Apparent Reaction Order Research Articles

Study of the curing kinetics of melamine/phthalonitrile resin system

The exploration of curing process is important for the application of phthalonitrile resins in advanced materials. In this study, the curing behaviors of 1,3-bis (3,4-dicyanophenoxy) benzene (3BOCN) and melamine (MI) system was studied by differential scanning calorimetry (DSC) at different heating rates. An autocatalytic model could describe the curing reaction of 3BOCN-MI. The curing parameters including apparent activation energy, reaction orders and pre-exponential factor were calculated. The average activation energies for the three different proportions of 3BOCN-MI (8:1, 8:2, 8:3) system were 93, 98 and 96 kJ/mol, respectively. Besides, the predicted models for the reaction of 3BOCN-MI curing fitted well with the experimental data.

Kinetic Modeling of Ethylene Epoxidation Kinetics as a Function of Chlorine Coverage over a Highly Promoted Silver Catalyst

Kinetic modeling of previously reported data demonstrate that chlorine exhibits an electrostatic influence, rather than solely ensemble site blocking, to improve the selectivity of ethylene epoxidation over promoted silver catalysts. Kinetic models that neglect the impact of surface chlorine content on either oxygen dissociation or ethylene adsorption enthalpies are unable to describe observed changes in the apparent reaction orders of ethylene consumption. Models that employ solely ensemble effects to adjust product selectivity with chlorine content falsely predict a simultaneous maximum in ethylene oxide (EO) and carbon dioxide synthesis rates with respect to chlorine coverage at 10–15% of a monolayer of chlorine. Incorporating electronic effects of chlorine on the transition states of the selectivity-determining steps into the model, however, properly describes the measured rate trends with surface chlorine content. Specifically, the model reflects the maxima observed in ethylene oxide synthesis rate with the concomitant monotonic decrease in combustion rates with increasing chloride content. Slight improvements to model predictions by combining ensemble and electronic effects on EO selectivity with increasing Cl coverage suggest that both effects may be relevant in combination but that ensemble effects alone cannot describe the observed behavior.

Influence of Light and Temperature on the Extractability of Cerium(IV) as a Surrogate of Plutonium(IV) and its Effect on the Simulation of an Accidental Fire in the PUREX Process.

Modeling of plutonium(IV) behavior during an accidental fire in a reprocessing plant was considered using various non-radioactive metallic surrogates. Among those elements, cerium(IV) was supposed to be a suitable candidate due to possible formation of a complex with TPB, but its extractability and stability have not been studied previously under representative plutonium uranium reduction extraction (PUREX) conditions. In this work, we investigated the chemical analogy between cerium(IV) and plutonium(IV) in this extractive process and combustion thereof. Distribution ratios are reported for acidities of 1–4 mol L–1 in equal volumes of nitric acid and a 30:70 mixture of tributylphosphate and hydrogenated tetrapropylene. The influences of light, temperature, and extraction time were studied by UV–vis spectroscopy. The results showed that cerium(IV) is extracted quantitatively but is reduced over time to cerium(III) in the organic mixture. Spectrophotometric investigations of this reaction kinetics revealed an apparent rate constant k of 0.021 ± 0.002 mol0.5 L0.5 min–1 at 298 K and an apparent fractional reaction order of 0.5. The activation energy of this reduction was found to be around 82 ± 2 kJ mol–1 by the Arrhenius plot method. The combustion of mono- and biphasic solutions prepared with a cerium(IV) concentration of 10 g L–1 revealed that the extracted complexes, Ce2O·6NO3·3TBP(org) or Ce4O4·8NO3·6TBP(org), are reduced during the combustion. Compositions of the resulting ashes and soot were analyzed and highlighted the presence of pyrophosphates and polycyclic aromatic hydrocarbons, with some traces of cerium. Ce(IV) is not suitable to represent Pu(IV) from a chemical point of view in HNO3/TBP–HTP solutions.

Production of bioalcohols and antioxidant compounds by acid hydrolysis of lignocellulosic wastes and fermentation of hydrolysates with Hansenula polymorpha.

