Pyrolysis Of Peat Research Articles

Investigation of Peat Pyrolysis Products by Pyrolytic Gas Chromatography

Investigation of Peat Pyrolysis Products by Pyrolytic Gas Chromatography

Vacuum Pyrolysis of Brazilian coal, peat and biomass – Results on characterization of feedstock, solid residues, pyrolysis liquids and conversion rates

Pyrolysis of solid fuels such as coal, peat and biomass enables conversion into solid and liquid products, with noncondensable gas being a by-product. The present study evaluates conversion characteristics of Brazilian coal, peat and biomass samples using vacuum pyrolysis techniques. Feedstock and their respective solid residues (chars) and pyrolytic liquids obtained under vacuum pyrolysis conditions were characterized by proximate and ultimate analyses, gross calorific value, petrographic analyses, reactivity to CO2, Raman spectroscopy and organic geochemical methods (extraction, liquid chromatography). Chemical and physical properties in the feedstock samples and solid residues are highly variable. In the coals mean vitrinite reflectances ranged from 0.44% to 1.18% Rrandom indicating a rank range from subbituminous to high volatile/medium volatile bituminous coal. Reflectance measurements obtained from vitrinoid particles identified in solid residues from coal, peat and biomass varied from 2.10% to 10.64% Rrandom. Analyses of the liquid products indicate a tendency of the aliphatic fraction to increase in most of the samples during the pyrolysis process, as well as the predominant formation of polar compounds in the condensable liquids. The results of this study suggest that among the coal samples investigated major conversion to liquids and gases (29.7%–33.2%) occurs in the high volatile bituminous coals from Santa Catarina, whereas in the biomass samples Mamona (Castor Beans), wood chips (Eucalyptus), wooden bars (pinus) and signal grass have all conversion rates > 60%. The conversion rates for the peat samples varied between 32.5 and 46.6%. Reflectance values determined on vitrinoid biomass chars indicate a potential use in soil amendment.

Theoretical and Experimental Demonstration of Advantages of Microwave Peat Processing in Comparison with Thermal Exposure during Pyrolysis

A series of theoretical and experimental studies was carried out with the aim of a direct comparison of the thermal and microwave destruction of peat during pyrolysis. Different heating mechanisms in these processes were investigated in the framework of simulations conducted using a commercial 3D software package, CST Studio Suite, to define their specific features. Based on these simulations, identical reactors were constructed exploiting an electric element and a microwave complex as a heat source, and an experimental technique was developed that allows these processes to be correctly compared under similar conditions. Using these reactors based on different heat sources, comparative experiments on peat pyrolysis were performed, and the results of the theoretical analysis were confirmed. As a result, the advantages of microwave exposure were demonstrated to achieve a more uniform and deep fragmentation of peat, increase the reaction rate and reduce the processing time, with high energy efficiency accompanying this method. As part of the experiments, the yield of pyrolysis products was analyzed. During the microwave destruction of peat, a high gas output (up to 27%) was obtained, which allows for a further increase in the efficiency of this processing method when burning these gases. The conducted elemental analysis showed an increase in the percentage of carbon from about 50% to 78% after microwave processing, which can become a raw material for obtaining effective environmentally friendly sorbents. The prospects for creating industrial microwave complexes for processing organic materials are discussed.

A Comparison Study on the δD Value of Polycyclic Aromatic Hydrocarbons in Hydrous Pyrolysate of Herbaceous Peat with Different Water Medium

AbstractTo investigate the influence of diagenetic water media on the hydrogen isotopes of individual sedimentary aromatic compounds, a series of hydrous pyrolyses were conducted on herbaceous peat. Polycyclic aromatic hydrocarbons (PAHs) in hydrous pyrolysed samples and their hydrogen isotopic composition characteristics were studied. The aqueous medium demonstrated a significant influence on the hydrogen isotopic composition of the individual PAHs generated during pyrolysis. The results showed that the PAHs formed after pyrolysis in the presence of a saltwater medium with high δD value from a salt lake had a heavy hydrogen isotopic composition. The PAHs formed after pyrolysis in the presence of a fresh water medium with low δD value from a swamp had a light hydrogen isotopic composition. The difference in the average PAH δD value between the two hydrous experiments varied from –174‰ to –109‰, suggesting that the hydrogen isotopic composition of individual sedimentary PAHs can reflect the source of the diagenetic water medium. In addition, a comparative study found that the hydrogen isotopes of PAHs were superior to those of n‐alkanes in the same sample for diagenetic water indications. The results indicated that the exchange of water‐derived inorganic hydrogen and organic hydrogen was more intensive in freshwater experiments than in saltwater experiments. With an increase in the simulation temperature, the average δD value of PAHs generated in the hydrous simulation experiments showed an increasing trend, reflecting that the δD value of sedimentary PAHs formed with the participation of diagenetic water media was still closely related to the thermal maturity of organic matter. Comparative studies showed that the δD values of different types of organic compounds produced by hydrous pyrolysis of peat were in the order, PAHs > n‐alkanes > methane.

