Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
A thermogravimetric method to determine the biomass composition in terms of cellulose, hemicellulose and lignin has been developed. Corn stover samples, raw material and steam exploded at 190°C, 200°C, 210°C, 220°C for 5 minutes, have been dried and grinded below 0.2 mm for the experiments of TGA. Typically, the heating rate has been set at 10°C min-1 and runs have been carried out in air. In these experiments, a PERKIN ELMER TGA7 apparatus with of a sensitivity of 10-4 mg has been used. Each thermogram consisted of about 2,000 couples of temperature- weight, the database has been exported and worked out with a computing software. To better point out the dependence of the weight loss on the biomass composition, the data have been reported on dry, ash free basis. The weight loss has been modelled as Tw = b0 + b1∙Co + b2∙Ho + b3∙Lo , where Tw is the temperature at which is W the remaining organic fraction. Co the initial cellulose content, Ho the hemicellulose and Lo the lignin. The coefficients bi have been calculated from samples of known composition. By using this linear model the fraction of cellulose and lignin in pretreated corn stover has bee determined with an error comparable with that of the wet way (4-5%), instead hemicellulose is quantified with an error of ±17%.