Morphological and functional aspects of zeolite filled siloxane composite foams

One of the main objectives of the recent research and development activities on adsorption heat pumps is the improvement of the volume-specific power while maintaining a reasonable thermodynamic efficiency. In this sense, a potentially effective approach is the development of adsorbent materials with high zeolite/support mass ratio such as zeolites-based foam adsorbent composites. In this work, the influence of the morphological aspects on adsorption performances of innovative SAPO-34 silicone composite foams has been investigated by varying zeolite filler content. The composite foam evidenced a mixed open/closed-cell structure, depending on zeolite amount. At low zeolite content (20%), a mainly open cell structure was obtained, while at large zeolite content foams (up to 70 wt %), a mainly closed-cell structure was obtained. Adsorption tests evidenced that SAPO-34 zeolite foams have a high adsorption efficiency when compared with pure zeolite highlighting the active behavior of siloxane matrix during water vapor diffusion. Based on the morphological and physical properties of the foam, a simplified model for vapor diffusion flow process in composite foams was proposed.