The concentrations of Al3+ and Li+ in an aqueous alkali affect the ability of the solution to capture CO2. When CO2 gas was forced into such a solution, CO2 was captured via the formation of a carbonate-containing compound. The carbonate-containing compound was Li-Al-CO3 hydrotalcite (Li-Al-CO3 LDH) or amorphous aluminium hydroxycarbonate. The former compound contained 2.84-3.22 wt% carbon, while the latter contained less carbon (1.52-1.97 wt%). The Li-Al-CO3 LDH was porous with nanosized pores and had a BET surface area of 114.8-161.8 m2 g-1. The injection of a relatively low CO2 gas flow rate into the Al3+- and Li +-containing aqueous solution favoured the production of Li-Al-CO3 LDH. For example, forcing CO2 gas into the aqueous solution at a flow rate of 70 mL min-1 produced Li-Al-CO 3 LDH. Injecting CO2 at a higher flow rate (120 mL min-1) into the same solution produced amorphous aluminium hydroxycarbonate. A CO2 capture capacity (mmol per gram AlLi IMC) of up to ∼30 mmol g-1 (1.30 kg CO2 per kg of AlLi) was achieved in 120 s. The fall in the pH of the alkaline solution during CO 2 bubbling was the critical factor that determined whether the final product was Li-Al-CO3 LDH or amorphous aluminum hydroxycarbonate.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)