Pyrolysis Products Of Cellulose Research Articles

Evaluating the effect of potassium on cellulose pyrolysis reaction kinetics

This paper proposes modifications to an existing cellulose pyrolysis mechanism in order to include the effect of potassium on product yields and composition. The changes in activation energies and pre-exponential factors due to potassium were evaluated based on the experimental data collected from pyrolysis of cellulose samples treated with different levels of potassium (0–1% mass fraction). The experiments were performed in a pyrolysis reactor coupled to a molecular beam mass spectrometer (MBMS). Principal component analysis (PCA) performed on the collected data revealed that cellulose pyrolysis products could be divided into two groups: anhydrosugars and other fragmentation products (hydroxyacetaldehyde, 5-hydroxymethylfurfural, acetyl compounds). Multivariate curve resolution (MCR) was used to extract the time resolved concentration score profiles of principal components. Kinetic tests revealed that potassium apparently inhibits the formation of anhydrosugars and catalyzes char formation. Therefore, the oil yield predicted at 500°C decreased from 87.9% from cellulose to 54.0% from cellulose with 0.5% mass fraction potassium treatment. The decrease in oil yield was accompanied by increased yield of char and gases produced via a catalyzed dehydration reaction. The predicted char and gas yield from cellulose were 3.7% and 8.4%, respectively. Introducing 0.5% mass fraction potassium treatment resulted in an increase of char yield to 12.1% and gas yield to 33.9%. The validation of the cellulose pyrolysis mechanism with experimental data from a fluidized-bed reactor, after this correction for potassium, showed good agreement with our results, with differences in product yields of up to 5%.

Muscarine-like compounds derived from a pyrolysis product of cellulose.

Cellulose represents a key component of a renewable biomass source, from which chiral compounds with a high added value in the application for the synthesis of potentially bioactive molecules can be obtained. The anhydrosugar (1R,5S)-1-hydroxy-3,6-dioxa-bicyclo[3.2.1]octan-2-one (LAC), produced on the gram-scale by catalytic pyrolysis of cellulose, was used as a building block in the synthesis of five new enantiomerically pure muscarine-like products. The structures of the target compounds 4-8 showed different substituents at the C-2 and C-4 positions, but each of them had the same (2S,4R) configuration as the natural (+)-muscarine. A renewed interest in new muscarinic analogues is due to the design and synthesis of molecules exhibiting a higher selectivity for a specific muscarinic receptor and due to the development of effective agents in the treatment of Alzheimer's disease and other cognitive disorders. In this context, products 4-8 were investigated with respect to their binding affinity to human M1-M5 muscarinic acetylcholine receptors. The data indicated that compound 8, emerging as the most active in the series with values comparable to natural (+)-muscarine and a moderate selectivity in favor of the hM2 subtype receptor, also exhibited the highest stability during the interaction with the hM2 (3UON) subtype muscarinic receptor by using a docking calculation.

Enhancing the production of renewable petrochemicals by co-feeding of biomass with plastics in catalytic fast pyrolysis with ZSM-5 zeolites

This study investigated catalytic fast pyrolysis (CFP) of a series of biomass (cellulose, lignin, and pine wood), plastics (low-density polyethylene (LDPE), polyethylene (PP), and polystyrene (PS)), and their mixtures with ZSM-5 zeolite. Co-feeding of cellulose with LDPE (mixing ratios of 4–1) produced much higher petrochemical (aromatics and olefins) yields (52.1–55.6 C%) and lower solid (coke/char) yields (22.6–10.9 C%) than those expected if there were no chemical interactions between the two feedstocks in co-feed CFP (37.4–39.2 C% and 25.0–15.9 C% for petrochemicals and solid, respectively, calculated by linear addition of the corresponding yields determined in CFP of cellulose and LDPE individually). This result indicates that cellulose and LDPE have a significant synergy that enhances the production of valuable petrochemicals and decreases the undesired coke in CFP. Similar synergy was also observed in co-feed CFP of pine wood and LDPE mixtures (mixing ratio of 2), which produced 49.5 C% petrochemicals and 19.5 C% solid residue. In comparison, CFP of pine wood and LDPE individually produced only 31.6 C% and 41.0 C% petrochemicals and 46.5 C% and 6.74 C% solid, respectively. This synergy, however, was less pronounced for the other combinations of biomass and plastics (cellulose/PP, cellulose/PS, and lignin/LDPE) tested in this study. The results suggest that the interactions between the primary pyrolysis products of cellulose and LDPE, especially Diels–Alder reactions of cellulose-derived furans with LDPE-derived linear α-olefins, play an important role in the synergy for petrochemical production and coke reduction in co-feed CFP. Co-feeding LDPE thus has great potential in improving the performance of CFP of natural lignocellulosic biomass, which usually contains a significant fraction (40–50wt.%) of cellulose component.

