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The pyrolysis process of various types of biomass (agricultural and wood by-products) in non-isothermal conditions using simultaneous thermal analyses (STA) was investigated. Devolatilization kinetics was implemented through combined application of model-free methods and DAEM (distributed activation energy model) using Gaussian distribution functions of activation energies. Results obtained were used in the curve prediction of the rate of mass loss against temperature at various heating rates by numerical optimization. The possible calculation of biomass samples behavior under pyrolytic conditions as the summation of their pseudo-components, hemicelluloses, cellulose, and lignin is also explored. The differences between experimental and calculated data are less than 3.20% offering a quality test of applicability of proposed model on the kinetic studies of a wide range of biomass samples. It seems that the most physically realistic model is the decomposition of biomass in three reactions, depending on the composition of the biomass regarding hemicelluloses, cellulose, and lignin. Kinetic model applied here may serve as a starting point to build more complex models capable of describing the thermal behavior of plant materials during thermochemical processing., Competing Interests: The authors have declared that no competing interests exist.

Thermo-chemical conversion of cigarette butt filters (CBF) waste was investigated using various thermal analysis techniques (simultaneous TG-DTG-DTA and DSC methods) at different heating rates in an inert atmosphere. Thermo- and thermophysical properties of waste material were discussed, from the point of view of chemical structure and the influence of experimental parameters on the conversion process. It was established that acetyl groups of plasticizer (triacetin) interact with cellulose acetate through dipolar interactions and hydrogen bonding's. Influence of these polar interactions can affect the position of glass transition temperature, Tg, of CBF. Based on estimated value of Tg from DSC analysis, it was found that cellulose acetate present in CBF has degree of substitution equals to 2.8, where the presence of cellulose triacetate was confirmed. It was assumed that an increase of degree of substitution leads to decline in the crystallinity. A decline of crystallinity causes the reduction of hydroxyl groups, leading to less organized chains, and whereby decreasing of inter-molecular interactions through hydrogen bonding. Based on the examination of thermophysical characteristics of the tested material, it was found that both, the heat capacity and the thermal inertia of material linearly increase with temperature, during pyrolysis progression. It was concluded that the type of bio-char produced in this process would have a large capacity to store the heat, which may depend on the formed particles size diameter and porosity. Furthermore, it was inferred that magnitude drops of thermal conductivity, κ, after Tg depends on the material fibrillation. [ABSTRACT FROM AUTHOR]

Thermo-chemical conversion via the pyrolysis of cigarette butt (CB) filters was successfully valorized and upcycled in the pre-carbonization and carbonization stages. The pre-carbonization stage (devolatilization) of the precursor material (cellulose acetate filter, r-CAcF) was analyzed by micro-scale experiments under non-isothermal conditions using TG-DTG-DTA and DSC techniques. The results of a detailed kinetic study showed that the decomposition of r-CAcF takes place via complex mechanisms, including consecutive reaction steps and two single-step reactions. Consecutive stages include the α-transition referred to as a cellulose polymorphic transformation (cellulose I → II) through crystallization mechanism changes, where a more thermodynamically ordered system was obtained. It was found that the transformation rate of cellulose I → II ('cellulose regeneration') is strongly affected by the presence of alkali metals and the deacetylation process. Two single-step reactions showed significant overlapping behavior, which involves a nucleation-controlled scission mechanism (producing levoglucosan, gaseous products, and abundant radicals) and hydrolytic decomposition of cellulose by catalytic cleavage of glycosidic bonds with the presence of an acidic catalyst. A macro-scale experiment showed that the operating temperature and heating rate had the most notable effects on the total surface area of the manufactured carbon. A substantial degree of mesoporosity with a median pore radius of 3.1695 nm was identified. The presence of macroporosity on the carbon surface and acidic surface functional groups was observed. [ABSTRACT FROM AUTHOR]

