Atmospheric Pressure Liquefaction of Dried Distillers Grains (DDG) and Making Polyurethane Foams from Liquefied DDG Fei Yu & Zhiping Le & Paul Chen & Yuhuan Liu & Xiangyang Lin & Roger Ruan Received: 15 May 2007 / Accepted: 4 September 2007 / Published online: 2 October 2007 # Humana Press Inc. 2007 Abstract In this study, dried distillers grains (DDG) was liquefied in acidic conditions at atmospheric pressure, and polyurethane foams were subsequently prepared from the liquefied DDG. Liquefaction was examined over a range of conditions including liquefaction time of 1–3 h, temperature of 150–170 °C, sulfuric acid (as catalyst) concentration of 1.0–3.0 wt%, and liquefaction solvent (ethylene carbonate) to DDG ratio of 3:1–5:1. The bio-polyols in the liquefied DDG were rich in hydroxyl groups, which can react with methylene diphenyl diisocyanate (MDI) to form cross-linked polyurethane networks. The biodegradability of the prepared polyurethane foams was also evaluated. This study strives to broaden the application of DDG as a feedstock for bio-polyurethane preparation. Keywords Dried distillers grains . Liquefaction . Bio-polyols . Polyurethane . Biodegradable Introduction Dried distillers grains (DDG), a co-product of the distillery industry is abundant in Minnesota. About 98% of the DDG in North America comes from corn plants that produce ethanol for oxygenated fuels. The remaining 1–2% of DDG is produced by the alcohol beverage industry. Approximately 3.2 million metric tons of DDG are produced in North America annually. In recent years, some regions of the USA, especially the Midwest, have required more use of oxygenated fuels (e.g., ethanol–gasoline blends) to reduce air pollution Appl Biochem Biotechnol (2008) 148:235–243 DOI 10.1007/s12010-007-8040-z F. Yu Department of Forest Products, Mississippi State University, Box 9820, Mississippi State, MS 39762, USA F. Yu : P. Chen : R. Ruan (*) Center for Biorefining and Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave., St. Paul, MN 55108, USA e-mail: ruanx001@umn.edu Z. Le : Y. Liu : X. Lin : R. Ruan Jiangxi Biomass Engineering Center, Nanchang University, Nanchang, China, 330047