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 improve- ment 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 com- posites. In this work, the influence of the morphological aspects on adsorption performances of innovative SAPO-34 silicone compos- ite 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.