Abstract
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 ∼0.6 Å 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 availability of the framework Mg 2+ 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 physisorption 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.
Original language | English |
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Pages (from-to) | 4135-4143 |
Number of pages | 9 |
Journal | Chemistry of Materials |
Volume | 16 |
Issue number | 21 |
DOIs | |
State | Published - Oct 19 2004 |
Externally published | Yes |