Intercalation and Retention of Carbon Dioxide in a Smectite Clay promoted by Interlayer Cations

A good material for CO(2) capture should possess some specific properties: (i) a large effective surface area with good adsorption capacity, (ii) selectivity for CO(2), (iii) regeneration capacity with minimum energy input, allowing reutilization of the material for CO(2) adsorption, and (iv) low cost and high environmental friendliness. Smectite clays are layered nanoporous materials that may be good candidates in this context. Here we report experiments which show that gaseous CO(2) intercalates into the interlayer nano-space of smectite clay (synthetic fluorohectorite) at conditions close to ambient. The rate of intercalation, as well as the retention ability of CO(2) was found to be strongly dependent on the type of the interlayer cation, which in the present case is Li(+), Na(+) or Ni(2+). Interestingly, we observe that the smectite Li-fluorohectorite is able to retain CO(2) up to a temperature of 35°C at ambient pressure, and that the captured CO(2) can be released by heating above this temperature. Our estimates indicate that smectite clays, even with the standard cations analyzed here, can capture an amount of CO(2) comparable to other materials studied in this context.