Biomass Char Research Articles

Towards furfural and biomass char production from Camellia oleifera husks using dilute hydrochloric acid pretreatment: a comprehensive investigation on adsorption performance

The whole component utilization of lignocellulose was achieved, and hemicellulose was used to prepare FF which was adsorbed with S-8 macroporous resin and purified. The residue including cellulose and lignin was converted to biomass char, which was used for the adsorption of methylene blue dye.

Biomass char gasification kinetic rates compared to data, including ash effects

This investigation provides both experimental and theoretical analyses of biomass char gasification kinetics over 1150–1350 °C in the environment of CO2, H2O and combinations of these reactants. The experimental data include continuous measurements of particle mass, external and internal temperatures, shape, and size with periodic but not continuous measurements of char porosity, pore size distribution, and pore surface area. The model describes heterogeneous char gasification for poplar wood, corn stover and switchgrass in different shapes and industrially relevant sizes (12.5 mm and smaller). Nonlinear least-squares regression produces optimized power-law model parameters for global kinetics that describe biomass char gasification with respect to both CO2 and H2O separately and in combination. A single set of kinetic parameters describes reaction rates for all three fuels. Model simulations agree with measured data at all stages of char conversion even though the observed mass loss rates change significantly with conversion. The change in rate with conversion depends strongly on ash content, and this investigation provides a simple and theoretically based reaction rate expression that includes the effect of inert ash occupying an increasing portion of the reactive surface with increased conversion.

Comparative investigation on the pyrolysis of crop, woody, and herbaceous biomass: Pyrolytic products, structural characteristics, and CO2 gasification

Pyrolysis and gasification are efficient clean energy conversion technologies used in energy research. Clean utilization of biomass energy can effectively alleviate severe energy challenges in the world. In this study, wheat straw, peach wood, and bamboo were pyrolyzed in a quartz tube furnace, and the pyrolysis gas production and physical and chemical properties of the char products were analyzed systematically. The CO2 gasification performance of the pyrolyzed char was investigated experimentally. The results indicated that the pyrolysis temperature had a significant effect on char properties. A high pyrolysis temperature accelerates the gas release rate and improves the final gas production. As the pyrolysis temperature increased, the quality of the char decreased, and the O/C and H/C molar ratios of the biomass char decreased gradually. The char calorific value was also affected by the temperature. The Fourier Transform Infrared Spectroscopy (FTIR) results demonstrated that the functional groups of the biomass decomposed. Scanning Electron Microscope (SEM) images indicated that as the pyrolysis temperature increased, pore development expanded, and various folds appeared on the surface. The fractal box dimensions first increased and then decreased. The specific surface area and micropore volume of the char first increased and then decreased; however, the temperature at which the peak value occurred was slightly different. In the gasification experiment, the peach wood char prepared by pyrolysis at 600 °C had a superior gasification effect. Biomass with a lower ash content, higher O/C ratio, and more developed pore structure exhibited superior gasification performance. The conclusions of this study have important reference value for large scale, clean, and efficient utilization of biomass resources.

Reactivity and Stability of Different Red Muds as Oxygen Carriers for Chemical Looping Combustion of Methane and Biomass in a Fluidized Bed

The reactivity and stability of two low-cost red muds (LuShan and XinFa) as oxygen carriers for chemical looping combustion (CLC) were experimentally investigated in a fluidized bed, with methane and biomass char, respectively. CH4 conversions using the present red muds were quite low, <20% after stable cycles. The XinFa red mud had better reactivity and stability in comparison with the LuShan red mud, with its CO2 selectivity maintained at about 80% during 50 cycles. Due to the high content of Ca in the LuShan red mud, its promoting effect on the water–gas shift reaction led to continuous high H2 production during biomass char-fueled experiments. The XinFa red mud achieved a complete conversion of char with only CO2 as the gaseous product. Further, it showed better resistance to attrition. The agglomeration affinity in the case of using biomass char as fuel was stronger than that when using methane as fuel. NaAlSiO4 with a high melting point was detected in both fresh and cycled oxygen carriers. Ca2Al2SiO7 was found in the LuShan red mud due to the interactions among Ca, Al, and Si at elevated temperatures.

