Main Biomass Components Research Articles

Pyrolysis of biomass components in a TGA and a fixed-bed reactor: Thermochemical behaviors, kinetics, and product characterization

The pyrolysis characteristics of three main components (hemicellulose, cellulose and lignin) of biomass were investigated using a thermogravimetric analyzer (TGA) and a fixed-bed reactor, respectively. In TGA, the pyrolysis of hemicellulose and cellulose occurred quickly with a weight loss from 210 to 370°C for hemicellulose and from 260 to 410°C for cellulose. Lignin decomposed over a wider range of temperature (from 200 to about 600°C) and generated a high char yield. As the heating rate increased, TG and DTG curves shifted to the higher temperatures. The Flynn-Wall-Ozawa method was introduced to analyze the thermal reaction kinetics, and the activation energy (E) values of hemicellulose, cellulose and lignin pyrolysis are in correspondence with thermostability sequence of these three components. In the fixed-bed reactor, the pyrolysis of lignin generated remarkably high solid residue yield (61%) and very low liquid yield (0.5%) compared with cellulose and hemicellulose. The noncondensable gas mainly consisted of H2, CH4, CO2 and CO. FTIR and GC–MS analysis of liquids showed that liquids from cellulose and hemicellulose pyrolysis included a range of light oxygenated compounds which was indicated that furans, aldehydes and ketones were the most prominent decomposition products. The depolymerization of lignin led to various phenols, including many methoxylated phenols. After pyrolysis, the carbon content in char increased while the hydrogen content decreased. All of the results and findings would help further understanding of thermal behavior of biomass and its thermo-chemical utilization for fuels and chemicals.

A decision support system for eco-efficient biorefinery process comparison using a semantic approach

Enzymatic hydrolysis of the main components of lignocellulosic biomass is one of the promising methods to further upgrading it into biofuels. Biomass pre-treatment is an essential step in order to reduce cellulose crystallinity, increase surface and porosity and separate the major constituents of biomass. Scientific literature in this domain is increasing fast and could be a valuable source of data. As these abundant scientific data are mostly in textual format and heterogeneously structured, using them to compute biomass pre-treatment efficiency is not straightforward. This paper presents the implementation of a Decision Support System (DSS) based on an original pipeline coupling knowledge engineering (KE) based on semantic web technologies, soft computing techniques and environmental factor computation. The DSS allows using data found in the literature to assess environmental sustainability of biorefinery systems. The pipeline permits to: (1) structure and integrate relevant experimental data, (2) assess data source reliability, (3) compute and visualize green indicators taking into account data imprecision and source reliability. This pipeline has been made possible thanks to innovative researches in the coupling of ontologies, uncertainty management and propagation. In this first version, data acquisition is done by experts and facilitated by a termino-ontological resource. Data source reliability assessment is based on domain knowledge and done by experts. The operational prototype has been used by field experts on a realistic use case (rice straw). The obtained results have validated the usefulness of the system. Further work will address the question of a higher automation level for data acquisition and data source reliability assessment.

Development of Photocatalytic Conversion of Glucose to Value-Added Chemicals by Supported-TiO<sub>2</sub> Photocatalysts

Biomass is an important renewable energy resource, which is used to replace the petroleum to produce chemicals. Glucose is a monomer of cellulose, which is the main component of biomass. In this work, conversions of glucose to value-added chemical by a simple method have been reported. TiO2 photocatalysts were fabricated by sol-microwave method. Value-added chemical production was successfully carried out via photocatalytic conversion of glucose with TiO2 photocatalysts. Arabinose, xylitol, gluconic acid, and formic acid were produced with photocatalytic reaction of TiO2 under UVA irradiation. The value-added products (gluconic acid, arabinose, and xylitol) can generally be further used as building blocks for biorefinery production, pharmaceutical production, and food industry. In the conventional sol-microwave method, the agglomeration of fabricated TiO2 particle was a limitation of photocatalytic activity. Therefore, the modification of TiO2 fabrication by use of zeolite as a TiO2 support was applied to increase efficiency of photocatalytic conversion of glucose and its selectivity. The effect of TiO2 dosage on zeolite (TiO2/zeolite) on photocatalytic activity and yield of products was monitored. The results from scanning electron microscopy (SEM) images indicated that zeolite supporter reduced agglomeration of spherical TiO2 particles. The well distribution of TiO2 particles on surface of zeolite particles could be observed in 15%TiO2/zeolite. It was found that the highest photocatalytic conversion of glucose (77.3%) was obtained from the use of 15%TiO2/zeolite as photocatalyst. The yields of gluconic acid, arabinose, xylitol, and formic acid were 8.6, 26.0, 3.7, and 33.89%, respectively.