Production of Low-Molecular-Weight Organic Components by the Microwave Pyrolysis of Peat

A facility for conducting experiments on the microwave (MW) pyrolysis of peat at a source operating frequency of 2.45 GHz has been developed. The MW pyrolysis of peat for the production of low-molecular-weight organic components has been experimentally studied. The products of peat MW radiationinduced decomposition were determined, and reaction schemes for the degradation of peat components were proposed. A carbonaceous residue with relative carbon, hydrogen, nitrogen, and sulfur contents of 83–85, 4–5, 2–3, and 0.3 wt %, respectively, was obtained.

Experimental Complex for Peat Fragmentation by Low-Temperature Microwave Pyrolysis

The design of a technological complex for microwave processing of organic materials is proposed. The electrodynamic system of an oversized microwave reactor for low-temperature pyrolysis has been developed. The constructive elements of the complex that allow its continuous failure-free operation in conditions of high radiation intensity are described. Based on the prototype of the elaborated reactor, model experiments on microwave pyrolysis of peat were carried out. The elemental composition of the solid fraction was analyzed during the conducted experiments. The possibility of the efficiency enhancement of the proposed processing method and potential applications of the novel technology are discussed.

Detecting tropical peatland degradation: Combining remote sensing and organic geochemistry.

Tropical peatlands are important carbon stores that are vulnerable to drainage and conversion to agriculture. Protection and restoration of peatlands are increasingly recognised as key nature based solutions that can be implemented as part of climate change mitigation. Identification of peatland areas that are important for protection and restauration with regards to the state of their carbon stocks, are therefore vital for policy makers. In this paper we combined organic geochemical analysis by Rock-Eval (6) pyrolysis of peat collected from sites with different land management history and optical remote sensing products to assess if remotely sensed data could be used to predict peat conditions and carbon storage. The study used the North Selangor Peat Swamp forest, Malaysia, as the model system. Across the sampling sites the carbon stocks in the below ground peat was ca 12 times higher than the forest (median carbon stock held in ground vegetation 114.70 Mg ha-1 and peat soil 1401.51 Mg ha-1). Peat core sub-samples and litter collected from Fire Affected, Disturbed Forest, and Managed Recovery locations (i.e. disturbed sites) had different decomposition profiles than Central Forest sites. The Rock-Eval pyrolysis of the upper peat profiles showed that surface peat layers at Fire Affected, Disturbed Forest, and Managed Recovery locations had lower immature organic matter index (I-index) values (average I-index range in upper section 0.15 to -0.06) and higher refractory organic matter index (R -index) (average R-index range in upper section 0.51 to 0.65) compared to Central Forest sites indicating enhanced decomposition of the surface peat. In the top 50 cm section of the peat profile, carbon stocks were negatively related to the normalised burns ratio (NBR) (a satellite derived parameter) (Spearman's rho = -0.664, S = 366, p-value = <0.05) while there was a positive relationship between the hydrogen index and the normalised burns ratio profile (Spearman's rho = 0.7, S = 66, p-value = <0.05) suggesting that this remotely sensed product is able to detect degradation of peat in the upper peat profile. We conclude that the NBR can be used to identify degraded peatland areas and to support identification of areas for conversation and restoration.

RESULTS AND PROSPECTIVE OF STUDIES DEVELOPMENTS IN THE FIELD OF THE GEOTECHNOLOGIES OF NATURE DISPERSIVE MEDIAS

The review of the results according to the research methods of the characteristics of heat and mass transfer during rocks freezing and the modelling of rocks is given in the article. In the direction of technological developments the plant for thermochemical proceeding of combustible shale and other materials by the pyrolysis method is represented. The way of utilization of polymeric wastes by the pyrolysis of peat and polymeric compositions is proposed. The rheological research of leaching disperses of peat of different content are held. It is revealed that the degree of decomposition has the greatest impact to all rheological parameters of peat and leaching suspensions. The content of humic substances, ash elements, and also non-hydrolyzed substances in it has stronger influence on the structure durability of peat disperses. The results on the study on colloidal and chemical features and the content of functional groups of humic peat substance are given. The research results on the use of ash from peat burning and the sediment of the systems&#x0D; of wet dedusting as raw for new materials production.