The effect of the H2SO4 concentration in the hydrolysis of sunflower-stalk waste, at 95ºC and using a liquid/solid relation of 20, was studied. In a later stage, the hydrolysates were fermented at different temperatures with the aim of ethanol and xylitol production. A total conversion of the hemicellulose at the acid concentration of 0.5mol/L was achieved; whereas an acid concentration of 2.5mol/L was needed to reach the maximum value in the conversion of the cellulose fraction. The analysis of the hydrolysis kinetics has enabled to determine the apparent reaction order, which was 1.3. The hydrolysates from hydrolysis process with H2SO4 0.5mol/L, once detoxified, were fermented at pH 5.5, temperatures 30, 40, and 50ºC with the yeast Hansenula polymorpha (ATCC 34438), resulting in a sequential uptake of sugars. In relation to ethanol and xylitol yields, the best results were observed at 50°C( =0.11g/g; =0.12g/g). Instantaneous xylitol yields were higher than in ethanol, at the three temperatures essayed. Different phenolic compounds were analyzed in the hydrolysates; hydroxytyrosol was the most abundant (3.79mg/L). The recovery of these compounds entails the elimination of inhibitors in the fermentation process and the production of high value-added antioxidant products.

Curing characteristics of bismaleimide/furan blends

The curing kinetics of the bismaleimiede/furan blending system is studied by differential scanning calorimetry (DSC) under dynamic conditions. When the content of bismaleimiede is 25wt%, the curing process parameters of the blending system are obtained by the extrapolation method of temperature-heat rate (T-β), that is, the gelation temperature, curing temperature and post-treatment temperature, thus providing a theoretical basis for the curing process of the system. The kinetic parameters of the system are calculated by using Kissinger equation and Crane equation, that is, apparent activation energy (Ea), apparent frequency factor (A) and reaction order (n), and then the curing kinetic model of the system is established according to the calculated kinetic parameters. The kinetic model is used to predict the curing reaction characteristics of the system under the same temperature and dynamic conditions.

Investigation on the environmental‐friendly poly(lactic acid) composites based on precipitated barium sulfate: Mechanical, thermal properties, and kinetic study of thermal degradation

ABSTRACTA novel environmental‐friendly poly(lactic acid) (PLA) composites based on precipitated barium sulfate (BaSO4) were prepared via melt‐compounding. The mechanical properties and thermal stability of PLA/BaSO4 composites were investigated. To dig the decomposition mechanism, kinetic analysis of thermal degradation was emphasized systematically based on nonisothermal thermograms. Results showed that the mechanical responses were improved remarkably both under the quasi‐static condition and subjected to high‐speed shock due to the well‐bonded interfaces between PLA and BaSO4. Meanwhile, the added BaSO4 suppressed the mass conversion rate of PLA phase and improved the thermal stability at high temperature. Due to the inhibition of BaSO4, the calculated activation energy was enhanced obviously according to model‐free isoconversional approaches. Finally, the apparent kinetic mechanism and reaction order for the over‐all thermal degradation were determined by the combination of model‐fitting approaches and Carrasco method. From this study, we hope to provide a facile method to prepare environmental‐friendly PLA composites with excellent mechanical properties and thermal stability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47995.

Study of optical and thermal properties of terbium manganate nanoparticles

We have studied the optical and thermal properties of terbium manganate (TbMnO3) nanoparticles at room temperature. The sample is successfully synthesized by sol–gel method. An orthorhombic phase of the sample is confirmed from XRD analysis. The Williamson–Hall analysis is done to study the contribution of strain and crystallite size on the peak broadening of the synthesized nanoparticles. Elemental analysis of the sample is evaluated from the EDX profile. TbMnO3 nanoparticles exhibit strong absorption in the UV region. The optical band gap is calculated using the Tauc method from UV–Vis absorption spectroscopic analysis. Urbach energy is found to be 0.28 eV for the existence of band distortion and defects in the material. Thermal behaviour of these nanoparticles is determined by non-isothermal thermogravimetric analysis at inert atmosphere. The effect of different heating rates (10, 12, 15 and 20 K/min) on thermal properties of the sample is also investigated. The kinetic parameters are evaluated using different model-free methods in the analysis of solid-state kinetics for thermal behaviour of TbMnO3 nanoparticles. The Coats–Redfern method is used here to determine the apparent reaction order which is found to be ~ 2.