Particle pyrolysis modeling and thermal characterization of pecan nutshell

A mathematical model for the pyrolysis process of pecan nutshells in a thermogravimetric balance was developed. The model included the application of mass and energy conservation equations that assumed that the milled nutshell had a spherical shape. A kinetic progressive conversion model (PCM) for the main biomass components was proposed in this work. The pecan nutshell was characterized through elemental and ultimate analyses. Additionally, thermogravimetry (TG) and differential scanning calorimetry (DSC) studies were conducted under pyrolytic conditions. The kinetic parameters and mass transport properties were obtained as a function of the particle size by adjusting the proposed model to fit the TG and DSC experimental data through a simplex optimization method. The best fitting of the proposed model was for particle diameters of 3 and 4 mm. The calculated activation energy values for hemicellulose were found to be very high when compared with values from other works, while the values for the cellulose and lignin were more similar. These results can be helpful in scaling up a pyrolytic pecan nut process, as well as improving the understanding of the phenomena involved during the pyrolysis.

Pyrolysis characteristics and kinetics of biomass torrefied in various atmospheres

This study aims at investigating into the pyrolysis characteristics and kinetics of torrefied Norway spruce obtained from our previous work on development of a biomass torrefaction process integrated with oxy-fuel combustion. Thermogravimetric analysis technique was employed to study the effects of different torrefaction conditions (including various torrefaction atmospheres and different temperatures) relevant to oxy-fuel combustion on the pyrolysis behavior of the torrefied biomass. Thereafter, a global kinetic model with an assumption of a three-pseudocomponent mechanism was used for kinetic modeling and evaluation. The results showed that torrefaction temperature and oxygen concentration in torrefaction gas have significant effects on the pyrolysis peak height and peak temperature of the torrefied biomass. In addition, more hemicellulose was removed during torrefaction in CO2, compared with torrefaction in N2 and CO2/H2O. Moreover, high oxygen concentration in torrefaction gas and high torrefaction temperature can completely remove hemicellulose. The kinetic evaluation revealed that non-oxidative torrefaction atmospheres do not influent the pyrolysis kinetics of three main biomass components, but only their contribution factors. However, the presence of oxygen in torrefaction gas and the torrefaction temperature have significant effects on the kinetic data.

Use of Extreme Vertices Method for Analysis of How Proportional Composition Affects Component Interactions and Product Distribution during Hydrothermal Treatment

The interaction among three biomass components (hemicellulose, cellulose, and lignin) in an autoclave was studied based on the extreme vertices of a constrained region that had a significant effect on the distribution and characteristics of the products. The mathematical model of the three components was established according to the yield distribution. Based on the model, the biomass components and the hydrothermal characteristics of biomass were predicted. Subsequently, the contents of the main biomass components were analyzed, thus eliminating the complicated testing process and providing a convenient and reliable calculation tool for determining the three biomass components. The gaseous products showed that products from cellulose hydrolysis promoted hemicellulose hydrolysis and generated large amounts of CO2. The lignin content, as well as the low cellulose and hemicellulose contents, inhibited the acids and ketones in light oil. In addition, the interaction among cellulose, hemicellulose, and lignin inhibited the production of acids in heavy oil and promoted phenolic synthesis. A series of hydrolysis product reactions such as polymerization and condensation were increased to produce a char at a high degree of aromatization by the interaction among the three components.

Cellulase Enzyme based Biodegradation of Cellulosic Materials: An Overview

Cellulose, a macromolecule of β -D- anhydroglucopyranose units linked by β (1,4)-glycosidic bonds, is the world’s most abundant organic polymer and is the main component of plant biomass that provides stability. Due to its sta-ble fibrous property, it has become one of the most important commercial raw materials for many industries. However, accumulation of waste cellulose due to natural and/or anthropogenic sources is a matter of concern in terms of environmental pollution. Wastes cellulosic substrates can be utilized as sources of energy through controlled hydrolysis using cellulases- a complex group of enzymes capable of degrading all types of cellulosic waste materials. A number of bacteria, fungi and insects are having the capability to degrade cellulose by production of cellulase enzymes. Further, the symbiotic insect-microbe relationships present in the insect gut microbiome for the production of cellulolytic system is of immense importance as this would lead to applications in different fields like biodegradation of cellulosic wastes, pollution reduction, biofuel production, insect/pest control etc. Cel-lulase gene can also be improved by genetic or protein engineering methods using recent technological advances. This review deals with the advances of cellulase enzymes and its utilization for different application.