Modeling the physiochemistry of levoglucosan during cellulose pyrolysis

Levoglucosan is the main product of cellulose pyrolysis and also a potential platform chemical for biobased products. Previously we reported that during cellulose pyrolysis, levoglucosan is initially a liquid that is subject to the competing processes of evaporation and polymerization. While levoglucosan that evaporates can be transported out of the pyrolysis reactor and recovered, the non-volatile anhydro-oligosaccharides are trapped within the reactor where they dehydrate to char and low molecular weight compounds. We propose a physiochemical model for pyrolysis of levoglucosan using experimentally determined kinetic parameters for evaporation and polymerization of levoglucosan. After verifying the accuracy of the model, we used it to simulate behavior of levoglucosan under fast pyrolysis conditions. The simulation results showed that increasing the sample mass and applying higher heating rates promote polymerization of levoglucosan at the expense of evaporation. The detrimental effects of heating rate on levoglucosan evaporation suggest that although increased amounts of levoglucosan form during cellulose pyrolysis when higher heating rates are applied, much of the levoglucosan cannot be recovered as vapor because it turns into oligosaccharides that subsequently dehydrate to light oxygenates and char. Adopting experimental conditions that enhance the evaporation of levoglucosan, such as higher sweep-gas rates or reduced system pressures in combination with higher heating rates, is highly recommended for increasing levoglucosan recovery.

Reaction pathways of β-d-glucopyranose pyrolysis to syngas in hydrogen plasma: A density functional theory study

In this work, density functional theory (DFT) was employed to investigate the reaction pathways of β-D-glucopyranose for better understanding the pyrolysis mechanism of cellulose in hydrogen plasma. Many possible reactions were considered, and the reaction enthalpies and activation energies of these reactions were calculated using density functional theory (DFT) with a Gaussian method of B3LYP and basic set of 6-31G(d,p). A most possible reaction pathway was brought up. According to this reaction pathway, the main products of cellulose pyrolysis in hydrogen plasma would be syngas, and few light hydrocarbons. CO mainly comes from the decomposition of aldehyde group, while H2 mainly comes from dehydrogenation processes. Active H in plasma are found to play a very important role in many reactions, and they can remarkably lower the energies needed for reactions.

The Role of Sample Dimension and Temperature in Cellulose Pyrolysis

Fast pyrolysis of biomass is a next-generation biofuels production process that is capable of converting solid lignocellulosic materials (in their raw form) to a transportable liquid (bio-oil) which can be catalytically hydrogenated to fuels and chemicals. While biomass fast pyrolysis has enormous potential to produce renewable fuels, an understanding of the fundamental chemistry that converts biomass components, such as cellulose, to bio-oil is not available in the literature. In this work, we use thin-film pyrolysis to reveal the effect of temperature under transport-free reaction conditions and then evaluate the effect of sample dimension (i.e., characteristic length scale) by comparing product distributions of conventional powders and thin films. In the first part of the work, we show that the yield of total furan rings (i.e., all products containing a five-membered furan ring) does not change significantly with increased reaction temperature compared to other pyrolysis products, such as light oxygenates and anhydrosugars. However, we find that the functional groups bound to the furan ring (e.g., alcohols and aldehydes) are easily cleaved to produce smaller furans. In the second part of the work, we show that sample dimension is a key descriptor for product yields. For example, levoglucosan (the most abundant product of cellulose pyrolysis) yield differs significantly between conventional powder (millimeter-sized samples which are transport-limited) pyrolysis and thin-film (micrometer-scale thin-films which are isothermal) pyrolysis (49% for powder; 27% for thin-film at 500 °C).

