Development of Liquid Lignin™ Technology
For more than a century, synthetic organic chemists have envisioned modifications that could be made to lignin to convert the natural polymer into useful products. Lignin has a plethora of functionalities that invite chemical modification. One huge barrier is that - at atmospheric pressure and temperature, after being extracted from biomass or recovered from pulping liquors - lignin is a solid. Additionally, lignin is insoluble in most organic solvents and is only partially soluble in highly polar solvents such as DMSO and THF. Conducting chemistry to modify solid lignin in commercial processes is challenging. In a Joint Development Agreement with Liquid Lignin Company, researchers at Clemson University are converting solid lignin into a liquid as shown in the pictures below by reacting lignin with fatty acids.
LiquidLignin is not the first technology for reacting lignin with fatty acid. For the past decade, two Swedish companies have been developing technology for reacting fatty acid with lignin. RenFuel AB uses acetic anhydride to convert the fatty acid to anhydrides which are more reactive with lignin. RenFuel has developed a liquid product which can be converted to biofuels by first “popping off” the molecular oxygen and then cracking the polymer to reduce its molecular weight. RenFuel uses a fatty-acid-to-lignin mass ratio (FA:L) as low as 1.5 to generate their liquid product. RenFuel’s technology has been licensed by Bioleum, an American biofuels company. Another Swedish company - Lignin Industries AB - reacts lignin with fatty acid in a vented extruder to remove the water formed during reaction. Lignin Industries’ technology can drive the FA:L ratio to very low levels, approaching 0.1. Lignin Industries’ products are solid pellets which they have named Renol®. Renol can be blended easily with thermoplastics and is being marketed as components in a wide variety of applications including LDPE film for plastic bags; polypropylene containers; consumer products; and ABS auto parts.
LiquidLignin technology follows a different pathway. A Provisional Patent Application has been filed. The technology focuses on the use of traditional reactors and catalysts that can be extracted following the reaction so that low-inorganic-solids content is achieved in the final product. Clemson is pursuing grants to accelerate the development. If a company is interested in partnering, even in a minor role like submitting a support letter for grant applications, they should contact Pat Layton at playton@clemson.edu.
This article is submitted by Michael A. Lake, PhD – Co-Founder of Liquid Lignin Company. Michael has been involved in process and product development of lignin since starting work at Westvaco in 1974. In addition to being a Co-Founder of Liquid Lignin Company which is commercializing its SLRP™ technology for recovering lignin from kraft black liquor, Michael consults in “all things lignin” through his consulting company TechLake & Associates, LLC. Michael can be reached at michael@techlake.net or by cell phone +1 (843) 345-0733.
