Efficiently Producing Ethylene from Ethane

Professor Fanxing Li
Professor Fanxing Li

This article is a slightly modified version of an article written by Matt Shipman, Research Lead in University Communications.

Professor Fanxing Li and his colleagues have engineered a new oxidation-reduction (redox) catalyst that can more efficiently convert ethane into ethylene. The discovery could be used in a conversion process to drastically reduce ethylene production costs and cut related carbon dioxide emissions by up to 87%.

According to The Essential Chemical Industry – online, “Ethene (ethylene) is the most important organic chemical, by tonnage, that is manufactured. It is the building block for a vast range of chemicals from plastics to antifreeze solutions and solvents.” Those include polyethylene (PE), polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polystyrene (PS) as well as fibers and other organic chemicals.

“Our lab previously proposed a technique for converting ethane into ethylene, and this new redox catalyst makes that technique more energy efficient and less expensive while reducing greenhouse gas emissions,” says Dr. Yunfei Gao (Ph.D. ’19), a postdoctoral scholar in Prof. Li’s research group and lead author of a paper on the work. “Ethylene is an important feedstock for the plastics industry, among other uses, so this work could have a significant economic and environmental impact.”

“Ethane is a byproduct of shale gas production, and the improved efficiency of our new catalyst makes it feasible for energy extraction operations in remote locations to make better use of that ethane,” says Prof. Li, corresponding author of the paper.

“It is estimated that more than 200 million barrels of ethane are rejected each year in the lower 48 states due to the difficulty of transporting it from remote locations,” Li says. “With our catalyst and conversion technique, we think it would be cost effective to convert that ethane into ethylene. The ethylene could then be converted into liquid fuel, which is much easier to transport.

“The problem with current conversion techniques is that you can’t scale them down to a size that makes sense for remote energy extraction sites – but our system would work well in those locations.”

The new redox catalyst is a molten carbonate-promoted, mixed-metal oxide, and the conversion process takes place at between 650 and 700 degrees Celsius with integrated ethane conversion and air separation. Current conversion techniques require temperatures higher than 800 degrees C.

“We estimate that the new redox catalyst and technique cut energy requirements by 60-87%,” Li says.

“Our technique would require an initial investment in the installation of new, modular chemical reactors, but the jump in efficiency and ability to convert stranded ethane would be significant,” Li says.

The paper, “A Molten Carbonate Shell Modified Perovskite Redox Catalyst for Anaerobic Oxidative Dehydrogenation of Ethane,” is published in the journal Science Advances. The paper was co-authored by postdoctoral researcher Dr. Xijun Wang and Ph.D. student Junchen Liu. Both are members of Prof. Li’s group. Other co-authors include Profs. Chuande Huang, Kun Zhao, Zengli Zhao, Xiaodong Wang at the Chinese Academy of Sciences, who assisted in characterizing the catalysts with Mossbauer spectroscopy and X-ray photoelectron spectroscopy.

The work was done with support from the National Science Foundation, under grant number CBET-1604605; the Department of Energy’s RAPID Institute, under grant number DE-EE007888-05-6; and the Kenan Institute for Engineering, Technology, and Science.