Torrefaction Temperature Research Articles

Comparison and characterization of torrefaction performance and pyrolysis behaviour of softwood and hardwood

ABSTRACT In this study, the torrefaction and pyrolysis behaviors of softwood (pinewood) and hardwood (teakwood) were experimentally explored. Three different torrefaction temperatures (i.e. 210, 240, and 270°C) and two different residence times (20 and 40 min) were adopted. Various property indicators, for example, solid and energy yields, enhancement factor of higher heating value (HHV), and torrefaction severity index, were used to characterize the torrefaction performance. The principal component analysis (PCA) demonstrated the correlation among different torrefied samples with the help of chemical composition, solid yield, and HHV. Moreover, slow pyrolysis experiments were conducted at three different heating rates (i.e. 15, 30, and 40°C/min) to investigate the thermal degradation behavior of the torrefied biomass samples. Both thermogravimetric and differential thermogravimetric curves shifted to a higher temperature as the pyrolysis heating rate increased. The activation energies E a were estimated by using three isoconversional methods, that is, Kissinger-Akahira-Sunose (KAS), Starink and Flynn-Wall-Ozawa (FWO) methods. The E a broadly increased with torrefaction severity. When using the FWO method, the average E a values ranged from 97.51 to 168.68 kJ/mol and 120.73 to 180.25 kJ/mol for torrefied pinewood and teakwood samples, respectively. Scanning electron microscopy (SEM) images revealed that at higher torrefaction conditions, the samples experienced severe structural damages, leading to crack formation and augmentation. All these observations not only reveal that torrefaction can turn raw biomass into fuel with improved properties but also help to clarify the differences between soft and hardwood for energy utilization purpose.

Downstream Torrefaction of Wood Pellets in a Rotary Kiln Reactor—Impact on Solid Biofuel Properties and Torr-Gas Quality

Solid biofuels produced from torrefaction have improved coal-like properties in comparison to raw biofuels, yet ensuring uniform product quality is still a challenge. In this study, downstream torrefaction of wood pellets was performed at temperatures between 200 and 270 °C in a rotary kiln reactor to understand the effect of torrefaction temperature on product quality. The torrefied solid biofuel was compared with dedicated fuel properties defined in ISO/TS 17225-8:2016-12. Based on the results, the optimal temperature for downstream torrefaction was found at temperatures of 230 and 250 °C. Above this temperature, the effect of bulk density superimposes not only the increased net calorific value but also values for mechanical durability, amount of fines, and bulk density of the solid biofuel, which were below the thresholds of the fuel standard. Moreover, increasing process temperatures caused higher heavy metal concentrations in torrefied pellets. The composition of condensable and non-condensable fractions of the torr-gas substantially increased between temperatures of 230 and 250 °C and remained on a similar level at higher temperatures. Thus, the utilization of torr-gas for energy recovery purposes and as a precursor for the recovery of valuable chemicals should be balanced with the quality of the solid biofuel in the aforementioned range of torrefaction temperatures to enable the utilization of torrefaction products at further steps.

Thermochemical valorization of argan nutshells: Torrefaction and air–steam gasification

The upswing of argan’s oil for the cosmetic industry has increased the farming of this plant and originated an unexplored residue of complex treatment, its nutshells. This work deals with the characterization of this feedstock, its pretreatment via torrefaction and its gasification either with or without the pretreatment stage. Torrefaction was carried out in a continuous auger reactor at two temperatures, 220 and 250 °C. Hemicellulose was almost totally removed from argan nutshells after torrefaction. Compared to the raw argan shells, the torrefied solids showed an increased content of fixed carbon, a noticeable reduction in the O/C ratio and a significant increase in the HHV, the higher the torrefaction temperature. Chemical thermodynamic equilibrium calculations were implemented to the gasification stage to calculate the equivalence ratio for auto-thermal operation and to assess the effect of temperature and steam-to-biomass ratio on gas yield and composition. Air-steam gasification was also experimentally tested for the raw and torrefied materials at the operational conditions drawn from the simulation results. The torrefied material gasification yielded four times more char than the raw material, while tar production from the torrefied material was only reduced in the presence of steam (anyway starting from a low value: 0.7 g/m3STP for raw argan shells vs 0.3 g/m3STP for the torrefied material). Nor gas production, neither the H2/CO ratio nor the energy content in syngas were improved by gasifying the torrefied material, so torrefaction does not appear to be a profitable pretreatment stage for the gasification of argan nutshells from the point of view of syngas quality.

