Grand canonical Monte Carlo and configurational-bias Monte Carlo techniques were employed to simulate the adsorption of binary mixtures of C4-C7 alkane isomers in ISV and MOR zeolites at 300 K, and the results were compared to that in MFI. Unlike in MFI, the amount of adsorption of the linear and branched alkanes all increases with pressure increasing in ISV and MOR for 0.5-0.5 gas-phase mixtures. The location of alkane isomers is astatic, and it does not exhibit obvious orientation in ISV and MOR. The interaction energy of 2-methylpropane-zeolite is obviously higher than that of n-butane-zeolite in MFI. As to ISV and MOR, the interaction energy between 2-methylpropane and zeolite is a little lower than that between n-butane and zeolite. It can be found that the zeolite MFI behaves quite differently in adsorption from ISV and MOR.

The molecular distribution and diusion of water confined in hydrophobic nanopores were studied by molecular dynamics simulations (MD). We found these water molecules have some unusual behavior than that of the bulk. The density profiles are extremely inhomogeneous and some vacuums and clusters occur in small-size pores at lower density. The diusivity in nanopores is much lower than that of the bulk, and it decreases as the pore width decreases. The diusivity in channel parallel direction oDxp are 4-10 times larger than that in channel perpendicular direction oDy; Dzpat higher temperatures.

Deuterium oxide solutions of schizophyllan, a triple-helical polysaccharide, undergoing an order-disorder transition centered at 17℃, were studied by optical rotation (OR) and heat capacity (Cp) to elucidate the molecular mechanism of the transition and water structure in the solution and frozen states. The ordered structure at low temperature consisted of the side chains and water in the vicinity forming an ordered hydrogen-bonded network surrounding the helix core and was disordered at higher temperature. In the solution state appeared clearly defined transition curves in both the OR and Cp data. The results for three samples of different molecular weights were analyzed theoretically, treating this transition as a typical linear cooperative transition from the ordered to disordered states and explained quantitatively if the molecular weight polydispersity of the ample was considered. The excess heat capacity Cp EX defined as the Cp minus the contributions from schizophyllan and D2O was estimated. In the frozen state it increased with raising temperature above 150 K until the mixture melted. This was compared with the dielectric increment observed in this temperature range and ascribed to unfreezable water. From the heat capacity and dielectric data, unfreezable water is mobile but more ordered than free water. In the solution state, the excess heat capacity originates from the interactions of D2O molecules as bound water and structured water, and so forth. Thus the schizophyllan triple helix molds water into various structures of differing orders in solution and in the solid state.

The azeotropic data of the cyclohexane+2-propanol+ethyl acetate+butanone quaternary system were measured by using a stainless steel azeotrope apparatus developed by the authors at elevated pressures of 101.3, 302.0, 502.0, 702.0, and 902.0 kPa and predicted by using the Wilson and NRTL activity coefficient models with the paired energy parameters obtained from binary azeotropic data of the six corresponding systems. The calculated results demonstrate that the predicted data are in good agreement with the experimental, and the Wilson and NRTL equations are of comparable accuracy in the prediction of azeotropes for this miscible quaternary system at elevated pressures.

A new stainless steel apparatus for measuring azeotropic points of binary as well as multicomponent systems at elevated pressures has been developed. The azeotropic temperatures and compositions of six binary systems composed of cyclohexane, 2-propanol, ethyl acetate, and butanone were determined at elevated pressures, correlated by empirical equations with pressure, and predicted by the UNIFAC group contribution method. The calculations demonstrate that the correlated data are in good agreement with experimental values.