The detailed kinetic analysis of slow pyrolysis process of apricot (Prunus armeniaca L.) kernal shells has been estimated, under non-isothermal conditions, through thermogravimetric analysis and derivative thermogravimetry. Thermal decomposition was implemented using four different heating rates (5, 10, 15, and 20 °C per minute), with consideration of how this parameter effects on the process kinetics. The higher heating rates provoke the shift of thermoanalytical curves towards more elevated temperatures. Using isoconversional differential method, the variation of activation energy, Ea, with conversion fraction, α, was detected, and pyrolysis reaction profile was discussed. After resolving the pyrolysis rate curves of individual biomass constituents, the temperature and conversion ranges of their thermal transformations were clearly identified. In the latter stage of analysis, every identified reaction step was considered through mechanistic description, which involves selection of the appropriate kinetic model function. The comparison of the results as well as discrepancies between them has been discussed. The corresponding rate-law equations related to thermal decomposition reactions of all biomass constituents present in the tested agricultural waste material have been identified. [ABSTRACT FROM AUTHOR]

In order to clarify relationship between apricot kernel shell biomass slow pyrolysis mechanism and its main constituents (viz. hemicelluloses, cellulose and lignin), the reactivity effects of main constituents on pyrolysis characteristics were determined by the non-isothermal simultaneous thermal analysis. It was found that four-step (parallel) reaction model is suitable for studying the slow pyrolysis process, within the semi-global model which excludes the strong interaction between biomass constituents (pseudo-components). The application of the proposed model was allowed by the results obtained from KAS iterative isoconversional (model-free) approach. The valorization of the model was confirmed by the process optimization. The complex (cumulative) apricot kernel shell pyrolysis rate curves at different heating rates are successfully resolved into the individual decomposition rate curves (arising from thermal conversion of hemicelluloses, cellulose, and primary/secondary lignin fragments) by four-parameter Fraser–Suzuki function. Besides hemicelluloses and cellulose pyrolyses, the proposed model distinguishes primary and secondary lignin reactions, which enhance the gaseous products releasing (primarily CO and CO2 gases) and charification of the solid residue (increased the bio-char yield). [ABSTRACT FROM AUTHOR]

In this work, plane tree seed-based activated carbons were characterized in detail for a variety of applications. The particularly important area of application would be in the artificial photosynthesis. After carbonization process of biomass precursor at 650°C, the resulting preliminary activated carbons were activated at various temperatures. The activated carbons were characterized by oxygen functionalities (a particularly important role has ester oxygen groups) which provide a unique microstructure. The chemical compositions of as-prepared activated carbons were analyzed through Fourier transform infrared and Raman spectra as well as gas chromatography–mass spectroscopy analysis, while morphology was observed by scanning electron microscopy analysis. Applied analysis showed that detected graphite mainly becomes uniformly nanocrystalline system. The current study also explored the applicability of carbon material obtained from plane tree seed as a potential gaseous adsorbent. The characterization showed that the tested material contains both mesopores and micropores, and this should be advantageous for the gas sorption process, since mesopores may provide low-resistant pathways for the diffusion of CO2 molecules, while the micropores are the most suitable for trapping of CO2. The sorption process analysis (including adsorption/desorption isotherms behavior) shows indication that the rate-limiting step of CO2 adsorption onto activated carbon is probably governed by diffusion-controlled process, especially at temperatures below 850°C. [ABSTRACT FROM AUTHOR]

Slow pyrolysis characteristics of agricultural residue feedstocks (corn brakes, wheat straw, and hazelnut shell) were investigated by simultaneous thermal analysis (STA–TG–DTG–DSC), coupled with mass spectrometry (MS). Thermal decomposition of agricultural residues was divided into three stages, corresponding to removal of water, devolatilization, and formation of bio-char. It was found that differences in thermal behavior of samples are due to differences in their composition. The MS results showed that H2, CH4, H2O, CO2 (C3H8), CO, and C2H6 were the main gaseous products released during pyrolysis. It was shown that hazelnut shells could be a good combustion fuel, since during its pyrolysis at high temperature, more gaseous products compared to other systems are very favored. For hazelnut shell pyrolysis, the CO2 can be used on the large scale for the production of CO-rich syngas. [ABSTRACT FROM AUTHOR]

