Typically,
the sample loaded in a quartz reactor was first pretreated with
high-purity He at 623K for 1 h. After the sample was cooled down
to 373K, CO2 adsorption was performed by switching the He flow
to a CO2–He (10 vol% CO2) gas flow and then keeping at 373K for
1 h. Then, the gas phase or the weakly adsorbed CO2 was purged
by high-purity He at the same temperature