Conversion Of Hemicellulose Research Articles

Integrated strategies for furfural production and lignocellulose fractionation in aqueous deep eutectic solvents

The current biomass refinery pretreatment using deep eutectic solvents (DES) has primarily focused on downstream utilization of cellulose and lignin, while often overlooking the potential of hemicellulose. Herein, an innovative and integrated strategy was proposed for simultaneous production of furfural (FF) and fractionation of lignin and cellulose from biomass using the same aqueous DES. To achieve this goal, response surface methodology (RSM) was employ to optimize the dilute hydrochloric acid (HA) pretreatment of corn stover, a representative of lignocellulosic material, ensuring complete removal of hemicellulose. The resulting hemicellulose hydrolysate was then efficiently converted into FF in aqueous DES system, achieving an impressive yield of 72.82 %. By introducing MgCl2 as a catalyst, the FF yield soared to an exceptional 86.94 %. Furthermore, a plausible mechanism was elucidated for the conversion of hemicellulose to FF in the aqueous DES. Concurrently, the solid residue resulting from the dilute HA pretreatment was fractionated using the same aqueous DES, successfully extracting cellulose and lignin fractions. Notably, the separated cellulose solid residue exhibited an outstanding digestion efficiency of 96.3 % after 72 h of enzymatic hydrolysis at 30 FPU/g, as confirmed through meticulous FTIR analyses. In addition, an advanced 2D-HSQC NMR technique was utilized to unveil the intricate structure of the obtained lignin, revealing a guaiacol-syringyl-p-hydroxyphenyl (G-S-H) type lignin enriched with abundant CH3O- and β-O-4 linkages. A mass balance analysis showed the production of 14.0 g FF, 31.9 g glucose and 14.2 g lignin from 100 g dry corn stover. This state-of-the-art approach presented not only pioneers a novel avenue for the concurrent production of FF but also offers a sustainable and eco-friendly method for the fractionation of lignin and cellulose using DES solvents.

Catalytic pyrolysis of cellulose and hemicellulose: Investigation on furans selectivity with different zeolite structures at microporous scale

Furans, as high-value chemicals, are very important target products for catalytic pyrolysis of biomass. In this work, the comparative performance of several different zeolites (SAPO18, SAPO11, SAPO34, and SSZ13 with different Si/Al ratios) for catalytic pyrolysis of cellulose and hemicellulose to generate furan compounds was investigated. SSZ13 was firstly found to improve the selectivity of the catalytic conversion of cellulose and hemicellulose to furans with up to 51.83% and 70.03%, respectively. The high selectivity of SSZ-13 was attributed to its smaller crystal size and higher total acid. SAPO11 was found for the first time to have a positive effect on the conversion of 5-HMF to 5-MFF. Correlation analysis suggested that isomerization was the limiting step in converting the cellulose to furans, while dehydration may be the determining step for hemicellulose. GC-MS results indicated the compound in the inner surface after pyrolysis was dominated by polycyclic aromatics and no furans were detected, supporting the hypothesis that the furans were formed on the external surface of zeolite. The difference in mass transfer rates formed on the inner and outer surfaces of the microporous zeolites contributed to the generation and transfer of furans. Compared to complex multifunctional catalysts, simple zeolite structures may have more application potential.

One-step conversion of corn stalk to glucose and furfural in molten salt hydrate/organic solvent biphasic system

An effective approach for glucose and furfural production by converting cellulose and hemicelluloses from corn stalk in a biphasic system of molten salt hydrate (MSH) and organic solvent using H2SO4 as catalyst was reported. Results showed that the system with LiBr·3H2O and dichloromethane (DCM) had excellent performance in cellulose and hemicelluloses conversion. Under the optimal reaction conditions (corn stalk:LiBr·3H2O:DCM ratio = 0.35:10:20 g/mL/mL, 0.05 mol/L H2SO4, 120 °C, 90 min), 58.9% glucose and 72.5% furfural were yielded. Meanwhile, lignin was obviously depolymerized by the cleavage of β-O-4′ linkages and fractionated with high purity and low molecular weight for potential coproducts. Fluorescence microscopy and confocal Raman microscope displayed that the LiBr·3H2O/DCM treatment caused decreasing intensities in carbohydrate and lignin, suggesting the degradation of the main components of biomass. This research provided a promising biorefinery technology for the comprehensive utilization of corn stalk.

