EFFECT OF STEAM STRIPPING COMBINED WITH OVER-LIMING ON THE DETOXIFICATION OF STEAM EXPLODED LIGNOCELLULOSIC HYDROLYZATE

摘要

In order to exam the effect of detoxification on lignocelluiose-derived hydrolyzate, steam stripping and overliming were applied. Corn stover was steam exploded; the filtrate was hydrolyzed with dilute sulfuric acid. The acid hydrolyzate was then detoxified and fermented by yeast. Soluble oligosaccharides presented in the filtrate of steam exploded corn stover could be hydrolyzed to monosaccharides with dilute sulfuric acid 30g/1at 121 °C for 45min. Steam stripping could remove volatile compounds from the acid hydrolyzate. At a steam stripping time of 120min, 81% acetic acid and 59% formic acid were removed, while furfural was stripped off completely. Overliming could reduce the contents of furfural and phenolics presented in the acid hydrolyzate, however, sugars, especially pentoses, were also removed partially. It is necessary to detoxify the acid hydrolyzate in order to ferment the sugars to ethanol. Acid hydrolyzate detoxified with a combination of steam stripping for 120min and overliming at pHI 1 and 60°C for 90min, its fermentability was significantly improved. Xylose was consumed nearly completely in 24h with an ethanol yield of 15.92g/l, 80.34% of theoretical.