Yield Of Levoglucosenone Research Articles

Phosphorus-modified mesoporous niobium pentoxide catalyst for fast pyrolysis of cellulose to selective production of levoglucosenone

Catalytic fast pyrolysis of biomass/cellulose is a promising way for the production of levoglucosenone (LGO) and other value-added anhydrosugars. Herein, ammonium dihydrogen phosphate (NH4H2PO4) modified mesoporous niobium pentoxide (P-Nb2O5) was first applied to selectively produce LGO. The catalyst had a stable amorphous mesoporous structure with abundant activity species (Nb-O-Nb, Nb-O-P, P-OH, and PO43-), which affected the dehydration and depolymerization reactions of cellulose to alter the competing relationship between levoglucosan (LG) and LGO. Micro-scale pyrolysis experiments demonstrated that the yield of LGO reached 19.6 wt% under the optimized condition (P loading of 50 wt%, pyrolysis temperature of 400 °C, and catalyst-to-cellulose mass ratio of 7). In lab-scale experiments, the highest yield of LGO attained 16.5 wt%, and the catalytic activity could maintain over 80% after five recycles. Overall, the P-Nb2O5 has been proven to be a promising catalyst to produce LGO from cellulose.

The impact of hydrothermal-acid infusion pretreatment on the pyrolytic behaviors of high-ash biomass

A coupling pretreatment on high-ash content biomass, namely rice straw (RS), followed by slow pyrolysis has been proposed to yield high-quality bio-oil and value-added chemicals. Hydrothermal pretreatment was combined to acid infusion to pretreat rice straw, and the physico-chemical properties and pyrolytic behavior of the pretreated rice straw were investigated. After the mentioned pretreatment, the thermal degradation temperature of pretreated RS decreased from 359 °C to 281 °C while the crystalline of cellulose decreased from 67.1% to 63.1%. The catalytic effect of alkali and alkaline earth metals in RS has been passivated with decreased amount of H2SO4, showing in the increment of bio-oil yield from 39.8 wt% to 47.0 wt%. Furthermore, the yield of levoglucosenone (LGO) from pretreated RS increased from 0.06 wt% to 8.4 wt% and the yield of monophenol products decreased from 4.8 wt% to 1.4 wt%. The present study offers an effective and sustainable method for processing agro-industrial waste with high content of ash, which enables the production of high-yield and quality bio-oil.

Sulfuric acid-catalyzed pyrolysis of iota-carrageenan in polyethylene glycol

The use of seaweed polysaccharides for fine chemical synthesis is a promising approach to replace fossil fuel-based feedstocks. In this work, acid-catalyzed pyrolysis of the polysaccharide iota-carrageenan from red seaweed has been studied using differential scanning calorimetry (DSC). DSC shows that sulfuric acid in a polyethylene glycol (PEG) solvent lowers the temperature of the exothermic decomposition peak by ca. 63 °C when compared with the pyrolysis of pure polysaccharide. Evolved products from the pyrolysis in a purpose-built glass tube vacuum reactor were analyzed using gas chromatography/mass spectrometry, and showed that levoglucosenone (LGO) and furfural were dominant. Yield of LGO was 12 mg/gIC or 9.0 mol% and of furfural was 2.8 mg/gIC or 2.8 mol% when 2% w/w H2SO4 was used as catalyst.

Levoglucosenone production by catalytic fast pyrolysis of cellulose mixed with alkali metal-doped Keggin heterpolyacid salt

Levoglucosenone (LGO) has shown a promising potential in the application of the sustainable chemistry. In this work, alkali metal-doped phosphotungstic acids, M2.5H0.5PW12O40 (M = Li, Na, K, Rb and Cs), were synthesized and employed for catalytic fast pyrolysis of cellulose to selectively produce LGO. The results show that levoglucosan, the main precursor of LGO, was produced with a yield of 33.5 wt% by non-catalytic pyrolysis of cellulose, while LGO by catalytic fast pyrolysis of cellulose is mainly regulated by the strong/weak acid sites of the M2.5H0.5PW12O40. Increasing the atomic radius of the alkali metals from Li to Cs doping to phosphotungstic acid led to an increase of LGO yield, attaining to 15.6 wt% at 300 °C over Cs2.5H0.5PW12O40 due to a high strong/weak acid site ratio. In addition, LGO yield was further enhanced to 19.2 wt% over (NH4)2HPO4 modified Cs2.5H0.5PW12O40 as a result of an increase of moderate strong acid sites. This study provides a potential method for LGO production by catalytic pyrolysis of cellulose.

