Levoglucosenone Research Articles

Catalytic Fast Pyrolysis of Cellulose and Biomass to Selectively Produce Levoglucosenone Using Activated Carbon Catalyst

Activated carbon (AC) prepared by chemical activation with H3PO4 (named AC-P) was employed for catalytic fast pyrolysis of cellulose and biomass to selectively produce levoglucosenone (LGO). The catalytic pyrolysis behaviors and product distributions were revealed via both analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale experiments. Moreover, the performance of AC-P catalyst was compared with previously reported strong acid catalysts and other ACs prepared by different activation methods. In addition, reusability and stability of the AC-P catalyst have been examined via recycling experiments. The results indicated that the AC-P catalyst was effective for selectively preparing LGO from both cellulose and biomass and performed better than other catalysts. Among the three biomass materials (pine wood, poplar wood, and bagasse), pine wood showed the best selectivity for producing LGO. The maximal LGO yields of 18.1 and 9.1 wt % were obtained from cellulose and pine wood, res...

Selective low-temperature pyrolysis of microcrystalline cellulose to produce levoglucosan and levoglucosenone in a fixed bed reactor

Selective low-temperature pyrolysis of microcrystalline cellulose was carried out to produce levoglucosan (LG) and levoglucosenone (LGO) using a fixed bed reactor. The effects of temperature, self-produced bio-char, different catalysts and catalytic pattern on product's yields and selectivities were studied. The results showed the self-catalysis of bio-char increased LGO yield from 0.14wt% to 1.35wt% by increasing almost 10 times with reaction feedstock mass increasing 3 times. The maximum LGO selectivity of 77.67% was obtained with H3PO4 catalysts at 270°C. Through comparing different catalysts including H3PO4, H2SO4, Fe2(SO4)3 and FePO4, the highest LGO yield of 2.65wt% was obtained with Fe2(SO4)3. Acid catalysts can obviously increase LGO selectivity and in-situ pattern performed better than ex-situ pattern during the pyrolysis for LGO. Finally, the mechanism with bio-char effect for producing LGO and LG from selective pyrolysis of microcrystalline cellulose was proposed.

Production of levoglucosenone and 5-hydroxymethylfurfural from cellulose in polar aprotic solvent–water mixtures

We demonstrate a process to produce levoglucosenone (LGO) and 5-hydroxymethylfurfural (HMF) from cellulose in up to 65% carbon yield using H2SO4as catalyst and a solvent consisting of tetrahydrofuran (THF) and H2O.

New catalytic strategies for α,ω-diols production from lignocellulosic biomass.

Catalytic strategies for the synthesis of 1,5-pentanediol (PDO) with 69% yield from hemicellulose and the synthesis of 1,6-hexanediol (HDO) with 28% yield from cellulose are presented. Fractionation of lignocellulosic biomass (white birch wood chips) in gamma-valerolactone (GVL)/H2O generates a pure cellulose solid and a liquid stream containing hemicellulose and lignin, which is further dehydrated to furfural with 85% yield. Furfural is converted to PDO with sequential dehydration, hydration, ring-opening tautomerization, and hydrogenation reactions. Acid-catalyzed cellulose dehydration in tetrahydrofuran (THF)/H2O produces a mixture of levoglucosenone (LGO) and 5-hydroxymethylfurfural (HMF), which are converted with hydrogen to tetrahydrofuran-dimethanol (THFDM). HDO is then obtained from hydrogenolysis of THFDM. Techno-economic analysis demonstrates that this approach can produce HDO and PDO at a minimum selling price of $4090 per ton.

Production of Levoglucosenone and Dihydrolevoglucosenone by Catalytic Reforming of Volatiles from Cellulose Pyrolysis Using Supported Ionic Liquid Phase

This paper presents a novel method for continuous production of a biomass-derived platform chemical, levoglucosenone (LGO), from cellulose without its pretreatment or use of solvent. First, cellulose is pyrolyzed, and then the volatiles are reformed over a catalyst consisting of a type of ionic liquid supported over porous char. The ionic liquid, having a moderate hydrogen-bond basicity, performs well in the dehydrative conversion of levoglucosan (LGA) and anhydrosugar oligomers in the volatiles to LGO at 275 °C. The catalytic reforming to LGO is highly selective, and consequently, the yield of LGO is determined mainly by the pyrolysis conditions that produce the LGO precursors. The highest LGO yield we obtained was 31.6% on a cellulose carbon basis (24.6 wt %) with fast pyrolysis that produced more precursors than the slow one. Furthermore, the reaction system is applicable to the production of dihydrolevoglucosenone (DLGO), a promising biobased alternative to dipolar aprotic solvents. Addition of hydrog...