An experimental study of the competing processes of evaporation and polymerization of levoglucosan in cellulose pyrolysis

While levoglucosan is a major pyrolysis product of cellulose, the yields reported in the literature vary significantly depending upon experimental conditions. In the present paper, we found that during pyrolysis in a micropyrolyzer, levoglucosan yield from cellulose can decrease significantly as sample size increases. According to our previous research, levoglucosan not only evaporates, but also forms polymers at elevated temperatures and these polymers can further dehydrate to char and low molecular weight volatiles such as water, furfural, furan, and acids. These results strongly suggest that experimental variables may influence the competing processes of evaporation and polymerization of levoglucosan during cellulose decomposition, and thereby affect the final yield of levoglucosan. In this paper, the influence of various experimental variables on the evaporation and polymerization of levoglucosan is evaluated in experiments conducted with a thermogravimetric analyzer. The pyrolytic residues are then quantified using a high performance liquid chromatography method. Experimental variables include sample size, ventilation condition, sweep gas, heating rate, and moisture content. The results show that all of the tested variables affect the competing processes of evaporation and polymerization of levoglucosan, and consequently affect the final recovery of levoglucosan.

Influence of hydroxyl group configuration on pyrolytic formation of 1,6-anhydrohexopyranoses from various hexoses: An experimental and theoretical study

1,6-Anhydrohexopyranose, which is a major pyrolysis product of cellulose and other carbohydrates, has a unique 1C4 chair conformer. Thus, during pyrolysis, the molecule must undergo a conformational transformation from the 4C1 to the 1C4 geometry, and this interconversion is expected to be influenced by the sugar's hydroxyl group configuration. In this article, the influences of the C2-, C3-, and C4-OH configuration on the 1,6-anhydrohexopyranose yield were evaluated under vacuum pyrolysis conditions for five hexoses (glucose, mannose, allose, galactose, and gulose). Furthermore, the results are discussed within the context of theoretical results that indicate the relative stability of two types of the conformers of glycopyranosyl oxocarbenium ions with C6-pseudo-equatorial and C6-pseudo-axial orientations, which were calculated with density functional theory (DFT). The latter conformation would lead to the formation of the 1,6-anhydrohexopyranose with a 1C4 conformation. The theoretical results were in good agreement with the experimental yields; C2-OH (both axial and equatorial) and C3-OH (equatorial) enhance 1,6-anhydrohexopyranose formation, while C4-OH (axial) inhibits the formation (axial/equatorial: in 4C1 form). These results also support the heterolysis mechanism for this transformation, and such conformational change was suggested to be more effective in the evaporation process from liquid to gaseous substance.

Ab Initio Dynamics of Cellulose Pyrolysis: Nascent Decomposition Pathways at 327 and 600 °C

We modeled nascent decomposition processes in cellulose pyrolysis at 327 and 600 °C using Car-Parrinello molecular dynamics (CPMD) simulations with rare events accelerated with the metadynamics method. We used a simulation cell comprised of two unit cells of cellulose Iβ periodically repeated in three dimensions to mimic the solid cellulose. To obtain initial conditions at reasonable densities, we extracted coordinates from larger classical NPT simulations at the target temperatures. CPMD-metadynamics implemented with various sets of collective variables, such as coordination numbers of the glycosidic oxygen, yielded a variety of chemical reactions such as depolymerization, fragmentation, ring opening, and ring contraction. These reactions yielded precursors to levoglucosan (LGA)-the major product of pyrolysis-and also to minor products such as 5-hydroxy-methylfurfural (HMF) and formic acid. At 327 °C, we found that depolymerization via ring contraction of the glucopyranose ring to the glucofuranose ring occurs with the lowest free-energy barrier (20 kcal/mol). We suggest that this process is key for formation of liquid intermediate cellulose, observed experimentally above 260 °C. At 600 °C, we found that a precursor to LGA (pre-LGA) forms with a free-energy barrier of 36 kcal/mol via an intermediate/transition state stabilized by anchimeric assistance and hydrogen bonding. Conformational freedom provided by expansion of the cellulose matrix at 600 °C was found to be crucial for formation of pre-LGA. We performed several comparison calculations to gauge the accuracy of CPMD-metadynamics barriers with respect to basis set and level of theory. We found that free-energy barriers at 600 °C are in the order pre-LGA < pre-HMF < formic acid, explaining why LGA is the kinetically favored product of fast cellulose pyrolysis.

