Truly reversible capture of CO2 by montmorillonite intercalated with soya oil-derived polyglycerols

Abstract

Three polyglycerol dendrimers with average molecular weights of 500, 1100, and 1700 were obtained starting from glycidol derived from soybean oil. Intercalation of Na-montmorillonite with these dendrimers produced effective organo-Mt adsorbents (NaMt-500, NaMt-1100 and NaMt-1700, respectively) for the reversible capture of CO2. The CO2 retention capacity (QCO2) was assessed through temperature-programmed desorption (TPD), and was found to increase with the number of OH groups incorporated. The latter turned out to be the main adsorption sites. Paradoxically, high dendrimer loadings and larger dendrimer generation did not necessarily raise the amount of adsorbed CO2, because of the formation of dendrimer clusters, which significantly reduces the number of accessible OH groups. The highest QCO2 values were registered for NaMt-1700 (3.88–7.14), NaMt-1100-1 (5.24) and NaMt-500 (11.70–16.42μmolg−1) at loading grades. Such adsorbents can release CO2 at much lower temperatures as compared to amines and other base-like compounds, and turn out to be more suitable for CO2 concentration from major emission sources prior to sequestration or uses in chemical or biological processes. This opens new prospects for the preparation of effective CO2 adsorbents starting from low-cost and ecofriendly materials like clay minerals and hyperbranched polyalcohols deriving from vegetal oils.