ENERGETICS AND SITING OF SORBED MOLECULES IN ZEOLITES BY COMPUTER-SIMULATIONS - COMPARISON WITH CALORIMETRIC AND STRUCTURAL RESULTS .2. N-ALKANES IN SILICALITE

In the first part of this work sorbent/sorbate interactions correspond ing to some zeolitic FAU(faujasite)/sorbate and MOR(mordenite)/sorbate systems using the exp-6-1 Buckingham theoretical model have been inve stigated. This second part concerns MFI(silicalite)/sorbate systems, w here it is shown that several almost equipotential sorption sites are available in the channel system for strictly linear C1 to C10 n-alkane s. For the C11-C18 range (n-undecane to n-octadecane) the n-alkane in the zig-zag channels looses its strictly linear and protracted configu ration. Two structural examples corresponding to n-hexane and n-decane reveal that the molecular alkane distribution in the zeolitic channel system depends on its nature and pore-filling. The calculated sorptio n energy for the n-alkanes varies linearly versus the aliphatic C1-C18 chain-length. As for MOR/alkane systems, it is found that in the pres ent case hexane isomers have comparable calculated sorption heats.