A study on high temperature CO2 capture by improved hydrotalcite sorbents

• High temperature CO2 capacity of hydrotalcite improved by synthetic means.
• Disruption in layer stacking led to higher surface area and in turn higher capacity.
• The capacity could be further improved by K2CO3 promotion.
• Promotional effect of K2CO3 was found to be temperature dependent.
• The sorbents were regenerable with stable dynamic CO2 capacity.

The effect of synthetic routes in improving the CO2 capacity of hydrotalcite based sorbents in the temperature range 300–400 °C has been studied. Ultrasonication and microwave irradiation of the synthesis gel during hydrotalcite precipitation leads to disruption in the layer stacking which in turn increases surface area. A correlation was observed between the increased surface area and improved equilibrium and dynamic CO2 capacity. A temperature dependent promotional effect of K2CO3 on CO2 capacity improvement was also observed. The CO2 loaded hydrotalcites were found to be regenerable by inert purge with or without evacuation at a slightly elevated temperature of ∼450 °C. The dynamic CO2 capacity was found to remain stable under cyclic adsorption regeneration conditions.