Assessing Biological Impacts of Land Reclamation in a Mining Region in Canada: Effects of Dolomitic Lime Applications on Forest Ecosystems and Microbial Phospholipid Fatty Acid Signatures

The ability of an ecosystem to withstand serious disturbances may depend in part on the diversity of the system, with soil microbiological communities being coupled to their associated vegetation. The main objectives of the present study were (1) to determine the association between soil microbial diversity, abundance, and activities with diversity and sustainability of remediated mining-damaged ecosystems in Northern Ontario, and (2) to assess the effects of dolomitic lime applications on aboveground and belowground biodiversity and community structures. Results revealed that liming increases soil pH, cation exchange capacity (CEC), forest tree species diversity and abundance, and the overall ecosystem health even 25 to 35 years after dolomite applications. The mean Shannon index value was significantly higher in limed compared to unlimed sites. Tree species richness was 4.0, 6.0, and 7.7 for unlimed, limed, and reference sites, respectively. Overall, the mean health index revealed a significant improvement in population health in limed sites (index score = 7) compared to unlimed areas (index score = 4). Soil microbial biomass and respiration were also increased by liming. Surprisingly, the main component of soil microbial biomass in limed, unlimed, and reference sites within the vicinity of the restored lands was bacteria (mostly Gram (−). Significant difference was also observed between limed, unlimed, and reference sites for arbuscular mycorrhizal fungi, Gram (−) bacteria, Gram (+) bacteria, anaerobe, and actinomycetes abundance. The ratios between fungi and bacteria and among other phospholipid fatty acid (PLFA) measures were extremely low suggesting that the targeted region is still under environmental stress. No apparent associations among soil microbial biomass, soil respiration, and forest plant diversity or abundance were observed. Soil pH levels and organic matter amounts and quality appear to be the main factors affecting these parameters. Molecular analysis of main tree species within the impacted region revealed no change in genetic variation among plant populations on either limed or unlimed lands contaminated with metals over two generations.

Pyrolysis Treatment of Chromite Ore Processing Residue by Biomass: Cellulose Pyrolysis and Cr(VI) Reduction Behavior.

The pyrolysis treatment with biomass is a promising technology for the remediation of chromite-ore-processing residue (COPR). However, the mechanism of this process is still unclear. In this study, the behavior of pyrolysis reduction of Cr(VI) by cellulose, the main component of biomass, was elucidated. The results showed that the volatile fraction (VF) of cellulose, ie. gas and tar, was responsible for Cr(VI) reduction. All organic compounds, as well as CO and H2 in VF, potentially reduced Cr(VI). X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine-structure (EXAFS) spectroscopy confirmed the reduction of Cr(VI) to Cr(III) and the formation of amorphous Cr2O3. The remnant Cr(VI) content in COPR can be reduced below the detection limit (2 mg/kg) by the reduction of COPR particle and extension of reaction time between VF and COPR. This study provided a deep insight on the co-pyrolysis of cellulose with Cr(VI) in COPR and an ideal approach by which to characterize and optimize the pyrolysis treatment for COPR by other organics.

Prediction of pyrolysis kinetic parameters from biomass constituents based on simplex-lattice mixture design

The aim of this study is to determine the effect of the main chemical components of biomass: cellulose, hemicellulose and lignin, on chemical kinetics of biomass pyrolysis. The experiments were designed based on a simplex-lattice mixture design. The pyrolysis was observed by using a thermogravimetric analyzer. The curves obtained from the employed analytical method fit the experimental data (R2>0.9). This indicated that this method has the potential to determine the kinetic parameters such as the activation energy (Ea), frequency factor (A) and reaction order (n) for each point of the experimental design. The results obtained from the simplex-lattice mixture design indicated that cellulose had a significant effect on Ea and A, and the interaction between cellulose and lignin had an important effect on the reaction order, n. The proposed models were then proved to be useful for predicting pyrolysis behavior in real biomass and so could be used as a simple approximation for predicting the overall trend of chemical reaction kinetics.

NMR analysis of the binding mode of two fungal endo-β-1,4-mannanases from GH5 and GH26 families.

The enzymatic digestion of the main components of lignocellulosic biomass, including plant cell wall mannans, constitutes a fundamental step in the renewable biofuel production, with great potential benefit in the industrial field. Despite several reports of X-ray structures of glycoside hydrolases, how polysaccharides are specifically recognized and accommodated in the enzymes binding site still remains a pivotal matter of research. Within this frame, NMR spectroscopic techniques provide key binding information, complementing and/or enhancing the structural view by X-ray crystallography. Here we provide deep insights into the binding mode of two endo-β-1,4 mannanases from the coprophilous ascomycete Podospora anserina, PaMan26A and PaMan5A, involved in the hydrolysis of plant cell wall mannans and heteromannans. The investigation at a molecular level of the interaction between the wild-type enzymes and inactive mutants with manno-oligosaccharides, revealed a different mode of action among the two glycoside hydrolases most likely due to the presence of the additional and peculiar -4 subsite in the PaMan26A binding pocket.