Production of Hemicellulose Sugars Combined with the Alkaline Extraction Lignin Increased the Hydro-Depolymerization of Cellulose from Corn Cob

Hydro-depolymerization is a novel method for converting agricultural waste into eco-friendly and promising products. Due to the complex structure and composition of corn cob (CC), a three-step process was developed, which involved pre-hydro-depolymerization of hemicellulose, alkaline extraction of lignin, and hydro-depolymerization of cellulose. The pre-hydro-depolymerization step was at first optimized to produce five-carbon and six-carbon sugars, achieving a maximum hemicellulose conversion rate of 78.48 ± 3.92%, and reducing a sugar yield of 59.12 ± 2.95%. Alkaline treatment achieved a maximum lignin extraction efficiency of 73.76 ± 3.68%. After hemicellulose removal and delignification, the cellulose conversion rate increased to 36.63% and further increased to 76.97% after five cycles. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were performed to confirm physical and chemical changes in CC residues. The integrated process of hydro-depolymerization and alkaline treatment enables the complete exploitation of cellulose, hemicellulose, and lignin, and thus holds great potential for application in the agriculture industry.

Synthesis and modification of graphene oxide-like carbon for conversion of hemicellulose to furfural from bagasse

The utilization of biomass to convert into valuable chemicals has been receiving research interest recently. In this study, the catalyst with a similar structure to graphene oxide was synthesized from bagasse (B-GO) by calcination using cellulose as the main carbon source. The influences of calcination temperature, calcination time, and cellulose:ferrocene ratios on the FTIR and furfural yield of B-GO were investigated, respectively. The sulfonated graphene oxide-like catalyst (B-SGO) was prepared from B-GO by sulfonation method with sulfuric acid for the application of converting hemicellulose in bagasse into furfural. The characteristics of B-GO and B-SGO materials were analyzed via modern analytical methods. The characteristic analysis of B-SGO results indicated that −SO3H was successfully attached to the B-GO with a sulfur mass ratio of 0.79%, increasing the acidity of the material and enhancing the catalytic efficiency. The effects of reaction temperature, reaction time, catalyst content, NaCl content, and hemicellulose dosage on the furfural yield of B-SGO were also investigated, respectively. The result showed the highest furfural yield achieved at 75.55% when conducting the reaction at 190°C in 120 min with the catalyst content at 1%, 0.1 mol/L NaCl, and a hemicellulose dosage of 1.5 g. Thereby, showing the potential application of synthesized materials from biomass in the process of converting hemicellulose into furfural along with utilizing the brackish water and wastewater containing low salt content as the solvent for the conversion process.

Fungal Selectivity and Biodegradation Effects by White and Brown Rot Fungi for Wood Biomass Pretreatment.

The biodegradation path and mechanism of wood varies depending on diverse fungi and tree species, as fungi possess selectivity in degradation of versatile wood components. This paper aims to clarify the actual and precise selectivity of white and brown rot fungi and the biodegradation effects on different tree species. Softwood (Pinus yunnanensis and Cunninghamia lanceolata) and hardwood (Populus yunnanensis and Hevea brasiliensis) were subjected to a biopretreating process by white rot fungus Trametes versicolor, and brown rot fungi Gloeophyllum trabeum and Rhodonia placenta with various conversion periods. The results showed that the white rot fungus Trametes versicolor had a selective biodegradation in softwood, which preferentially convert wood hemicellulose and lignin, but cellulose was retained selectively. Conversely, Trametes versicolor achieved simultaneous conversion of cellulose, hemicellulose and lignin in hardwood. Both brown rot fungi species preferentially converted carbohydrates, but R. placenta had a selectivity for the conversion of cellulose. In addition, morphological observation showed that the microstructures within wood changed significantly, and the enlarged pores and the improved accessibility could be beneficial for the penetration and accessibility of treating substrates. The research outcomes could serve as fundamental knowhows and offer potentials for effective bioenergy production and bioengineering of bioresources, and provide a reference for further application of fungal biotechnology.

