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.