Pyrolysis Gas Chromatography Mass Spectrometry Studies to Evaluate High-Temperature Aqueous Pretreatment as a Way to Modify the Composition of Bio-Oil from Fast Pyrolysis of Wheat Straw

Hot water pretreatment was systematically studied to determine whether reaction selectivity of cellulose toward the production of anhydrosugars and furanics could be improved. Samples of wheat straw and alpha-cellulose were treated using hot compressed water at temperatures ranging between 150 and 260 degrees C. The effect of hot water pretreatment oil pyrolysis selectivity was measured using pyrolysis gas chromatography mass spectrometry (Py-GC/MS). Various representative peak area ratios were compared and used as all index of pyrolysis selectivity. The chemical and Py-GC/MS analysis of solid residues resulting from hot water pretreatment Suggest that. as the tempera tire increased, the hemicelluloses and amorphous cellulose were solubilized. The relative areas of the Py-GC/MS results associated with levoglucosan increased for both straw and alpha-cellulose with increasing treatment temperature. The results show that the selectivity of thermochemical reactions toward the production of sugars and furanics call be enhanced if the material is treated in hot water at temperatures between 220 and 260 degrees C, and file amount of acetic acid is reduced substantially. Thus, hot water pretreatment may be a viable method to modify the chemical composition of bio-oils produced via fast pyrolysis.