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The non-isothermal thermogravimetric method (TGA) was applied to different chars produced from lignite (LN), sawdust (SD) and their blends at the different mass ratios in order to investigate their thermal reactivity under steam atmosphere. Through TGA analysis, it was determined that the most prominent interaction between sawdust and lignite occurred at the mass ratio of sawdust/lignite as 1:4, but with further dose of more sawdust into its blends with lignite, the positive interaction deteriorated due to the agglomeration and deactivation of the alkali mineral involved in sawdust at high steam gasification temperature. Through systematic comparison, it could be observed that the random pore model was the most suitable among the three gas-solid reaction models adopted in this research. Finally, rational kinetic parameters were reached from these gas-solid reaction models, which provided a basis for design and operation of the realistic system of co-gasification of lignite and sawdust in this research., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

This study aims to investigate the interaction and kinetic behavior of CO2 gasification of coal, biomass and their blends by thermogravimetry analysis (TG). The gas products evolved from gasification were measured online with Fourier Transform Infrared Spectroscopy (FTIR) coupled with TG. Firstly, TG experiments indicated that interaction between the coals and biomasses mainly occurred during co-gasification process. The most significant synergistic interaction occurred for LN with SD at the blending mass ratio 4:1. Furthermore, thermal kinetic analysis indicated that the activation energy involved in co-gasification decreased as the SD content increased until the blending ratio of SD with coal reached 4:1. The rise of the frequency factor indicated that the increase of SD content favored their synergistic interaction. Finally, FTIR analysis of co-gasification of SD with LN indicated that except for CO, most gases including CH3COOH, C6H5OH, H2O, etc., were detected at around 50-700°C., (Copyright © 2014. Published by Elsevier Ltd.)

To study the catalytic role of alkali and alkaline earth metallic species and eliminate their negative impact during biomass thermal utilization, different leaching methods have been applied in numerous experiments. Thus it is necessary to investigate the potential influence on biomass physicochemical structure using different agents. Rice straw was selected to study the demineralization impact on physicochemical structure and pyrolysis characteristics. It is shown that strong acid leaching exhibited higher removal efficiency of minerals, but it introduced more notable impact on physicochemical structure of biomass comparing to water and weak acid leaching. Different leaching methods give chance to study catalysis characteristics of intrinsic metals on biomass thermal reaction. Contrast to alkaline earth metals especially Ca hindering thermal decomposition, alkali metals promoted this reaction obviously. In addition, comparing to physicochemical structure changes created by leaching process, the influence of removal of minerals played the dominant role in biomass thermal behavior., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The structural evolution characteristics of maize stalk/char particles during pyrolysis were investigated. The char was prepared by pyrolyzing at temperatures ranging from 200 to 900 degrees C. Maize stalk and chars were characterized by thermogravimetric analysis, ultimate analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), helium density measurement and N(2) adsorption/desorption method. The char yield decreased rapidly with increasing temperature until 400 degrees C. As temperature increased, the char became progressively more aromatic and carbonaceous. The hydroxyl, aliphatic C-H, carbonyl and olefinic C=C groups were lost at high temperatures. Below 500 degrees C, the removal of volatile matter made pore opening. High temperatures led to the occurrence of softening, melting, fusing and carbon structural ordering. The aromatization process started at approximately 350 degrees C and continued to higher temperatures. The shrinkage of carbon structure occurred above 500 degrees C, which was concurrent with the aromatization process.

Biomass occupies a significant proportion of municipal solid waste. For the high-value processing of waste biomass, a hydrothermal-carbonization method was chosen because of the advantages of effective and mild conditions. Four typical types of waste biomass (banana peel, mangosteen peel, orange peel, and pomelo peel) were used in this work to prepare high-value carbon aerogels (CA) via hydrothermal-carbonization treatment for cracking ethanol. Four kinds of CA all had good performances in the ethanol cracking reaction and improved the yield of H2 from 21 wt% to about 40 wt%. The banana peel-based carbon aerogel (BPCA) showed the best performance in the reaction; it cracked ethanol and obtained 41.86 wt% of H2. The mechanism of ethanol cracking by CA was revealed: On one hand, the self-cracking of ethanol was improved due to the extension of residence time, which benefited from the abundant pores in CA. On the other hand, the heterogeneous reaction occurred on the surface of CA where the inorganic components, mainly Ca, Mg, and K, can promote the bond-breaking and reorganization in ethanol. The CO2 in byproducts was also fixed by Ca and Mg, improving the positive cracking reaction. [ABSTRACT FROM AUTHOR]

