Analysis of Hardwood

Catalytic hydropyrolysis of beech wood has been conducted in a fluid bed reactor at 450 C with a sulfided CoMo catalyst followed by a fixed bed hydrodeoxygenation (HDO) reactor with a sulfided NiMo catalyst at hydrogen pressures between 3.0 and 35.8 bar. Using both reactors the condensable organic yield (condensed organic and C4+ in gas) varied between 18.7 and 21.5 wt% dry ash free basis (daf) and was independent of the hydrogen pressure. At 15.9 bar hydrogen or higher the condensed organic phase was essentially oxygen free (<0.01 wt% dry basis (db)), but decreasing the hydrogen pressure to 3.0?bar increased the oxygen content to 7.8 wt% db. The char and coke yield was close to constant (11.0-12.7 wt% daf) at hydrogen pressures between 15.9 and 35.8 bar, but increased to 15.7 wt% at 3.0 bar hydrogen due to an increase in the polymerization of pyrolysis vapors. The measured carbon content on the spent catalysts from both the fluid bed and HDO reactor showed that coking of the catalysts increased when the hydrogen pressure was decreased below 15.9 bar. The increased coking at low hydrogen pressure (<15.9 bar) was ascribed to the polymerization of the more reactive oxygenates produced in the fluid bed reactor.

Levoglucosan has significant potential in commercial applications for the synthesis of polymers, solvents and pharmaceuticals. It is currently overlooked for commercial applications due to its high cost of synthesis and purification. We have developed a system to produce pure crystals of levoglucosan based on the fast pyrolysis of lignocellulosic biomass. A novel bio-oil recovery system concentrated levoglucosan along with other anhydrosugars, sugars and phenolic compounds in a non-aqueous 'heavy ends' fraction. Liquid-liquid water extraction separated sugar-rich solubilized carbohydrates from non-soluble phenolic compounds. The solubilized carbohydrate fraction, contaminated with partially soluble phenolic monomers, was filtered through Sepabeads SP207 adsorption resin to produce clarified juice. The composition of the clarified juice on a dry basis after resin filtration and rotary evaporation was 81.2% sugars, 4.45-4.60% volatile non-sugar, 1.71% carboxylic acids and 12.5-12.6% unidentified compounds, which was sufficiently pure to crystallize the sugars by evaporation. A cold solvent rinse of the crystal mass separated and purified levoglucosan from other sugars. Levoglucosan purity was 102.5% +/- 3.109% at the 99% confidence level. Techno-economic analysis of a plant pyrolyzing 250 tonne per day of pretreated biomass to produce cellulosic sugars indicated a minimum selling price (MSP) for pure levoglucosan crystals of $1333 per MT, which is less than one-tenth its current average market price. Operating hours of the plant, fermentable syrup yield and fixed capital are the most significant parameters affecting MSP.

A catalytic process for the upgrading of woody biomass into mono-aromatics, hemi-cellulose sugars and a solid cellulose-rich carbohydrate residue is presented. Lignin fragments are extracted from the lignocellulosic matrix by cleavage of ester and ether linkages between lignin and carbohydrates by the catalytic action of homogeneous Lewis acid metal triflates in methanol. The released lignin fragments are converted into lignin monomers by the combined catalytic action of Pd/C and metal triflates in hydrogen. The mechanism of ether bond cleavage is investigated by lignin dimer models (benzyl phenyl ether, guaiacylglycerol-?-guaiacyl ether, 2-phenylethyl phenyl ether and 2-phenoxy-1-phenylethanol). Metal triflates are involved in cleaving not only ester and ether linkages between lignin and the carbohydrates but also B-O-4 ether linkages within the aromatic lignin structure. Metal triflates are more active for ?-O-4 ether bond cleavage than Pd/C. On the other hand, Pd/C is required for cleaving ?-O-4, 4-O-5 and B-B linkages. Insight into the synergy between Pd/C and metal triflates allowed optimizing the reductive fractionation process. Under optimized conditions, 55 wt% mono-aromatics - mainly alkylmethoxyphenols - can be obtained from the lignin fraction (23.8 wt%) of birch wood in a reaction system comprising birch wood, methanol and small amounts of Pd/C and Al(III)-triflate as catalysts. The promise of scale-up of this process is demonstrated.