COMPUTER-SIMULATIONS OF THE ENERGETICS AND SITING OF N-ALKANES IN ZEOLITES

The adsorption of the n-alkanes, ranging from butane to dodecane, in t he zeolites silicalite and (all silica) mordenite has been studied in the zero coverage limit using computer simulations. The heats of adsor ption, Henry coefficients, and distribution of the n-alkanes over the different zeolite channels are calculated. The calculated heats of ads orption are in good agreement with available experimental data. The ca lculated heats of adsorption in silicalite show an unexpected alkane l ength dependence. The incremental heat of adsorption per carbon atom i s larger for the longer alkanes than for the shorter alkanes. This obs ervation is attributed to preferential adsorption of the longer alkane s in the straight channels of silicalite. Simulations of this type wer e made possible through the development of a novel Monte Carlo simulat ion technique which is orders of magnitude more efficient than the con ventional simulation techniques.