Characterization and Modelling of Reversible CO2 Capture From Wet Streams by a MgO/zeolite Y Nanocomposite

The synthesis of CO2 sorbents capable of working on combustion flue gases is a challenging topic in the field of carbon capture and sequestration. Indeed, the presence of moisture in combustion exhausts makes most of the materials capturing CO2 through physisorption ineffective, being their larger affinity for H2O than for CO2. In this work, we investigate a novel nanocomposite sorbent based on a Mg overexchanged zeolite Y (MgOHY), showing single Mg2+ ions and nanoconfined (MgO)n clusters. The interaction of CO2 with the material is studied thoroughly by combining IR spectroscopy and simulation, comparing dry and wet conditions. IR spectroscopy shows that, while in dry conditions the adsorption in mainly driven by the Mg2+ ions, in wet ones the (MgO)n clusters react with carbon dioxide by forming (bi)carbonate-like species. These easily decompose at mild temperatures (25-200 °C). DFT simulations are used to investigate the origin of the CO2 interaction with representative (MgO)n clusters in the periodic z...