Torrefaction characteristics of cellulose loaded with boric acid

To explore the catalytic effect of boric acid on biomass, cellulose loaded with boric acid was roasted by a tubular furnace. The gaseous products were adsorbed by activated carbon and then analyzed by GC-MS. Boric acid was shown to improve the selectivity of the product levoglucosenone (LGO). The effects of the parameters such as boric acid loading, nitrogen flow, and temperature on the torrefaction behavior of cellulose were investigated. In the studied temperature range of 240–420 °C, the yield of LGO first increases and then decreases. In addition, its yield increases directly with increasing nitrogen flow rate. The results show that the highest LGO yield of 6.64% (analytical value) can be obtained under 10% (w/w) boric acid loading, 380 °C and nitrogen flow rate of 65 ml/min conditions.

Municipal sludge derived solid acids for levoglucosenone production via cellulose fast pyrolysis

In the present study, a series of municipal sludge derived solid acids, synthesized through hydrothermal pre-carbonization coupled with secondary pyrolysis method, were developed for levoglucosenone (LGO) production via cellulose fast pyrolysis. Specific physico-chemical characterizations such as XRD, FTIR, N2 adsorption-desorption, NH3-TPD, etc., were undertaken to reveal the structural properties of as-prepared solid acids. Phosphoric acid and sulfuric acid decorated municipal sludge derived carbon-based materials containing abundant Brønsted acid sites remarkably facilitated the selective formation of LGO. Particularly, high LGO yield (~20 wt%) were achieved using both phosphoric and sulfonic acid functionalized municipal sludge derived porous carbon. The as-prepared municipal sludge derived solid acids could be reused for multiple cycles in LGO preparation without significant decline in pyrolysis performance. This research will provide good reference for the resource utilization of lignocellulosic biomass and municipal sludge, particularly in the aspect of valuable chemicals manufacture.

Catalytic pyrolysis of cellulose with sulfonated carbon catalyst to produce levoglucosenone

In this study, a new method for the efficient preparation of levoglucosenone (LGO) by biomass catalytic pyrolysis with sulfonated carbon catalyst was proposed. The influence of pyrolysis temperature and the mass ratio of catalyst to glucose or cellulose on the formation of LGO was systematically studied. The results show that when the mass ratio of glucose to sulfonated carbon is 1:1 and the pyrolysis temperature increases from 300 °C to 500 °C, the LGO selectivity first increased and then decreased, reaching a maximum value of 46.4% at 400 °C. Meanwhile, the yield of LGO increased steadily with the increase in pyrolysis temperature, and the yield of LGO was reached a maximum value of 2.48 wt% at 500 °C. However, with the increasing amount of catalyst, the selectivity of LGO increased steadily, while the yield of LGO increased at first and then decreased. Overall, the optimum pyrolysis temperature and mass ratio of the glucose/sulfonated carbon catalyst for LGO production were 400 °C and 1:1, respectively. Density functional theory calculations showed that the catalytic action of sulfonated carbon changed the reaction pathway of glucose pyrolysis, making glucose more inclined to form LGO through a 1,2 dehydration mechanism.