Slow pyrolysis (gradual heating over a wide range of temperatures) characteristics of various biomasses (corn brakes, wheat straw, and hazelnut shell) were investigated by simultaneous thermal analysis (STA-TGA-DTG-DSC), coupled with mass spectrometry. Thermal decomposition of these samples was divided into three stages corresponding to removal of water, devolatilization, and formation of bio-char. It was found that differences in thermal behavior of the samples are due to differences in their composition. The mass spectrometry results showed that H2, CH4, H2O, CO2 (C3H8), CO, and C2H6 were main gaseous products released during pyrolysis. Within the pyrolysis processes, it was found that CO2 can be used on the large scale for production of CO-rich syngas. [ABSTRACT FROM AUTHOR]

Highlights • Perspective biofuel for replacement of low energy lignites with HHV = 15.86 MJ kg−1. • Pyrolytic products were stimulated by decomposition of cellulose and lignin fractions. • Catalytic activities of mineral content and influencing the devolatilization kinetics. • The great abundance of PAH compounds was identified from carbonized material. • Promoted graphitization of bio-char where Al acts as a pulsar in acceleration process. Abstract This paper describes the pyrolysis of Poplar fluff (from Populus alba) using on-line apparatus, and carbonization process at 850 °C using the fixed bed reactor. Characteristics of pyrolysis products were examined. Elemental and chemical analyses were shown that Poplar fluff has higher energy content characterized by increased content of fibrous structure (particularly cellulose). Independent parallel reactions model very well describes devolatilization process. It was found that increased amount of extractives can significantly affect on increased release of light gaseous products, but declining hydrocarbons, mostly the alkanes. Liquid product is mainly composed of phenolics, aldehydes, acids, esters and ketones. The carbonization process produces the great abundance of polycyclic aromatic hydrocarbons (PAH's), where naphthalene is the most abundant. Mechanism for PAH's formation was suggested. This study represents the first step in a much wider and more comprehensive way in thermal conversion processes of this type of fuel. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Pyrolysis of five different biomasses was studied by STA-MS in dynamic conditions. • Effects of biomass species and heating rates on pyrolysis behaviors were evaluated. • Gaseous products and bio-char yields were analyzed. • Kinetic parameters are derived from substantial properties of pyrolysis rate curves. • Biomass structure plays an important role in pseudo-components decomposition. Abstract Slow pyrolysis characterization and kinetic modeling study of five different biomasses (corn brakes (CB), wheat straw (WS), hazelnut shell (HS), sawdust (Beech), and sawdust chemically treated (SDCT)) were performed in this work, using STA-MS techniques. Thermal decomposition of these samples was divided into three stages corresponding to removal of water, devolatilization, and formation of bio-char. Mass spectrometry (MS) showed that H 2 , CH 4 , H 2 O, CO 2 (C 3 H 8), CO, and C 2 H 6 were the main gaseous products released during the pyrolysis of biomasses. It was found that H 2 O, CO and CO 2 evolutions for all biomass samples arise from lignin source in biomass, followed by the cellulose, and hemicelluloses. It was established that the pseudo-component fraction estimated by the theoretical calculations is dependent on the heating rate. Using Gaussian multi-peak fitting and peak-to-peak approaches, regardless of the type of biomass, it was found that decomposition of lignin occurs independently of decomposition of remaining two pseudo-components and that there is no interaction between them. Namely, it was assumed that during pyrolysis process of biomasses, carbohydrate (hemicelluloses + cellulose)—lignin chemical structures most likely exist, where the variety of lignin structure units in different types of biomass affects on the level of energy required for its decomposition. [ABSTRACT FROM AUTHOR]

