THE HOST GUEST INTERACTION OF ORGANIC-MOL ECULES ON SILICALITE-1 STUDIED BY TG/DTG/DTA/

The thermal desorption behaviour of hydrocarbons, alcohols and alkyl- amines from zeolite silicalite - 1, which possesses perfect framework without cations and Si-OH defect, was studied by TG/DTG/DTA. The tempe ratures gf desorption of these organics from silicalite - 1 are lower than 300 degrees C. A(T) a new concept on affinity of silicalite frame work to the guest molecule has been defined as difference between T-d and T-b, where T-d is the temperature of weight loss peak at DTG curve and T-b the boiling temperature at standard pressure. The A(T) values for saturated hydrocarbons are 60 similar to 90, while 6 similar to 1 3 for benzene, toluene, ethyl- benzene and p-xylene. The A(T) value ev idently decreases for alkyl - alcohol since stronger electronegativety of its hydroxy group. The A(T) values are negative for alcohols with muti - hydroxy groups. For methylamine and ethylamine, the A(T) values are 160 and 127 respectively, much higher than that for other alkylam ines. The endothermal effect of desorption from silicalite - 1 in DTA curves is obvious for p-xylene, alkyl- alcohols and alkylamines. The d ifference in A(T) value as well as thermal effect of desorption is fro m the different interaction between the framework micropore surface co nstructed by O2- and C-H groups and other polar groups of organics, an d from the different situation of associate for the molecules adsorbed , which is limited by the void space in framework of silicalite - 1. T hese facts reflect a different type of supermolecular interaction for host/guest system.