The progression of lignin conversion to dicarboxylic acids. Image courtesy of Dr. Xiao Zhang, WSU.
The progression of lignin conversion to dicarboxylic acids. Image courtesy of Dr. Xiao Zhang, WSU.

NARA supports research that discovers ways to develop commercially valuable products from forest residuals. When forest residuals are converted to biojet fuel, a significant amount of the material remains. That remaining material is a mixture of many byproducts from the conversion process, but the predominant component is lignin.

NARA researchers are investigating using this lignin-rich material to make activated carbon products for mercury absorption and super capacitors, asphalt dispersants, thermoplastics and epoxy resins. Generating commercial products from the lignin-rich material will add value to the forest residuals and improve the economics of a wood residual to biojet fuel supply chain.

In a recently published paper funded by NARA, Washington State University-Tri Cities researcher Xiao Zhang and his team describe a novel method to selectively produce dicarboxylic acids from softwood lignin.

View here to read Selective Conversion of Biorefinery Lignin into Dicarboxylic Acids.

Multiple Dicarboxylic Acids (DCA) are produced

The technology developed by Dr. Zhang and his team uses the mineral chalcopyrite and hydrogen peroxide to produce high yields of DCAs including malonic acid, succinic acid, malic acid and maleic acid. These acids are used commercially to produce biopolymers, pharmaceuticals and food additives. Not only did Dr. Zhang’s team produce the dicarboxylic acids, but they also investigated how the reaction proceeds from lignin to DCA. The initial lignin-to-DCA conversion yields were low (14% based on carbon) in this study, but yields should increase with further optimization of the reaction conditions. The team is currently working with an industrial partner to design and test a two-step reaction system to improve the DCA yields.

In addition to the experimental work, Dr. Zhang’s team is developing a techno-economic model to evaluate the feasibility of this technology.