(544c) Recovery of Coumaric and Ferulic Acids from Industrial Lignin Streams

Authors: 
Rover, M., Iowa State University
Johnston, P. A., Iowa State University
Smith, R. G., Iowa State University
Brown, R. C., Iowa State University
Lignin, an aromatic renewable resource, is a low-cost byproduct from industrial streams such as cellulosic ethanol. Often these lignin streams are used for boiler fuel in the production of process heat for the plant. Byproduct lignin streams are a source of high value molecules that can be utilized as green building blocks. Cornstover, a herbaceous biomass, contains approximately 15-16% (w/w) lignin. Hydroxycinnamic acids (coumaric and ferulic) are phenolic acids found in herbaceous biomass which can be utilized to produce oxtinoxate, vanillin, green epoxides, as well as, other high value chemicals. Our research goal is to demonstrate cost-effective means of converting cornstover enzymatic hydrolysis lignin into an oil that can be utilized for the production of high-value chemicals. This research includes mild base extraction followed by low-temperature low-pressure hydrogenation (LTLP-H) to convert the lignin into oil. The base treatment is a 5 wt% solution of sodium hydroxide NaOH) in water refluxed for 6 h at 125°C and 145°C. The base treatment products were hydrogenated for 12 h at room temperature and 1 atmosphere absolute pressure, yielding 101 wt% dry basis (db) oil at 125°C and 95.1 wt% (db) oil at 145°C. The theoretical yield of coumaric acid in the cornstover enzymatic hydrolysis lignin were 2.42 ± 0.263 wt% (db), whereas, the theoretical yield for ferulic was 1.57±0.275 wt% (db). We obtained 1.83 wt% (db) coumaric acid and 0.764 wt% (db) ferulic in the 125°C treatment. This is 75.8 wt% (db) of theoretical yield for coumaric acid and 48.7 wt% (db) of theoretical yield for ferulic acid. For the 145°C treatment we obtained 1.98 wt% (db) coumaric acid and 0.789 wt% (db) ferulic acid, 81.7 wt% (db) theoretical yield and 50.2 wt% (db) theoretical yield, respectively.