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A New Hybrid Solution for the Propane/Propylene Separation: the Gas-Phase Simulated Moving Bed PP Splitter

Final Report Summary - GPSMB-PPSPLITTER (A New Hybrid Solution for the Propane/Propylene Separation: the Gas-Phase Simulated Moving Bed PP Splitter)

Project context and objectives

Propylene is one of the world's most important commodities, and the propane/propylene separation, usually performed by means of cryogenic distillation, is considered to be one of the most difficult energy-consuming operations currently practised. Recently, researchers in the Laboratory of Separation and Reaction Engineering at the University of Porto in Portugal (LSRE-FEUP) proposed a propane/propylene separation relying on a classical gas phase simulated moving bed (SMB) apparatus. The main idea is to convert the energy-expensive separation of propane/propylene into two easier ones: propane/desorbent and propylene/desorbent. Preliminary results showed that this separation is feasible with SMB technology, providing high-purity propylene (>99.5 %), high recovery (>99.0 %), and quite promising productivity values >1000 kg of propylene/(m3zeolite.h).

The Gas-Phase SMB PP-Splitter (GPSMB-PPSplitter) has been identified as a promising solution for propane/propylene separation - the main technical objective of the project was to find out if it is worth pursuing this. To clarify this point, the complete process must be simulated (SMB plus desorbent recovery units), optimised and different adsorbents, desorbents as well as other technologies must be considered. Therefore, three tasks were defined:
-1) process optimisation and evaluation;
-2) development of suitable adsorbent/desorbent recognition routines;
-3) identification of new hybrid solutions.

Project work

To accomplish such tasks, an interdisciplinary approach was planned: from the physical fundamentals (adsorption, distillation, membranes), passing through mathematical optimisation routines, to the economic and financial analysis. The return host institution (LSRE-FEUP) contributed with adsorption and membranes know-how, while the outgoing host institution, PSEL lab at ChemE-MIT, supported with distillation, dynamic modelling, simulation and optimisation expertise. In this way, the fellow was trained in a world-ranked institute and reintegrated this knowledge in Europe, promoting his career in the European Research Area and supporting a sustainable (energy-efficient) and competitive solution for an important application, the propane/propylene separation.

Project results

Such activity resulted in robust optimisation and evaluation routines for both conventional and vapour recompression distillation, such as the GPSMB-PPSplitter approaches to the propane/propylene separation; and a new intensified process for fructooligosaccharides (FOS) synthesis by means of an SMBR.

In addition, during the outgoing phase the fellow also had the opportunity to participate in seminars, attend undergraduate and graduate classes at the Massachusetts Institute of Technology, and take part in different scientific and cultural associations and other networking initiatives. During the return phase, it was possible for the fellow to exchange knowledge with his colleagues at LSRE-FEUP and disseminate not only the project results, but also, by organising a workshop at the University of Porto, promote knowledge transfer in the field of sustainable energy systems and networking opportunities.