Pyrolysis reaction networks for lignin model compounds: unraveling thermal deconstruction of β-O-4 and α-O-4 compounds

Although lignin is one of the main components of biomass, its pyrolysis chemistry is not well understood due to complex heterogeneity.

Characteristics of Biochar Obtained by Hydrothermal Carbonization of Cellulose for Renewable Energy

The effect of hydrothermal carbonization on the properties of cellulose present in lignocellulosic biomass was investigated for converting it into a renewable energy resource with high energy recovery efficiency. The biochar obtained from cellulose subjected to hydrothermal carbonization showed a significant increase in its carbon content and a calorific value. 13C NMR spectroscopy showed that when raw cellulose was subjected to hydrothermal carbonization above 220 °C, the resulting biochar had more aromatic and aliphatic fractions than those in raw cellulose. The resulting composition of the biochars was comparable to that of solid fuels and was between that of lignite and sub-bituminous coal. Therefore, cellulose, the main component of lignocellulosic biomass, was used to investigate the effects of varying the reaction temperature during hydrothermal carbonization. The energy recovery efficiency calculations showed that the optimum reaction temperature for the transformation of a mixture of cellulose was approximately 220 °C.

Deep Eutectic Solvents: Fractionation of Wheat Straw

Deep eutectic solvents (DESs) are a relatively new topic in science. Their usage is not yet clearly defined, and the areas in which DESs may be applied are constantly growing. A simple and clean fractionation of the main components of biomass represents a very important step in creating a clean, renewable carbon economy. A major challenge is the use of DESs for fractionation of biomass components at lower temperatures, without the use of expensive raw materials. In this work, wheat straw was pretreated with six different DES systems composed of choline chloride with urea (1:2), malonic acid (1:1), lactic (1:9; 1:10), malic (1:1), and oxalic acid (1:1). The pretreated biomass was characterized in terms of lignin content, ash, and holocellulose. A deep eutectic solvent, composed of choline chloride and oxalic acid, was found to produce the best delignification results. The solvents are not selective in the process of delignification.

Characterization and identification of the xylanolytic enzymes from Aspergillus fumigatus Z5.

BackgroundPlant biomass, the most abundant natural material on earth, represents a vast source of food and energy in nature. As the main component of plant biomass, xylan is a complex polysaccharide comprising a linear β(1,4)-linked backbone of xylosyl residues substituted by acetyl, arabinosyl, glucuronysyl and 4-O-methylglucuronycyl residues.ResultsAspergillus fumigatus Z5 is an efficient plant biomass depolymerization fungus. In this study, its crude xylanolytic enzymes were characterized and identified by two-dimensional gel electrophoresis (2-DE). The optimal temperature for the crude xylanases was close to 60 °C, the highest xylanase activity was achieved at pH ranged from 3 to 6, and the crude xylanases also showed a very broad region of pH (3–11) stability. The maximal xylanase activity of 21.45 U · ml−1 was observed in the fourth day of cultivation at 50 °C and 150 rpm with 2 % xylan as the sole carbon source. Zymogram analysis indicated that there were more than seven secreted proteins with xylanase activity. In the crude enzyme, two major endoxylanases, five cellulases and several associated enzymes were identified to be involved in the hydrolysis of polysaccharides. Of the total 13 xylanase genes in the Z5 genome, 11 were observed using q-PCR to be induced by xylan, one of which, An endo-1,4-β-xylanase with a low secretion level, was also expressed and characterized. The final hydrolysis products of xylan by crude enzyme mainly consisted of xylobiose.ConclusionsThis study provides a comprehensive understanding of the depolymerization of xylan by Z5 and will help to design enzymatic strategies for plant biomass utilization.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0463-z) contains supplementary material, which is available to authorized users.