Kinetics of Levoglucosenone Isomerization.

We studied the acid-catalyzed isomerization of levoglucosenone (LGO) to 5-hydroxymethylfurfural (HMF) and developed a reaction kinetics model that describes the experimental data across a range of conditions (100-150 °C, 50-100 mm H2 SO4 , 50-150 mm LGO). LGO and its hydrated derivative exist in equilibrium under these reaction conditions. Thermal and catalytic degradation of HMF are the major sources of carbon loss. Within the range of conditions studied, higher temperatures and shorter reaction times favor the production of HMF. The yields of HMF and levulinic acid decrease monotonically as tetrahydrofuran is added to the aqueous solvent system, indicating that water plays a role in the LGO isomerization reaction. Initial-rate analyses show that HMF is produced solely from LGO rather than from the hydrated derivative of LGO. The results of this study are consistent with a mechanism for LGO isomerization that proceeds through hydration of the anhydro bridge, followed by ring rearrangement analogous to the isomerization of glucose to fructose.

Comparison of Acids and Sulfates for Producing Levoglucosan and Levoglucosenone by Selective Catalytic Fast Pyrolysis of Cellulose Using Py-GC/MS

Levoglucosan (LG) and levoglucosenone (LGO) are two high-valued chemicals, which can be produced by catalytic fast pyrolysis of cellulose with proper catalysts. This work investigated the catalytic characteristics of different acids and metal salt catalysts to produce LG and LGO using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis (TGA). The results showed that weak acids (such as formic acid and acetic acid) enhanced LG yield, whereas sulfuric acid and phosphoric acid promoted the yield and selectivity of LGO with inhibitory effects on LG production. The maximum LGO selectivity of 61.8% was obtained with 10% phosphoric acid, while the maximum LG selectivity of 87.6% was obtained with 10% acetic acid. In comparison with two impregnation methods, the filtration method can increase LGO yield, while the evaporation method enhanced the selectivity of LGO (up to 82.6%) with lower concentration of phosphoric acid. The effects of metal salts on pyrolysis of cellulose wer...

Chemo-Enzymatic Synthesis of Chiral Epoxides Ethyl and Methyl (S)-3-(Oxiran-2-yl)propanoates from Renewable Levoglucosenone: An Access to Enantiopure (S)-Dairy Lactone

Chiral epoxides—such as ethyl and methyl (S)-3-(oxiran-2-yl)propanoates ((S)-1a/1b)—are valuable precursors in many chemical syntheses. Until recently, these compounds were synthesized from glutamic acid in four steps (deamination, reduction, tosylation and epoxide formation) in low to moderate overall yield (20%–50%). Moreover, this procedure requires some harmful reagents such as sodium nitrite ((eco)toxic) and borane (carcinogen). Herein, starting from levoglucosenone (LGO), a biobased chiral compound obtained through the flash pyrolysis of acidified cellulose, we propose a safer and more sustainable chemo-enzymatic synthetic pathway involving lipase-mediated Baeyer-Villiger oxidation, palladium-catalyzed hydrogenation, tosylation and treatment with sodium ethoxide/methoxide as key steps. This route afforded ethyl and methyl (S)-3-(oxiran-2-yl)propanoates in 57% overall yield, respectively. To demonstrate the potentiality of this new synthetic pathway from LGO, the synthesis of high value-added (S)-dairy lactone was undertaken from these epoxides and provided the target in 37% overall yield from LGO.

Lipase-Catalyzed Baeyer-Villiger Oxidation of Cellulose-Derived Levoglucosenone into (S)-γ-Hydroxymethyl-α,β-Butenolide: Optimization by Response Surface Methodology.

