PROFESSOR OBTAINS PATENT FOR IMIDAZOLE-BASED CAPTURE SYSTEM

Tamar Hallerman
GHG Monitor
9/6/13

A University of Alabama professor was recently granted a U.S. patent for an organic solvent he says could more efficiently capture CO2 compared to traditional amine post-combustion capture systems. Jason Bara, a professor of chemical and biological engineering at the University of Alabama, was granted the patent last month for his capture system that utilizes imidazoles, low-volatility organic solvents that need less water to separate CO2 from flue gas compared to basic amines used for carbon capture like monoethanolamine (MEA). In an interview with GHG Monitor this week, Bara said imidazoles separate CO2 similarly to amines, but since his system uses less water it has a lower boiling point, requiring less energy to separate CO2 than counterparts like MEA. “The initial data we have suggests a 50 percent reduction of energy use compared to MEA,” he said. “Having less water means you’re not going to spend the energy boiling the water as you would using MEA.”

Bara said imidazoles present another advantage because they are physically and chemically “tunable.” “With the imidazole structure, you’ve got some room to tweak certain properties like vapor pressure to [the level] you might want in the process,” he said. Bara’s research was funded by grants from the Department of Energy, the National Science Foundation and the American Chemical Society Petroleum Research Fund. He said the technology has since been licensed by the clean technology company ION Engineering in Boulder, Colo., which Bara co-founded. He said next steps include more smaller-scale testing and modeling, as well as eventual field work.

Ionic Liquids

Imidazoles have mainly been used in the past in the pharmaceutical industry and as a corrosion inhibitor for metals like copper. In recent years, the material has also been tested in early R&D work as a potential building block for ionic liquids, seen as another promising method for post-combustion capture. However, Bara said he was one of the first to view imidazoles as their own class of solvents. “Ionic liquids are certainly interesting, but they have drawbacks for post-combustion capture like viscosity, cost and stability. When I started at the University of Alabama, it occurred to me that since we make ionic liquids from imidazoles, why don’t we just start looking at the imidazoles themselves? It’s a lower cost material with low viscosity and low vapor pressure, so it seemed like a pretty attractive thing to be doing, and no one had been studying that before,” Bara said.

Bara emphasized that while his work with imidazoles is new, many of the materials and equipment he hopes to use are not. “We’re the same on the outside compared to [traditional amine-based post combustion capture]—the process will look fundamentally the same from the steel, the pipes, the pumps, etc., But on the inside is where we try to make the difference,” Bara said. “We benefit from being the same in that we operate in essentially the same manner as typical aqueous amine processes.” He added that while imidazoles themselves are not widely manufactured on their own, all of the component materials are readily available from major chemical companies. “The components are very much commodities,” Bara said.