Production of depolymerized lignin resin material from lignocellulosic biomass using acetone–water binary solution

The use of lignin, one of the main components of biomass, has only been for the recovery of energy through the combustion due to its complex structure. However, it needs to be used as more valuable material to make biorefinery feasible. In this study, the development of the lignin conversion method into resin materials was examined. Lignin was extracted from biomass with acetone/water binary solution at 220°C. The extracted lignin solution was treated under the severer condition for the depolymerization using flow reaction system. Through these two-step treatment, the extracted lignin was depolymerized to Mw<1000 fractions, which possessed many active sites for curing. More than 76.8% of lignin were recovered as depolymerized lignin through the whole treatment. The depolymerized lignin showed a fine activity of uniform curing with 10–15 per hundred resins (phr) of hexamine at 150°C. This resinification method of lignin was confirmed to be adaptive to some types of biomass, despite the belonging groups such as a coniferous tree, a broadleaf tree, or herbaceous biomass. One of thus produced resins was confirmed to be the competitive resin with a conventional phenolic novolac resin.

Kinetic analysis of biomass pyrolysis using a double distributed activation energy model

Pyrolysis is a fundamental step in thermochemical processes of biomass materials, so a suitable kinetic model is an essential tool to predict the evolution of the resulting products of reaction. However, many difficulties arise in modeling this process step due to the very high number of the involved reactions. In this work, a new double-Gaussian distributed activation energy model was applied in fitting the experimental data of olive residue pyrolysis obtained by thermogravimetric analysis. 2-DAEM formulation considers two sets of parallel reactions occurring and sharing the same pre-exponential factor, but shows different distributions of the activation energy, described by two separate Gaussian distributions that, in turn, grasp the two pyrolysis steps with a high accuracy. Since it is well known that in fitting all the kinetic parameters the pre-exponential factor results highly correlated with the activation energy, the former parameter was separately estimated as a linear combination of the values obtained for the three main biomass components, cellulose, hemicellulose and lignin.

Tailoring Biomass for Biochemical, Chemical or Thermochemical Catalytic Conversion

Biomass has one‐third the energy density of crude oil and lacks petroleum's versatility as a feedstock for fuels and chemicals. Chemical catalysis and fast pyrolysis can overcome these limitations by transforming the main components of biomass (cellulose, xylan, and lignin) from grasses and trees directly to liquid hydrocarbons and aromatic co‐products. Our data show that, regardless of conversion process, biomass structural complexity at molecular, nanoscale, and mesoscale levels impacts the yields and selectivities of desired reaction products from catalytic and pyrolytic transformations. Therefore, we have modified the composition and architecture of cell wall components to optimize post‐conversion product yields without compromising pre‐conversion biomass yields. Our strategies to deliver metal catalysts throughout the cell wall structure and create functionalized sites ready for catalytic transformations may dramatically increase the effective surface area for catalysis of cellulose and xylan. Genetic redesign of the lignin network simplifies its architecture to enable facile catalytic disassembly and conversion of aromatics. Prior disassembly of about half of the lignin from intact woody biomass using a catalytic system dramatically improves subsequent saccharification yield and allows a re‐visioning of the cellulosic biorefinery concept.

Biochemical changes in cyanobacteria during the synthesis of silver nanoparticles.

The methods of synthesis of silver (Ag) nanoparticles by the cyanobacteria Spirulina platensis and Nostoc linckia were studied. A complex of biochemical, spectral, and analytical methods was used to characterize biomass and to assess changes in the main components of biomass (proteins, lipids, carbohydrates, and phycobilin) during nanoparticle formation. The size and shape of Ag nanoparticles in the biomass of both types of cyanobacteria were determined. Neutron activation analysis was used to study the accumulation dynamics of the Ag quantity. The analytical results suggest that the major reduction of Ag concentration in solutions and the increase in biomass occur within the first 24 h of experiments. While in this time interval minor changes in the N. linckia and S. platensis biomass took place, a significant reduction of the levels of proteins, carbohydrates, and phycobiliproteins in both cultures and of lipids in S. platensis was observed after 48 h. At the same time, the antiradical activity of the biomass decreased. The obtained results show the necessity of determining the optimal conditions of the interaction between the biomass and the solution containing Ag ions that would allow nanoparticle formation without biomass degradation at the time of Ag nanoparticle formation by the studied cyanobacteria.

Characterization of the anhydrosugar content in pyrolysis liquids with column chromatography and iodometric titration

Since cellulose and hemicelluloses along with lignin are the main components of biomass, fast pyrolysis of wood yields a complex mixture of products, among which sugars and anhydrosugars are one of the most abundant and valuable components. Because of the presence of high molecular compounds, this sugar mixture of pyrolysis products has proven to be difficult to analyze. In this study, research has been done to improve the characterization of pyrolysis liquids by sample separation on an ion exchange resin. In order to characterize the pyrolysis liquids, an iodometric titration method is used to determine sugar and anhydrosugar content in the pyrolysis liquids with and without sample separation on an ion exchange column.