Thermogravimetric Study on Peat Catalytic Pyrolysis for Potential Hydrocarbon Generation

Peat has attracted considerable interest as a potential source of alternative fuel in terms of improving hydrocarbons production and satisfying market demand. The next decade is likely to witness a raise in its exploitation. Nevertheless, the characteristics of peat pyrolysis process, via which many experts expect a considerable generation of hydrocarbons, have not been dealt with in depth. In the present study we have applied thermal analysis combined with isoconversional and model methods for clarifying the kinetic and thermodynamic aspects of the process of generating hydrocarbons from peat via pyrolysis in the absence and presence of iron tallates as a catalytic agent. The obtained results showed a positive effect of the opted catalyst on the process of peat pyrolysis. It has been shown that the catalyst is able to reduce the energy of activation of peat pyrolysis process. Moreover, the Gibbs energy, enthalpy and entropy of complex formation values have been found lower in the presence of iron tallates for all the applied isoconversional methods (Friedman and KAS). The evidence from the present study points toward the beneficial effect generated from the utilization of iron tallates in the processes of hydrocarbons generation from peat for improving energy production in the future.

Studies on individual pyrolysis and co-pyrolysis of peat–biomass blends: Thermal decomposition behavior, possible synergism, product characteristic evaluations and kinetics

Chemical reaction engineering of pine branches and peat is crucial yet challenging in enhancing pyrolysis products quality for the synergistic effect and kinetic parameters distribution. Herein, the three-phase product yield and tar component distribution were studied through a series of characterization methods. Thermogravimetric analysis (TGA) data at different heating rates was obtained and synergistic effect in the CPBP were discussed. Through the three kinetic models to calculate the obtained TGA data and determine the kinetic parameters. The characteristics of mass loss from individual pyrolysis and co-pyrolysis registered in TGA during temperature programmed heating is attributed mainly to devolatilization of volatile fragments, and the heating rate and the mixing ratio of the samples experienced significant change on the weight loss. A weaker interaction in the process of co-pyrolysis of pine branches and peat (CPBP) is observed under the condition of multiple factors investigated in this work. The pyrolysis temperature is lower than 400 °C, the volatiles are not released in time, and remain in the pores of the pyrolysis char, which increases the yield difference of char. The relative abundance of the number of substituents in the monocyclic aromatic structure in tar is C3 < C0 < C1 < C2. The relative abundance of two methyl groups in the benzene series in tar exhibited the largest value, as indicated from GC–MS results. Conventional gas products such as H2O, CO2, CO, CH4 and H2 were detected. The activation energy was not a constant value, but changed with the progress of the reaction, indicating that the decomposition reaction mechanism changed as the reaction progressed. The activation energy and linear correlation determined using the KAS and FWO methods were higher. The aforementioned methods were more appropriate and reliable for the thermo-kinetics studies in CPBP.

Analysis of the products of low-temperature microwave pyrolysis of peat

To increase the efficiency and intensity of processing of organic natural caustobiolite or peat, a prototype laboratory microwave reactor with an increased loading volume of the processed material has been developed. The modernized experimental setup is a microwave reactor under reduced pressure with a constant removal of pyrolysis gases through a trap with liquid nitrogen into a gas sampler. The increase in the volume of the microwave reactor was achieved through the use of additional systems for transporting microwave radiation and a special system of absorption of reflected power from the reactor volume. The reactor was connected to a microwave source (industrial magnetron) with a frequency of 2.45 GHz, with a total power of 1 kW. The duration of microwave irradiation of peat in the reactor was 16 minutes. As a result of a series of experiments, samples of three fractions – solid, liquid, and gaseous – were obtained and analyzed. A comparative analysis of the products of low-temperature pyrolysis of bog sphagnum peat obtained by heating based on heat transfer from the walls of the reactor (conventional thermal heating) and heating by microwave radiation. The main difference between heating by radiation and heat transfer is that in the first case there is an increase in temperature throughout the volume, and not just in the zone of the phase boundary, which increases the intensification and the efficiency of the process. This is especially evident when heating solid objects in which there is no heat transfer by convection. Comparison of the products of the three fractions obtained was carried out using gas chromatography analysis data with massspectrometric detection, as well as using the results of elemental analysis. The study has shown that microwave heating causes a deeper destruction of the initial substrate – to the carbon residue and low molecular weight products of inorganic and organic nature. In addition, the surface of the solid fraction was examined using a scanning electron microscope; the presence of porous structures with pore sizes from 5 to 7 μm has been detected.