Electrochemical Impedance Analysis of Symmetrical Ni/Gadolinium-Doped Ceria (CGO10) Electrodes in Electrolyte-Supported Solid Oxide Cells

One of the most powerful tools in solid oxide cell (SOC) characterization is electrochemical impedance spectroscopy, which can unfold important insights into SOC performance characteristics and degradation behavior. To obtain a better understanding of the electrochemical behavior of Ni/CGO fuel electrodes, this work presents a comprehensive investigation of state-of-the-art Ni/CGO10-based electrolyte-supported cells. Commercial Ni/CGO10|CGO10|3YSZ|CGO10|Ni/CGO10 symmetrical cells were characterized between 550–975°C at pH2 = 0.8 bar and pH2O = 0.2 bar, and for different H2/H2O gas mixtures at 550°C. (i) Small electrode area, (ii) thin electrodes and (iii) large gas flow rates were used to minimize mass transport contributions. Based on distribution of relaxation times (DRT) analysis an equivalent circuit model was derived. Electrode process contributions on Ni/CGO were determined by means of a complex non-linear least square fit of the equivalent circuit model to the experimental data. One low frequency process at 0.1–1 Hz and one middle frequency process at 10–100 Hz were identified and correlated to a surface and a bulk process, respectively. Values for the apparent activation energy barriers and reaction orders with respect to steam and hydrogen content were determined.

Apparent kinetic and thermodynamic calculation for thermal degradation of stearic acid and its esterification derivants through thermogravimetric analysis

Abstract Thermal degradation properties of stearic acid and its esterification derivants of methyl stearate and ethyl stearate are investigated through thermogravimetric analysis. Based on experiments, which are conducted at the temperature heated rates of 10, 15 and 20 K min−1, the iso-conversional methods of Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa are used to calculate the apparent activation energy. Further, the Avrami theory is used to estimate the apparent reaction order. Apparent thermodynamic parameters of the apparent enthalpy change, apparent Gibbs free energy change and apparent entropy change are calculated. Calculations of apparent kinetic and thermodynamic parameters illustrate that thermal activity of stearic acid is distinctly heightened after esterification and the derived derivants are more easily activated. Meanwhile, influences of alcohol type on esterification products are weak. Conclusions from this study make more comprehensive understanding of the thermal events of biodiesel to be favor for its commercial application.

Kinetics of photocatalytic, self-cleaning surfaces: A decision tree approach for determination of reaction order

Self-cleaning photocatalytic surfaces have several decades of application, yet satisfactory rate equations for analyzing the kinetics of reactions on such solid surfaces are lacking, due in large part to the many configurations of the catalyst and the deposited contaminants.We analyze the existing literature and show that nearly all studies can be described by application of the power law for rate of reaction:Rate = kcat [C] nwhere n = apparent reaction order, and kcat is a fundamental constant of the catalytic material. The value of reaction order, n, we show requires answers to the following six questions. In each case, the observed apparent kinetic order depends upon interplay among the distributions of photocatalyst, reactant, and irradiance.1. Is the photocatalyst porous or non-porous?Example: Stearic acid on/within non-porous/porous photocatalyst layer.2. Is the photocatalytically active layer optically thin or thick?Example: Dye conversion in TiO2 layers vs. 10% TiO2/SiO2?3. Is the probe reactant deposit a submonolayer or multilayer?Examples: Dye sub/multilayers with TiO24. Is probe reactant light absorption negligible or important?Example: Stearic acid vs. soot5. Is the probe reactant present as a continuous film or as a distribution of discrete islands?Example: Long chain carboxylic acids on TiO26. If distributed, what is breadth of distribution?Example: Stearic acid on TiO2For contaminant removal we demonstrate apparent reaction orders of 0, ½, 1, and 2! Simple analysis is used to explain this diversity of apparent reaction orders. We use the six questions posed to construct a decision tree for determination of the apparent reaction order, n, as a function of responses to the six questions.

Kinetics of Photocatalyzed Reactions: Five Lessons Learned.

