Modular Conversion of Stranded Ethane to Liquid Fuels

Executive Summary

Ethane can represent up to 20 vol.% of shale-gas, exceeding the 10 vol. % allowed in “pipeline-quality” natural gas. Each year, over 210 million barrels (liquid equivalent) of ethane are rejected in the lower 48 states. Upgrading low- to negative-value ethane to easily transportable liquid fuels is a promising solution to this supply glut. The key to this process is development of modular systems that can operate economically at stranded sites. Conventional gas-to-liquids (GTL) technologies face significant challenges such as high capital cost and limited efficiency. This project will develop a fundamentally improved modular ethane-to-liquids (M-ETL) concept. The proposed M-ETL technology uses a modular Chemical Looping-Oxidative Dehydrogenation (CL-ODH) system to convert ethane and natural gas liquids (NGLs) efficiently into olefins (primarily ethylene) via cyclic redox reactions of highly-effective redox catalyst particles. The resulting olefins are converted to gasoline and mid-distillate products via oligomerization. The proposed project will also advance the M-ETL technology to make it ready for full-scale demonstration. A pilot-scale testbed will be designed and constructed for CL-ODH demonstration. The reactor channels of the testbed will be at a scale comparable to those of the proposed modular system.

Technical Challenge

Long term stability and performance of the CL-ODH redox catalysts
Efficiency of oligomerization of ethylene rich olefin mixtures from CL-ODH to gasoline and mid-distillates

Potential Impact

The M-ETL technology can lead to 80% reduction in energy demand for ethane conversion. This will also result in corresponding reductions in carbon dioxide and NOx emissions. Due to the simplified process scheme compared to conventional GTL, 20+% savings in capital cost can be achieved. Therefore, significant improvements in energy productivity is expected from M-ETL. This modular system can be particularly suited for valorization of stranded ethane at shale gas production sites. Moreover, the CL-ODH component of M-ETL can also potentially used for polymer grade olefin production in centralized facilities with significantly reduced energy intensity and emissions compared to existing approaches.

Resources

The North Carolina State University team is equipped with multiple sets of fully automated gas delivery and product analyses systems for CL-ODH demonstrations. The team is also fully equipped with catalyst-synthesis, characterization, and mechanistic investigation/simulation tools. EcoCatalytic (ECT) LLC has extensive experience with converting light olefinic products to liquid fuels. ECT also pursues significant Technology Transfer and Outreach activities related to commercialization of the modular units including creation of a commercialization plan.