The role of solvent soaking and pretreatment temperature in microwave-assisted pyrolysis of waste tea powder: Analysis of products, synergy, pyrolysis index, and reaction mechanism

This study focuses on microwave-assisted pyrolysis (MAP) of fresh waste tea powder and torrefied waste tea powder as feedstocks. Solvents including benzene, acetone, and ethanol were used for soaking feedstocks. The feedstock torrefaction temperature (at 150 °C) and solvents soaking enhanced the yields of char (44.2–59.8 wt%) and the oil (39.8–45.3 wt%) in MAP. Co-pyrolysis synergy induced an increase in the yield of gaseous products (4.7–20.1 wt%). The average heating rate varied in the range of 5–25 °C/min. The energy consumption in MAP of torrefied feedstock (1386 KJ) significantly decreased compared to fresh (3114 KJ). The pyrolysis index dramatically varied with the solvent soaking in the following order: ethanol (26.7) > benzene (25.6) > no solvent (10) > acetone (6). It shows that solvent soaking plays an important role in the pyrolysis process. The obtained bio-oil was composed of mono-aromatics, poly-aromatics, and oxygenated compounds.

A comprehensive study on torrefaction of penicillin mycelial residues: Analysis of product characteristics and conversion mechanisms of N

Torrefaction is a promising method for biomass pretreatment, and the analysis of products properties is the essential way to reveal mechanism. In this study, torrefaction of penicillin mycelial residue was carried out at 200–320 °C. The results showed that the gaseous products were mainly CO2, followed by CO, and with the increase in temperature, CH4 and H2 were detected successively. GC–MS results showed that the tar mainly contained ketone, furan, ester, phenolic and N-containing compounds, among which the relative content of N-containing compounds was the highest (23.16–31.91 %). Torrefaction made the TG and DTG curves of solid products move to the upper right upon removal of volatiles, and enhanced the fuel thermal stability. XPS results showed that torrefaction increased the relative content of C-(C, H) and decreased that of OC-OH in solid products. And higher torrefaction temperature promoted the decomposition of protein-N and inorganic quaternary-N and the formation of pyridine-N. Based on the above results, the migration mechanism of N was also summarized. And torrefaction could eliminate the residual antibiotic and achieve safe disposal of AMR.

Three-stage pretreatment of food waste to improve fuel characteristics and incineration performance with recovery of process by-products

As of 2020, the annual generation of municipal solid waste (MSW) in China has surged to 235.12 Mt, and food waste (FW) accounts for more than 60 %. The most common treatment method is incineration, which accounts for 62.13 %. This research proposes a three-stage pretreatment method for FW that is suitable for incineration while recovering by-products and energy from the pretreatment process. The first stage is dehydration; as compared to hot air drying (HAD) processes, freeze drying (FD) exhibits a higher dehydration and oil preservation rate, allowing for the preservation of organic matter content and the recovery of freshwater resources from FW. The second stage is oil recovery; the FW extracted oil (FWEO) can be used to produce biodiesel, and this stage also helps to improve the effectiveness of the subsequent torrefaction process. The third stage improves the energy and fuel characteristics of the organic residue of FW and enhances the combustion performance by optimizing the torrefaction temperature. The solid fuel obtained at a torrefaction temperature of 350 °C shows the best combustion performance, with a solid yield of 35.76 %, a torrefaction temperature of 300 °C might be chosen to further improve the solid yield.

High-Strength Formed Coke from Torrefied Biomass and Its Blend with Noncaking Coal