Elucidation of kinetics of photocatalyzed chemical mechanisms occurring at interfaces (gas-solid, liquid-solid) has been challenging. We summarize here five lessons learned over five decades.1. An assumed reaction network leads to a single kinetic model, but a common model, the Langmuir–Hinshelwood rate equation, r = kcat K C/ [1 +KC], arises from multiple mechanisms, hence models alone do not reveal unique mechanisms.2. The Langmuir–Hinshelwood model parameter kcat represents the slow step at a catalyst surface, and in thermal catalysis, depends upon the reactant structure. However, early photocatalysis work with light chlorinated hydrocarbons in aqueous solutions showed a single kcat value, independent of reactant structure.3. The dependence of the Langmuir-Hinshelwood parameters, kcat and K, upon intensity indicates that a pseudo-steady state approach is more fundamental than the presumed equilibrated adsorption of the LH model.4. Dyes and phenols are commonly studied, and claimed as first order reactions, despite often exhibiting rate constants which diminish with increasing contaminant concentration. We show that such studies are the result of intrinsic zero order data plotted on a semilog graph, and involve zero order rate limitation by reactant saturation, electron transfer to O2, oxygen mass transfer, or light supply.5. The apparent kinetics for contaminant removal from photocatalytic self-cleaning surfaces depends upon multiple circumstances, including the geometry of reactant deposit, catalyst porosity, and reactant light absorption. A single decision table suffices to indicate the apparent reaction order, n, to assume when fitting photocatalytic kinetic data from self-cleaning surfaces to a power law rate form, rate = k Cn.

Esterification Reaction Kinetics Using Ion Exchange Resin Catalyst by Pseudo-Homogenous and Eley-Ridel Models

This work deals with kinetics and chemical equilibrium studies of esterification reaction of ethanol with acetic acid. The esterification reaction was catalyzed by an acidic ion exchange resin (Amberlyst-15) using a batch stirred tank reactor. The pseudo-homogenous and Eley-Rideal models were successfully fitted with experimental data. At first, Eley-Rideal model was examined for heterogeneous esterification of acetic acid and ethanol. The pseudo-homogenous model was investigated with a power-law model. The apparent reaction order was determined to be (0.88) for Ethanol and (0.92) for acetic acid with a correlation coefficient (R2) of 0.981 and 0.988, respectively. The reaction order was determined to be 4.1087x10-3 L0.8/(mol0.8.min) with R2 of 0.954. The adsorption constants of acetic acid and ethanol were calculated as 0.023 and 0.044 L/mol, respectively and the lumped reaction constant were determined to be 5*10-4 L2/gcat.mol.min. The results of the reaction kinetic study show that the high acetic acid/ethanol molar ratio was favored. The maximum conversion of 70 % was obtained at 70°C for acetic acid/ethanol molar ratio of 4.

Propylene oxide inhibits propylene epoxidation over Au/TS-1

The kinetics of propylene epoxidation over Au supported on titanium silicalite-1 (Au/TS-1) catalysts were measured in a continuous stirred tank reactor (CSTR) free from temperature and concentration gradients. Apparent reaction orders measured at 473 K for H2 (0.7 order), O2 (0.2), and propylene (0.2) for a series of Au/TS-1 with varied Au (0.02–0.09 wt%) and Ti (Si/Ti: 75–143) contents were consistent with those reported previously. Co-feeding propylene oxide enabled measurement of the apparent reaction order in propylene oxide (−0.4 to −0.8 order) and the determination that relevant pressures of propylene oxide reversibly inhibit propylene epoxidation over Au/TS-1, while co-feeding carbon dioxide and water had no effect on the propylene epoxidation rate. Analysis of previously proposed two-site reaction mechanisms in light of reaction orders for O2 (0.4), H2 (1), and C3H6 (0.4), corrected to account for propylene oxide inhibition, provides further evidence that propylene epoxidation over Au/TS-1 occurs via a simultaneous mechanism requiring two distinct, but adjacent, types of sites, and not a sequential mechanism that invokes migration of H2O2 formed on Au sites to PO forming Ti sites. H2 oxidation rates are not inhibited by propylene oxide, implying that the sites required for hydrogen oxidation are distinct from those required for propylene epoxidation.

Curing Kinetics of Cyanate Resin Modified by ESi

The kinetics of the curing reaction of cyanate resin modified by ESi was studied using DSC. The apparent activition energy, reaction order and frequency factor of the curing reaction of the resin were obtained as being E=68.58kJ mol-1, A=2992.06 s-1, n=0.89 respectively. In addition, the gel point, setting point, post cure temperature of this resin was found to be at 149.40°C, 180.72°C, 238.98°C.

