ORGANOSOLV PRETREATMENT FOR ENZYMATIC-HYDROLYSIS OF POPLARS .2. CATALYST EFFECTS AND THE COMBINED SEVERITY PARAMETER

The effects of added catalysts such as sulfuric acid, phosphoric acid, and their acid salts to methanol-water delignification of poplars in the 160-170 °C temperature range and 1-2.5-h residence time range are discussed in semiquantitative terms, through the modification of the severity parameter R? = t exp[(Tr-Tb)/14.75], where Tris the reaction temperature and Tbis the temperature chosen for reference as a base case, by the pH of the pulping liquor at 40 °C. This function is used to explain lignin and xylan removal from poplars over a wide range of experimental conditions and trends in the rate of hydrolysis of the pretreated cellulosic residues by enzymes. Such parameters unify time, temperature, and a simple acidity function such as pH. They are a useful tool in planning experiments and increasing the data base necessary for the more complete understanding of such processes. © 1990, American Chemical Society. All rights reserved.