Corresponding state behaviour of capillary condensation of confined alkanes

Abstract

ABSTRACTThe corresponding state behaviour of capillary condensation of confined alkanes is studied by means of GC-TMMC simulations. In this study, alkane is considered under graphite and mica slit pore confinements of various slit widths. Corresponding state phase coexistence envelopes of capillary condensation display insignificant effect of surface chemistry for slit pore confinements of 6 Å for methane and 15 Å for n-butane and n-octane. On the other hand, the significant effect of surface chemistry on the corresponding state coexistence envelope is observed for larger slit pore width. Moreover, at a given slit width, more shrinking in the corresponding state coexistence envelope of alkane is observed with the mica slit pore as compared to graphite slit pore. The local behaviour of capillary condensation of corresponding state is also investigated in some typical cases using local density profiles, to understand the overall behaviour of corresponding state capillary condensation. Moreover, for a given slit pore width smaller size alkane has shown more shrinking of the corresponding state coexistence envelope, irrespective of surface chemistry. However, the effect of surface chemistry on the corresponding state coexistence envelope of different alkanes becomes insignificant in smaller slit pore width. Fluctuating positive and negative deviations in the corresponding state vapour–liquid equilibrium pressure with respect to corresponding bulk values are observed in studied slit pore confinements. The corresponding state vapour−liquid interfacial tension of alkanes is less in mica slit pore as compared to graphite slit pore for the studied range of reduced temperatures.