Platinum/polypyrrole-carbon electrocatalysts for direct borohydride-peroxide fuel cells

Polypyrrole-carbon (PPy-C) composites having different amounts of carbon (5–35 wt.%) decorated with platinum nanoparticles (Pt/PPy-C) were prepared and investigated for borohydride oxidation reaction (BOR) in alkaline medium and for hydrogen peroxide reduction reaction (HPRR) in acidic medium. Structural and morphological properties and composition of these electrocatalysts were determined by FTIR, Raman, XPS, SEM/EDS, TEM and ICP-MS analyses. Pt/PPy-C electrocatalysts were evaluated for BOR and HPRR by cyclic voltammetry and chronoamperometry. Faradaic and kinetic parameters, such as the number of exchanged electrons, n, charge transfer coefficient, α, apparent activation energy, Eaapp, and order of reaction, β, were calculated. n for BOR ranged from 6.0 to 7.6, while n for HPRR ranged from 1.0 to 2.0. Eaapp was found to range from 10 to 18 kJ mol−1 for BOR and from 8 to 14 kJ mol−1 for HPRR. The BOR was found to be a 1st order reaction with respect to BH4−. Pt/PPy-C35% electrocatalyst showed the best activity for both reactions. Fuel cell tests were done with Pt/PPy-C electrodes as anode, as cathode and as both anode and cathode in a direct borohydride-peroxide fuel cell (DBPFC). DBPFC with Pt/PPy-C35% as anode electrocatalyst gave the highest peak power density of 1432 W gPt−1 at current density of 2046 A gPt−1 and cell voltage of 0.70 V.

Leaching kinetics of mechanically activated boron concentrate in a NaOH solution

Mechanical activation is an effective pretreatment method that can change the properties of boron concentrates, thus promoting B2O3 leaching from samples. Four boron concentrate samples were milled for 0, 10, 30, and 60 min and leached in a NaOH solution at various leaching temperatures and initial NaOH concentrations. We investigated the main control steps for leaching and obtained the kinetic parameters. We discuss the influences of the specific surface area and surface free energy on the apparent rate constants. During the early-stage leaching (0–20 min), the leaching process was controlled by a combination of the surface chemical reaction and diffusion through the product layer; however, the surface chemical reaction was the main controlling step with an apparent activation energy of 29.37–39.77 kJ/mol. During the late-stage leaching (>40 min), the leaching process of the milled samples was controlled by a combination of the surface chemical reaction and diffusion through the product layer; in contrast, that of the unmilled sample was controlled by the surface chemical reaction and showed a high apparent activation energy of 69.14 kJ/mol. With increasing milling time, the apparent activation energy and reaction order decreased, thus reducing the dependence on temperature and NaOH concentration. The leaching rate constants were related to the specific surface area, surface free energy, and other properties, such as crystal amorphization and chemical bonds stability. After milling for 60 min, the surface free energy increased from 26.88 to 33.99 mJ/m2, and the Lewis acid component increased from 0 to 3.31 mJ/m2, promoting the absorption of the solvent and OH– in the leaching solution, which also accelerated the leaching rate.

A kinetic study of CFB boiler separated bottom ashes during the steam hydration reaction

Abstract Although petcokes/coals can be efficiently combusted in a circulating fluidized bed (CFB) boiler with in-situ limestone desulfurization, only 20%–40% calcium of limestone particles is typically sulfated. Here, the CFB boiler separated bottom ashes are activated by 200 °C steam in a 15 rpm rotary drum to be recycled as the secondary desulfurization sorbent. Calcium oxide hydration reaction effectively cracks the ash calcium sulfate shell by the formation of calcium hydroxide from ash calcium oxide core and steam. The maximum conversion reaches 76% after ca. 5 min hydration time for 260 µm BA particles with an initial loading of 2 kg. The reaction kinetic study shows that the reaction has an apparent reaction order of 3.4 ± 0.5 to the concentration of core calcium oxide. The water vapor diffusion through the calcium sulfate layer is the likely to be the reaction rate-limiting step as predicted by the shrinking core model.