Ionic buffering biphase systems as catalysts and solvents for efficient dehydration of xylose and hemicellulose to furfural

The utilization of biomass instead of fossil resources for the synthesis of various chemicals is regarded as one of the most important strategies to realize sustainable and environmentally-friendly chemical industry. The design and development of suitable catalysts for biomass conversion are of particular significance. Herein, ionic buffering biphase systems (IBBSs) consisting of ionic buffering catalysts (IBCs) and an organic phase as extractant are proposed and developed for the dehydration of xylose and hemicellulose to furfural (FF). The systems can efficiently catalyze the conversion of xylose and hemicellulose to FF and significantly reduce the use of NaCl. High FF yields of 76.4% or 85.1% were realized with almost complete conversion of hemicellulose or xylose. The IBBSs have advantages of simple preparation, thermal stability, and low cost, not to mention the facts that they enable both the excellent extraction of FF product from aqueous phase to oil phase and the easy recycling of ionic buffering catalyst. This work offers a new strategy of designing and developing catalytic reaction-separation coupling systems for the efficient conversion of xylose and hemicellulose to FF.

A green process for producing xylooligosaccharides via autohydrolysis of plasma-treated sugarcane bagasse

Due to alarming energy consumption and population growth, the transition to a circular economy is being pursued by searching for alternative resources to produce chemicals and energy. In this regard, lignocellulosic biomass, as the most abundantly accessible plant material, is a suitable alternative for satisfying this high demand. Sustainable lignocellulose biorefineries could convert cellulose, hemicellulose, and lignin into high-value products. Most available approaches prioritize cellulose and lignin over hemicellulose. In this work, autohydrolysis treatment of sugarcane bagasse is developed to produce xylooligosaccharides (XOS) with a variable degree of polymerization (2−6) using low-temperature atmospheric-pressure plasma and ball-mill treatment on raw bagasse. The reactive oxygen, ozone, hydronium ions (H3O+), and nitrogen species generated by plasma increase hemicellulose conversion. XOS hydrolysate obtained from plasma pre-treated samples (41.1%) was quantified for xylobiose (12.1%), xylotriose (10.1%), xylotetrose (6.9%), xylopentaose (7.1%), and xylohexaose (4.9%) (6 h of autohydrolysis at 135 °C). Xylan hydrolysate was also yielded 21.2% xylose, and 2.2% furfural, respectively. The entire process (plasma and autohydrolysis) was conducted in water without using any other chemicals. These results suggest the potential role of plasma pre-treatment prior to hydrothermal treatments to selectively produce XOS.

Sustainable synthesis of cellulose-derived magnetic iron oxide/sulfonated graphene oxide-like material from corncob for conversion of hemicellulose to furfural

Developing a method to convert biomass sources into valuable products has always been a matter of great interest to many researchers. In this work, a cellulose-derived magnetic iron oxide/sulfonated graphene oxide-like (Cel-MSGO) material was synthesized from corncob by sulfonation and hydrothermal processing, in order to catalyze the conversion of hemicellulose to furfural. Characteristics of the as-synthesizedCel-MSGO were investigated using modern analytical methods. Scanning electron microscopy revealed that Fe3O4particles were attached to the surface of sheets structurally similar to sulfonated graphene oxide. The sheet-like structure of the obtained Cel-MSGO was also observed from high-resolution transmission electron microscopy as similar to that of graphene oxide. The Cel-MSGO material was investigated for its ability to convert hemicellulose of corncob into furfural through the following factors: reaction temperature, reaction time, amount of catalyst, and solvent ratio H2O:γ-valerolactone (H2O:GVL). The Cel-MSGO material showed excellent catalysis with a furfural yield of 55.05%, xylose conversion of 97.80%, and furfural selectivity of 57.20% under reaction conditions of 190°C, a reaction time of 150 min, and a catalyst amount of 10 wt% in a solvent system consisting 80:20 H2O:GVL (v/v). Furthermore, the catalyst showed good reusability after6 cycles. This study opens a new application direction in utilizing biomass to synthesize high-value products, contributing to reducing environmental pollution and solving the situation of exhausted renewable raw materials.

