Carbon dioxide retention over montmorillonite–dendrimer materials

Microporous organo-montmorillonites (organo-Mt) bearing weak base OH sites were prepared through montmorillonite intercalation with polyol dendrimers at different proportions (0.5, 1.0 and 3.0 mass%). These materials turned out to be suitable for the reversible capture of carbon dioxide, inasmuch as high amount (0.5–2.5 mmol/g organo-Mt) of CO2 can be retained, and easy regeneration can be achieved upon slight heating up to 100 °C. The CO2 retention capacity (CRC) was correlated to the number of OH groups of the dendritic moiety, the dendrimer content and the specific surface area. Excessive dendrimer size and content appear to affect the CRC value, due to a decrease in both the specific surface area and number of accessible OH groups. The retention of larger amounts of CO2 than predicted by stoichiometry confirms that the OH groups interact with CO2 only through physical interactions.