This work provides insight into possibilities of maximum utilization of C3-C4 energy crops for thermo-chemical conversion (slow pyrolysis) into high value biochemicals, platform chemicals, drop-in fuels and combustible gases, using coupled kinetic and thermodynamic analyses. In order to examine the kinetics of decomposition of lignocellulosic components, model-free and model-based methods faded from thermal analysis data were used. Thermodynamic compensation was used for explicatory of entropy controlled process, where conformational changes and chemical exchange directly affect the type and distribution of obtained pyrolytic products. It was shown that external variable (i.e. the heating rate/temperature) does not change either an entire reaction mechanism (mechanistic nature of MG and AD pyrolyses) or transition state, but it changes activation enthalpy and activation entropy which lead to differences in terms of heat energy consumption, pyrolysis favorability and thus rates of generation of activated complex among feedstocks. To investigate the interplay of catalysts (present in feedstocks as minerals) and reactants, selective energy transfer (SET) model was applied. The model showed an activity of catalyst with different outputs towards two reactants, lignin part of the structure in MG and 1,8-cineole in AD. It was shown that AD is more convenient for thermal conversion than MG, regarding to lower transformation energy requirement, higher reactivity, as well as much faster accumulation of products. [Display omitted] • Enthalpy-entropy compensation is a source of KCE for perennial grasses slow pyrolysis. • Pyrolysis is strongly influenced by disorder level (entropy driven) during conversion. • Pyrolysis favorability is lower for Miscanthus×giganteus -MG than for Arundo donax -AD. • AD has high reactivity accumulating more products (bio-oils and high value chemicals). • Applied selective energy transfer model shows interplay of the catalyst and reactant. [ABSTRACT FROM AUTHOR]

In this work, plane tree seed-based activated carbons (AC) were used for possible application in carbon dioxide capture and storage (CCS) technology. After carbonization process at 850 °C, resulting preliminary AC’s were activated at various temperatures. The high levels of the growth in basal planes of graphite structure in carbonized sample were detected. Also, it was found that the samples activated at 750 and 850 °C have a lower graphitization degree and contained substantially disordered sections and defects, which are characteristic of typical amorphous porous carbons. Process modeling has shown that the CO 2 sorption can be described by multi-parametric continuous distributed reactivity model. Analysis showed the occurrence of gas reduction process, involving gibberellic acid and coenzymes which can produce the methane gas. The highly ordered arrangement of the gas molecules on the carbons was assumed. [ABSTRACT FROM AUTHOR]

Bayesian inference was used to test the powdered cellulose pyrolysis, under the isothermal experimental conditions. A completely new procedure that was based on obtaining the reliable distribution functions of the effective (apparent) activation energy ( E) values by the statistical derivation of prior and posterior functions was introduced. It has been found that the pyrolysis of the powdered cellulose can be described by the kinetics, which differs from the first-order model. It was established that the apparent activation energy value presented as average magnitude in the conversion fraction range of 0.20 ≤ α ≤ 0.65 does not represent the 'lumped' kinetic parameter, so in indicated conversion range, the pyrolysis process can be described through single-step reaction model with six-eighths-order ( n = 0.75) kinetics. Based on the presented Bayesian inference results, it was assumed that mechanism of pyrolysis takes place through the decomposition reactions which start from the cellulose chains. From the main characteristics of the prior distribution, relationship between the ingredients of Bayesian inference and the cellulose characteristic energy constant ( c) [which is related to the rigidity angle (ψ) as a measure of tenseness of the cellulose chains] has been established in this paper. Based on evaluated prior and posterior distributions and their characteristics, it was found that the pyrolysis process of powdered cellulose takes place probably through formation of levoglucosan, where depolymerization represents the primary reaction path. Bayesian approach can be applied to highly structured reaction systems and complex physico-chemical processes, which include the reactivity distribution of various energy counterparts, which has been often un-tractable by traditional statistical access. [ABSTRACT FROM AUTHOR]

