Sorbate densities on 5A zeolite above and below the critical conditions: n alkane data evaluation and modeling

The sorbate densities of n-alkanes C-1-C-20 in 5A zeolite are modeled. For validation of this model, the n-alkane adsorption data for gases and liquids on 5A zeolite is critically evaluated using the concept of sorbate densities. The adsorbed phase critical temperatures appear to occur at a reduced temperature of 0.975 different from the vapor-liquid critical reduced temperatures of 1.0 for C-3 to C-20 n-alkanes. For methane and ethane species, the critical adsorbate reduced temperatures T (CAR) occur earlier at reduced temperatures of 0.83 and 0.96 respectively. The modified Rackett equation of Spencer and Danner (1972) is satisfactorily used to calculate the adsorbate loading for q (max) below adsorbed phase critical reduced temperature, T (CAR). Above the critical adsorbate reduced temperatures, the saturated loading appears to be constant and equal to 8 +/- 1 g/100 gZ for all the alkanes. The data in this region is scarce however, as there are not many isotherms above a T (r) of 1.15. However the available isotherms appear to have a fairly equal and constant saturation loading between T (r)=T (CAR) and T (r)=1.652.