This study reports the importance of plastic volatiles on char-volatiles interactions during co-pyrolysis of polypropylene (PP) and biomass components under non-catalytic conditions in a two-stage reactor. PP-volatiles were generated and interacted with biochar from cellulose and lignin downstream at different temperatures. Different experiment configurations were designed in order to explore the contribution of the tarry and waxy materials in PP-volatiles to the char-volatiles interactions. Experimental results showed that the char-volatiles interactions altered the yield and the chemical structure of PP-oil and biochar. The O-containing and aromatic species in biochar acted as active sites during interactions. Large aromatic rings in the biochar were predominant during the cracking of the tarry materials in PP-volatiles, while the O-containing species dominated during the recombination and polymerization of the waxy material in PP-volatiles. At higher temperatures, waxy and tarry materials released H-radicals inside the cellulose-char matrix, and strengthened the ring aromatic condensation reactions, while waxy and tarry materials were involved in heavier aromatic structures in lignin-char, leading to the fragmentation of lignin. In addition, even at low temperatures (e.g. 500 °C), waxy material can provide hydrogen and slightly enhance the condensation of the aromatic ring systems in lignin-char. [Display omitted] • Aromatics in PP-volatiles fragment lignin-char. • H-reactive species enhance aromatic ring condensation in cellulose-char. • Bio-char promote the cracking of tarry volatiles. • Bio-char enhance the polymerization of waxy volatiles. • Char-waxy volatiles and char-tarry volatiles interactions differ. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quick measurement method of three components was established based on PT-TGA. • The method can be applicated with high heating rates up to 300 °C/min. • The time for three-component content measuring test can be as short as 3 min. • Maximum deviation of relative contents of three components was less than 3.32%. Cellulose, hemicellulose, and lignin are the major components of lignocellulosic biomass, and fast and accurate measurement of the three components' content is beneficial for the efficient application of biomass. However, the current chemical dissolution and titration method was tedious and time-consuming. In this study, a quick determination method of three components in biomass was developed for determining their contents based on a photo-thermal thermo-gravimetric analyzer (PT-TGA). Cellulose was modeled using a single F1 model, while hemicellulose and lignin were fitted with two consecutive processes according to their pyrolysis characteristic with F2 and F1 models. Using the kinetic parameters obtained from the fast pyrolysis of cellulose, hemicellulose and lignin on the PT-TGA, the contents of the three components in biomass samples were calculated by fitting the DTG curves with different peaks. Under the heating rate of 300 °C /min, the relative content deviation of the three components of rice straw was less than 2.00 % with the measurement time within 3 min. Furthermore, coconut shell and pine were used to verify that the maximum difference determined by the kinetic fitting method and the chemical method was only 3.32 %, demonstrating that the method could reliably and rapidly measure the contents of the three components in lignocellulosic biomass. This study provided a fast and effective method for determining the relative content of biomass components. [ABSTRACT FROM AUTHOR]

Based on the concentrated photo-thermal thermogravimetry analyzer (PT-TGA) reactor, the pyrolysis of the cellulose, hemicellulose and lignin with different ratios at 100 °C/min and 550–850 °C was performed. The interaction among the three components significantly reduced the reaction temperatures and increased the maximum weight loss rate. The cellulose/lignin interactions were the main reason for the increase of gas production, especially for the H 2 production which reached 128.13 mL/g biomass, much higher than the calculated value of 75.35 mL/g biomass without considering the interactions. What occurred during the co-pyrolysis of cellulose/lignin was the combination of free radicals without consuming the hydrogen radicals, while the formation of chemicals in others' interactions integrated with the hydrogen radicals inhibited the production of H 2 at high temperatures. For full-component pyrolysis, the yield of C-containing gas can be calculated by adding a coefficient of interaction between two components, indicating that the effect of the three-component interaction was much lower than that of the two-component. This study established the interaction mechanism for the three components of biomass during photo-thermal pyrolysis based on free radicals. [Display omitted] • Inner-particle reaction significantly accelerated the fast pyrolysis process. • C-containing gases of components mixed in different ratios could be predicted. • Radicals from hemicellulose only promoted C-containing gas yields before 650 °C. • The combination of radicals from cellulose/lignin enhanced the production of H 2. [ABSTRACT FROM AUTHOR]

Ionic liquid combined with metal species is considered as a promising catalytic system for biomass liquefaction, which complies with the requirement of green chemistry and promotes utilization of biomass resources. The catalytic systems containing imidazolium-based ionic liquids and nickel chloride were applied to the hydro-liquefaction of major biomass constituents (cellulose, xylan and lignin) in this work. The anion type in ionic liquid played a vital role in the liquefaction of feedstock. The results indicated that the maximum conversion and bio-oil yield were achieved in 1-butyl-3-methylimidazolium bromide ([BMIM]Br)/NiCl 2 system, which was attributed to the strong nucleophile and coordinating capacity of bromide ion. The ionic liquid-based catalyst was more effective in the conversion of cellulose and xylan, due to their high reactivity. Additionally, the ionic liquid-based catalyst facilitated the thermal degradation of feedstocks and intermediates, resulting in the increased content of organics with the smaller molecular sizes. The deoxy-hydrogenation reaction was enhanced over ionic liquid-based catalyst, improving the quality of the resulting bio-oils. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel concept called Solar Char-Cycling Pyrolysis (SCCP) has been developed. • Solar enhanced char-cycling biomass pyrolysis process was modeled for the first time. • In SCCP process, pyrolysis has the highest exergy destruction due to no combustion. • Due to the external biochar, the SCCP process showed the highest CH 4 and CO yields. Pyrolysis is an efficient technology for converting biomass into value-added products, characterized by endothermal reactions. The introduction of induced solar irradiance can boost product yields and reduce carbon emissions associated with incineration. However, direct solar pyrolysis faces challenges due to difficulties in maintaining a clean solar window, which is essential to ensure efficient sunlight penetration. To address this issue, a novel concept called Solar Char-Cycling Pyrolysis (SCCP) has been developed. In this work, to demonstrate the potential of solar enhanced biomass pyrolysis process as a promising biomass treatment technology, energy and exergy analyses of Autothermal Pyrolysis (AP), Solar Direct Pyrolysis (SDP), and Solar Char-Cycling Pyrolysis (SCCP) processes were studied in Aspen Plus. The results showed that SCCP has the highest energy and exergy efficiencies, which were 90.81% and 76.51%, respectively. In comparison, the solar energy utilization efficiency of char-cycling was 82.18% due to the high radiative heat absorptivity of biochar. Meanwhile, the energy efficiencies for AP and SDP were 87.17% and 80.23 %, respectively. The lower efficiency of SDP was attributed to window contamination. When the solar adsorption efficiency of the SDP process falls below 82.18%, it leads to a lower efficiency than the SCCP process. Through the energy analysis, it was proved that in the SCCP process, solar energy could fully cover the pyrolysis energy requirement since it overcame the problem of window contamination. Through the exergy analysis, it was shown that the SCCP process has the highest exergy efficiency compared to AP and SDP, which was caused by avoiding biochar incineration and enhanced solar energy utilization. This study gives a comprehensive evaluation of biomass solar pyrolysis applications, with the char-cycling method presenting an innovative approach for the efficient utilization of solar energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Formation and evolution process of PFRs during biomass pyrolysis was investigated. • Effect of biomass property and pyrolysis temperature on the PFRs was clarified. • Relationships between PFRs characteristics and chemical structure were established. • Three-stage evolution mechanism of PFRs in biochar during pyrolysis was revealed. The persistent free radicals (PFRs) in biochar can play a crucial role during biochar's utilization, but the formation and evolution mechanism of PFRs in biochar are poorly understood because of biochars' element specificity and chemical structure complexity. In order to further understand the formation and evolution mechanism of PFRs, the PFRs characteristics, chemical structure and element composition of six types of biomasses were investigated. The results revealed that the changing trend of the PFRs types, concentration and line width with pyrolysis temperature is similar for all six feedstocks. The difference in the feedstocks' properties just affects the absolute value of PFRs' characteristic parameters. The arrangement and combination of elements and carbon skeleton structure in biochar determine the evolution of PFRs in the pyrolysis process. Additionally, the (H + O)/C atomic ratio of the biomass feedstock and the content of substitutional groups on aromatic rings were found to influence the types of PFRs in biochar. When biochar has a similar O/C atom ratio, a higher H content can reduce the carbon-centered PFRs in biochar. Besides, the reduction in O element content contributes to a decrease in line width due to the reduction in the effect of heteroatoms. The good correlation between O/C atomic ratio, H/C atomic ratio, chemical structure and PFRs characteristics can be used to predict the PFRs characteristics. Combining the changing characteristics in PFRs concentration and carbon skeleton structure of biochar, a three-stage model of PFRs formation and evolution was constructed. [ABSTRACT FROM AUTHOR]