Mechanism and microkinetics of methanol synthesis via CO2 hydrogenation on indium oxide

Indium oxide has emerged as a highly effective catalyst for methanol synthesis by direct CO2 hydrogenation. Aiming at gathering a deeper fundamental understanding, mechanistic and (micro)kinetic aspects of this catalytic system were investigated. Steady-state evaluation at 5 MPa and variable temperature indicated a lower apparent activation energy for CO2 hydrogenation than for the reverse watergas shift reaction (103 versus 117 kJ mol−1), which is in line with the high methanol selectivity observed. Upon changing the partial pressure of reactants and products, apparent reaction orders of −0.1, 0.5, −0.2, and −0.9 were determined for CO2, H2, methanol, and water, respectively, which highlight a strong inhibition by the latter. Co-feeding of H2O led to catalyst deactivation by sintering for partial pressures exceeding 0.125 MPa, while addition of the byproduct CO to the gas stream could be favorable at a total pressure below 4 MPa but was detrimental at higher pressures. Density Functional Theory simulations conducted on In2O3(1 1 1), which was experimentally and theoretically shown to be the most exposed surface termination, indicated that oxygen vacancies surrounded by three indium atoms enable the activation of CO2 and split hydrogen heterolytically, stabilizing the polarized species formed. The most energetically favored path to methanol comprises three consecutive additions of hydrides and protons and features CH2OOH and CH2(OH)2 as intermediates. Microkinetic modeling based on the DFT results provided values for temperature and concentration-dependent parameters, which are in good agreement with the empirically obtained data. These results are expected to drive further optimization of In2O3-based materials and serve as a solid basis for reactor and process design, thus fostering advances towards a potential large-scale methanol synthesis from CO2.

Pyrolysis of Waste Castor Seed Cake: A Thermo-Kinetics Study

Biomass pyrolysis is a thermo-chemical conversion process that is of both industrial and ecological importance. The efficient chemical transformation of waste biomass to numerous products via pyrolysis reactions depends on process kinetic rates; hence the need for kinetic models to best design and operate the pyrolysis. Also, for an efficient design of an environmentally sustainable pyrolysis process of a specific lignocellulosic waste, a proper understanding of its thermo-kinetic behavior is imperative. Thus, pyrolysis kinetics of castor seed de-oiled cake (Ricinus communis) using thermogravimetric technique was studied. The decomposition of the cake was carried out in a nitrogen atmosphere with a flow rate of 100mL min-1 from ambient temperature to 900 °C. The results of the thermal profile showed moisture removal and devolatilization stages, and maximum decomposition of the cake occurred at a temperature of 200-400 °C. The kinetic parameters such as apparent activation energy, pre-exponential factor, and order of reaction were determined using Friedman (FD), Kissinger-Akahira-Sunose (KAS), and Flynn-Wall-Ozawa (FWO) kinetic models. The average apparent activation energy values of 124.61, 126.95 and 129.80 kJmol-1 were calculated from the slopes of the respective models. The apparent activation energy values obtained depends on conversion, which is an evidence of multi-step kinetic process during the pyrolytic decomposition of the cake. The kinetic data would be of immense benefit to model, design and develop a suitable thermo-chemical system for the conversion of waste de-oil cake to energy carrier.

Microwave torrefaction of Prosopis juliflora: Experimental and modeling study

This study is focused on evaluating the effect of particle size and microwave power on torrefaction of the invasive biomass species, Prosopis juliflora (PJF), via experiments and theoretical model. Experiments were conducted using a central composite design (CCD) approach to construct response surfaces capturing the effects of these two factors on three key characteristics of the obtained char, viz. yield, calorific value and energy recovery. Highest char yield was obtained at an intermediate microwave power for a given particle size, while the calorific value increased with both the parameters. The response surface for energy recovery was convex with maxima at 481W power for 1.9mm particles. A microwave-based thermogravimetric study was conducted to obtain the mass loss profile during torrefaction. Assuming a global, single-step, power-law kinetic model with Arrhenius-type rate constant for torrefaction, the apparent activation energy and reaction order were estimated to be 173.93kJmol−1 and 1.3, respectively. To explain the trends of char yields, a new approach was proposed that integrates the temperature profile information with the inferred kinetic model. Two parameters, viz. torrefaction time and average temperature, are introduced to quantify the temperature profiles during torrefaction. The generic model can be extended to any biomass species and reactor configuration by conducting suitable experiments. Detailed composition analysis of the bio-oil revealed that, unlike conventional torrefaction, significant degradation of lignin also occurred along with hemicellulose degradation at low bulk temperatures during microwave torrefaction.