Bio-oil Analysis Using Negative Electrospray Ionization: Comparative Study of High-Resolution Mass Spectrometers and Phenolic versus Sugaric Components

We have previously demonstrated that a petroleomic analysis could be performed for bio-oils and revealed the complex nature of bio-oils for the nonvolatile phenolic compounds (Smith, E.; Lee, Y. J.Energy Fuels 2010, 24, 5190−5198). As a subsequent study, we have adapted electrospray ionization in negative-ion mode to characterize a wide variety of bio-oil compounds. A comparative study of three common high-resolution mass spectrometers was performed to validate the methodology and to investigate the differences in mass discrimination and resolution. The mass spectrum is dominated by low mass compounds with m/z of 100–250, with some compounds being analyzable by gas chromatography–mass spectrometry (GC–MS). We could characterize over 800 chemical compositions, with only about 40 of them being previously known in GC–MS. This unveiled a much more complex nature of bio-oils than typically shown by GC–MS. The pyrolysis products of cellulose and hemicellulose, particularly polyhydroxy cyclic hydrocarbons (or wh...

Pyrolytic conversion of cellulose to fuels: levoglucosan deoxygenation via elimination and cyclization within molten biomass

Fast pyrolysis of biomass thermally cracks solid biopolymers to generate a transportable liquid (bio-oil) which can be upgraded and integrated with the existing petroleum infrastructure. Understanding how the components of biomass, such as cellulose, break down to form bio-oil constituents is critical to developing successful biofuels technologies. In this work, we use a novel co-pyrolysis technique and isotopically labeled starting materials to show that levoglucosan, the most abundant product of cellulose pyrolysis (60% of total), is deoxygenated within molten biomass to form products with higher energy content (pyrans and light oxygenates). The yield of these products can be increased by a factor of six under certain reaction conditions, e.g., using long condensed-phase residence times encountered in powder pyrolysis. Finally, co-pyrolysis experiments with deuterated glucose reveal that hydrogen exchange is a critical component of levoglucosan deoxygenation.

I213 セルロース熱分解における非平衡Arプラズマ供給の影響(OS-11: バイオマス関連の基礎研究と利活用(1))

The influence of non-equilibrium Ar plasma on the yield and composition of cellulose pyrolysis product is investigated. Dielectric barrier discharge (DBD) is used to obtain Ar plasma. The amount of products (gas, collected tar and residual char) are determined and the composition of the collected tar is analyzed by GC-MS. Gas yield decreases and the collected tar in the low temperature range increases with plasma, whereas the temperature in the pyrolysis furnace may change little. It is also suggested that applying plasma may change the reaction pathway of cellulose decomposition because the composition of collected tar has the different tendency to that observed with the temperature increase.

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.

Efficient levoglucosenone production by catalytic pyrolysis of cellulose mixed with ionic liquid

Levoglucosenone is a synthetically valuable and versatile compound that is present as a minor product of cellulose pyrolysis. Here, we report the catalytic pyrolysis of cellulose by mixing with 1-butyl-2,3-dimethylimidazolium triflate ionic liquid (IL), forming levoglucosenone in high yield. The catalysis of the IL was selectively directed to form levoglucosenone, while the low content of IL (50%) effectively prevented formation of char, leading to a yield near 20% even at 250 °C. The thermally stable IL could be fully recovered from the mixture pyrolyzed up to 300 °C and reutilized for pyrolysis.

