Elevated temperature carbon dioxide capture via reinforced metal hydrotalcite

Hydrotalcite-like compounds (HT) were synthesized following a combustion-recrystallization-impregnation procedure using aluminum, magnesium nitrates precursors and carbonate solutions. Different types and amount of fuels, different amount of carbonate and different synthesis temperature were used during HT synthesis in order to understand their roles in forming HT structure and CO2 adsorption level. It was discovered that the addition of fuels to facilitate the reaction into mixed oxides and later HT influenced the capacity of CO2 adsorption. Beside type and amount of fuels, the carbonate amount and synthesis temperature also played important roles in forming the HT structure and thus, the CO2 adsorption level. The highest adsorption capacity was observed at 1.21 mmol/g by K–Na HT (K of 18.5% and Na of 1.5%) at operating temperature of 300 °C and 0.4 bar of CO2 partial pressure in the presence of N2 (equivalent to total pressure of 1.34 bar). The HT exhibited Type IV isotherm, a typical mesoporous and slit shape pore material with pore size of 5.4 Å and BET surface area of 124 m2/g.

SEM images of the samples after combustion at 650 °C (HT oxide-Na, HT oxide-K), and after the oxides making contact with carbonate solution (HT-Na, HT-K). The former samples show agglomeration of micro-particles in less orderly manner, while the later samples show more orderly packed microstructure and are more crystalline on the same carbonate source. Both mixed oxide and recrystalized samples containing Na appear less granular and more refined, respectively. The metal reinforced sample with K and Na loading of 18.5% and 1.5%, respectively, is found to be able to adsorp 1.21 mmol/g of CO2 after five cycles, operating at 300 °C and 0.4 bar CO2 partial pressure in the presence of Nitrogen (total pressure 1.34 bar). The adsorbent material is essentially mesoporous in nature despite low BET surface area of 124 m2/g.Figure optionsDownload as PowerPoint slideResearch highlights
► A relatively new procedure for Mg–Al hydrotalcite-like compounds production via combustion-recrystallization-impregnation procedure is introduced for high temperature application such as in the capture of CO2 from coal-fired power plant flue gas.
► This procedure was selected due to its energy and time saving since the procedure involves a very rapid chemical process.
► The mesoporous sample from this study was found to be capable of adsorbing 1.21 mmol/g at 300 °C and 1.34 bar after five cyclic adsorption and desorption. This was achievable despite the relatively low BET surface area of 124 m2/g.