Recovery of Olefins

Ethylene and propylene are produced by several different processes in the chemicals and refining industries. The first
process, used in chemical plants, is steam cracking of feeds comprising ethane, propane, mixtures of the two or butane (all
derived from natural gas) as well as naphtha and gas oil. The preferred feedstocks are the natural gas liquids (NGLs)
because the yield of desired products is greater. The second process involves the recovery of light ends from fluid
catalytic cracking.

In both cases, the products of the conversion reactors are mixtures of chemicals that require further separation and
purification. Traditionally, this has been done by distillation; and the separation of ethylene from ethane or propylene from
propane must be carried out under cryogenic conditions at elevated pressures, because of the low boiling points of these
liquids. Cryogenic distillation, however, is extremely energy intensive, resulting in substantial costs to separate olefins from
paraffins. Over a decade ago Humphrey and coworkers [1], in a report prepared for DOE, estimated that these two
separations "accounted for 6.3 % (about 0.15 quadrillion BTUs) of the energy used by the chemical and petrochemical
industries" leading the National Research Council to suggest in their 1999 report [2] that "less energy-intensive separations
would be useful for the petroleum refining industry."

Trans Ionics is developing an olefin/paraffin separation process called MMEO (for Membrane Mediated Extraction of
Olefins) that has shown promise in Phase I tests supported by the U. S. Department of Energy as a potential replacement
for cryogenic distillation. MMEO incorporates several unique process components to recover olefins under non-cryogenic
conditions; and Trans Ionics was awarded a Phase II SBIR grant totaling $750,000 (over two years) to carry out laboratory
and pilot plant studies to scale up MMEO for commercial application in early 2009.