The aim of this work was to study some basic aspects of uranium biosorption by powdered biomass of lake-harvested cyanobacterium water-bloom, which consisted predominantly of Microcystis aeruginosa. The optimum pH for uranium biosorption was between 4.0 and 8.0. The batch sorption reached the equilibrium within 1 h. The isotherm fitted the Freundlich model well. Although the Langmuir model fitted the experiment data well at pH 3.0, 5.0 and 7.0, it did not fit at pH 9.0 and 11.0 at all. This implies that different biosorption mechanisms may be involved at different pH values. 0.1 N HCl was effective in uranium desorption. The results indicated that the naturally abundant biomass of otherwise nuisance cyanobacterium bloom exhibited good potential for application in removal of uranium from aqueous solution. [Copyright &y& Elsevier]

Torrefaction of biomass is a well-known pretreatment method that can remarkably influence evolution of property of pyrolytic products in subsequent pyrolysis. Automobile shredder residue (ASR) is an important product in car recycling and it needs to be pretreated before recycling via pyrolysis. Nevertheless, how torrefaction impacts the composition and pyrolysis behaviours of ASR is still unknown, as ASR has a distinct composition from biomass. Thus, this study investigates the effect of torrefaction on the formation of heavy components in pyrolysis oil. ASR samples were torrefied from 240 °C to 330 °C and subsequently pyrolyzed from 600 °C to 800 °C with varied heating rates (ca. 80 °C /s and 0.17 °C /s). Results indicate that compared to raw ASR pyrolysis oil, torrefaction enhances the interaction between the volatile and semi-char, promoting the polymerization to form precursors of heavy components, thus the relative content of heavy components increases by >50% and heavy components containing heteroatoms decrease by >30% in the torrefied ASR pyrolysis oil, with the release of volatile heteroatom-containing compounds during torrefaction. More aliphatic heavy components are generated, reducing the overall aromaticity and degree of unsaturation of heavy components in the pyrolysis oil. [Display omitted] • Torrefaction promotes the formation of heavy components in ASR pyrolysis oil. • Torrefaction reduce the heteroatomic content in ASR pyrolysis oil. • The unsaturation degree of heavy components was reduced after torrefaction. • A proposed formation mechanism of heavy components in ASR's oil is provided. [ABSTRACT FROM AUTHOR]

An analysis was conducted on two integrated models involving direct co-firing and pyrolysis co-firing systems within a typical 600 MW coal-fired power generation plant. The study assessed the performance of various biomass sources (sawdust, corn straw, and rice husk) using distinct co-firing ratios (5%, 10%, 15%, 20%) across technological, environmental, and economic dimensions. The findings revealed that in terms of thermal and exergy efficiency, the pyrolysis co-firing approach exhibited lower results compared to direct co-firing. Notably, among the biomasses tested, sawdust demonstrated the least impact on boiler efficiency. The CO 2 emission was estimated by the Life Cycle Assessment method. The emission of the conventional boiler, along with direct and pyrolysis co-firing of corn straw at a 20% ratio, resulted in CO 2 emissions of 1.075 kg, 0.954 kg, and 0.942 kg per 1kWh of electricity, respectively. The different feeding methods were also discussed, providing technically and economically rational options for coal-fired power plants. The economic feasibility of both co-firing systems was also proposed. At carbon tax rates of 410 CNY/t and 464 CNY/t for the direct co-firing and pyrolysis co-firing models respectively, the operational cost of the co-firing systems becomes comparable to that of a coal-fired boiler. However, when the by-product price exceeds 3700 CNY/t, the pyrolysis co-firing model becomes the more economically favorable option. This study primarily concentrates on investigating the real-world application and effective utilization of biomass co-firing systems within the specific framework of China's energy scenario. [Display omitted] • Co-firing processes of coal and biomass has been simulated and taken a 3E assessment. • Increased blending ratio leads to higher power generation cost and lower efficiency. • Providing options to select co-firing methods, ratio and biomass type. • Byproduct char can be sold and has economic benefit than direct combustion in boiler. [ABSTRACT FROM AUTHOR]