Analysis of model dimensionality, particle shrinkage, boundary layer reactions on particle-scale modelling of biomass char conversion under pulverized fuel combustion conditions

In this work, the effects of model dimensionality, particle shrinkage, and boundary layer reactions on particle-scale modelling of biomass char conversion under pulverized fuel combustion conditions have been analysed by using six models: zero-dimensional models with constant particle size (0D_Cons) or shrinking particle size (0D_SPM), one-dimensional models with/without considering particle shrinkage (1D_Cons/1D_SPM), and 1D_Cons and 1D_SPM with considering boundary layer reactions (1D_Cons_BH and 1D_SPM_BH). A comparison with existing experimental data shows that the 1D_SPM_BH model with consideration of intra-particle heat and mass transfer, particle shrinkage, and boundary layer reactions is an appropriate model to describe biomass char conversion over a wide range of conditions. The 0D_Cons model is a good approximation for the conditions of small particle size (< 1 mm) at 1273–1473 K, but overestimates the char conversion rate for larger biomass char particle or at high temperatures (regime III). The 0D_SPM model gives a reasonable prediction on char conversion time but predicts a larger contribution of reaction between char and O2 as compared to the 1D_SPM_BH model. The consideration of intra-particle heat and mass transfer in particle-scale modelling (1D_Cons and 1D_SPM) is beneficial to improving the model prediction of char conversion time and the contributions of char oxidation and gasification reactions. The boundary layer reactions have a significant effect on the prediction of char conversion for large particles (> 1 mm) and high temperatures (> 1473 K). An implication for the selection of a particle-scale model in CFD modelling is also given.

Thermoelectric Micro-Scale Generation by Carbonaceous Devices

The paper reports on research focused on the use of largely available carbonaceous materials, such as graphite, carbon black and chars, as thermoelectric materials for micro-generation at high temperature. The key feature is the possibility to ignite the thermoelectric device to self-sustain electric generation. The results of the tests performed with such materials, under both cold and hot conditions, showed that a significant change of the electromotive force, with absolute increase up to three orders of magnitude, occurred under hot conditions with flame irradiation, achieving measured values of electromotive force up to 55 mV, in the best case. Monoliths based on biomass chars and covered with a layer of gunpowder gave rise to similar variation of the Seebeck coefficient, as the case of the flame exposed samples. This result confirms the basic idea of the investigation and the possibility of generating an electrical peak in a self-sufficient combustion thermoelectric device with power up to 1.0 W. A theoretical assessment has been proposed to provide an interpretation of the observed phenomenology, which is related to the non-linear dependence of the material properties on temperature, in particular the Seebeck coefficient and thermal conductivity.

In-situ study on structure evolution and gasification reactivity of biomass char with K and Ca catalysts at carbon dioxide atmosphere

The structural evolution and gasification reactivity of biochar prepared from the pyrolysis of wheat straw were investigated by in-situ Raman spectroscopy and thermogravimetric analysis. The Raman spectra consisted of a combination of four Lorentzian bands (D1, D2, D4, G) and one Gaussian band (D3) in the first-order region. The experimental results showed that the addition of catalysts or the presence of ash could improve the CO2 gasification reactivity of biochar and result in a larger ID1/IG ratio and a lower IG/IALL ratio, meaning that the carbon structure was less ordered, and there were also more active sites such as amorphous carbon and cross-linked structures; Ca-based catalysts and K-based catalysts changed the evolution of biochar structure in a different way in CO2 atmosphere, the ID3/ID1 of Ca-based biochar was close to the value of non-catalyst biochar and decreased slowly, indicating that the Ca-based catalysts can stabilize the aromatic rings, while the IG/IALL of K-based biochar decreases significantly and the ID3/ID1 increased significantly, indicating the increase of carbon structure defects and the cracking of large aromatic rings in bio-char into small ones; a scheme of K and Ca reaction with biochar in CO2 gasification process was proposed.

