Sorghum is a tropical grass grown primarily in semiarid and drier parts of the world, especially areas too dry for corn. Sorghum production also leaves about 58 million tons of by-products composed mainly of cellulose, hemicellulose, and lignin. The low lignin content of some forage sorghums such as brown midrib makes them more digestible for ethanol production. Successful use of biomass for biofuel production depends on not only pretreatment methods and efficient processing conditions but also physical and chemical properties of the biomass. In this study, four varieties of forage sorghum (stems and leaves) were characterized and evaluated as feedstock for fermentable sugar production. Fourier transform infrared spectroscopy and X-ray diffraction were used to determine changes in structure and chemical composition of forage sorghum before and after pretreatment and the enzymatic hydrolysis process. Forage sorghums with a low syringyl/guaiacyl ratio in their lignin structure were easy to hydrolyze after pretreatment despite the initial lignin content. Enzymatic hydrolysis was also more effective for forage sorghums with a low crystallinity index and easily transformed crystalline cellulose to amorphous cellulose, despite initial cellulose content. Up to 72% hexose yield and 94% pentose yield were obtained using modified steam explosion with 2% sulfuric acid at 140 degrees C for 30 min and enzymatic hydrolysis with cellulase (15 filter per unit (FPU)/g cellulose) and beta-glucosidase (50 cellobiose units (CBU)/g cellulose).

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Vanadium phosphorous oxide (VPO) is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO 4 ·0.5H 2 O (the precursor) followed by in situ activation to produce (VO) 2 P 2 O 7 (the active phase). This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V) triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO 4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m 2 /g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO 4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.