Molecular sieve sorbents for kinetic separation of propane/propylene

The separation of propane-propylene mixtures is one of great industrial importance. It is also one of the most difficult and costly to achieve. In this work, the feasibility of using sorbents based on kinetic (due to differences in diffusion rates) or steric (due to size exclusion) effect for gas-phase separation of propane-propylene was determined. Equilibrium isotherms and uptake curves were measured on NaA (4A), NaLiA, and AlPO4-14 zeolites. All of the sorbents were capable of selectively adsorbing propylene over propane. PSA simulations were used to compare these sorbents against pi-complexation sorbents such as AgNO3/SiO2. The best sorbents were AlPO4-14 and AgNO3/SiO2. In both cases, over 99% propylene product purities could be obtained at reasonably high recoveries and throughputs. (C) 2000 Elsevier Science Ltd. All rights reserved.