Competing reactions limit levoglucosan yield during fast pyrolysis of cellulose

Lindstrom, Jake K.; Proano-Aviles, Juan; Johnston, Patrick A.; Peterson, Chad A.; Stansell, Jackson S.; Brown, Robert C.

doi:10.1039/c8gc03461c

Cited by 56 publications

(48 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is in line with other studies that have found no evidence for hydrolysis to be a primary pathway. 25,26 These differences between theory and experiment suggest a need for re-examining the intramolecular bondmaking and bond-breaking events that influence glycosidic bond activation with a special emphasis on explaining the peculiar similarity between α and β-isomers.…”

mentioning

confidence: 99%

Glycosidic C–O Bond Activation in Cellulose Pyrolysis: Alpha Versus Beta and Condensed Phase Hydroxyl-Catalytic Scission

2020

View full text Add to dashboard Cite

Mechanistic insights into glycosidic bond activation in cellulose pyrolysis were obtained via first principles density functional theory calculations that explain the peculiar similarity in kinetics for different stereochemical glycosidic bonds (β vs α) and establish the role of the three-dimensional hydroxyl environment around the reaction center in activation dynamics. The reported activating mechanism of the α-isomer was shown to require an initial formation of a transient C1-O2-C2 epoxide, that subsequently undergoes transformation to levoglucosan. Density functional theory results from maltose, a model compound for the α-isomer, show that the intramolecular C2 hydroxyl group favorably interacts with lone pair electrons on the ether oxygen atom of an α-glycosidic bond in a manner similar to the hydroxymethyl (C6 hydroxyl) group interacting with the lone pair electrons on the ether oxygen atom of a β glycosidic bond. This mechanism has an activation energy of 52.4 kcal/mol, which is similar to the barriers reported for non-catalytic transglycosylation mechanism (~50 kcal/mol). Subsequent constrained ab initio molecular dynamics (AIMD) simulations revealed that vicinal hydroxyl groups in the condensed environment of a reacting carbohydrate melt anchor transition states via two-to-three hydrogen bonds and lead to lower free energy barriers (~32-37 kcal mol-1) in agreement with previous experiments. File list (2) download file view on ChemRxiv ChemRxiv_Narrative_Vineet_AlphaBeta_ver_05.pdf (0.92 MiB) download file view on ChemRxiv Vineet_theory_GBactivation_SI_ver_02.pdf (576.67 KiB)

show abstract

mentioning

confidence: 99%

Glycosidic C–O Bond Activation in Cellulose Pyrolysis: Alpha Versus Beta and Condensed Phase Hydroxyl-Catalytic Scission

2020

View full text Add to dashboard Cite

show abstract

“…A cellulose chain with DP of 2048 was chosen as the starting point, which is a reasonably close to the DP value of 1871 for cellulose reported by Lindstrom et al [18].…”

Section: Methodsmentioning

confidence: 63%

“…2% LG in quartz tube reactor at a temperature of 530 o C. Increasing the residence time reduced this yield to 53.1%, whilst increasing the reaction temperature to 630 o C at the shorter residence time reduced the yield to 51.1%. Patwardhan et al [17] achieved yields of 58.8% at 500 o C using a single shot micropyrolyser whilst Lindstrom et al [18] reported LG yields of 54.4% using a CPD-Quench micropyrolyser at the same temperature.…”

Section: Introductionmentioning

confidence: 99%

“…The previously proposed mechanisms for LG formation are generally limited to dimers and trimers of cellulose and anhydrocellulose, however the experimental works of Lindstrom et al [18] and of Proano-Aviles [30] show clearly that the generation of LG is dictated by a balance of mid-chain cracking and chain-end LG generating reactions, highlighting the importance of considering cellulose polymers rather than short chain oligosaccharide structures. Additional kinetic investigation on depolymerisation and LG formation from cellulose polymer is yet to be reported.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanistic and kinetic investigation on maximizing the formation of levoglucosan from cellulose during biomass pyrolysis

