SBIR-STTR Award

Ethylene and propylene, two of the most important building blocks of the U.S. petrochemical industry, are produced by steam cracking of ethane, propane, or heavier hydrocarbons and are also a by-product of fluid catalytic cracking. Unfortunately, as produced, these species are always in admixture with other species from which they must be separated. The conventional method of separation is cryogenic distillation, which is extremely energy intensive. In addition to ethane and propane, there are numerous liquid streams in chemical plants that contain olefins that must also be separated from other components by distillation. This project will demonstrate the efficacy of membrane mediated extraction for the recovery of olefins from both dilute liquid streams and from more concentrated gas streams. During Phase I, selected solvents and complexing agents will be synthesized and used in a laboratory apparatus that will be built to measure the flux and selectivity for ethyelene/ethane mixtures, propylene/propane mixtures and for dilute 1-octene streams in n-octane (that simulates a waste stream of high commercial interest). Effect of solvent type, complexing agent composition, feed flow rate, temperature, membrane area and other parameters will be determined systematically during the experimental work.

Commercial Applications and Other Benefits as described by the awardee:
The first anticipated application for this process is the recovery of 1-octene from a waste stream produced by a major chemical company in Texas. The waste stream contains approximately 1 wt % 1-octene in Isopar E (an isoparaffininc solvent) and is currently incinerated for lack of a cost-effective method of recovering the olefins. Therefore, the process also should result in environmental credits for eliminating incineration. Once demonstrated on for this application, the process will be applied to ethane/ethylene or propane/propylene separation in steam cracking operations

Ethylene and propylene, two of the most important building blocks of the U.S. petrochemical industry, are produced by steam cracking of ethane, propane, or heavier hydrocarbons and are also a by-product of fluid catalytic cracking. Unfortunately, as produced, these species are always in admixture with other species from which they must be separated. The conventional method of separation is cryogenic distillation, which is extremely energy intensive. In this project, the best features of liquid-liquid extraction and membranes will be combined into a novel membrane-mediated extraction (MME) process. The process will use complexing agents, which are commercially viable and for which their ability to extract olefins has been quantified; their use in a high-surface-area membrane module will enhance their extraction efficiency due to the increased transport area. During Phase I, selected solvents and complexing agents were synthesized and used in batch laboratory extractions. The effect of solvent type, complexing agent composition, feed molecular type, and other parameters were evaluated for the extraction of olefins of commercial interest. During Phase II, the nature of the molecular interactions between olefins of different size and specific complexing agents will be quantified. The optimum complexing-agent/solvent combination will be scaled up and used in a pilot plant, which will be constructed in Phase II.

Commercial Applications and Other Benefits as described by the awardee:
The MME process could be used to effectively recover olefins from waste streams. Correspondingly, the first application for this process will be the recovery of valuable olefin from a waste stream produced by a major chemical company in Texas. The waste stream contains approximately 13 wt % of this olefin in an isoparaffininc solvent and is currently incinerated for lack of a cost-effective method of recovering the olefins. The process also provides environmental credits for eliminating incineration. Once demonstrated on a small scale for this application, the process would be expected to work well for ethane/ethylene or propane/propylene separation in steam cracking operations