Comprehensive effects of different inorganic elements on initial biomass char-CO2 gasification reactivity in micro fluidised bed reactor: Theoretical modeling and experiment analysis

In this study, a theoretical model of biomass char gasification reactivity was developed, focusing on the catalytic effect of inorganic elements on the char gasification process. A comparison with previous research results shows that the catalytic ability of K in a fixed bed reactor is stronger than that of Ca, while the catalytic ability of Ca in a fluidised bed reactor is stronger than that of K. The migration and transformation of K and Ca in a fixed bed reactor and fluidised bed reactor are compared. In the fluidised bed reactor, a larger proportion of Ca is transformed into an ion-exchanged state than K, which is contrary to the experimental results in the fixed bed reactor. Then, according to the equivalent-volumetric impregnation method, the saturated loading ratio of K was determined to be 35%, and the full catalytic ratio of K was determined experimentally. Finally, eight typical biomass char samples were selected to perform experiments at different temperatures in the micro fluidised bed reactor to determine the char gasification reactivity, and the results were compared with the calculated values of the model. Results show that the model can effectively predict the char gasification reactivity both in trend and accuracy.

Pore-Resolving Simulations of Biomass Char Particle Combustion

Biomass char morphology affects combustion behavior at the particle scale for zone II conditions, in which both heterogeneous reaction and intra-particle diffusion govern the overall rate. Furthermore, particle-scale processes affect reactor-scale outputs, and reactor-scale simulations are sensitive to particle-scale models. However, most char particle combustion models employ coarse-grained, effective-continuum approaches, which treat all porosity at the subgrid-scale. Effective-continuum approaches are not valid or accurate in the presence of large, irregular pores which can approach the size of the particle. A 3-D, pore-resolving CFD simulation approach using real biomass char particle geometries obtained from X-ray micro-computed tomography (micro-CT) is therefore used to examine the impact of morphology on zone II combustion for pulverized (∼100 µm) biomass char particles for the first time. In contrast to larger, millimeter to centimeter sized particles, the sub-millimeter, high aspect ratio biomass char particles exhibited localized reactant penetration into the innermost regions of the particles, facilitated by the presence of large pores connected to the external surface. The oxygen mole fraction distributions were governed by the large pore morphology, were non-monotonic with distance from the surface, and achieved minima in thick microporous char regions surrounding the large pores. A comparison between the pore-resolving simulation and an equivalent, spatially resolved, effective-continuum simulation revealed that even in the microporous char, the effective-continuum model underpredicted reactant penetration. A careful comparison was then performed between 30 pore-resolving particle simulations and several effectiveness factor models that employed particle-specific parameters. Commonly used uniform cylinder models significantly underpredicted effectiveness factors for these real pulverized pine char particles, while accessible hollow cylinder models achieved less than 10% relative error when averaged over all 30 particles.

Influence of the synergistic effects and potassium on the combustion behaviors of biomass under high heating rate

