INVESTIGATIONS OF THE ADSORPTION OD HALOG ENATED HYDROCARBONS ON MICROPOROUS ADSORBENTS .1. CALORIMETRIC MEASUREMENTS OF THE ADSORPTION HEATS OF PERFLUORO-N-HEXANE AND N-HEXANE ON ZEOLITES OF FAUJASITE TYP

The differential molar heats of adsorption were measured for n-C6F14 a nd n-C6H14 on two different zeolites of faujasite-type at 303 K by usi ng a Calvet-type calorimeter. Comparing the heat curves of the perfluo rinated compound on NaX and DY it is found that the molecular sieve wi th the smaller Si/Al ratio (higher electrostatic field) exhibits an ab out 10 kJ/mol larger heat of adsorption than the zeolite with the high er Si/Al ratio. The substitution of the H-atoms in the hydrocarbon by F-atoms brings about an increase of the adsorption heat for n-C6F14 of 9.0 and 6.0 kJ/mol on the zeolites NaX and DY, respectively. Using a simple approximate equation the zero heats of adsorption of n-paraffin s and perfluoro-n-paraffins from C1 to C-7 were calculated.