In continuation of our previous study on production of high-strength metallurgical coke from torrefied softwood (cedar), we studied coke production from a mixture of torrefied cedar (TC) and noncaking coal by pulverization to sizes <100 μm, mixing, binderless hot briquetting, and carbonization. These sequential processes produced coke with a tensile strength of 5–17 MPa, which was equivalent to or greater than that of conventional coke (5–6 MPa), from TC-coal mixtures over the entire ranges of TC mass fraction in briquette of 0–100%, torrefaction temperature of 250–300 °C, and choice of coal (sub-bituminous or medium-volatile bituminous coal). The mixing of TC and coal hindered densification of coke due to hindrance of shrinkage of more-shrinkable TC-derived particles during the carbonization under many of the conditions. Nevertheless, positive synergy occurred in the coke strength at TC mass fractions of over 50%, where coal-derived particles were dispersed in the matrix of TC-derived particles, bonded to them during the carbonization, and behaved as a reinforcement of the matrix. The bonding between TC-derived and coal-derived primary particles was revealed by scanning electron microscopy. Copulverization of mixed TC and coal to sizes <40 μm before the briquetting gave cokes having strengths as high as 23–28 MPa. The fine pulverization increased the frequencies of mutual bonding of TC-derived particles and coal-derived particles and bonding between TC-derived and coal-derived particles per coke volume. The strength of coke from the TC-coal mixture generally followed volume-based additivity of strengths of cokes from TC and coal. This was realized by mixing primary particles of TC and coal within ≈10 μm scale or even smaller.

Investigation of the Effects of Torrefaction Temperature and Residence Time on the Fuel Quality of Corncobs in a Fixed-Bed Reactor

Biomass from agriculture is a promising alternative fuel due to its carbon-neutral feature. However, raw biomass does not have properties required for its direct utilization for energy generation. Torrefaction is considered as a pretreatment method to improve the properties of biomass for energy applications. This study was aimed at investigating the effects of torrefaction temperature and residence time on some physical and chemical properties of torrefied corncobs. Therefore, a fixed-bed torrefaction reactor was developed and used in the torrefaction of corncobs. The torrefaction process parameters investigated were the torrefaction temperature (200, 240, and 280 °C) and the residence time (30, 60, and 90 min). The effects of these parameters on the mass loss, grindability, chemical composition, and calorific value of biomass were investigated. It was shown that the mass loss increased with increasing torrefaction temperature and residence time. The grinding throughput of the biomass was improved by increasing both the torrefaction temperature and the residence time. Torrefaction at higher temperatures and longer residence times had greater effects on the reduction in particle size of the milled corncobs. The calorific value was highest at a torrefaction temperature of 280 °C and a residence time of 90 min. The energy yield for all treatments ranged between 92.8 and 99.2%. The results obtained in this study could be useful in the operation and design of torrefaction reactors. They also provided insight into parameters to be investigated for optimization of the torrefaction reactor.

Effect of torrefaction on the evolution of carbon and nitrogen during chemical looping gasification of rapeseed cake

Chemical looping gasification (CLG) is a novel approach to efficiently convert rapeseed cake (RC) to tunable syngas and NH3. However, the low energy density of RC seriously hinders its utilization. Meanwhile, torrefaction is an effective pretreatment for biomass upgrading. Hence, the combination of torrefaction with CLG is proposed as an alternative technology to efficiently utilize RC. In this work, the effect of torrefaction temperature on the evolution behaviors of carbon and nitrogen in CLG of RC with Ca2Fe2O5 OC was systematically investigated using TG-FTIR. Results show that torrefaction can effectively improve the physiochemical properties of RC. The torrefied RC possesses higher energy density and HHV, and lower atomic H/C and O/C ratios. Additionally, higher torrefaction temperature can facilitate the thermal degradations of N-IN and labile NP, with the productions of NH3 and HCN. During CLG, the rise of OC/Fuel mass ratio can increase the yields of the major gases (CO2, CO, CH4, NH3 and HCN), owing to both the oxidative effect of the lattice oxygen (O*) and the catalytic effects of Fe3+ and Ca2+ in OC. Moreover, torrefaction pretreatment can improve the CLG behavior of RC and the optimal torrefaction temperature is 250 °C, attributing to the improvement of fuel stability after torrefaction. Besides, torrefaction can marginally reduce the yields of the major nitrogen species (NH3 and HCN). This is ascribed to both the more stable structure of heterocyclic-N and the insufficiency of H radical in the torrefied RC compared to the raw. These findings provide a feasible guidance for the effective insight in nitrogen evolution during CLG coupled with torrefaction, and thereafter for the efficient utilization of biomass.

