Propylene is one of the world's more important commodities. Nonetheless, its production involves an high energy demanding separation step from a propane-propylene mixture. In this work, an alternative separation of propane-propylene mixtures using simulated moving bed (SMB) technology over 13X zeolite and isobutane as desorbent is presented. Driven by this process novelty, a design strategy for this separation is also proposed, based on three major questions: Is it possible?; Is it reasonable? and Is it worth it? For each question, different approaches are used, starting from equilibrium assumptions through more detailed models, accounting for mass transfer resistances, temperature and pressure drop effects, and presenting, in the end, an introductive note to some relevant aspects for the project evaluation stage. The results show that this separation is possible with the SMB technology, providing high purity propylene (>99.5%), at high recovery (>99.0%) and quite promising productivity values, above 1000 kg of propylene/(m(ads)(3) h). (c) 2008 Elsevier Ltd. All rights reserved.