Efficient transformation of hemicellulosic biomass into sugar alcohols with non-precious and stable bimetallic support catalyst

The conversion of hemicellulosic biomass to sugar alcohols commonly applies homogeneous acids and noble metals as catalysts, which is neither economical nor environmentally friendly. In order to overcome the deficiencies of the reports, a series of non-precious catalysts were synthesized through the co-precipitation method and incipient wetness impregnation (IWI) method in converting hemicellulosic biomass, i.e., hemicellulose and xylose into sugar alcohols (i.e., xylitol and arabitol). Reaction experiments showed that the Ni8.98Fe1 @ 1.54SiO2 catalyst prepared by the IWI method has excellent catalytic performance for converting xylose to sugar alcohols in the neutral aqueous solution, and can be applied to the direct conversion of hemicellulose as well. Specifically, the optimum yield of xylitol and arabitol could obtain 99.48 mol% and 26.01 mol% for xylose as the substrate and 88.16 mol% and 20.55 mol% for hemicellulose as the substrate, respectively. Characterization techniques such as X-ray diffraction (XRD), N2 adsorption-desorption isotherm, transmission electron microscopy (TEM), scanning electron microscope (SEM), H2 temperature-programmed reduction (H2-TPR), NH3 temperature-programmed desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy of pyridine (Py-FTIR), and SQUID vibrating sample magnetometry (SQUID -VSM) were performed to study physicochemical properties of the catalyst. N2 adsorption-desorption isotherm and NH3-TPD characterizations indicated that the catalyst with mesoporous properties and proper acidic sites is vital for hydrolyzing hemicellulose to pentose (i.e., xylose and arabinose). TEM, H2-TPR, and XPS techniques revealed that the (111) plane of metallic Ni is the main active phase for the hydrogenation of pentose into sugar alcohols, and Fe2+ and Fe3+ species act as effective promoters to enhance the pentose hydrogenation. Py-FTIR characterization and reaction conditions indicated that the appropriate ratio of Brønsted to Lewis acidic sites could facilitate the conversion of xylose to arabitol. The reaction mechanisms for converting hemicellulosic biomass to sugar alcohols were proposed based on the systematic study of reaction conditions and characterizations. N2 adsorption-desorption, H2-TPR, and XPS indicated that the catalyst with strong metal-support interaction, large specific surface area and pore volume could be beneficial for catalytic stability, which is verified in leaching and reusability tests. The catalyst has superparamagnetic, which can be quickly separated from the reaction system under the external magnetic field, facilitating the recovery and utilization of the catalyst.

Catalytic Transformation of Biomass-Derived Hemicellulose Sugars by the One-Pot Method into Oxalic, Lactic, and Levulinic Acids Using a Homogeneous H2SO4 Catalyst

This article presents the conditions for the conversion of hemicellulose with different contents of C6 and C5 carbohydrates and uronic acids based on the OrganoCat process, and the abbreviations M1, M2, and M3 are used. Homogenous catalysis with sulfuric acid (VI) in the concentration range of 0.1–1 M was used in the study to determine its activity on the ability to transform a hemicellulose mixture. The process was carried out using the one-pot technique in the temperature range of 100–250 °C for 1–5 h. Based on the use of the chromatographic technique (HPLC-RID) together with a comparison with standard substances, the resulting chemical compounds were determined and identified from the post-reaction mixtures. The degree of covalence of the raw material, the selectivity of the obtained chemical compounds, and the yield of lactic acid were also determined. Based on the obtained results, lactic acid with the highest yield (64.57%) was obtained after 1 h of the process from the M1 mixture at the temperature of 100 °C with 0.1 M sulfuric acid (VI) as a catalyst. The formation of oxalic acid was also observed, which is present in all post-reaction mixtures, regardless of the composition of the raw material, temperature, and time. Its efficiency was determined at an average level of 90%.

Complete Low-Temperature Transformation and Dissolution of the Three Main Components in Corn Straw.

The conversion of biomass faces the challenge of mass and heat transfer, as well as the exertion of heterogeneous catalyst, because raw biomass exists usually in solid state. In this work, the simultaneous transformation and dissolution of the three main components (hemicellulose, cellulose, lignin) in corn straw were achieved in ethanol/ valerolactone (GVL)/H2 O (10 : 10 : 40, v/v/v) co-solvent system. With the assistance of AlCl3 ⋅ 6H2 O, the conversion of hemicellulose, lignin and cellulose was >96 % at 170 °C. The conversion of solid biomass into fluid, overcoming the mass transfer restrictions between solid biomass and solid catalysts, provides new raw materials to further upgrading. H2 O could penetrate inside the crystalline cellulose to swell even dissolve it, while ethanol and GVL acted as media to dissolve especially the G unit in lignin. The H+ derived from AlCl3 ⋅ 6H2 O hydrolysis could break the linkages of lignin-hemicellulose and glycosidic bond in saccharides, and aluminum chloride promoted the next degradation of polysaccharides to small molecules. Consequently, as high as 33.2 % yield of levulinic acid and 42.2 % yield of furfural were obtained. The cleavage of β-O-4 and Cβ -Cγ bonds in lignin produced large amounts of lignin-derived dimers and trimers. The total yield of monomeric phenols is up to 8 %.