Impact of torrefaction on thermal behavior of wheat straw and groundnut stalk biomass: Kinetic and thermodynamic study

This study investigates the physicochemical behavior of Wheat Straw and Groundnut Stalk biomass and its impact on the thermal behavior during torrefaction process. The torrefaction was experimentally investigated by thermogravimetric analysis (TGA) at five isothermal heating rates of 20, 30, 40 and 50 °C/min. Results revealed that during the torrefaction process, significant fraction of hemicellulose and volatile content reduces that improves the high heating value. The results indicated that torrefaction treatment improved the fuel properties with elevated torrefaction temperature, including the lower volatile content, higher carbon content, and higher heating value. Kinetic parameter analysis indicated that the Ozawa–Flynn–Wall and Starink model were significant in calculating the activation energy, and the average activation energy was 240 kJ/mol and 238 kJ/mol (Wheat Stalk and torrified wheat Stalk) 127 kJ/mol and 129 kJ/mol (Groundnut Stalk and torrified Groundnut Stalk). An excellent linear relationship between lnA and Eα was observed, indicating that the compensation effect existed between the Eα and lnA during torrification. These results provide important basic data support for the thermochemical conversion of cornstalk to energy and chemicals.

Effects of Torrefaction Temperature on the Characteristics of Betung (Dendrocalamus asper) Bamboo Pellets

The objective of this study was to evaluate the effects of torrefaction temperature on the physical and mechanical properties of betung bamboo (Dendrocalamus asper) pellets. Torrefaction was conducted in an electric furnace at 200°C, 240°C, and 280°C for 50 minutes. The physical properties evaluated included color change, density, moisture content, water resistance, and water adsorption. The mechanical properties were also investigated by compressive strength test. The result showed that torrefaction affected the color properties of betung bamboo pellets with ∆E values of more than 12 or totally changed. The density and moisture content of torrefaction bamboo betung pellets decreased with increasing torrefaction temperature. The results also showed that the hydrophobic properties of the bamboo betung pellets improved with the increased of torrefaction temperature. The highest compressive strength value was obtained by bamboo betung pellets torrefied at 200°C and the values decreased with the increase of temperature. In conclusion, there were differences in the physical and mechanical properties of bamboo betung pellets that were torrefied at different temperatures. Torrefaction with an electric furnace effectively improved the quality of betung bamboo pellets. Keywords: Bamboo betung, pellets, temperature, torrefaction

Catalytic pyrolysis of torrefied olive stone for production of potential petrochemical alternatives

AbstractBench‐scale fluidized bed fast pyrolysis of as‐received and torrefied residual olive stone (OS) was carried out at 500 °C in the presence or absence of a solid acid catalytic bed. Light to mild torrefaction conditions were investigated, with temperatures of 200, 225, and 250 °C, set in a bench‐scale fluidized bed torrefier. Light torrefaction temperatures (200 and 225 °C) did not yield appreciable differences in the thermogravimetric pyrolysis studies, despite notable changes in mass and energy yield resulting from the influence of temperature difference. The mass and energy yields decreased from 91.1 to 74.0% and from 92.0 to 80.9%, respectively, moving from light to mild torrefaction. The higher heating value (HHV) increased linearly with an increase in torrefaction temperature, reaching a maximum of 22.1 MJ/kg at 250 °C, which was 9.7% greater than the as‐received OS sample. A comparison was made between the influence of light and mild torrefaction on subsequent bench‐scale pyrolysis experiments. In particular, the quality of bio‐liquids for torrefaction coupled to fast pyrolysis shifted signifcantly towards the production of higher phenolic and aromatic derivatives that may find applications as potentaila drop‐in alternative hydrocarbons. © 2022 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley &amp; Sons Ltd.

Investigation of the thermal behavior of Pinus wood pellets during torrefaction for application in metallurgical processes

The aim of this study is to investigate the thermal behavior of Pinus wood pellets during torrefaction under different operational conditions, as well as to evaluate the potential application of the torrefied product in metallurgical processes. Torrefaction tests were carried out in an oxidizing atmosphere (245 °C) and in an inert atmosphere (270 and 290 °C) at residence times of 15 and 60 min. The results of torrefaction in inert atmosphere were also statistically evaluated. To evaluate the potential application of torrefied biomass in metallurgical processes, reactivity tests with CO2 were performed in the temperature range of 200–1000 °C. The results showed that high torrefaction temperature and residence time decreased the mass yield. Statistical analysis showed the possibility of combining high temperatures with low residence times, or vice versa, to obtain satisfactory mass yields. The experimental results showed the highest reactivity for the torrefied biomass obtained in an inert atmosphere, at 290 °C and 60 min. However, considering the mass yield and reactivity with CO2, the best torrefaction conditions for biomass with potential application in metallurgical processes were in an inert atmosphere, at 290 °C and a residence time of 15 min.