Pyrolysis process of coffee paper cup samples was investigated in a flow stream of nitrogen at different heating rates (10, 20, 30 and 40°Cmin−1), using thermo-analytical techniques. It was found that second pyrolysis stage can be described by Šesták-Berggren (SB) autocatalytic model, with mechanism function f(α)=α0.011(1−α)1.459. Based on analysis of SB kinetic exponents (designated by M and N), it was found that second pyrolysis stage is mainly controlled by chemical process, involving reactions with reaction-order (n) higher than unity. Applying specific statistical analysis, in order to obtain precise distribution of reactivity, the discrete (binomial) distribution has shown that there are two important areas of current distribution for corresponding energy outcomes, within the apparent activation energy as random variable. The first "concentration" area of energy outcomes corresponds to start of chain end depolymerization reaction forming levoglucosan at high enough temperature region, while second "concentration" area of energy outcomes includes occurrence of macro-radicals in liquid phase propagate with radical addition on unsaturated C-C bonds, with cross-linking and formation of small chemical species. It was found that further elevating of temperature (above 340°C), will leads to fact that rate of tar-forming reactions increases and formation of char decreases. [ABSTRACT FROM AUTHOR]

The non-isothermal decomposition process of commercial silver nitrate used as the precursor for the USP procedure was investigated by simultaneous TGA--DTA measurements at different heating rates, in an argon atmosphere. Detailed kinetic and thermodynamic analyses, with special emphasis on the formation of a complete mechanistic scheme of the process were performed. It was found that the process under study can be described by the acceleratory power law kinetic model (P2), in the range of the extent of conversion (α) values (0.15 ≤ α ≤ 0.85), where the value of the apparent activation energy (Ea) can be considered as the constant (141.3 kJ mol-1). The kinetic prediction analysis was shown that only the power law kinetic model (f(α) = 2α1/2) gives the value of Ea which is consistent with the value obtained from the isothermal conditions. The critical temperature (Tc) of decomposition process was determined. The resulting value of Tc was in fairly good agreement with the starting temperature of thermal decomposition of silver oxide (Ag2O). The thermodynamic functions of decomposition process are calculated by the activated complex theory and showed that the silver--oxygen bond secession can be interpreted as a "slow" stage of the decomposition process. [ABSTRACT FROM AUTHOR]

This work deals with the isothermal pyrolysis of Pine and Beech wood samples and kinetic studies, using the thermo-analytical technique, at five different operating temperatures. Pyrolysis processes were investigated by using the distributed apparent activation energy model, which involves the complex mixture of different continuous distribution functions. It was found that decomposition processes of wood pseudo-components take place in different conversion areas during entire pyrolyses, whereby these areas, as well as the changes in apparent activation energy ( E) values, are not the same for softwood and hardwood samples. Bulk density (Bden) and energy density (ED) considerations have shown that both biomass samples suffer from low Bden and ED values. It was concluded that pyrolysis can be used as a means of decreasing transportation costs of wood biomass materials, thus increasing energy density. The 'pseudo' kinetic compensation effect was identified, which arises from kinetic model variation and wood species variation. In the current extensive study, it was concluded that primary pyrolysis refers to decomposition reactions of any of three major constituents of the considered wood samples. Also, it was established that primary reactions may proceed in parallel with simultaneous decomposition of lignin, hemicelluloses and cellulose in the different regions of wood samples, depending on the operating temperature. It was established that endothermic effects dominate, which are characterized with devolatilization and formation of volatile products. It has been suggested that the endothermic behavior that arises from pyrolyses of considered samples may indicate the endothermic depolymerization sequence of cellulose structures. [ABSTRACT FROM AUTHOR]

Abstract: The detailed kinetic analysis of the non-isothermal pyrolysis of Brazilian oil shale was carried out using thermogravimetric analysis (TGA) and the derivative thermogravimetry (DTG). The investigated process was modeled using a statistical Weibull 2-component mixture model. By using different kinetic methods, it was found that the investigated process is very complex. Application of the differential and the integral isoconversional methods showed that the pyrolysis of Brazilian oil shale takes place through three reaction steps. It was found, that the third reaction step of the investigated pyrolysis process cannot be modeled by the simple first order reaction kinetics. It was established that the third reaction step can be described with the n-th order (n≠1) kinetics, including f(α)=(1−α)1.23 mechanism function. The kinetic compensation effect (KCE) was identified for observed oil shale pyrolysis. Based on the behavior of the shape parameter (θ) in complex statistical model under the consideration, it was determined that no change in the rate-limiting step occurs for the investigated pyrolysis process. [Copyright &y& Elsevier]