This work aims to study the synergistic effects between lignin, hemicellulose, and cellulose, as well as potassium on the combustion behaviors of biomass at high heating rate conditions. The combustion behaviors of biomass are studied in a Hencken flat burner with a high-speed camera, and the radiant energy analysis technology is used to calculate the flame temperature. The results indicate that the ignition delay time (IDT) and the char ignition delay time (IDT-CHAR) increase with the increase of the cellulose content when the cellulose content in biomass is less than 41%, and decrease significantly when the cellulose content is more than 41%. The homogeneous ignition of the cellulose and lignin with removing alkali metals (LIG-R) mixtures is not affected by the synergistic effects between cellulose and LIG-R. The catalysis of potassium significantly promotes the synergistic effects between cellulose and lignin without removing alkali metals (LIG-NR) in the blending ratio range from 50% to 75%, and the rapid decomposition of cellulose provides hydrogen donors for the pyrolysis of lignin and accelerates the release of combustible matters in lignin, resulting in the promotion of the homogeneous ignition. The promoted homogeneous ignition results in the significant decrease in the ignition of the biomass which has higher ratios of cellulose and lignin (50%-75%) and higher cellulose content (more than 40%). The catalysis of potassium on the synergistic effects between cellulose and lignin for the biomass homogeneous ignition and char ignition need to satisfy-two conditions: (1) the mass ratio of cellulose in the mass sum of cellulose and lignin in biomass should be in the range of 50%-75%, and (2) the cellulose content should be greater than 40%.

Hydrogen-rich syngas production form biomass char by chemical looping gasification with Fe/Ca-based oxygen carrier

Iron based oxygen carrier is attractive for chemical looping gasification due to its abundance, however it suffers low reactivity. Several materials have been utilized in the literatures to solve this issue, of which Ca is promising. In this work, iron has been modified by two Ca ratios to obtain CaFe2O4 and Ca2Fe2O5 oxygen carriers via sol–gel method. Oxygen carriers have compared in hydrogen-rich syngas production form biomass char in a fixed-bed system, and the effect of temperature and cycling ability have also considered. A series of characterizations including X-ray diffraction, scanning electron microscope, H2-temperature-programmed reduction, nitrogen adsorption and desorption and X-ray photoelectron spectroscopy were utilized to investigate the fresh and spent oxygen carriers. The result showed that the CaFe2O4 sample obtained an excellent H2 yield (0.87Nm3/kg) at 750℃ and oxygen carrier: biochar ratio of 1:1. Compared with gas–solid and solid–solid reactions at different temperature, the only CO and CO2 were produced in solid–solid reaction, and the conversion activity of CO into CO2 noticeable increase with raising temperature. On the other hand, the H2 is dominant component on production, and the H2 yield (2.0 Nm3/kg) was a maximum at 850 ℃. In the cycle experiment, the H2 yield was stable through 5th cycles. However, the Si generated by biochar cause the destruction of CaFe2O4, decreasing the CO production and conversion.

Predictions of burnout times of biomass char using experimentally determined CO to CO2 ratio

The ratio of CO to CO2 produced during char combustion is an important parameter affecting the temperature of the char particle, the rate of mass transfer of gaseous species to and from the surface of the particle, and, consequently, the burnout time. In the present work, the ratio of CO to CO2 from combustion was measured for a biomass char using a thermogravimetric method. A sample of biomass char was combusted in conditions where the process was entirely limited by transfer of oxygen to the external surface of the fuel particles. The experimentally-obtained rate of combustion was compared with the expected rate of CO and CO2 transport, from which the ratio of CO to CO2 was calculated. The CO/CO2 ratio was determined for a char derived from birch wood and the results were compared with those from graphite and activated carbon at the same conditions. The experiments were conducted at various temperatures between 973 and 1173 K, with a range of partial pressures of oxygen in the oxidising gas from 0.0057 to 0.023 bar.The experimental CO/CO2 ratios were used to model the combustion of a single particle of char, predicting the total burnout time. Two models were developed: (1) an analytical solution for the burnout time assuming pseudo-steady state combustion, and (2) a numerical model of a char particle, accounting for gas transport and the combustion reaction inside the porous fuel particle. To validate the models, a separate set of experiments was performed where single particles of birch wood (6 mm dia.) were mounted on the tip of a thin thermocouple, then inserted into a hot reactor through which was flowing N2. The wood particle pyrolysed, leaving a single particle of char (∼4 mm dia.). The char was then burned in a laminar flow of oxidising gas. The burnout times obtained with both models agreed well with the experimental results. Commonly-used empirical expressions for CO/CO2 ratios from the literature were also employed in simulations but were found to under-predict the burnout time.