Inhibition mechanism of calcium hydroxide on melting and agglomeration behaviors of lignin under torrefaction temperature range

Torrefaction is an efficient pretreatment method to upgrade fuel properties of biomass. Whereas, lignin melted and agglomerated under relatively low temperature causes serious problems for subsequent pyrolysis or combustion utilization, especially in large-scale installations. In this study, the swelling of lignin during torrefaction temperature range was inhibited via Ca(OH)2 addition. The inhibition mechanism of melting and agglomeration was studied. The results showed that Ca(OH)2 firstly reacted with active functionalities in lignin structure, and then linked single lignin molecule to form cross-linked macromolecule polymers, which further improved thermal stability of lignin during torrefaction. Ascribed to the improved thermal stability, the water mainly released by condensation reactions was reduced. Consequently, drop in the melting point of lignin caused by moisture was suppressed as well. Melting and agglomeration problems of lignin was gradually inhibited with rising Ca(OH)2 amount. Impacts of torrefaction temperature upon lignin were opposite due to the enhanced condensation reactions. Positive effects derived from Ca(OH)2 addition was gradually decreased as torrefaction temperature rising.

Effect of torrefied biomass on hydrophobicity and mechanical properties of polylactic acid composite

In this study, the physicochemical properties of torrefied biomass (larch and yellow poplar) were investigated based on torrefaction temperature. The effect of torrefied biomass on the hydrophobicity and mechanical properties of a polylactic acid (PLA) composites was evaluated. Hemicellulose was removed from the biomass during torrefaction, whereas the cellulose and lignin contents increased slightly. The color of the biomass changed from brown to black. The grindability of the torrefied biomass improved as the torrefaction temperature increased, which contributed to the production of fine particles (>100 mesh). A PLA composite was prepared using torrefied biomass (10 %) and polylactic acid. At 280 °C, water contact angle was the highest, regardless of the particle size and biomass species. Tensile strength of the PLA composite was slightly lower than that of PLA alone, regardless of the particle size of torrefied biomass. Nevertheless, the strength increased with the torrefaction temperature, except for larch with a relatively large particle size (<100 mesh). The tensile strength of the control was 68.0 MPa, whereas that of the torrefied biomass ranged from 61.1 to 65.8 MPa.

One-pot synthesis of fluorescent nitrogen-doped graphene quantum dots for portable detection of iron ion

Nitrogen-doped graphene quantum dots (N-GQD) were synthesized by direct thermal decomposition of ammonium citrate tribasic. With the increment of torrefaction temperature, the average size of N-GQD was increased from 2.56 to 3.73 nm. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy analysis (XPS) proved the successful doping of nitrogen atoms. Besides, the N-GQDs showed blue fluorescence which was quenched by Fe3+ ions, and the fluorescence intensity of N-GQDs decayed exponentially. Accordingly, the same quenching effect was observed on a test paper prepared by soaking paper in N-GQDs dispersion. The quenching mechanism was due to electron transfer between Fe3+ and functional groups on the surface of N-GQDs which could be confirmed by XPS and diameter growth. Therefore, through this simple method, N-GQDs with high blue fluorescence and high production yield (64%) can be prepared, which provided a new strategy for monitoring and collecting Fe3+ in environmental water.

Effect of gas-pressurized torrefaction on the upgrading and pyrolysis characteristics of corn stalk

Corn straw was torrefied under different temperatures and pressures to verify the influence of gas pressure on the torrefaction of biofuel. The torrefied products were characterized by proximate analysis, ultimate analysis, FT-IR, TGA and pyrolysis experiments. The results indicate that the deoxidation efficiency and energy density of torrefied products under both atmospheric pressure (AP) and gas pressured (GP) conditions increase with the increase of torrefaction temperature. The temperature required for GP torrefaction is almost 40 °C lower than that for AP torrefaction to obtain the same mass yield. The energy yield, carbon yield, deoxidation efficiency and the energy density of GP-torrefied corn straw are 1.125, 1.142, 1.539 and 1.131 times higher than those of AP-torrefied one, respectively. The GP-torrefied samples show better hydrophobicity and are easier to dehydrate. In addition, the pyrolysis of GP-torrefied corn straw produces significantly higher fractions of CH4 and H2 in the gaseous product than the pyrolysis of AP-torrefied one. Meanwhile, the relative content of phenols in the liquid products for the pyrolysis of GP-torrefied samples increases up to 51.11%, whereas the contents of furans and acids decrease considerably. The results suggest that GP torrefaction performs better in biofuel upgrading than AP torrefaction under the same temperature.

