An Investigation into the Carbon Dioxide Removal Performance of a Novel Hydrophobic Adsorbent

Under contract to the UK Ministry of Defence (MoD), QinetiQ has been investigating the feasibility of an atmospheric carbon dioxide removal system, based on a novel hydrophobic adsorbent produced by impregnating mesoporous silica MCM41 with an imine. The silica/imine material has been found to perform better in humid conditions than when dry. This is in contrast to traditional zeolite molecular sieves, where carbon dioxide adsorption is adversely affected by the presence of water. The use of a hydrophobic adsorbent that functions regardless of the presence of water vapour, has the potential to greatly simplify temperature swing molecular adsorption systems by eliminating the need for an up-stream dryer bed, whilst eliminating the risk of the ammonia and monoethanolamine emissions associated with ‘wet amine’ scrubbers. The objective of the present work was to establish the performance characteristics of the adsorbent under a range of carbon dioxide concentrations, humidities and regeneration conditions.