(258b) Process Intensification through Membrane Separation of Olefins and Paraffins

Ethylene and propylene are two of the major building blocks for the chemical industry. The separation of ethylene and propylene from their alkane counterparts is highly energy-intensive. It is estimated that separating alkanes from alkenes through distillation uses 0.3% of energy globally. In addition, distillation columns to separate these molecules are very capital-intensive. A membrane based olefin-paraffin separation technology has the potential to provide substantial economic benefit to the petrochemical industry and to drastically reduce the energy required for this separation. In addition, membrane systems are scalable, allowing their implementation for smaller, stranded streams where distillation columns have not previously been installed due to limited economic value. Membrane processes utilizing facilitated transport membranes have been extensively studied for separating olefin/paraffin mixtures. While separations have been demonstrated in the laboratory, problems with membrane stability have prevented development of commercial systems.

Compact Membrane Systems (CMS) has developed the Optiperm^TM membrane, a customized amorphous fluoropolymer (CAF) containing silver ions that selectively transport olefin molecules from a mixture of olefin and paraffin. The technology exploits a reversible complexation reaction mechanism known as facilitated transport. Silver incorporated into the membrane polymer backbone acts as a binding site for the double bond in the olefins transporting them across the membrane as depicted in the cartoon below. Saturated paraffins do not have the same interaction. This difference in affinity allows for olefins to pass through the membrane at a significantly higher rate than do paraffins.

This talk will share the latest field results from both the pilot currently running at the Delaware City Refining Company as well as any results coming out of the RAPID-funded collaboration with Dow Chemical. The DCRC pilot is operating on a stream with a 10-20% concentration of propylene while the Dow Chemical work will focus on higher olefins concentrations of both C2 and C3 streams. This will include performance data, longevity and membrane stability results as well as any learnings from these projects. Thus far, the DCRC pilot has demonstrated over 45 days of stable membrane operation with propylene permeance >75 GPU and selectivity >20 for propylene over propane.