Effects of biopretreatment of corn stover with white-rot fungus on low-temperature pyrolysis products

The thermal decomposition of biopretreated corn stover during the low temperature has been studied by using the Py-GC/MS analysis and thermogravimetric analysis with the distributed activation energy model (DAEM). Results showed that biopretreatment with white-rot fungus Echinodontium taxodii 2538 can improve the low-temperature pyrolysis of biomass, by increasing the pyrolysis products of cellulose, hemicellulose (furfural and sucrose increased up to 4.68-fold and 2.94-fold respectively) and lignin (biophenyl and 3,7,11,15-tetramethyl-2-hexadecen-1-ol increased 2.45-fold and 4.22-fold, respectively). Calculated by DAEM method, it showed that biopretreatment can decrease the activation energy during the low temperature range, accelerate the reaction rate and start the thermal decomposition with lower temperature. ATR-FTIR results showed that the deconstruction of lignin and the decomposition of the main linkages between hemicellulose and lignin could contribute to the improvement of the pyrolysis at low temperature.

An efficient route towards a new branched tetrahydrofurane δ-sugar amino acid from a pyrolysis product of cellulose

(1R,5S)-1-hydroxy-3,6-dioxa-bicyclo[3.2.1]octan-2-one, is a bicyclic lactone obtained in gram-scale by catalytic pyrolysis of the renewable source cellulose. Now it has been used as a chiral building block in the preparation of the new δ-sugar amino acid, (3R,5S)-5-(aminoethyl)-3-hydroxytetrahydrofurane-3-carboxylic acid, by an efficient synthesis in five steps with a 67% overall yield. The structure of this tetrahydrofurane amino acid, isolated in protonated form, was assigned by extensive mono- and bidimensional (1)H- and (13)C-NMR analysis and mass spectrometry, including measurements by electrospray and matrix-assisted laser desorption ionization techniques, the latter one for high-resolution experiments. This amino acid is an isoster of dipeptide glycine-alanine (H-Gly-Ala-OH), with a potential use in the access of new peptidomimetics with conformationally restricted structures due to the presence of tetrahydrofurane ring. As a preliminary study in order to disclose this effect, density functional theory calculation performed in water using polar continuum model was applied to the new amino acid and H-Gly-Ala-OH dipeptide, so that to evaluate and compare the relative torsional angles for the energy-minimized structures.

Influence of inorganic salts on the primary pyrolysis products of cellulose

Processing bio-oil with the help of currently existing petroleum refinery infrastructure has been considered as a promising alternative to produce sustainable fuels in the future. The feasibility of bio-oil production and upgrading processes depend upon its chemical composition which in turn depends on the biomass composition and the process conditions of the fast pyrolysis reactions. The primary goal of this paper was to investigate the effect of mineral salts including mixtures of salts in the form of switchgrass ash on the chemical speciation resulting from primary pyrolysis reactions of cellulose and to gain an insight of the underlying mechanisms. Various concentrations of inorganic salts (NaCl, KCl, MgCl2, CaCl2, Ca(OH)2, Ca(NO3)2, CaCO3 and CaHPO4) and switchgrass ash were impregnated on pure cellulose. These samples were pyrolyzed in a micro-pyrolyzer connected to a GC–MS/FID system. Effects of minerals on the formation of (a) low molecular weight species – formic acid, glycolaldehyde and acetol, (b) furan ring derivatives – 2-furaldehyde and 5-hydroxy methyl furfural and (c) anhydro sugar – levoglucosan are reported exclusively. Further, the effect of reaction temperature ranging from 350 to 600°C on the pyrolysis speciation of pure and ash-doped cellulose is also reported. The pyrolysis speciation revealed the competitive nature of the primary reactions. Mineral salts and higher temperatures accelerated the reactions that led to the formation of low molecular weight species from cellulose as compared to those leading to anhydro sugars.

