You are here:
STRUCTURAL EFFECTS ON THE HIGH TEMPERATURE ADSORPTION OF CO2 ON A SYNTHETIC HYDROTALCITE
Citation:
Hutson*, N, S. A. Speakman, AND E. A. Payzant. STRUCTURAL EFFECTS ON THE HIGH TEMPERATURE ADSORPTION OF CO2 ON A SYNTHETIC HYDROTALCITE. Chemistry of Materials. American Chemical Society, Washington, DC, 16(21):4135-4143, (2004).
Description:
Hydrotalcite-like compounds (HTlcs) are solid sorbents that may potentially be used for high temperature separation and capture of CO2. The high-temperature adsorption of CO2 on Mg-Al-CO3 HTlc is affected by structural changes that take place upon heating of the material. The structural changes of a synthetic HTlc upon heating to 200 and 400°C in a vacuum were characterized using various analytical techniques. These structural changes were then related to observed behavior with respect to the physisorption and chemisorption of CO2 at 200°C. Upon heating to 200°C, the material retains its layered structure, though the interlayer spacing is decreased by ∼0.6Å due to loss of interlayer water. Chemisorption of CO2 at 200°C represents more than half of the total adsorption capacity (at 107 kPa) due to increased availablity of the framework Mg2+ cation and the subsequent formation of MgCO3. There is no significant increase of surface area or pore volume after heating to 200°C. Upon heating to 400°C the CO32- in the interlayer is decomposed and the material is completely dehydrated and partially dehydroxylated. The resulting amorphous 3-D structure with increased surface area and pore volume and decreased availability of the Mg2+ cation favors physiosorption over chemisorption for these samples. An increased understanding of structure-property relationships will help in the further development of HTlcs as viable CO2 solid sorbents.
To receive a PDF copy of a preprint of this journal article, send an email request to: RTP_APPCD_ Archivist@EPA.gov