Cellulose-derived levoglucosenone (LGO) has been efficiently converted into pure (S)-γ-hydroxymethyl-α,β-butenolide (HBO), a chemical platform suited for the synthesis of drugs, flavors and antiviral agents. This process involves two-steps: a lipase-catalyzed Baeyer-Villiger oxidation of LGO followed by an acid hydrolysis of the reaction mixture to provide pure HBO. Response surface methodology (RSM), based on central composite face-centered (CCF) design, was employed to evaluate the factors effecting the enzyme-catalyzed reaction: pka of solid buffer (7.2–9.6), LGO concentration (0.5–1 M) and enzyme loading (55–285 PLU.mmol-1). Enzyme loading and pka of solid buffer were found to be important factors to the reaction efficiency (as measured by the conversion of LGO) while only the later had significant effects on the enzyme recyclability (as measured by the enzyme residual activity). LGO concentration influences both responses by its interaction with the enzyme loading and pka of solid buffer. The optimal conditions which allow to convert at least 80% of LGO in 2 h at 40°C and reuse the enzyme for a subsequent cycle were found to be: solid buffer pka = 7.5, [LGO] = 0.50 M and 113 PLU.mmol-1 for the lipase. A good agreement between experimental and predicted values was obtained and the model validity confirmed (p < 0.05). Alternative optimal conditions were explored using Monte Carlo simulations for risk analysis, being estimated the experimental region where the LGO conversion higher than 80% is fulfilled at a specific risk of failure.

Catalytic pyrolysis of cellulose using MCM-41 type catalysts

The pyrolysis of microcrystalline cellulose in contact with MCM-41 and Fe−, Al− and Cu− substituted samples was carried out at 400°C in a fixed-bed glass reactor in order to obtain high bio-oils yields. The acid properties of the catalysts were determined by potentiometric titration with n-butylamine, while the redox properties were studied by TPR. BET surface area, pore volume and pore size were measured by means of N2 sorptometry. The effect of the different catalysts on the composition of the bio-oils was analyzed in the light of the characterization results. Mainly the concentration of levoglucosan (LG), levoglucosenone (LGO), 1,4:3,6-dianhydro-β-d-glucopyranose (DGP) and (1S,5R)-5-hydroxy-3,7-dioxabicyclo[3.2.1]octan-4-one (LAC) were measured. The presence of the solid catalysts increased the liquid formation and strongly modified the chemical composition of the bio-oils compared to the non-catalytic pyrolysis. All the catalysts decreased the production of LG and increased that of LGO, LAC and DPG. The mild acidity of the catalysts promoted dehydration reactions, while redox properties led to a higher production of isomerization products. A much higher LGO yield was obtained over Al-MCM-41 (53wt% of cellulose is converted to LGO over this catalyst) than by non-catalytic pyrolysis of cellulose previously washed with phosphoric acid (7wt% of washed cellulose is converted to LGO). In order to evaluate the reuse of the catalyst, the spent sample was submitted to calcination at 400°C. The physicochemical properties were not modified after the calcination treatment and the pyrolysis employing the spent sample led to a similar bio-oil composition (though with a smaller yield) as in the case of the fresh catalyst. A second regeneration of the catalyst diminished the specific surface area and the surface acidity. Concomitantly a notable decrease of the yield of LGO was observed.

Mechanistic Insights into Water-Catalyzed Formation of Levoglucosenone from Anhydrosugar Intermediates by Means of High-Level Theoretical Procedures

Levoglucosenone (LGO) is an important anhydrosugar product of fast pyrolysis of cellulose and biomass. We use the high-level G4(MP2) thermochemical protocol to study the reaction mechanism for the formation of LGO from the 1,4:3,6-dianhydro-α-d-glucopyranose (DGP) pyrolysis intermediate. We find that the DGP-to-LGO conversion proceeds via a multistep reaction mechanism, which involves ring-opening, ring-closing, enol-to-keto tautomerization, hydration, and dehydration reactions. The rate-determining step for the uncatalyzed process is the enol-to-keto tautomerization (ΔG‡298 = 68.6 kcal mol–1). We find that a water molecule can catalyze five of the seven steps in the reaction pathway. In the water-catalyzed process, the barrier for the enol-to-keto tautomerization is reduced by as much as 15.1 kcal mol–1, and the hydration step becomes the rate-determining step with an activation energy of ΔG‡298 = 58.1 kcal mol–1.