Photo-thermal (PT) pyrolysis has emerged as a promising technique for efficiently converting biomass into high-quality bio-oil. The pyrolysis characteristics of rice straw (RS) and rapeseed cake (RC) were analyzed using a photo-thermal reactor with heating rates of 20, 200 and 500 °C/min and compared with 20 °C/min fixed-bed (FB) pyrolysis at 750 °C. Due to the uneven temperature distribution caused by its limited heating area, fast PT heating significantly increased the presence of high molecular weight components (>650) in the bio-oil. PT pyrolysis of RS exhibited higher phenolic contents compared to FB pyrolysis, whereas RC oil showed enhanced decomposition of fatty acids through ketonization. In terms of N-compounds, PT slow pyrolysis oil contained more nitriles but fewer linear amines/amides than FB, while more cyclic amides were formed under fast PT pyrolysis. Furthermore, the analysis of heavy components revealed that more aromatic compounds with low H/C ratios were produced in fast PT pyrolysis oil. Overall, PT heating exerted dual effects by reducing secondary reactions and synergistically enhancing inner-particle reactions with fast heating. This study provides valuable insights into the mechanism of bio-oil evolution under PT pyrolysis. [Display omitted] • PT pyrolysis produces bio-oil with more MW > 650 components. • Phenols in RS oil reach 33.2% in fast PT pyrolysis, but only 19.4% in fixed-bed. • PT pyrolysis benefits the fatty acids decomposition to ketones in RC oil. • Nitriles and lactams are promoted in RC slow and fast PT pyrolysis respectively. • Fast PT pyrolysis enhances the aromaticity of the heavy components. [ABSTRACT FROM AUTHOR]

Stable free radicals are the long-lived macromolecule radicals formed in pyrolysis, and their reactions play an essential role in biochar formation. The alkali and alkaline earth metals (AAEMs) in biomass might be involved in the radical reactions during pyrolysis. Figuring out the effect of AAEMs on the reactions of stable free radicals can further understand the radical reaction mechanism and the formation of biochar in pyrolysis. In this paper, the in-situ electron paramagnetic resonance (EPR) spectroscopy was used to detect the stable free radicals in cocoanut pyrolysis, and the effect of AAEMs was analysed by the comparative experiments. The results indicate that the stable free radicals in nascent chars, which are generated from the thermal decomposition of biomass, could react and couple with each other. The AAEMs in biomass improve the activity of stable free radicals and promote the radical-radical coupling during high-temperature pyrolysis above 400 °C, which inhibits the condensation of aromatic structure and generates more weak bonds in hot nascent char. After stopping the heating, the weak bonds will be broken by cooling stress, thus inducing radical reactions and further changing the char structure. • In-situ EPR detection was used to study stable radicals during biomass pyrolysis. • Effect of alkali and alkali earth metals on stable radical reactions was analysed. • Nascent char formed in pyrolysis has secondary reaction after volatiles releasing. • Alkali and alkali earth metals promote coupling of stable radicals during pyrolysis. • Unstable structures formed by stable radicals coupling can be broken during cooling. [ABSTRACT FROM AUTHOR]

Graphical abstract fx1 Abstract Biomass raw materials are widely regarded as a significant source of renewable energy, which significantly reduces the dependence on traditional fossil fuels, especially in the case of countries that are able to obtain biomass from various sources. Recently, pelletization has been widely used for mass and energy densification of biomass to overcome the problems associated with raw material use. As the global pellet market has developed quickly, the use of wood residues became no longer sufficient to fulfill the market needs. The standards of pellets provide limits for both physical and mechanical characteristics of produced pellets. Characteristics of produced pellets depend mainly on the feedstock characteristics as particle size and moisture content and operating conditions as applied pressure and die temperature. Thus, this paper provides rich information on the factors affecting the physical and mechanical properties of granules included in pellets. The main goal of the paper is to review the latest and comprehensive research on the physical and mechanical properties of most types of single and mixed pellets from biomass. The analysis of the effect of properties, adhesives, humidity, pressure and temperature as well as the physical and mechanical properties of the pellets studied was carried out. In addition, the critical and optimal values of various factors for different materials in which the following is of importance: high quality of pellets and biomass from which they are produced were analyzed. The principle and effect of applying post-production conditions as steam explosion and torrefaction on the characteristics of the pellets were reviewed in details. Moreover, this study proposes some recommendations for further development of the pelletization analysis and characteristics. Highlights • Comprehensive research on the characteristics of biomass pellets was studied. • The effect of operating parameters on the characteristics of pellets was analyzed. • New types of binder materials and their impact on the pellets have been introduced. • Future prospects for of the pelletization analysis have been suggested. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The stable and efficient immobilization of silver nanoparticles (AgNPs) on/into processable biomass-based macro-support with porous networks is a promising and sustainable strategy to achieve both high catalytic activity and excellent reusability for heterogeneous catalysis. In this work, a collagenic composite film was facilely fabricated at room temperature, via the self-assembly of natural collagen fibers (CFs) and gallic acid modified silver nanoparticles (GA@AgNPs) induced by chromium (III) cross-linking in water. The morphology and microstructure of such GA@AgNPs-Cr-CFs composite film was investigated by Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The results revealed that the cross-linking based on the coordinated complexation between chromium ions (Cr3+) and carboxyl groups on CFs and GA@AgNPs played the critical role in the interwoven of collagen fibers, leading to a three dimensional (3D) interconnected porous network of the composite film with simultaneously incorporation and high payload of silver nanoparticles. Furthermore, this GA@AgNPs-Cr-CFs composite film exhibited excellent catalytic activity toward the reduction of 4-nitrophenol (4-NP), taking the advantage of its high specific surface area given by the interwoven fibrous network structure. More than that, such sustainable composite catalyst could be easily recovered and reused for ten cycles because of its high stability based on cross-linking. This catalytic platform constructed by natural fibers, noble metal nanoparticles and trivalent metal ions showed a sustainable avenue for heterogeneous catalytic system. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pre-oxidation enhances specific surface area by 54.6% in CO 2 activation and 30.0% in H 2 O activation. • O 2 breaks rigid structure of biochar, forming activated carbon of microporous with larger diameters. • O 2 promotes conversion of olefinic C = C to aromatic C = C in activation, accelerating aromatization. • Promoting pores formation of O 2 is confirmed in activation of cellulose, pine needle and spirulina. Carbonization plus activation of resulting biochar is a commonly used method for producing activated carbon (AC) from biomass. Nevertheless, carbonization produces biochar of highly aromatic nature, increasing difficulty for creating pores via activation. Herein, O 2 (7.7%) was introduced to pre-oxidize lotus root and other biomasses-derived biochar before being activated with CO 2 or H 2 O for tackling chemical inertness of biochar at 800 °C. The results indicated that O 2 could enhance mass yield of AC (by 16.5% in CO 2 activation and 50.6% in a H 2 O activation) and bio-oil. Moreover, O 2 oxidized organics on AC, forming oxygen-containing aliphatic structures. Such a transformation enhanced reactivity of biochar with CO 2 or H 2 O, facilitating generation of pores. The AC from activation with O 2 -CO 2 was significantly higher than that from CO 2 alone (533.7 m2 g−1 of AC from O 2 -CO 2 activation versus 345.2 m2 g−1 of AC from CO 2 activation). O 2 also could remarkably increase the specific surface area of AC activated with H 2 O by 30.0%. Such an enhancement in pore structures was confirmed in activation of cellulose, pine needle and spirulina with O 2 presence. The pre-oxidation activated biochar destroyed partially rigid structure, facilitating gasification with CO 2 /H 2 O, forming dominantly micropores with enlarged diameters. The characterization with in-situ IR indicated that O 2 could enhance aromatization via aiding formation of aromatic C = C from olefinic C = C, producing AC of more regular alignments of carbon crystals. [ABSTRACT FROM AUTHOR]