In-depth study of synergism between torrefaction and catalyst for balanced production of bio-oil from rice husk pyrolysis based on hydrocarbons production, energy yield and deoxygenation degree

Previous studies concerning biomass to bio-oil mainly focused on hydrocarbons production, and how to balance the bio-oil production in terms of hydrocarbons production, energy yield and deoxygenation degree is a challenging issue. After the pretreatment of torrefaction, catalytic fast pyrolysis (CFP) was performed at two-zone fixed-bed reactor. The synergism between torrefaction and catalyst during torrefaction-catalytic fast pyrolysis (T-CFP) was investigated for the balanced production of bio-oil from rice husk. Firstly, the results of two catalysts（ZrO2/n-ZSM-5 and ZrO2/n-ZSM-5/attapulgite) indicated that the catalyst with the incorporation of attapulgite (ATP) could realize the balance between the acid and basic sites, which resulted in deeper deoxygenation. Then, the results of torrefaction-catalytic pyrolysis showed that, among three torrefaction temperatures adopted, mild torrefaction (210 °C) had better synergistic effects with both catalysts. Specifically, catalytic pyrolysis of biomass after mild torrefaction over both catalysts realized the enhancement of deoxygenation degree and energy yield. Moreover, with the pretreatment of mild torrefaction, the performance of ZrO2/n-ZSM-5/ATP turned out to be obviously superior to ZrO2/n-ZSM-5 in terms of hydrocarbons production (7.5%＞0.8%) and deoxygenation mode. Therefore, the combination of ZrO2/n-ZSM-5/ATP and mild torrefaction could achieve more balanced production of bio-oil from T-CFP process.

Torrefaction of sludge under CO2 atmosphere to improve the fuel properties for high temperature gasification with coal

Take CO2 as a torrefaction medium is effective in improving fuel performance. This study discusses the possibility of industrial solid waste sludge (SL) pretreated by torrefaction under CO2 for gasification with Yangchangwan coal (YC). The study was performed in a thermogravimetric analyzer and a high-frequency furnace. The results showed that the optimal torrefaction temperature of SL was 300°C under CO2, and its release intensity of gases higher than that of Ar. –OH and C–H were decreased relative to Ar. At 1100°C, the reactivity index R0.9 of SL pretreated under CO2 was 1.78 times higher than that of untreated chars. At 1200–1400°C, the R0.9 of chars was lower than that of 1100°C. The activation energy of chars was showed an overall increasing trend with increasing carbon conversion levels. The torrefaction-pretreated SL under CO2 can be better applied to high-temperature gasification of YC.

Torrefaction of fibrous empty fruit bunch under mild pressurization technique

The use of inert gases such as nitrogen continuously during torrefaction causes a burden in terms of operational cost. Therefore, a novel concept of mild pressurization has been introduced to eliminate the dependence on the inlet gas completely. In the present study, the torrefaction of fibrous empty fruit bunch (EFB) was performed for various temperatures of 250 °C–300 °C and residence times of 30–90 min. The pressure exerted by the load during torrefaction was 0.0230 MPa. The results show that torrefaction temperature is a dominant parameter in affecting physical and physicochemical properties as well as thermal stability of the torrefied EFB rather than residence time. An increase in temperature causes an improvement in gross calorific value, hydrophobicity, atomic H/C and O/C ratios as well as thermal stability. Besides, it was found that the EFB experiences a significant change after torrefaction at temperature of 300 °C in terms of surface, microstructure, crystallographic structure and functional groups. This is mainly due to the significant decomposition of the main biomass constituents especially hemicellulose and cellulose. Overall, it can be concluded that the best performance was obtained at torrefaction temperature of 300 °C and residence time of 90 min.