Selective Production of Levoglucosenone from Catalytic Fast Pyrolysis of Biomass Mechanically Mixed with Solid Phosphoric Acid Catalysts

Solid phosphoric acid (SPA) catalysts with different carriers were prepared and used for catalytic fast pyrolysis of poplar wood to produce levoglucosenone (LGO), a valuable anhydrosugar derivative that can be used in various organic synthesis applications. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed to evaluate the catalytic capabilities of these catalysts under different reaction conditions. The results indicated that SPA catalyst prepared with the SBA-15 carrier exhibited the best catalytic capability for selectively producing LGO. Both the catalytic pyrolysis temperature and catalyst-to-biomass ratio affected the pyrolytic products greatly. The maximal LGO yield reached as high as 8.2 wt% from poplar wood, obtained at the pyrolysis temperature of 300 °C and the catalyst-to-biomass ratio of 1. The by-products during the catalytic pyrolysis process were mainly acetic acid (AA) and furfural (FF). In addition, the SPA catalyst possessed better catalytic capability than the liquid phosphoric acid (H3PO4) catalyst to produce LGO.

Dehydration of cellulose to levoglucosenone using polar aprotic solvents

Herein, we report an approach to produce levoglucosenone (LGO) from cellulose in yields up to 51% under mild reaction conditions (170–230 °C; 5–20 mM H2SO4) using polar, aprotic solvents such as tetrahydrofuran (THF).

Catalytic fast pyrolysis of cellulose and biomass to produce levoglucosenone using magnetic SO42−/TiO2–Fe3O4

Magnetic superacid (SO42−/TiO2–Fe3O4) was prepared for catalytic fast pyrolysis of cellulose and poplar wood to produce levoglucosenone (LGO). Its catalytic activity was evaluated via pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) experiments, and compared with the non-magnetic SO42−/TiO2, phosphoric acid (H3PO4) and sulfur acid (H2SO4) catalysts. Moreover, the LGO yield was quantitatively determined. The results indicated that the magnetic SO42−/TiO2–Fe3O4 was effective to selectively produce LGO from both cellulose and poplar wood. Its catalytic capability was a little better than the non-magnetic SO42−/TiO2 and H3PO4, and much better than the H2SO4. The maximal LGO yields from both cellulose and poplar wood were obtained at 300°C with the feedstock/catalyst ratio of 1/1, reaching as high as 15.43wt% from cellulose and 7.06wt% from poplar wood, respectively.

The mechanism for the formation of levoglucosenone during pyrolysis of β-d-glucopyranose and cellobiose: A density functional theory study

Levoglucosenone (LGO) is a valuable anhydrosugar product from fast pyrolysis of cellulose/biomass, but its formation mechanism is still unclear at present. In this study, density functional theory (DFT) method was employed to examine the different LGO formation pathways from pyrolysis of both β-d-glucopyranose and cellobiose, and the most favorable pathways were clarified. The results corroborate the previous studies that levoglucosan (LG) is unlikely the essential intermediate to produce LGO. The most feasible LGO formation pathways from both β-d-glucopyranose and cellobiose include sequential 1,2-dehydration, six-membered hydrogen transfer and enol-keto tautomerization steps. Enol-keto tautomerization is the rate-determining steps for both reactions to form LGO.

Feasibility of broadening the feedstock choice for levoglucosenone production by acid pre-treatment of wood and catalytic pyrolysis of the obtained lignocellulose

Levoglucosenone (LGO) (6,8-dioxabicyclo[3.2.1]oct-2-en-4-one) is commonly produced by synthetic preparation and catalytic pyrolysis of cellulose, both. Feasibility of LGO production from birch lignocellulose (LC) as well as birch and pine wood was studied by analytical pyrolysis. We found that the presence of elevated amounts of lignin and the full or partial elimination of hemicelluloses favor LGO formation during orthophosphoric acid catalyzed LC pyrolysis at 375°C. The yield of LGO reached up to 29–30rel.% from LC pyrolysis products. A known positive effect of lignin on the thermal stability of cellulose during the heating stage prior to the stage of the active decomposition of cellulose was demonstrated. An increased LGO yield from the cellulose mass unit in bulk of wood and LC in comparison with isolated cellulose was observed. The process of LGO production is promising as a method for LC utilization in a complex enterprise of wood hydrothermal processing into chemicals.