Molecular-scale elucidating of lignocellulose biomass char steam gasification for ultimately converting to syngas

Lignocellulosic biomass char gasification plays an irreplaceable role in alleviating environmental problems caused by greenhouse effects. Elucidating the molecular-scale gasification mechanism is significant in ultimately converting the lignocellulosic biomass char to clean syngas and reducing pollutant emissions. In this study, the molecular-scale structure of sawdust char (SC) is carefully established using 13C NMR, FTIR, and XPS. The results compare well with the results of previous work. The mechanism of its steam gasification is investigated by molecular dynamics simulation. Results show that the main products of the gasification process after complete reaction are H2 and CO, and CO is always released before H2. The gasification equivalent ratio decreases, H2 increases significantly and is more from steam. The maximum carbon number of single molecule in the product is re-increased, and the increase of H2O molecules hinders the decomposition of light tar into small molecules of gas. The reaction mechanism is clearly defined: the aromatic carbon rings substituted by oxygen-containing functional groups are firstly gasified, followed by bridge bond breakage of the macromolecular char into several multiple aromatic rings. Each of the rings is gasified separately and ring-opening to form C5-C13 (light tar). Finally, C5-C13 completes the conversion to generate a large amount of H2, accompanied by CH4 reforming and dehydrogenating small molecule compounds. The migration paths of N elements are pyrrole (N)→CN→CON→C1-3H1-3N→HCN. This work elucidates the steam gasification process of lignocellulosic biomass char at a molecular scale, which provides a theoretical basis for the clean utilization of biomass and CO2 reduction.

Assessment of utilization potential of biomass volatiles and biochar as a reducing agent for iron ore pellets

ABSTRACT India is an agricultural country and near about 500 MT of agricultural wastes are generated each year. India has huge reserves of low-grade iron ore fines. Therefore, considering the availability of these two, the present study mainly focuses on utilization of solid waste in iron and steel industry; also, biomass being carbon-neutral fuel, promotes mitigation of environmental issues. To carry out this study, agricultural wastes like groundnut shell and corn cob which contain more than 70% of volatile matter were considered. Hence, an attempt has been taken to utilize this volatiles as well as char (prepared at 350°C) of corn cob and groundnut shell as a reducing agent for reduction of iron ore pellets. Maximum reduction percentage was achieved at 1000°C and 75 min using corn cob as a reductant, i.e. 78.38% with its volatile and 92.01% using its char. Higher intensity of elemental iron is also reflected by X-ray Diffraction analysis of reduced pellets. Further, cost estimation of reduction of iron ore pellets was also done using both the reducing agents, which signifies that the reduction process using biomass volatiles is much more economical than biochar. The total cost of producing DRI from corn cob volatiles is 56% less than coal followed by groundnut shell volatiles 53.36% and minimum in the case of groundnut shell char 36.17%. Highlights Effects of biomass volatiles and char on iron ore pellets reduction @ 1000°C at different time interval of 15, 30, 45, 60 & 75 min. Comparative assessment of iron ore pellets reduction through XRD and FESEM analysis. Economic evaluation of iron ore reduction using volatiles and char of biomass.

Insight into the relationship between CO2 gasification characteristics and char structure of biomass

Biomass gasification consists of three thermochemical stages: drying, pyrolysis, and char gasification, of which char gasification is the rate-limiting step. This study compared the char structure of biomass components (cellulose, hemicellulose, lignin, starch, and pectin) and revealed its quantitative relationship with the CO2 gasification reaction rate. Gasification experiments were performed in a self-built macro-thermogravimetric analyzer (Macro-TGA), and the char was characterized by proximate analysis, ultimate analysis, Fourier transform infrared (FTIR) spectroscopy, N2 adsorption/desorption isotherm, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The char gasification starting temperature from low to high was pectin ≈ starch < lignin < xylan. SEM revealed that the cellulose and starch chars had larger block structures. According to the FTIR results, the hydroxyl groups in the char enhanced the reactivity of char gasification. C–C/C=C was the dominant functional group in char, and O-containing groups, especially C–O, positively affected char gasification reactivity. It was found that the relationship between the gasification mass loss rate r and the char structure was r = 0.384 × surface area0.12 × ash content0.24. This study helps understand the relationship between biomass char gasification and its structure.

