SORBATE FRAMEWORK AND SORBATE/SORBATE INTERACTION OF ORGANICS ON SILICEOUS MFI TYPE ZEOLITE/

Thermal analyses were used to study the sorbate/framework and sorbate/ sorbate interaction on siliceous MFI type zeolite. Alkanes, aromatics, alkyl alcohols, multivalue hydroxyl alcohols, alkylamines, organic ac ids, acetaldehyde, ethyl ether, acetone, and ethyl acetate were invest igated as the adsorbate. The adsorption and desorption behavior of hig h silica MFI type zeolite is greatly influenced by the presence of fra mework aluminum, cations, and silanol defects. There is a perfect Si-O -Si micropore surface without cations and silanol defects in the high hydrophobic zeolite silicalite. The essential host/guest interaction c an be clearly studied by the thermal desorption behavior from silicali te. A general hydrophobic/organophilic property of 27 organic compound s with different functional groups on silicalite has been compared in terms of the affinity index A(T) determined by DTG. The physical meani ng of the A(T) value, and the nature of the host/guest interaction are discussed. Silicalite has a strong affinity for some organic compound s with high polarity and is usually phobic to organics with hydroxyl g roups. The special sorbate/framework and sorbate/sorbate interactions for certain organics can be identified from the double peaks in the DT G curves and thermal effects in the DTA curves. The formation of the d ouble-molecule complexes of p-xylene, toluene, phenol, ethylene glycol , and ethylamine in silicalite is revealed.