A novel hydroxy functionalized polyester obtained by ring opening copolymerization of L‐lactide with a pyrolysis product of cellulose

AbstractA hydroxylactone ((1R,5S)‐1‐hydroxy‐3,6‐dioxabicyclo [3.2.1] octan‐2‐one, abbreviated as LAC) obtained from catalytic pyrolysis of cellulose was investigated as a monomer in the synthesis of polyesters by ring‐opening polymerization (ROP) with L‐lactide. Although stannous octoate resulted inactive, ROP initiated by zirconium (IV) acetylacetonate afforded novel copolyesters from LAC and lactide mixtures in the bulk at 110 °C. Copolymers were obtained with different LAC content (from 19 to 45%) with a random microstructure as established by detailed NMR analysis. FTIR spectrometry confirmed the presence in the polymer chain of the OH groups originally present in LAC, which do not react during polymerization due to steric hindrance and inter/intramolecular hydrogen bonding. Reaction with trichloroacetylisocyanide proved that OH groups of the polyesters can be readily derivatized. The application of LAC as a comonomer enables the insertion of the alcohol functionality in polylactide avoiding protection/deprotection steps and potentially expanding the realm of biomaterials affordable from carbohydrate feedstock. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 247–257, 2009

Organic molecular compositions and temporal variations of summertime mountain aerosols over Mt. Tai, North China Plain

Total suspended particles (TSP) were collected at the summit of Mt. Tai (1534 m above sea level) on a daytime and nighttime basis during a summertime campaign (May–June 2006) and were characterized for organic molecular compositions using solvent extraction/derivatization and gas chromatography/mass spectrometry technique. The n‐Alkanes, fatty acids, fatty alcohols, sugars, glycerol and polyacids, and phthalate esters were found as major organic compound classes, whereas lignin and resin products, sterols, aromatic acids, hopanes, and polycyclic aromatic hydrocarbons (PAHs) were detected as minor classes. Sugars (49.8–2115 ng m−3, average 640 ng m−3 in daytime; 18.1–4348 ng m−3, 799 ng m−3 in nighttime) were found to be the dominant compound class. Levoglucosan, a specific cellulose pyrolysis product, was detected as the most abundant single compound, followed by C28 fatty alcohol, diisobutyl and di‐n‐butyl phthalates, C29n‐alkane, C16 and C28 fatty acids, and malic acid. By grouping organic compounds based on their sources, we found that emission of terrestrial plant waxes was the most significant source (30–34%) of the TSP, followed by biomass burning products (25–27%) (e.g., levoglucosan and lignin and resin products), soil resuspension (15–18%) due to agricultural activities, secondary oxidation products (8–10%), plastic emission (3–10%), marine/microbial sources (6%), and urban/industrial emissions from fossil fuel use (4%). However, low molecular weight dicarboxylic acids (such as oxalic acid) of photochemical origin were not included in this study. Malic acid was found to be much higher than those reported in the ground level, suggesting an enhanced photochemical production in the free troposphere over mountain areas. Temporal variations of biomass burning tracers (e.g., levoglucosan, galactosan, mannosan) and some higher plant wax derived compound classes suggested that there were two major (E1 and E2) and one minor (E3) biomass‐burning events during this campaign. Most of the compound classes showed higher concentrations in nighttime samples when organic aerosols can be long‐range transported from different source regions to the summit of Mt. Tai above the planetary boundary layer (PBL). This study also demonstrates that the free troposphere over Mt. Tai is heavily influenced by field burning of agricultural wastes such as wheat straws in the North China Plain during the harvest season in early summer.

Catalysis Mechanism Study of Potassium Salts on Cellulose Pyrolysis by Using TGA-FTIR Analysis

The catalytic effect of three kinds of potassium salts on cellulose pyrolysis kinetics and products was studied on a thermogravimetric analyzer coupled with a Fourier transform infrared spectroscopy. Experimental results showed that potassium salts catalyzed the dehydration and depolymerization reactions in the initial pyrolysis stage, enhanced the release of oxygenated gases, intensively catalyzed the formation of char, and restrained the production of volatiles. Kinetic modeling showed that the presence of potassium ions provided a mechanistic route with lower activation energy, and accelerated the pyrolysis rate. Both KCl and K2CO3 restrained the release of levoglucosan, glycoaldehyde and C=O containing compounds, while K2SO4 largely promoted the formation of levoglucosan. The presence of KCl and K2CO3 might have retarded the unzipping reaction at the terminal units of the cellulose chain, and thus restrained the formation of levoglucosan. K2SO4 exhibited different catalytic mechanisms, which uniquely catalyzed the formation of levoglucosan.