- Mass spectrometric studies of fast pyrolysis of cellulose
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A fast pyrolysis probe/linear quadrupole ion trap mass spectrometer combination was used to study the primary fast pyrolysis products (those that first leave the hot pyrolysis surface) of cellulose, cellobiose, cellotriose, cellotetraose, cellopentaose, and cellohexaose, as well as of cellobiosan, cellotriosan, and cellopentosan, at 600°C. Similar products with different branching ratios were found for the oligosaccharides and cellulose, as reported previously. However, identical products (with the exception of two) with similar branching ratios were measured for cellotriosan (and cellopentosan) and cellulose. This result demonstrates that cellotriosan is an excellent small-molecule surrogate for studies of the fast pyrolysis of cellulose and also that most fast pyrolysis products of cellulose do not originate from the reducing end. Based on several observations, the fast pyrolysis of cellulose is suggested to initiate predominantly via two competing processes: The formation of anhydro-oligosaccharides, such as cellobiosan, cellotriosan, and cellopentosan (major route), and the elimination of glycolaldehyde (or isomeric) units from the reducing end of oligosaccharides formed from cellulose during fast pyrolysis.
- Degenstein, John C.,Hurt, Matt,Murria, Priya,Easton, McKay,Choudhari, Harshavardhan,Yang, Linan,Riedeman, James,Carlsen, Mark S.,Nash, John J.,Agrawal, Rakesh,Nicholas Delgass,Ribeiro, Fabio H.,Kentt?maa, Hilkka I.
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p. 321 - 326
(2016/03/25)
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- High-pressure fast-pyrolysis, fast-hydropyrolysis and catalytic hydrodeoxygenation of cellulose: Production of liquid fuel from biomass
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A lab-scale, high-pressure, continuous-flow fast-hydropyrolysis and vapor-phase catalytic hydrodeoxygenation (HDO) reactor has been successfully designed, built and tested with cellulose as a model biomass feedstock. We investigated the effects of pyrolysis temperature on high-pressure cellulose fast-pyrolysis, hydrogen on high-pressure cellulose fast-hydropyrolysis, reaction pressure (27 bar and 54 bar) on our reactor performance and candidate catalysts for downstream catalytic HDO of cellulose fast-hydropyrolysis vapors. In this work, a liquid chromatography-mass spectrometry (LC-MS) method has been developed and utilized for quantitative characterization of the liquid products. The major compounds in the liquid from cellulose fast-pyrolysis (27 bar, 520 °C) are levoglucosan and its isomers, formic acid, glycolaldehyde, and water, constituting 51 wt%, 11 wt%, 8 wt% and 24 wt% of liquid respectively. Our results show that high pressures of hydrogen do not have a significant effect on the fast-hydropyrolysis of cellulose at 480 °C but suppress the formation of reactive light oxygenate species like glycolaldehyde and formic acid at 580 °C. The formation of permanent gases (CO, CO2, CH4) and glycolaldehyde and formic acid increased with increasing pyrolysis temperature in the range of 480 °C-580 °C in high-pressure cellulose fast-pyrolysis, in the absence of hydrogen. Candidate HDO catalysts Al 2O3, 2% Ru/Al2O3 and 2% Pt/Al 2O3 resulted in extents of deoxygenation of 20%, 22% and 27%, respectively, but led to carbon loss to gas phase as CO and CH4. These catalysts provide useful insights for other candidate HDO catalysts for improving the extent of deoxygenation with higher carbon recovery in the liquid product.
- Venkatakrishnan, Vinod Kumar,Degenstein, John C.,Smeltz, Andrew D.,Delgass, W. Nicholas,Agrawal, Rakesh,Ribeiro, Fabio H.
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p. 792 - 802
(2014/02/14)
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- EFFECT OF PROTECTING GROUPS AND SOLVENTS IN ANOMERIC O-ALKYLATION OF MANNOPYRANOSE
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Anomeric O-alkylation of mannopyranoses with various protecting groups was investigated using mannose derivatives and 2,3-O-isopropylidene-1-O-trifluoromethanesulfonyl-D-glycerol (1) as alkylating agent.Generally, in polar solvents higher α/β ratios were obtained than in nonpolar solvents.Sterically demanding protecting groups at the 6-O-position and polar solvents led to higher yields.Reactivity differences were explained by different complex formation.Based on these results mannopyranosyl-α(1-4)glucopyranosides 26 and 27 were synthesized using mannose derivatives 5 and 6 having a 6-O-(p-methoxyphenyl)diphenylmethyl group and galactosyl trifluoromethanesulfonate 24 or nonafluorobutanesulfonate (nonaflate) 25, respectively, as alkylating agents.
- Tamura, Junichi,Schmidt, R. R.
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p. 895 - 912
(2007/10/02)
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- Anomeric O-Alkylation, 9. Disaccharide Synthesis via Anomeric O-Alkylation
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Base-promoted reaction of tetra-O-benzyl-glucose 1a with secondary alkyl trifluoromethanesulfonates 2 and 3 in toluene provides in the presence of 15-crown-5 preferentially β-glycosides 2aβ and 3aβ, respectively, in high yields.For reactions carried out a
- Tsvetkov, Yury E.,Klotz, Wolfgang,Schmidt, Richard R.
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p. 371 - 376
(2007/10/02)
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- TOTAL SYNTHESIS OF CYCLOMALTOHEXAOSE
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Described for the first time is a total synthesis of cyclomaltohexaose, in 0.3percent overall yield, in 21 steps starting from maltose.Maltose was transformed into allyl O-(2,3,6-tri-O-benzyl-α-D-glucopyranosyl)-(1->4)-2,3,6-tri-O-benzyl-β-D-glucopyranosi
- Takahashi, Yukio,Ogawa, Tomoya
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p. 277 - 296
(2007/10/02)
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