Enhanced production of levoglucosenone from pretreatment assisted catalytic pyrolysis of waste paper

A new method was developed for the selective production of levoglucosenone (LGO) from catalytic pyrolysis of waste paper. Copy paper (CP) was selected as the representative waste paper and subjected to single or combined pretreatment with ethanol and HCl solutions. The influences of pretreatment method, acid concentration, and pretreatment temperature were systematically investigated to reveal their impacts on the physicochemical properties and pyrolytic characteristics of CP as well as LGO formation. The catalytic pyrolysis experiments of pretreated CP were conducted using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale device under different pyrolysis temperatures and sample/catalyst ratios. The results showed that the combined ethanol-HCl pretreatment was the most conducive to LGO production, with the optimal pretreatment conditions of acid concentration of 23% and pretreatment temperature of 80 °C. With phosphoric acid-activated carbon (PAC) as the catalyst, the maximum yields of LGO reached 18.15 wt% and 14.76 wt% at 260 °C from Py-GC/MS and lab-scale experiments with sample/catalyst ratios of 4 and 5, respectively. Compared with cellulose and biomass materials, catalytic pyrolysis of pretreated CP had the advantages of high LGO yield and low production temperature.

Catalytic conversion of cellulose to levoglucosenone using propylsulfonic acid functionalized SBA-15 and H2SO4 in tetrahydrofuran

The catalytic conversion of cellulose to levoglucosenone (LGO) was studied using dilute sulfuric acid and propylsulfonic acid functionalized SBA-15 (PS-SBA-15) in tetrahydrofuran (THF). We show that the addition of small amounts of a liquid acid catalyst such as sulfuric acid complements the use of a solid acid catalyst for the conversion of cellulose. Sulfuric acid promotes the depolymerization of cellulose into levoglucosan (LGA). The main role of the solid Brønsted acid catalyst is to dehydrate the LGA into LGO. The addition of low concentrations of H2SO4 to PS-SBA-15 resulted in an increase in LGO yield of up to 37% (from 18% obtained using an equivalent amount of H2SO4 only). Our approach provides a novel alternative for a more environmentally friendly production of LGO.

Catalytic deep eutectic solvent for levoglucosenone production by pyrolysis of cellulose

This work presents the selective production of the versatile bio-based platform levoglucosenone (LGO) using deep eutectic solvents (DESs) as catalysts during cellulose pyrolysis. Among 18 types of DESs examined, those containing p-toluenesulfonic acid as a hydrogen bond donor possessed the requisite thermal stability for use in the pyrolysis of cellulose. When those DESs were combined with cellulose, the pyrolysis temperature could be reduced which led to greater selectivity for LGO, the highest yield being 41.5% on a carbon basis. Because of their thermal stability, the DESs could be recovered from the pyrolysis residue and reused. The DESs recovery reached 97.9% in the pyrolysis at a low temperature with the LGO yield of 14.0%. Thus, DES-assisted cellulose pyrolysis is a promising methodology for LGO production.

Synergistic effects for fast co-pyrolysis of strong-acid cation exchange resin and cellulose using Py-GC/MS

This study aimed to investigate the co-pyrolysis characteristics of strong-acid cation exchange resin (Amberlyst-15, denoted as A15) and cellulose (CE), in which the existing synergistic interaction effects were uncovered. Crucial variables including pyrolytic temperature, A15-to-CE mass ratio and heating rate were taken into consideration. The levoglucosenone (LGO) production from CE and inorganic sulfur-containing species release from functional sulfonic acid groups of A15 were enhanced in a temperature range of below 400 °C. In this regard, the LGO yield achieved approximately 7 wt% at 300 °C with A15-to-CE mass ratio of 1:1. Relatively, elevating the temperature and heating rate accelerated the A15 self-decomposition and small molecule fragments restructuring to give much more monocyclic and polycyclic aromatics. Noticeably, organic sulfur-containing compounds also were produced in an unignorable amount of 8.2% under preset conditions of pyrolytic temperature of 700 °C and heating rate of 20,000 °C/s. The plausible pathway for the co-pyrolysis transformation of A15 and CE was also proposed on the basis of experimental results. The present work will provide a probable and feasible strategy for the high-value utilization of biomass and waste ion-exchange resins, particularly in the aspect of the generation of certain chemicals.