Shaw

Zhang

Kabalan

et al. 2021

Fuel

View full text Add to dashboard Cite

Attempts to understand and control the formation of levoglucosan, as a key bio-oil compound and an important intermediate chemical, during biomass pyrolysis have recently generated a large number of experimental and computational studies. Whilst promising mechanisms have been put forward to explain levoglucosan formation, there has yet to be clarity on the factors that inhibit the stoichiometric yields from cellulose, and, current available mechanisms adopt model compounds of short chain oligosaccharide structures rather than cellulose polymer. In this work, kinetic models describing cellulose (with Degree of Polymerisation DP of 2048) decomposition and levoglucosan formation have been constructed.It was found that temperature and residence time co-ordinately influenced the yield of levoglucosan, i.e. maximum yield can be reached within 80 seconds at 600 o C, however, around 10 minutes is required at 550 o C. Anhydro-oligosaccharides greater than DP8 will be generated and then consumed in 60 seconds with pyrolysis temperatures of 500 o C and over. The results also showed that the current available concerted initiation and depropagation reactions are insufficient to explain the experimentally observed high rates of cellulose depolymerisation and levoglucosan formation, other key factors such as side reactions have to be considered.Additionally, it was found that the rate of levoglucosan generation is independent of the initial cellulose chain length, which is a finding that will facilitate future studies in the area of bioenergy and biomass decomposition.

show abstract

“…The presence of K in biomass ash has a catalytic effect on pyrolysis, favoring the yield of phenolics in bio-oil 20 . The alkali and alkaline earth metals naturally present in biomass ash serve as strong ring-fragmentation catalysts, likely due to ion–dipole forces, yielding to light acid oxygenated compounds and a chemical unstable bio-oil 21 .…”

Section: Resultsmentioning

confidence: 99%

Colored cotton wastes valuation through thermal and catalytic reforming of pyrolysis vapors (Py-GC/MS)

Silva

Calixto

Medeiros

et al. 2021

Sci Rep

View full text Add to dashboard Cite

This study aims to analyze the products of the catalytic pyrolysis of naturally colored cotton residues, type BRS (seeds from Brazil), called BRS-Verde, BRS-Rubi, BRS-Topázio and BRS-Jade. The energy characterization of biomass was evaluated through ultimate and proximate analysis, higher heating value, cellulose, hemicellulose and lignin content, thermogravimetric analysis and apparent density. Analytical pyrolysis was performed at 500 °C in an analytical pyrolyzer from CDS Analytical connected to a gas chromatograph coupled to the mass spectrometer (GC/MS). The pyrolysis vapors were reformed at 300 and 500 °C through thermal and catalytic cracking with zeolites (ZSM-5 and HZSM-5). It has been noticed that pyrolysis vapor reforming at 500 °C promoted partial deoxygenation and cracking reactions, while the catalytic reforming showed better results for the product deoxygenation. The catalyst reforming of pyrolysis products, especially using HZSM-5 at 500 °C, promoted the formation of monoaromatics such as benzene, toluene, xylene and styrene, which are important precursors of polymers, solvents and biofuels. The main influence on the yields of these aromatic products is due to the catalytic activity of ZSM-5 favored by increased temperature that promotes cracking reactions due expanded zeolites channels.

show abstract

Competing reactions limit levoglucosan yield during fast pyrolysis of cellulose

Abstract: Efforts to understand the reaction mechanisms of cellulose pyrolysis have been stymied by short reaction times and difficulties in probing the condensed phase of cellulose intermediate products.

Cited by 56 publications

References 52 publications

Glycosidic C–O Bond Activation in Cellulose Pyrolysis: Alpha Versus Beta and Condensed Phase Hydroxyl-Catalytic Scission

Glycosidic C–O Bond Activation in Cellulose Pyrolysis: Alpha Versus Beta and Condensed Phase Hydroxyl-Catalytic Scission

Mechanistic and kinetic investigation on maximizing the formation of levoglucosan from cellulose during biomass pyrolysis

Colored cotton wastes valuation through thermal and catalytic reforming of pyrolysis vapors (Py-GC/MS)

Contact Info

Product

Resources

About