Protic Brønsted acidic ionic liquids with variable acidity for efficient conversion of xylose and hemicellulose to furfural

Furfural (FF) is an important platform molecule originated from biomass, but it’s synthesis through the traditional acid-catalyzed dehydration reaction of xylose and hemicellulose remains problematic due to the poor activity and equipment corrosion. Therefore, a series of [HSO4]-based protic Brønsted acidic ionic liquids (BAILs) are employed as green catalysts to achieve efficient and sustainable preparation of FF from xylose or hemicellulose in this work. Furfural yields of 75.4% or 80.4% were achieved under optimal operating conditions with [Hpy][HSO4] as catalyst, hemicellulose or xylose as substrates, higher than those catalysed with most ionic liquids reported so far. The chemical structures of BAILs were confirmed by NMR and FT-IR spectroscopy, and the Hammett acidity (H0) were determined using UV–vis spectroscopy with 4-nitroaniline as probe. The acidity of BAILs were tuned through methyl substitution on the pyridinium ring, and its effect on the catalysis performance was investigated. In addition, the reaction constants and the corresponding activation energies of BAILs for dehydration of xylose to FF were calculated by kinetic equations. Overall, the highly efficient catalysis performance, good recyclability and low cost enables [Hpy][HSO4] to be potentially applied for large-scale preparation of FF.

Conversion of cellulose into aromatic compounds using supported metal catalysts in high-temperature water.

Production of aromatic compounds from lignocellulosic biomass has recently been one goal of efforts to establish a sustainable society. We studied cellulose conversion into aromatic compounds over charcoal-supported metal catalysts (Pt/C, Pd/C, Rh/C, and Ru/C) in water at temperatures of 473-673 K. We found that charcoal-supported metal catalysts enhanced conversion of cellulose to aromatic compounds such as benzene, toluene, phenol, and cresol. The total yields of aromatic compounds produced from cellulose decreased in the order: Pt/C > Pd/C > Rh/C > no catalyst > Ru/C. This conversion could proceed even at 523 K. The total yield of aromatic compounds reached 5.8% with Pt/C at 673 K. The charcoal-supported metal catalysts also enhanced conversion of hemicellulose to aromatic compounds.

Larix Sibirica Arabinogalactan Hydrolysis over Zr-SBA-15; Depolymerization Insight.

Arabinogalactan depolymerization over solid Zr-containing SBA-15-based catalyst was studied via HPLC, GPC, and theoretical modeling. Arabinogalactans (AG) are hemicelluloses mainly present in larch wood species, which can be extracted on an industrial scale. The application of solid acid catalysts in the processes of hemicellulose conversion can exclude serious drawbacks such as equipment corrosion, etc. Characterization of 5%Zr-SBA-15 confirmed the successful formation of the mesoporous structure inherent to SBA-15 with fine Zr distribution and strong acidic properties (XRD, XPS, FTIR, pHpzc). Carrying out the process at 130 °C allowed us to achieve total products yield of up to 59 wt%, which is represented mainly by galactose (51 wt%) and minor (less than 9 wt%) presence of arabinose, furfural, 5-HMF, and levulinic acid. The temperature increases up to 150 °C resulted in a total product yield drop down to 37 wt%, making temperature elevation above 130 °C obsolete. According to the theoretical investigations, arabinogalactan depolymerization follows the primary cleavage of the β(1→3) bonds between the D-galactose units of the main chain, which is also confirmed by GPC.

