10.1021/la204164q.s001 Henrik Hemmen Henrik Hemmen Erlend G. Rolseth Erlend G. Rolseth Davi M. Fonseca Davi M. Fonseca Elisabeth L. Hansen Elisabeth L. Hansen Jon Otto Fossum Jon Otto Fossum Tomás S. Plivelic Tomás S. Plivelic X-ray Studies of Carbon Dioxide Intercalation in Na-Fluorohectorite Clay at Near-Ambient Conditions American Chemical Society 2012 ambient CO 2 intercalates CO 2 intercalation interlayer repetition distance 2O clay intercalation rate Carbon Dioxide Intercalation magnitude 2012-01-24 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/X_ray_Studies_of_Carbon_Dioxide_Intercalation_in_Na_Fluorohectorite_Clay_at_Near_Ambient_Conditions/2556655 We show experimentally that gaseous CO<sub>2</sub> intercalates into the interlayer space of the synthetic smectite clay Na-fluorohectorite at conditions not too far from ambient. The mean interlayer repetition distance of the clay when CO<sub>2</sub> is intercalated is found to be 12.5 Å for the conditions −20 °C and 15 bar. The magnitude of the expansion of the interlayer upon intercalation is indistinguishable from that observed in the dehydrated–monohydrated transition for H<sub>2</sub>O, but the possibility of water intercalation is ruled out by a careful analysis of the experimental conditions and repeating the measurements exposing the clay to nitrogen gas. The dynamics of the process is observed to be dependent on the pressure, with a higher intercalation rate at increased pressure. The rate of CO<sub>2</sub> intercalation at the studied conditions is found to be several orders of magnitude slower than the intercalation rate of water or humidity at ambient pressure and temperature.