Markedly Different Decomposition Temperature and Products of Biomass Pyrolysis at Low Temperature—Differentiation of Acids in Their Effects on Pretreatment

Pine as a softwood and poplar as a hardwood pretreated with hydrochloric acid (HCl), phosphoric acid (H3PO4), and hypophosphorous acid (H3PO2) are studied for the pyrolytic properties and products in thermogravimetry (TG) and fixed bed reactor. The pyrolysis performances are pronouncedly distinguished due to the compositional and structural changes induced by the acid pretreatments. Reduction in the mineral content in the biomass feedstocks by pretreatment with the acids results in significant changes in the pyrolytic products. The residual P in the H3PO2-pretreated biomass apparently catalyzed the biomass deeper dehydration in pyrolysis compared to the other two mineral acids. TG analysis shows a shift of the temperature of maximum mass loss (Tmax) by more than 40 °C to lower temperature in the decomposition of the H3PO2-pretreated biomass from that of the untreated and the HCl- and H3PO4-pretreated biomass. Inspired by the striking differences in TG profiles of biomass pretreated by the three acids, thermal pyrolysis of pretreated biomass was carried out in a fixed bed reactor aimed at producing biochemicals at low temperatures (330 °C and 400 °C). The liquid products obtained from the fixed bed reactor show remarkably different major anhydrosugars as a result of pretreatment by the three acids. While phenolics dominate in the collected pyrolysis liquid from untreated biomass samples, biomass pretreated with all three acids results in substantially reduced phenolics in the bio-oils. The reduction in phenolic compounds in the bio-oil may be attributed to the reduction in mineral content in the feedstock. Consequently, the yields of anhydrosugars, mainly levoglucosan (LG) and levoglucosenone (LGO) are increased. LG yields of 20.9–28.5% from the cellulose content are obtained from HCl- and H3PO4-pretreated pine/poplar, with very low LGO yield (less than 1.7%). However, H3PO2-pretreated biomass is selective to produce LGO, especially at 330 °C. LGO yields of 7.4% and 6.7% are obtained from H3PO2-pretreated pine and poplar, respectively.

Catalytic Conversion of Cellulose to Levoglucosenone Using Propylsulfonic Acid Functionalized Sba-15 and H2so4 In Tetrahydrofuran

The catalytic conversion of cellulose to levoglucosenone (LGO) was studied using dilute sulfuric acid and propylsulfonic acid functionalized SBA-15 (PS-SBA-15) in tetrahydrofuran (THF). We show that the addition of small amounts of a liquid acid catalyst such as sulfuric acid complements the use of a solid acid catalyst for the conversion of cellulose. Sulfuric acid promotes the depolymerization of cellulose into levoglucosan (LGA). The main role of the solid Bronsted acid catalyst is to dehydrate the LGA into LGO. The addition of low concentrations of H 2 SO 4 to PS-SBA-15 resulted in an increase in LGO yield of up to 37% (from 18 % obtained using an equivalent amount of H 2 SO 4 only). Our approach provides a novel alternative for a more environmentally friendly production of LGO.

Evolution of 1,6-anhydrosugars in the pyrolysis of biomass with phosphoric acid and P-containing activated carbon

The formation of 1,6-anhydrosugars and other main volatiles from catalytic pyrolysis of birch wood and lignocelluloses on it its base obtained by hydrothermal treatment at 150 and 180 °C was studied using Py-GC/MS/FID. Phosphoric acid and phosphorous-containing activated carbons, based on the carbonized residue from the levoglucosenone production, were used as the catalysts. The promising application of lignocelluloses as precursors for the pyrolysis for the levoglucosenone production is demonstrated. It is shown that P-containing activated carbon can be used for the levoglucosenone production in the same way as phosphoric acid. In the case of lignocellulose obtained at 180 °C yield of levoglucosenone was more than 20 % calculating on raw material.

