Comparison of binary sorption of propane and N-butane on 5A and 13X Zeolites

Abstract

The objectives of this work are to measure the binary adsorption equilibrium data of propane and n-butane on 5A and 13X zeolites, and to model the behavior of this system. This will provide a basis for the choice of the best conditions for separation of these gases by zeolites. Data of pure component sorption of propane and n-butane on 5A and 13X zeolites for temperatures of 348, 423 and 498 K is reported. Binary sorption data for these two components at the same temperatures are also reported for total pressures of 66.7 kPa. The pure component data is modelled using the Schirmer et al., Ruthven, vacancy solution and virial models. In general, the Schirmer et al. model gives the best fit. The form of the virial model used here presents the pure component data in generalized form. The binary data is found to be approximately ideal. The selectivity coefficient for propane, which is the reciprocal of the relative volatility, is found to be in the range of 0.08 to 0.40 for the temperatures and pressures studied. The separation increses with decreasing temperature and shows a slight increase with decreasing pressure. The 5A zeolites gives a smaller selectivity coefficient and hence larger separation than the 13X zeolite. However, the difference between the selectivities coefficients for the two zeolites is small. The binary data is modelled using the Schirmer et al., Ruthven et al., vacancy solution and IAST binary models. In general, the Schirmer et al. and the ideal adsorption solution theory (IAST) models give the best fit.