(355c) Evaluation of Facilitated Transport Membrane for Olefin/Paraffin Separation

Currently, the commercial scale separation of olefins (ethylene, propylene and butene(s)) from paraffins (ethane, propane and butane(s)) in petrochemical industries is accomplished almost exclusively by distillation and is considered highly energy intensive.  Consequently, there is an enormous economic incentive to explore alternative separation technologies with lower energy consumption and an opportunity to achieve related reductions in environmental impact from air pollutant and GHG emissions.

Several attempts have been made in the past to develop alternative separation technologies for this application, including significant work on facilitated transport membranes. One of the main unresolved challenges was membrane instability over time. Imtex Membranes Corp. has developed a membrane that has shown performance stability over thousands of hours of operation on both coupons and spiral wound test units. Imtex membranes are based on Chitosan, a polysaccharide material, and silver nitrate as a facilitation agent.

LyondellBasell Industries and Imtex Membrane Corp. have undertaken a collaborative effort to evaluate the performance of Imtex membrane in the olefin/paraffin separation, namely C2, C3 and C4 splitter applications. The performance results were very encouraging for C2, C3 and C4 splitters as greater than 99.5% purity was achieved in all cases.

Based on the membrane performance results, we believe that the technology presents potential opportunities in upgrading refinery grade propylene to polymer grade propylene as the membrane was evaluated under operating conditions comparable to those of commercial plants.  There is also a promising potential for butene/butane separations where distillation separations require large numbers of trays and extremely high reflux ratios, or are difficult to achieve at all. Applying Imtex membranes in C4 separation can have a very positive impact on the economics of olefin metathesis, an increasingly important source of propylene.