Co-pyrolysis of lignocellulosic biomass (LCB) with plastic has gained significant attention recently. Studying the pyrolysis kinetic behavior of LCB and plastic is beneficial for developing a framework for designing and improving biofuel production. The co-pyrolysis behavior, synergistic interactions and kinetic triplet parameters of the three main LCB components, i.e., cellulose, hemicellulose and lignin, and two plastics (polyethylene terephthalate [PET] and polyvinyl chloride [PVC]) were evaluated using a fast heating concentrating photothermal TGA system. The maximum decrease in mass loss rate with increasing heating rates was observed for cellulose with PET (1.23–0.94%/°C) and with PVC (1.05–0.62%/°C). The mechanism of synergistic interaction between hemicellulose and PET proceeded with polymer degradation and conversions of monomer units into excess volatiles in the higher heating rate regime. Distributed Activation Energy Model [DAEM] and Coats-Redfern [CR]) were used to calculate the kinetic parameters. DAEM results confirmed that mixed samples required lower activation energy to start the reaction. Using the CR method, the first degradation phase showed the best synergistic effect for lowering the PET and PVC activation energy, particularly with hemicellulose and lignin. [Display omitted] [ABSTRACT FROM AUTHOR]

Four types of biomass-derived organics (toluene/1-methylnaphthalene/phenol/ethanol) were catalytically decomposed and steam reformed over Ni/α-Al 2 O 3 for co-production of hydrogen and carbon nanotubes (CNTs). In the decomposition reaction, the oxygen functional group in phenol and ethanol promoted the co-production of hydrogen and CNTs, while a small amount of toluene and 1-methylnaphthalene were cracked to hydrogen and amorphous carbon. In the reforming reaction, the yields of hydrogen and CNTs sharply increased. More than 2000 mmol/(g-cata∗h) of H 2 and 260 mg/(g-cata∗h) of CNTs were produced after the reforming of toluene and ethanol. However, 1-methylnaphthalene was difficult to be reformed and small amount of CNTs were formed. The organics with low molecular weight and low degree of unsaturation conduced to the formation of hydrogen and CNTs. The growth of CNTs on Ni/α-Al 2 O 3 mainly follows the tip-growth mechanism. The diameter distribution of CNTs is not only influenced by Ni particle size, but also related to the different organics and steam addition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-pyrolysis was performed in a photothermal TG system under high heating rates. • Activation energy relative difference was used to quantify the synergistic effect. • Thermo-kinetic properties were significantly affected by high heating rates. The heating rate would significantly impact the pyrolysis process, especially for the reactions containing synergistic effects between two different feedstocks. Co-pyrolysis of two widely available biomass (CC–corncob and PS–peanut shell) with plastic (PET–polyethylene terephthalate and PVC–polyvinyl chloride) was studied in a concentrating photothermal thermogravimetric analysis (CP-TGA) system at three heating rates (100, 500, 1000℃/min). The TG and DTG curves of CC and PS differ due to their polymeric components (holocellulose and lignin); two pronounced levels at 100 and 500 ℃/min heating rates were present in PVC. With increasing heating rate, the lateral shift towards higher temperature regions in the TG and DTG curves exceeded 100 °C. The synergistic effects on the blend samples were concentrated in the main decomposition region (250–580℃) due to rapid volatiles release, and the discrepancy values further stabilized at the final decomposition stages. The activation energy (Ea) was assessed using a comparative study of isoconversional methods, namely Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Starink. The isoconversional methods demonstrated that the co-pyrolysis process required about 30 % less activation energy than the pyrolysis of plastic (PET/PVC) alone. Coats-Redfern's (CR) model-fitting approach was used to identify the kinetic triplet of the devolatilization stage. The CR models revealed that biomass–PET blends belong to two to four-dimensional diffusion models, whereas biomass–PVC blends are dominated by chemical reactions of 1.5 and 2 orders. The energy barrier between activation energy (Ea) and change in enthalpy (ΔH) for all the blend samples was lower (∼5–6 kJmol−1), which slightly increased at higher heating rate. [ABSTRACT FROM AUTHOR]