Chemical Looping Combustion of a Biomass Char in Fe2O3-, CuO-, and SrFeO3−δ-Based Oxygen Carriers

This research focuses on the combustion of biomass char in fluidized beds of various particulate solids, which, under the conditions of the reaction, were either inert or capable of supplying oxygen to reactions. The latter were termed oxygen carriers. The solids used were SiO2, as an inert material, and three oxygen carriers: (1) Fe2O3 prepared from a natural pyrite ore, (2) CuO supported on mayenite, and (3) SrFeO3−δ strontium ferrite perovskite. Combustion experiments were undertaken by introducing a sample of partially devolatilized biomass (commercial “biochar”) to a hot bubbling bed (inner diameter of 30 mm), fluidized by a mixture of oxygen and nitrogen, then analyzing the composition of the off-gas and the burnout time of the char sample. In the temperature range investigated in this work (1023–1168 K), CuO and SrFeO3−δ but not Fe2O3 thermally decomposed, releasing gaseous O2 [so-called “chemical looping oxygen uncoupling” (CLOU)]. Hence, to make the combustion conditions comparable to various oxygen carriers, all experiments were performed using a fluidizing gas with a fixed partial pressure of O2 (pO2) of ∼0.015 bar. Despite the same nominal pO2, the occurrence of the oxygen uncoupling reaction increased the total net amount of O2(g) available in the process, affecting external mass transfer of O2 to the char particle and accelerating its rate of combustion. The time needed to totally combust 0.1 g of biochar particles in different beds at 1168 K followed the trend CuO < SrFeO3−δ < Fe2O3 ≈ silica sand. The difference in the performance of CuO and SrFeO3−δ was ascribed to the lower oxygen availability via CLOU in perovskite compared to copper oxide. Interestingly, combustion in the bed of Fe2O3 particles took a similar amount of time as combustion in the inert bed of SiO2, despite iron oxide playing an active role in the process. The finding is explained by Fe2O3 reacting with CO produced from incomplete char combustion, which results in the reduced oxide competing with char for O2(g) and effectively decreasing the local pO2.

Effect of the Mass Conversion Degree of an Oxygen Carrier on Char Conversion and Its Implication for Chemical Looping Gasification.

Chemical looping gasification (CLG) is an emerging process that aims to produce valuable chemical feedstocks. The key operational requirement of CLG is to limit the oxygen transfer from the air reactor (AR) to the fuel reactor (FR). This can be accomplished by partially oxidizing the oxygen carrier in the AR, which may lead to a higher reduction degree of the oxygen carrier under the fuel conversion. A highly reduced oxygen carrier may experience multiple issues, such as agglomeration and defluidization. Given such an interest, this study examined how the variation of the mass conversion degree of ilmenite may affect the conversion of pine forest residue char in a fluidized bed batch reactor. Ilmenite was pre-reduced using diluted CO and then underwent the char conversion at 850, 900, 950, and 975 °C. Our investigations showed that the activation energy of the char conversion was between 194 and 256 kJ/mol, depending upon the mass conversion degree of ilmenite. Furthermore, the hydrogen partial pressure in the particle bed increased as the oxygen carrier mass conversion degree decreased, which was accompanied by a lower reaction rate and a higher reduction potential. Such a hydrogen inhibition effect was confirmed in the experiments; therefore, the change in the mass conversion degree indirectly affected the char conversion. Langmuir–Hinshelwood mechanism models used to evaluate the char conversion were validated. On the basis of the physical observation and characterizations, the use of ilmenite in CLG with biomass char as fuel will likely not suffer from major agglomeration or fluidization issues.

