Continuous Olefin/Paraffin Separation with Imtex Facilitated Transport Membranes

As worldwide demand for light olefins increases, there is an enormous incentive to explore reliable alternatives to distillation for the separation of olefins from paraffins with lower energy consumption, reduced capital cost and less environmental impact. In pursuing increases in production capacity, many facilities are faced with the challenges of expense and complexity of additional distillation equipment. Attempts have been made to develop alternative separation technologies, including significant work on facilitated transport membranes. The main unresolved challenge was membrane performance instability over time. Imtex Membranes Corp. has developed a membrane separation process that has shown performance stability over extended periods of operation during trials using spiral wound membrane elements. Imtex continued to optimize the hydrogel-based membrane process, and through a significant technology advancement, has demonstrated continuous, uninterrupted operation in olefin/paraffin gas separation. The performance stability of the Imtex membrane stands in contrast to dry solid polymeric and immobilized liquid membrane technologies for which stability, permeation rate and selectivity challenges have been well documented. Results were very encouraging for C₂, C₃ and C₄ splitting applications as greater than 99.5% olefin purity was achieved in all cases with steady permeation at commercially viable rates.  With these characteristics and its modular nature, Imtex membrane technology is presented as a practical alternative to the costly distillation approach. In addition to ethylene production, this technology can be applied in other commercial applications such as upgrading refinery grade propylene to polymer grade or in propane dehydrogenation and other on-purpose propylene processes that are becoming more prevalent due to the trend towards lighter feeds to ethylene plants. There is also promising potential for butene/butane separations where traditional distillation separations require large numbers of trays and extremely high reflux ratios. Monomer recovery from polyolefins production or recovering valuable olefins from other types of purge or waste streams are other potential applications. Extended tests were performed at Imtex to verify the stability and continuity of operations relevant to these applications.  The promising findings are presented.