Comprehensive analysis of ethanol production from coffee mucilage under sustainability indicators

This article shows the results obtained by analyzing an emerging technology to produce bioethanol from coffee mucilage under sustainable development constraints. The investigation showed that the addition of an antibiotic is important to avoid contamination of the mucilage related to the presence of bacteria since these microorganisms can eat the sugars present in the biomass for their metabolism. On the other hand, for the conversion of cellulose and hemicellulose into simple reducing sugars present in coffee mucilage, the addition of the enzyme pectinase was necessary. The ANOVA analysis showed that the cellulase dose is the most significant factor in the hydrolysis process. The adequate doses of enzymes for the enzymatic hydrolysis process of coffee mucilage were obtained by the response surface method, finding an optimal value of 0,352 mL and 0,134 mL of cellulase and hemicellulase, respectively, per 100 mL of mucilage. From the logistics approach, the supply of coffee mucilage to a second-generation ethanol pilot plant with an installed capacity of 15.000 liters of mucilage per week was considered. Ideally, the pulping process must be carried out mechanically without water, ensuring a mucilage Brix content between 16 and 21, which would favor an ethanol yield close to 8% (v/v) in the must. A potential production of 4,137 liters of ethanol could be achieved with a total logistics cost of USD 305 if the available mucilage is collected. A potential reduction of 7,650 kg of carbon dioxide is possible if the ethanol produced is used to replace the same amount of gasoline in the transportation industry.

An accessory enzymatic system of cellulase for simultaneous saccharification and co-fermentation

The enhanced hydrolysis of xylan-type hemicellulose is important to maximize ethanol production yield and substrate utilization rate in lignocellulose-based simultaneous saccharification and co-fermentation system. In this study, we conduct δ-integration CRISPR Cas9 to achieve multicopy chromosomal integration with high efficiency of reductase–xylitol dehydrogenase pathway in Saccharomyces cerevisiae. Subsequently, we devise a consolidated bioprocessing-enabling S. cerevisiae consortium, in which every engineered yeast strain could secrete or display different assembly components to be adaptively assembled on the surface of scaffoldin-displaying yeast cell for synergistic catalysis and co-fermentation from steam-exploded Pennisetum purpureum. Despite the accumulation of xylitol, the maximum ethanol titer of the genetically engineered yeast strain reached 12.88 g/l with the cellulose conversion of 91.21% and hemicellulose conversion of 55.25% under 30 ºC after 96 h with the addition of commercial cellulase. The elaborated cellulosomal organization toward genetic engineering of an industrially important microorganism presents a designed approach for advanced lignocellulolytic potential and improved capability of biofuel processing.Graphical

Computer simulation in lignocellulosic biomass conversion processes: A review

Much attention has been paid to the solubilization and conversion processes of cellulose, hemicellulose, and lignin to produce high value-added chemicals and fuels. Computer simulation shows great potential in understanding the conversion process of plant biomass. This paper reviewed the solubilization processes, catalytic conversion, and pyrolysis of cellulose, hemicellulose, and lignin by density functional theory and molecular dynamics. The authors also provide prospects for the challenges and future developments in this area.

Green synthesis of sulfonated graphene oxide-like catalyst from corncob for conversion of hemicellulose into furfural

Green synthesis of sulfonated graphene oxide-like catalyst from corncob for conversion of hemicellulose into furfural

Improved yields of high value-added ketones in bio-oil from biomass fast pyrolysis employing ZnO-modified magnesium aluminum spinel catalys

Ketones are an important class of multi-purpose products used for the production of high value-added chemicals. Herein, a novel method for the generation of methylcyclopentenone and pyridone via the modification of a magnesium aluminum spinel catalyst is proposed. In this study, zinc oxide, magnesium aluminum spinel, and ZnO-loaded magnesium aluminum spinel were used as catalysts for the catalytic pyrolysis of rape straw, corn stalk, and camphorwood powder at different reaction temperatures. Experimental results showed that different experimental temperatures and catalyst types played a crucial role in the formation of methylcyclopentenone and pyridone. Catalytic pyrolysis of rape straw with ZnO-loaded magnesium aluminum spinel increased the yield of methylcyclopentenone by greater than 6-fold compared to the yield without the catalyst, and the catalytic pyrolysis of corn stover increased the production of pyridone to 12.4%. The increase was primarily attributed to the conversion of cellulose and hemicellulose to ketones promoted by the ZnO-loaded magnesium aluminum spinel. These findings demonstrated that ZnO-loaded magnesium aluminum spinel catalysts can provide a new approach for enhancing the yield of methylcyclopentenone and pyridone during biomass fast pyrolysis.