-CaFeO2.5 exhibited rapid CO2 capture ability within few seconds. In addition, almost no decay in CO2 capture capacity was observed even after 30 cycles of carbonation–calcination of nano-CaFeO2.5, which is quite remarkable. Such nanostructured systems can be potential candidates for practical applications of capturing CO2 from hot exhaust gases.

 

 

Highlights

• Spontaneous CO2 capture in nano-CaFeO2.5 exposed for different durations in air.
• Rapid CO2 capture ability in 2-min carbonation–calcination cycles in TGA at 500 °C.
• Negligible decay in CO2 capture capacity of nano-CaFeO2.5, even after 30 cycles.
• Change in morphology to nano-sheets after carbonation–calcination cycles.
• Nano-CaFeO2.5, a promising material for CO2 capture in hot industrial exhaust gases