ABPDU and Partners Develop Bio-Derived Ionic Liquids

ABPDU senior engineer Chang Dou and staff scientist Ning Sun.

Ionic liquids serve as either catalysts or solvents critical to over 50 industrial applications. However, they are made from nonrenewable sources such as petroleum and natural gas. Making ionic liquids from inexpensive, renewable sources will help to improve their sustainability, and better enable large scale applications.

Toward this goal, researchers at the Advanced Biofuels and Bioproducts Process Development Unit (ABPDU), Illium Technologies, and the Queens University of Charlotte have successfully produced ionic liquids derived from lignin, a natural polymer found in plant cell walls. Their target application for these bio-derived ionic liquids is biopolymer processing, in which lignin and other biopolymers, such as cellulose, can be converted to useful materials.

The research, supported by an award from the U.S. Department of Energy’s Office of Technology Transitions’ Technology Commercialization Fund (TCF), laid the groundwork for the team’s ability to transform plant waste into a useful catalytic solvent. 

“We are the first to show that ionic liquid can be produced from commercial lignin,” said Ning Sun, a staff scientist at ABPDU who co-led the project with Aaron Socha, founder of Illium Technologies. Their work builds on years of research done by Sun and Socha, who first started working together on bio-derived ionic liquids while they were both researchers at the Joint BioEnergy Institute (JBEI). 

Socha went on to start Illium Technologies with the goal of making bio-derived ionic liquids from cheap, abundant materials to minimize the use of petroleum and maximize the use of waste. After some promising initial research results, Socha and Sun applied for the TCF award to continue this work. 

Queens University of Charlotte researchers Addison (Addy) Hitt, Griffen Gonzalez, Kyle McGuff and Illium Technologies founder Aaron Socha.

“We have shown that we can take the lignin, break it down into small phenolic molecules, and use reactions from sophomore organic chemistry to convert these compounds into ionic liquid precursors (benzylamines), and subsequently ionic liquids,” Socha said. 

Their research utilized commercial lignin from industrial paper and pulp producers. This lignin, essentially a waste product left over from paper and pulp manufacturing plants, is typically burned for fuel. By instead using this lignin to create more environmentally friendly ionic liquids, it not only makes use of a low-value byproduct, but also could make ionic liquids cheaper to produce. 

Though biopolymer processing is the researchers’ target application for these bio-derived ionic liquids, they could also be blended with conventional ionic liquids for use in other applications, or used in other novel applications. For example, the team has shown differential antibacterial activity among ionic liquids derived from softwood and hardwood lignin. 

So far, the researchers were able to produce over 10 grams of their bio-derived ionic liquid precursors using commercial lignin, but their goal is to further scale up this technology so it can be used in industry. 

“Our preliminary experimental data, along with our techno-economic and life-cycle analyses, show the potential of this technology under optimized conditions,” said Chang Dou, ABPDU senior engineer. “We demonstrated that some lignin derived ionic liquids have a lower carbon footprint and, in an optimal scenario, are more cost-effective compared with petroleum-based ionic liquids.”