Determination of size and porosity of chars during combustion of biomass particles

This research focused on the size and overall porosity (pore volume) of carbonaceous chars, originating from high-heating rates and high-temperature pyrolysis and/or combustion of biomass. Emphasis was given to torrefied biomass chars. First, the porosity of char residues of single biomass particles of known mass was determined, based on an assumed value of skeletal density and by comparing experimentally observed temperature-time histories with numerical predictions of their burnout times. The average char porosities (effective porosities) of several raw and torrefied biomass particles were calculated to be in the range of 92–95%. Thereafter, these deduced porosity values were input again to the model to calculate the size of chars of other biomass particle precursors, whose initial size and mass were not known. Such biomass particles were sieve-classified to different nominal size ranges. This time, besides the porosity, representative time-temperature profiles of biomass particles in the aforementioned size ranges were also input to the model. Biomass particles are highly irregular with large aspect ratios and, in many cases, they melt and spherodize under high heating rates and elevated temperatures. Knowledge of the initial size of the chars, upon extinction of the volatile flames, is needed for modeling their heterogeneous combustion phase. For this purpose, numerical predictions were in general agreement with measurements of char size obtained from both scanning electron microscopy of captured chars and real-time high-speed, high-magnification cinematographic observations of their combustion. Results showed that the generated chars of the examined biomass types were highly porous with large cavities. The average initial dimension of the chars, upon rapid pyrolysis, was in the range of 50–60% the mid-value of the mesh size of the sieves used to size-classify their highly irregular parent biomass particles.

Impact of biomass constituent interactions on the evolution of char’s chemical structure: An organic functional group perspective

An in-depth investigation of the chemical structural evolution of char throughout the pyrolysis process is critical for subsequent biochar utilization. Therefore, the interaction mechanism among biomass constituents was studied by the examination of product distribution, bio-oil and bio-gas composition, organic functional groups, and two-dimensional correlation infrared spectrum characteristic of char. Char evolution was influenced by primary interaction (at 300 or 400 °C) and secondary interaction (at 500 or 650 °C). Polymer depolymerization and phenylpropane side chain breaking were aided by the primary interaction. Due to a “melting and wrapping” effect, it hindered ring opening, recombination, and polymerization of D-allose/D-xylose molecules, allowing the char to preserve its original C-O-C and C-OH structure. The secondary interaction stimulated the cyclization and intramolecular dehydration of D-allose, leading pyrolysis to advance to the pyran pathway. It also encouraged the ring opening, cyclization, rearrangement, and polymerization of monomer molecules, resulting in the char's C = O, C = C, and C-OH structures with greater aromatization degree. The discovery advances the understanding of the interacting mechanism of biomass pyrolysis and char formation.

Preparation of coke from biomass char modified by vapour deposition of tar generated during pyrolysis of woody biomass

ABSTRACT In this study, in order to use woody biomass for coke production, carbon/carbon composites are first prepared using the vapour deposition (VD) method, whereby gaseous-tars generated by the pyrolysis of pine sawdust is deposited onto the pyrolysed pine sawdust char by a vertical flow-type fixed-bed reactor with pyrolysis and VD zones. Then, coke properties and gasification reactivity of composite and composite/coal blends are investigated to clarify the binder effect of biomass tar on the properties of prepared coke. The carbon/carbon composites could be prepared with a high yield at a low VD temperature. High-strength and high-reactivity coke was produced from the composite. The properties of the coke produced from composite/caking coal blending showed that the optimum blending amount depends on the type of caking coal, but high-strength and high-gasification reactivity coke can be produced. Additionally, it was found that 3–15wt-%-biomass could be added as char for coke production.