In pyrolysis of biomass pellet, heterogeneity in char is almost inevitable, due to the intra-particle mass/heat transfer limitation. In this study, the effects of temperature (350–600 °C) and aspect ratio of a cylindrical sawdust pellet (Diameter = 6, 8, 12, or 16 mm) on the heterogeneity of char structure at radial and axial directions were investigated with a micro-Raman spectroscopy. Based on the spatial distribution of Raman band area ratios, heterogeneity index was proposed to quantify the degree of heterogeneity in char structures. Results show that the heterogeneity exists in both radial and axial directions and could be weakened by the increase of temperature or enlarging the variance between radius and height of the pellet through enhancing the average heat and mass transfer inside the pellet. The heterogeneity index of different biochar decreased with increasing surface-area-to-volume ratio. The char structures was the most heterogeneous (HI(A D /A G) = 5.399 × 10−5, HI(A D /A (Gr+Vr+Vl)) = 2.359 × 10−5) for the pellet with a diameter of 8 mm. • Effects of temperature and aspect ratio on heterogeneity in char were investigated. • The heterogeneity of char structure at radial and axial directions was quantified. • A heterogeneity index was proposed to reflect heterogeneous structure in char. • The heterogeneity of pellet char could be weakened by the increase of temperature. [ABSTRACT FROM AUTHOR]

This work aimed to investigate effects of inherent alkali and alkaline earth metallic species (AAEMs) on biomass pyrolysis at different temperatures. The yield of CO, H 2 and C 2 H 4 was increased and that of CO 2 was suppressed with increasing temperature. Increasing temperature could also promote depolymerization and aromatization reactions of active tars, forming heavier polycyclic aromatic hydrocarbons, leading to decrease of tar yields and species diversity. Diverse performance of inherent AAEMs at different temperatures significantly affected the distribution of pyrolysis products. The presence of inherent AAEMs promoted water–gas shift reaction, and enhanced the yield of H 2 and CO 2 . Additionally, inherent AAEMs not only promoted breakage and decarboxylation/decarbonylation reaction of thermally labile hetero atoms of the tar but also enhanced thermal decomposing of heavier aromatics. Inherent AAEMs could also significantly enhance the decomposition of levoglucosan, and alkaline earth metals showed greater effect than alkali metals. [ABSTRACT FROM AUTHOR]

Highlights: [•] Volatile–char interactions can result in tar destruction during pyrolysis. [•] The effects of char on tar destruction are not proportional to the amount of char. [•] O-containing functional groups in char enhance tar destruction. [•] Aromatic ring size and substitutional groups in tar are important for tar destruction. [ABSTRACT FROM AUTHOR]

To investigate gas generation characteristics and the kinetics mechanism of biomass pyrolysis process at fast heating rates, a concentrated Photo-thermal TGA reactor (Pt-TGA) was set up. The reactor was reliable for the study of thermochemical kinetics because the average difference between the commercial TGA and Pt-TGA curves for the cellulose pyrolysis process was only 2.1%. Four kinds of typical Chinese forest and agriculture wastes were selected to study the pyrolysis process in Pt-TGA. At higher heating rates, the volatiles from pyrolysis eventually formed more non-condensable gases because of inner-particle secondary reactions. In the range of 450–850 °C, with the temperature rising, the production of H 2 increased, and the highest H 2 yield reached 279 mL/g. Combined with kinetic analysis, with the increase of heating rate, heat and mass transfer had a more prominent effect on the pyrolysis of biomass particles, and the reactions were controlled by three-dimensional diffusion model. [Display omitted] • Established a reliable photo-thermal TGA with a heating rate of up to 500 °C/min. • The main gas yields were strongly correlated with the pore structure of char. • The H 2 yield of rice straw can reach 279 mL/g with a heating rate of 500 °C/min. • The kinetic model changed to a three-dimensional diffusion model at 200 °C/min. • Inner-particle secondary reactions significantly affected the conversion of tar. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bio-oil from biomass with a small particle size can generate more gases. • Bio-oil produced with maximum is not suitable for syngas production. • Bio-oil with high oligomers produces more tar and aromatic molecular structures. • Organic fraction of bio-oil determines the gas yield to a great extent. • Bio-oil with low oligomers and high organics is suitable for syngas production. This paper investigated the effects of initial bio-oil production conditions (temperature and biomass particle size) on the downstream catalytic and non-catalytic steam reforming of bio-oil. The various bio-oil samples obtained from different pyrolytic temperatures (375, 500, and 580 °C) as well as from different biomass particle sizes (average size from 0.3 to 5.2 mm) were condensed as liquid and then fed into the reforming reactor. The results indicated that the tar yield from the steam reforming decreased significantly by as much as 80% as the original biomass particle size increased from 0.3 to 0.8 mm, but remained almost unchanged for further increasing the particle size up to 5.2 mm. As the biomass particle size increased, the aromatic ring systems in the tars decreased, and the amount of aromatic ring systems in bio-oil tars was much lower than that in biomass tars at the same reforming condition. Additionally, the trends of the effects of bio-oil production temperature and biomass particle size on the tar yields followed the trends of these effects on bio-oil yields, i.e. , the higher the bio-oil yield, the higher the tar yield from bio-oil reforming. The tar yields were affected by the amount of oligomers in the bio-oil to a great extent. The gas yields from steam reforming gradually decreased as the biomass particle size increased. The content of oligomers in bio-oil was not the key factor dominating the formation of gases products, while the content of organics in bio-oil determined the gas yields significantly. According to the results, bio-oil produced at higher temperatures (e.g., 580 °C) from biomass with a small particle size (≤0.3 mm) could generate more syngas from steam reforming using the Fe-loaded bio-char catalyst. [ABSTRACT FROM AUTHOR]