Abstract: The non-isothermal pyrolysis kinetics of Acetocell (the organosolv) and Lignoboost® (kraft) lignins, in an inert atmosphere, have been studied by thermogravimetric analysis. Using isoconversional analysis, it was concluded that the apparent activation energy for all lignins strongly depends on conversion, showing that the pyrolysis of lignins is not a single chemical process. It was identified that the pyrolysis process of Acetocell and Lignoboost® lignin takes place over three reaction steps, which was confirmed by appearance of the corresponding isokinetic relationships (IKR). It was found that major pyrolysis stage of both lignins is characterized by stilbene pyrolysis reactions, which were subsequently followed by decomposition reactions of products derived from the stilbene pyrolytic process. It was concluded that non-isothermal pyrolysis of Acetocell and Lignoboost® lignins can be best described by n-th (n >1) reaction order kinetics, using the Weibull mixture model (as distributed reactivity model) with alternating shape parameters. [Copyright &y& Elsevier]

• Novel data about pyrolysis kinetics of PS/DVB type (Wang) resin. • Homolytic cleavage of C C bonds induced by heating represents the weakest links. • Friedman plots analysis showed the existence of accelerated reaction by the product. • It was founded that autocatalytic reaction is less dependent on pyrolysis temperature. • By attacks from free radicals above 360 °C material is vulnerable shortening life-time. This study provides new information on the thermal stability and kinetics of pyrolysis of commonly used resins in solid-phase peptide synthesis. Pyrolysis process of 4-benzyloxybenzyl alcohol resin was monitored by simultaneous TGA-DTG measurements in a nitrogen atmosphere, at four different heating rates (5, 10, 20 and 30 K min−1). Kinetic computations included the model-free (isoconversional) and model-based methods for reliable estimation of kinetic parameters and the mechanism of investigated process. Based on the findings from applied methods, the pyrolysis process can be described by three reaction steps, where one of them encompasses the consecutive reactions. The first step (n -th order reaction, referred to F n) is attributed to the random scission of the main chain in PS (polystyrene) solid support, where polymer radicals were formed. The second step proceeds through homolytic cleavage path of ether linkage of the resin (by the first-order reaction, referred to F1) and then via phenoxy radical (semiquinone) formation which is converted into the benzoquinone through a dehydrogenation (by autocatalysis reaction, referred to C nm). Finally, the third step (referred to F n reaction) was characterized by depolymerization mechanism, which takes place at higher temperatures (T > 385 °C). With determined kinetic parameters and the most probable mechanism functions, the model agrees excellently with experimental data. By applying the obtained kinetic results, isothermal life-time prediction was also performed. [ABSTRACT FROM AUTHOR]

Pyrolytic tire (PT) chars were first produced from waste car tires (WCT) through carbonization process at 800 °C, for different retention times. Then, best PT-char sample by its physicochemical properties (WCT 800(1 h)) was further tested for its ability to adsorb Rhodamine B (RhB) dye from aqueous solutions. Structural characterization of synthesized material showed existence of graphene-based material, with average pore diameter of 22.8 nm and specific surface area of 55.8 m2·g−1. Obtained carbon material meets specifications of commercial carbon black (CB). The yield of 33.6% of CB recovered has been achieved. Under the optimal conditions, 99.57% of RhB was removed. Adsorption of RhB obeys pseudo second-order model and Langmuir isotherm model. DFT (the density functional theory) was revealed that effective bonding of RhB onto WCT 800 originates from π-electron interactions with aromatic moieties and chemical (or at least the electrostatic) interactions, between positive nitrogen and electron-rich surface groups. [Display omitted] • Reuse of pyrolytic waste tire char to a commercial effective carbon adsorbent • The applied carbonization process allows yield of 33.6% of carbon black recovered. • A new adsorbent characterizes by graphene defects structure of low graphitization. • Pore penetration/adsorbent-adsorbate interaction results to later gradual RhB uptakes. • The positive N interacts with different electron-rich surface groups or carbon defect. [ABSTRACT FROM AUTHOR]