Improvement of levoglucosenone selectivity in liquid phase conversion of cellulose-derived anhydrosugar over solid acid catalysts

The pyrolysis of cellulose produces anhydrosugars, levoglucosan (LGA) in particular, as a primary product. In this work, the liquid phase conversion of anhydrosugars over solid acid catalysts was investigated, mainly using LGA, as a method for producing levoglucosenone (LGO), which is a bio-renewable platform for fine and commodity chemicals. The screening of typical organic solvents revealed they had a significant influence on the type of reaction selectivity and identified dimethyl sulfoxide (DMSO) as a suitable solvent. Among the solid acid catalysts examined, Amberlyst 70 in combination with DMSO was found to work the best, producing LGO with a yield of up to 32.3%-C. The yield of LGO was further improved to 40.4%-C by in-situ removal of water, which promoted undesired reactions, such as hydrolysis of LGA and isomerization of LGO to hydroxymethylfurfural. Moreover, an experiment using bio-oil, derived from cellulose pyrolysis, as the feedstock showed that a portion of heavier saccharides contributed as a source of LGO without inhibiting the conversion of LGA.

Study of levoglucosenone obtained in analytical pyrolysis and screw-type reactor, separation and distillation

This research is dedicated to the study on the formation of levoglucosenone and other main volatiles from the catalytic pyrolysis with the addition of phosphoric acid of birch wood and lignocelluloses obtained by birch wood hydrothermal treatment. Py-GC/MS/FID method was used to evaluate the contents of the main products. Lignocelluloses were found to be a more promising precursor to obtain levoglucosenone with lesser content of furfural: For birch wood and lignocelluloses hydrothermally treated at 150 and 180 °C, Py-GC/MS/FID revealed levoglucosenone yields of 12.83, 16.94 and 21.08%, correspondingly (at 5% phosphoric acid addition). When birch wood impregnated with 5% H3PO4 was pyrolized in the laboratory screw-type reactor, the levoglucosenone yield was 6.5%. The composition and content of volatiles formed in analytical pyrolysis, bio-oil and its chloroform extract were compared. Extraction of bio-oil with chloroform and consequent distillation resulted in fractions containing 79.14% of levoglucosenone.

Selective Microwave-Assisted Pyrolysis of Cellulose towards Levoglucosenone with Clay Catalysts.

Levoglucosenone (anhydrosugar) is one of the most promising chemical platforms derived from the pyrolysis of biomass. It is a chiral building block for pharmaceuticals as well as an intermediate in the production of solvents and polymers. Therefore, the development of cost-efficient, low-energy production methods is vital for a future sustainable biorefinery. Here, a novel, green approach to the production of levoglucosenone was developed by using a microwave (MW)-assisted pyrolysis of cellulose in the presence of readily available clays. It was shown that natural and pillared clays in the presence of MW irradiation significantly increase the yield of levoglucosenone from cellulose. Both the water content and the presence of acid centres are critical characteristics that influence the yield and distribution of catalysed products. A unique experiment was designed by using a synergetic effect between different types of catalysts, which enhanced the levoglucosenone yield to 12.3 wt % with 63 % purity.

Two-step conversion of cellulose to levoglucosenone using updraft fixed bed pyrolyzer and catalytic reformer

In this work, production of levoglucosenone, a promising biorenewable platform chemical, from cellulose was investigated using a two-step continuous process that consists of an updraft fixed bed reactor for fast pyrolysis of cellulose and a catalytic reformer for the volatiles conversion. The updraft fixed bed pyrolyzer produced levoglucosan, which was a precursor of levoglucosenone, with the yield of 38.4% on a carbon basis (%-C) at the optimized temperature of 500 °C. The yield of levoglucosenone significantly depended on the type of catalyst used for the reforming of volatiles. Acidic activated carbons prepared with sulfuric or phosphoric acid treatment showed good catalytic activity toward levoglucosenone formation, when mixed with cellulose in the catalytic pyrolysis, but were unavailable in the two-step process due to the quick deactivation by coke deposition. Supported ionic liquid (IL: 1-butyl-2,3-dimethylimidazolium triflate) phase catalysts enabled selective production of levoglucosenone independent of the support material examined (silica, γ-alumina, and activated carbon). The continuous operation was possible with the maximum levoglucosenone yield of 16.6%-C, but the IL catalysts also suffered from problems such as coke deposition and IL decomposition. The problems were quantitatively assessed in the experiments at different conditions.

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 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...