The quantity of organic solid waste (OSW) discharged by the public has increased significantly in recent years. Herein, we consider bio-waste and plastic waste. Bio-waste, also known as biomass, is a sustainable and abundant energy source available in diverse forms. Plastic waste is a cheap hydrogen source contained within OSW. The transformation of OSW via pyrolysis involves the thermochemical conversion of biomass and plastic. This conversion can mitigate waste accumulation issues and lead to synergistic product improvements for fuels and chemicals. This paper reviews the occurrence and extent of the synergistic/interactive effect during the co-pyrolysis of plastic waste and biomass. The influence of various factors, including the plastic type, biomass type, mixing ratio, reactor type, heating rate, reaction temperature, and catalysts, on the synergistic effect is considered. Furthermore, reasonable interaction mechanisms related to the synergistic effect during co-pyrolysis are presented. The outcome of this review revealed that the interaction mechanisms by which the synergistic effect may occur are the transfer of active hydrogen radicals from plastic to the biomass unstable oxygenated radicals, the catalytic activity of the alkali/alkaline earth metal species in biomass, and the heat and mass transfer during the co-conversion. Biomass pre-treatment, the use of catalysts, and the similarity between the chemical structure of the biomass and the plastic used can strengthen the interactions. Synergistic effects are likely to occur to a great extent at a low heating rate at high temperatures. The conclusions regarding the blend ratio are inconclusive. • Lignin and aromatic plastics can promote the oil yield up to 50%. • Biomass and olefin plastics can promote aromatics up to 3 times the theoretical value. • Biomass pre-treatment and the use of catalyst can promote synergy up to 60%. • Excessive reaction temperature can inhibit aromatics formation up to 15%. • Possible co-pyrolysis interaction mechanisms of biomass and plastic were explored. [ABSTRACT FROM AUTHOR]

• A two-phase method was applied to analyze pyrolytic char structure. • Difference between pellet and powder char structural evolution was revealed. • There are more radicals in extraction of pellet char than that of powder char. • More lipids were detected in extraction of pellet char at high temperatures. The understanding of the evolution of char is critical to optimizing the thermochemical process of biomass. In this study, sawdust powder and pellet chars are prepared at various pyrolysis temperatures and separated into two phases by microwave-assisted extraction. More detailed information on the chemical composition of the chars is gained by characterization of two separated phases using different analytical methods. The results show that the extraction residues of powder and pellet chars have similar stable radical concentration at the same temperature. However, there are more macromolecules (>200 Da) in the extractable components of the pellet chars having steric hindrance effect, resulting in more stable radicals of pellet char than that of powder char. The extractable components of pellet chars contain more aromatic structures than that of powder chars from pyrolysis at same conditions. The reactions involved of these aromatic structures promoted by these radicals, such as the volatile-char interaction, are enhanced with increasing temperatures, leading to the formation of recombined compounds, such as lipid compounds. [ABSTRACT FROM AUTHOR]

Co-pyrolysis of various biomasses is beneficial by offering advantages such as better quality and yield of synthetic fuels due to synergistic effects. Furthermore, considering the lack of practical application of this technology, a tool for quick and good accuracy estimation is necessary for producing synthetic fuels based on co-pyrolysis of biomass. This study presents an integrated model of co-pyrolysis in Aspen Plus for the production of added value fuel to determine the operating conditions for optimized process performance. The scheme for the design and modeling of each main unit equipment in the system is outlined in detail. The model simulation was performed based on the experimental result from Pyrolysis-Gas Chromatography/Mass-Spectrometry (Py-GC/MS) analysis to achieve optimum performance on process design, including the maximum yields of product and a full utilization of by-products and recovery streams. Simulation results revealed 66% and 35% efficiencies, respectively, for co-pyrolysis plant and biorefinery from the co-pyrolysis of empty fruit bunches (EFB) and oil palm kernel shell (PKS) by the ratio of 0.8EFB/0.2PKS. Finally, a life cycle analysis was conducted to identify impact factors that lead to environmental impacts within the processing system. This study provides a guidance to biofuel production and a convenience to commercialization. [Display omitted] • A simulation for the co-pyrolysis process and an environmental evaluation with LCA. • Higher prediction capacity by using experimental data combined with modeling data. • The blending ratio and types of feedstock affect product quality from co-pyrolysis. • Improvements to increase the sustainability & environmental friendliness. [ABSTRACT FROM AUTHOR]

The vapor-/solid-phase interactions are the inevitable phenomenon in biomass pyrolysis process, which significantly affects the formation of heavy components (molecular weight > 200 Da) in bio-oil (HCO). In this study, to deeply understand the mechanism of the formation of HCO during biomass pyrolysis, the effects of the vapor-/solid-phase interactions among cellulose, hemicellulose, and lignin (biomass three components) on the formation of HCO during pyrolysis were studied in a fixed-bed reactor system. The HCO were analyzed by the FT-ICR MS spectrometer and the UV-F spectrometer. The results showed that the vapor-phase interactions mainly promoted the formation of heavy phenolic compounds at a slow heating rate, and the total content of HCO was increased. The vapor-phase interactions decreased the total content and the O content of HCO obviously at a fast heating rate; meanwhile, the highly reactive compounds (e.g., furans, acids, and ketones) generated from the pyrolysis of cellulose and hemicellulose could interact with the phenol monomers. Thus the phenolic compounds were transformed into large aromatic compounds via the vapor-phase interactions. The solid-phase interactions facilitated the transformation of O-containing structures of the HCO into the char via cross-condensation reaction, decreasing the yield of HCO, especially the phenolic compounds and the saccharides. • Vapor-/solid-phase interactions affect the heavy components formation in bio-oil. • Effects of vapor-/solid-phase interactions vary with the changes in heating rate. • Vapor-/solid-phase interactions affect the primary and secondary reaction pathways. • Interactions are hard to bring new O-/H-structures into the heavy components. [ABSTRACT FROM AUTHOR]

