| Popis: |
The heat and entropy of benzene and hexane adsorption for AIPO 4 -ll, AIPO 4 -5, AIPO 4 -31, VPI-5, and SSZ-24 have been determined from adsorption isotherms. As the pore diameter decreases, the heat of adsorption and entropy change increase. This reflects increased zeolite—hydrocarbon interaction and more highly ordered systems as the size of the hydrocarbon approaches the zeolite pore size. The measured ΔH agrees well with calculated values that were determined by the molecular mechanics program PCK6. The relative size of Henry's constants are largely influenced by ΔH for VPI-5 and AIPO 4 -5; however, for AlPO 4 -1l and AIPO 4 -31, ΔS plays a large role. When the adsorption parameters of AIPO 4 -5 were compared to those for isostructural SSZ-24, differences in benzene adsorption were observed, reflecting different surface compositions. |
