The capture of carbon dioxide by transition metal aluminates, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate

Abstract

The capture of CO2 by transition metal (Mn, Ni, Co and Zn) aluminates, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate was carried out at pre- and post-combustion temperatures. The prepared metal adsorbents were characterized by Xray diffraction (XRD), scanning electron microscope (SEM), surface area analysis and acidity/alkalinity measurements. The different experimental variables affecting the adsorbents ability to capture CO2, such as the mol ratio of metal ions, the pressure of CO2, the exposure time and the temperature of the adsorbent were also investigated. Calcium zirconate captured 13.85 wt-% CO2 at 650°C and 2.5 atm and calcium silicate captured 14.31 wt-%at 650°C. Molecular sieves (13X) and carbon can only capture a negligible amount of CO2 at high temperatures (300°C–650°C). However, the mixed metal oxides captured reasonable amount of CO2 at these higher temperatures. In addition, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate adsorbents captured CO2 at both pre and post-combustion temperatures. The trend for the amount of captured carbon dioxide over the adsorbents was calcium aluminate < lithium zirconate < calcium zirconate < calcium silicate.