• Oxy-steam combustion of solid and hollow pellets was performed using plasma system. • Combustion behaviour studied numerically using an upgraded single particle model. • Experimental and numerical solutions fit perfectly for surface and center temperature profiles. • At 30%H 2 O/30%O 2 /30%CO 2 /10%N 2 , higher particle temperature was obtained. • At high CO 2 concentration, the char gasification reaction led to lower temperatures. Oxy-steam combustion behaviour of rice straw (RS) pellets was studied at high temperatures experimentally in a new plasma combustion system and numerically using an upgraded one-dimensional unsteady-state single particle combustion model with a new homogeneous devolatilization volatile combustion and heterogeneous char oxidation sub-models under different O 2 /H 2 O/CO 2 /N 2 gas compositions. Experimental results showed that the temperature gradient profiles for both the surface and center decreased significantly when the steam was added to the gas mixture at 20 and 40%. At 30% H 2 O, the heat consumption of the gasification reaction decreased which resulted in a higher particle temperature and a higher char oxidation reaction rate. Combustion characteristics for heating, ignition, devolatization, and combustion stages were obtained and confirmed through the time of recorded pictures by high-speed camera. The obtained experimental results were validated through fitting the measured values of surface and center temperature-time profiles, ignition time, final pellet diameter, and time for the maximum amount of released volatiles, under different H 2 O and CO 2 concentrations, with those predicted from the model solution. Also, the mass of the released volatiles and pellet diameter history were predicted from the model solution. Results of the model solution proved the reality and credibility of the measured and calculated experimental findings. [ABSTRACT FROM AUTHOR]

Biomass pellet is a popular fuel, and pyrolytic char can be a promised carbon material, further understanding char structural evolution can promote its utilization. To deeply investigate the evolution of char chemical structure and its heterogeneity during biomass pellet pyrolysis process, a new method was developed to fragment the char in space, and the chemical structures of the fragmented sections were analyzed by a micro-Raman spectroscopy (equipped with a 532 nm laser). The first-order Raman spectra (800–1800 cm−1) of varied positions of sawdust pellet pyrolytic char were curve-fitted with 10 Gaussian bands to reveal the temporal and spatial evolutions. The results indicate that pyrolysis of sawdust pellet can be divided into two stages: i) the decomposition of raw biomass (temperature heterogeneity in pellet remains); ii) the condensation reactions of aromatic ring systems (temperature in pellet becomes uniform). The axial and radial heterogeneity of char chemical structure is mainly caused by heat transfer when the whole pellet temperature is uniform during heating. While mass transfer, in accordance with volatile diffusion, can eliminate the heterogeneity of char chemical structure by volatile-char interaction. The combined effects of heat and mass transfer lead to a heterogeneity in pellet char chemical structure. • An expanded Raman method by combining micro positioning and analysis was developed. • Chemical structure heterogeneity of sawdust pellet pyrolytic char was quantified. • Temporal and spatial evolutions of pyrolytic char chemical structure were revealed. • Combined effects of heat and mass transfer on char chemical structure were found. [ABSTRACT FROM AUTHOR]

Co-combustion of biomass offers a great potential to reduce CO 2 emissions but rarely mentioned co-combustion behavior of pelletized coal-biomass mixtures and inconclusive results based on single determinants formed obstacle for industrial application. In this study, ignition and flame characteristics, reaction and kinetic parameters and pollutant generation path were comprehensively investigated. Intrinsic combustion experiments were carried with the gas phase maintaining at room temperature in a concentrating photothermal reactor at heating rate over 200 °C/s. Same "homogeneous" ignition was evidenced while advanced devolatilization but more intense slagging behaviors were identified with the increase of biomass proportion. With the biomass proportion increased from 0% to 40%, the activation energies during devolatilization to ignition decreased non-linearly from 47.44 kJ/mol to 8.03 kJ/mol, indicating the existence of synergistic effect. CO exhibited relative high generation rates and the generation rate increased with the biomass content. Three fitted CO peaks were identified during co-combustion, which were contributed by devolatilization of coal and biomass, and combustion of char, respectively. First increased and then decreased NO emission with the increase of biomass proportion was evidenced for the higher N content in biomass but enhanced reduction by char and NH radicals with higher biomass proportion. • Co-combustion behaviors (ignition, slagging, kinetic and pollutant) were studied • The Ea decreased non-linearly from 47.44 kJ/mol to 8.03 kJ/mol with biomass addition • CO exhibited high intrinsic generation rate and biomass formed an independent CO peak • Biomass enhanced primary fuel-N emission and NO reduction by char and NH radical • Synthetic effects were proved by combustion characteristics and kinetic analysis [ABSTRACT FROM AUTHOR]

Biochar from the pyrolysis of rice husk, pine wood and rice straw under the temperature from 250 °C to 800 °C were obtained and characterized by Raman spectroscopy. The biochar properties and chemical structure evolution were investigated, and correlations between biochar properties and Raman spectral parameters were set up. The results indicate that pyrolysis temperature has a more significant influence on biochar yield than feedstock. The volatile content in raw biomass linearly decreases with the decrease of biochar yield, and the atom H/C ratio of biochar linearly decreases with the decrease of V daf (volatile content in dry ash free basis). The change characteristics of Raman bands position and bandwidth indicate that carbon order degree of biochar progressively increases with the increase of pyrolysis temperature, and detailed chemical structure of biochar from different raw biomass can significantly differ from each other. Reasonable correlations between biochar properties including yield, V daf , the atom H/C ratio and the fluorescence interference degree in Raman spectrum (defined as α) of biochar have been found. A series of functions were proposed for rapid evaluation of biochar properties. Specially, the correlation that H/C = 0.3652 + 2.2887∗α-2.4035∗α^2 + 0.8221∗α^3 can be universal for carbon-based fuels including biochar, coals, coal chars and bio-oil chars. • Properties and structure of biochar were investigated with Raman spectroscopy. • Correlations between biochar properties and Raman spectral parameters were set up. • Fluorescence interference in Raman spectrum is sensitive to biochar properties. • Series functions were proposed for efficient evaluation of biochar properties. • H/C = 0.3652 + 2.2887∗α-2.4035∗α^2 + 0.8221∗α^3 is fit for biochar, coal and coal char. [ABSTRACT FROM AUTHOR]