(124d) Olefin-Paraffin Separation with Customized Amorphous Fluoropolymer (CAF) Facilitated Transport Membranes

Ethylene and propylene are major chemical industry raw materials and consume a great deal of energy in their production. The separations of these materials are some of the costliest, most energy intensive, and most technically difficult separations in the industry due to the very similar size and nature of the molecules being separated. The technology currently employed for the separation of ethylene and propylene from paraffins is distillation and is estimated to consume 250 trillion BTU/year of energy.

A membrane based olefin-paraffin separation process would provide substantial economic benefit to petrochemical processes and drastically reduce the energy required. Membrane processes utilizing facilitated transport membranes for separating ethylene/ethane or propylene/propane have been extensively studied and described in the literature. While good separations have been demonstrated in the laboratory, problems with membrane stability have prevented development of commercial systems.

Compact Membrane Systems has developed a customized amorphous fluoropolymer (CAF) facilitated transport membrane (FTM) containing silver ions that selectively transport olefin molecules from a mixture of olefin and paraffin. The silver containing FTM has shown high propylene flux and propylene/propane selectivity in the laboratory over a period of 300 days. The permeance and selectivity combination of the membranes are above the industry Robeson curve. Similar results were also obtained with ethylene and ethane gas mixtures. We have also evaluated membrane stability in presence of known poisons such as hydrogen sulfide, acetylene and hydrogen. Recently, we have scaled up the membrane area from ~10 cm² to ~2000 cm² and performed separation at a larger scale. These silver based CAF membranes are now being tested with actual refinery gas mixture from a distillation column ahead of a pilot scale implementation at a refinery. We will discuss these test results as well as some of our economic modeling results showing very low payback times and positive IRRs for a variety of scenarios governing petrochemical processes.