Pyrolytic behavior of cellulose in presence of montmorillonite K10 as catalyst

Cellulose and cellulose/montmorillonite K10 mixtures of different ratio (9:1, 3:1, 1:1) were subjected to pyrolysis at temperatures from 350 to 500°C with different heating rate (10°C/min, 100°C/s) to produce bio-oil and selected chemicals with high yield. The pyrolytic oil yield was in the range of 46–73.5wt% depending on the temperature, the heating rate and the amount of catalyst. The non-catalytic fast pyrolysis at 500°C gives the highest yield of bio-oil (84wt%). The blending cellulose with increasing amount of montmorillonite K10 results in significant, linear decrease in bio-oil yield. The great influence of montmorillonite K10 amount on the distribution of bio-oil components was observed at 450°C with a heating rate of 100°C/s. The addition of catalyst to cellulose promotes the formation of 2-furfural (FF), various furan derivatives, levoglucosenone (LGO) and (1R,5S)-1-hydroxy-3,6-dioxabicyclo-[3.2.1]octan-2-one (LAC). Simultaneously, the share of levoglucosan (LG) in bio-oil decreases from 6.92wt% and is less than 1wt% when cellulose:MK10 (1:1, w/w) mixture at 450°C is rapidly pyrolyzed. Additionally, several other compounds have been identified but in minor quantities. Their contributions in bio-oil also depend on the amount of catalyst.

Catalytic fast pyrolysis of cellulose mixed with sulfated titania to produce levoglucosenone: Analytical Py-GC/MS study

Sulfated titania (SO42-/TiO2) was prepared and used for catalytic fast pyrolysis of cellulose to produce levoglucosenone (LGO), a valuable anhydrosugar product. Analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique was employed in this study to achieve the catalytic fast pyrolysis of cellulose and on-line analysis of the pyrolysis vapors. Experiments were performed to investigate the effects of several factors on the LGO production, i.e. pyrolysis temperature, cellulose/catalyst ratio, TiO2 crystal type, and pyrolysis time. The results indicated that the SO42-/TiO2 catalyst lowered the initial cellulose decomposition temperature and altered the pyrolytic product significantly. Levoglucosan (LG) was the most abundant product in the non-catalytic process, while levoglucosenone (LGO) was the major product in the catalytic process. The maximal LGO yield was obtained at the set pyrolysis temperature of 400 °C, while the highest LGO content was obtained at 350 °C, with the peak area% over 50%. In addition, the SO42-/TiO2 (anatase) was confirmed the best catalyst for the LGO production.

Preparation of levoglucosenone through sulfuric acid promoted pyrolysis of bagasse at low temperature

Fast pyrolysis of bagasse pretreated by sulfuric acid was conducted in a fixed bed reactor to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The liquid yield and LGO yield were studied at temperatures from 240 to 350°C and sulfuric acid loadings from 0.92 to 7.10wt.%. An optimal LGO yield of 7.58wt.% was obtained at 270°C with a sulfuric acid pretreatment concentration of 0.05M (corresponding to 4.28wt.% sulfuric acid loading). For comparison, microcrystalline cellulose pretreated by 0.05M sulfuric acid solution was pyrolyzed at temperature from 270°C to 320°C, and bagasse loaded with 3–5wt.% phosphoric acid was pyrolyzed at temperature from 270°C to 350°C. The highest yield of LGO from bagasse was 30% higher than that from microcrystalline cellulose, and treatment with sulfuric acid allowed a 21% higher yield than treatment with phosphoric acid.

Catalytic Fast Pyrolysis of Cellulose with HZSM-5

An analytical pyrolyzer coupled with Gas Chromatography and Mass Spectrometry (Py-GC/MS) was employed to study the influence of HZSM-5 on the pyrolysis products of cellulose. The results revealed that pyrolysis products of cellulose consisted of light molecular weight products with linear chain, anhydrosugars and furan compounds. Light molecular products were mainly acetaldehyde and 2-propanone, 1-hydroxy; anhydrosugars were mainly levoglucosan (LG), levoglucosenone (LGO) and 1,4:3,6-Dianhydro-α-d-glucopyranose (DGP); Furans were mainly furfural (FF) and 5-(hydroxymethyl) furfural (HMF). The addition of HZSM-5 changed the contents of main products from fast pyrolysis of cellulose, especially for aromatic hydrocarbons, which belonged to light molecular products and increased rapidly. In addition, plenty of carbon dioxide appeared. With the addition of HZSM-5, the dehydration of LG was enhanced to produce LGO and then LGO was further decomposed into small molecular products with HZSM-5: cellulose ratio increasing. And the formation of FF and HMF were both inhibited with the addition of HZSM-5, but the formation of furan was improved. It was inferred that the addition of HZSM-5 could effectively promote the further dehydration of initial products from cellulose fast pyrolysis by the breakage of side chain.