Screening the effect of water vapour on gas adsorption performance: application to CO₂ capture from flue gas in metal–organic frameworks

A simple laboratory-scale protocol that enables the evaluation of the effect of adsorbed water on CO₂ uptake is proposed. 45 metal–organic frameworks (MOFs) were compared against reference zeolites and active carbons. It is possible to classify materials with different trends in CO₂ uptake with varying amounts of pre-adsorbed water, including cases in which an increase in CO₂ uptake is observed for samples with a given amount of pre-adsorbed water. Comparing loss in CO₂ uptake between “wet” and “dry” samples with the Henry constant calculated from the water adsorption isotherm results in a semi-logarithmic trend for the majority of samples allowing predictions to be made. Outliers from this trend may be of particular interest and an explanation for the behaviour for each of the outliers is proposed. This thus leads to propositions for designing or choosing MOFs for CO₂ capture in applications where humidity is present.