ТЕПЛОФИЗИЧЕСКОЕ ОБОСНОВАНИЕ ПИРОЛИТИЧЕСКОЙ ПЕРЕРАБОТКИ ВОЗОБНОВЛЯЕМОЙ БИОМАССЫ ЗА СЧЕТ ТЕПЛОТЫ РАЗЛОЖЕНИЯ

Актуальность исследования обусловлена необходимостью увеличения доли использования возобновляемых источников энергии в топливно-энергетическом балансе для снижения вредного воздействия на окружающую среду. Цель: оценка возможности пиролиза древесной биомассы и торфа за счет тепловыделения от разложения органической части сырья. Объекты: образцы торфа с двух месторождений Томской области, являющихся перспективными для разработки в энергетических целях, – Суховского и Аркадьевского, а также древесные отходы двух видов – щепа и опилки. Методы: физический эксперимент и дифференциально-термический анализ. Теплотехнические характеристики древесной биомассы определены с помощью методик ГОСТ Р 56881-2016, ГОСТ 33503-2015 и ГОСТ Р 55660-2013; теплотехнические характеристики торфа – с помощью ГОСТ 11306-2013, ГОСТ 11305-2013 и ГОСТ Р 55660-2013. Теплота сгорания сырья определена на бомбовом калориметре АБК-1 (РЭТ, Россия), элементный состав определен на анализаторе Vario Micro Cube (Elementar, Германия) с учетом содержания диоксида углерода карбонатов, устанавливаемого объёмным методом согласно ГОСТ 13455-91. Результаты. Установлены оптимальные параметры пиролитической переработки различных видов биомассы – температура пиролиза и влажность исходного сырья. Оптимальной температурой для пиролиза древесных отходов, доведенных до воздушно-сухого состояния, является 400 °C, при которой суммарный тепловой эффект максимален и составляет 36,3 кДж/кг для опилок и 78,8 кДж/кг для щепы, для суховского торфа при 500 °C суммарный тепловой эффект равен 149,7 кДж/кг. Максимальные значения влажности, обеспечивающие покрытие тепловых затрат за счет теплоты экзотермических реакций, при данных температурах пиролиза составили 10 % для древесных отходов и 14 % для суховского торфа. Величина суммарного теплового эффекта пиролиза аркадьевского торфа даже в сухом состоянии имеет отрицательное значение.

Pyrolysis char derived from waste peat for catalytic reforming of tar model compound

The pyrolysis char derived from solid waste peat was used in the removal of biomass tar. A laboratory dual-stage reactor was designed to obtain a cost-effective and eco-friendly tar removal approach using peat pyrolysis char-based catalyst. Rich pore structure of pyrolysis char can enhance the adsorption and removal performance of tar, the KOH and CO2 activation method were used to increase the pore structure of pyrolysis char. Toluene was chosen as the model compound of biomass tar for basic research. The effects of pyrolysis char and transition metal Fe on toluene removal were studied. The investigated reforming parameters were reaction temperature (700–900 °C), residence time (0.3–0.8 s) and steam-to-carbon ratio (1.5:1–4:1). The results indicated that the peat pyrolysis char-based Fe catalysts showed excellent catalytic performance (toluene conversion >89%) and gas selectivity, especially the catalyst that activated by CO2 had the best selectivity for syngas (88.1 mol%), and the waste peat catalyst was compared with other waste pyrolysis char-based catalysts. Textural characterization showed that the excellent catalytic activity and stability of the catalysts are due to the presence of FeC and FeSiO3 structures. Such the peat pyrolysis char can as a carrier be used to remove tar and produce high content syngas in pyrolysis process.

Production of Metallurgical Coke by the Pyrolysis of Peat, Biomass, and Tar Mixtures

The production of metallurgical coke by the low-temperature pyrolysis of peat, biomass, and tar mixtures was investigated. Data on the effects of the preliminary treatment of raw mixtures, the tar content of the mixtures, and the process temperature on the characteristics of the products obtained are presented. It was experimentally established that the maximum yield of semicoke was achieved with a tar content of 20–40%, and the addition of tar to the mixture increased the mechanical strength of the resulting semicoke.

Peat-based activated carbons as adsorbents for simultaneous separation of organic molecules from mixed solution of poly(acrylic acid) polymer and sodium dodecyl sulfate surfactant

The activated carbons obtained from peat were applied for simultaneous removal of low-molecular weight poly(acrylic acid) – PAA (2 000 Da) and sodium dodecyl sulfate (SDS) from their mixed solution. There were applied three samples of activated carbons: N – obtained by peat pyrolysis followed by the steam activation, N9C – obtained from N by means of physical activation with CO2 and N9K – obtained from N by chemical activation with K2CO3. The final products are characterized by mesoporous structure, well-developed surface area and specific acidic-basic properties of the surface. The effect of solution pH, influencing PAA chains conformation (changes in polymer carboxyl groups dissociation) and solid surface charge density were examined. The applied adsorbents were characterized using the low-temperature nitrogen adsorption-desorption method, Fourier-transform infrared spectroscopy (FTIR), elemental analysis and back-titration method. Moreover, the adsorption affinity of PAA and SDS for the activated carbon surface was characterized based on the adsorption and electrokinetic data obtained from the spectrophotometric experiments, potentiometric titrations and zeta potential measurements. Additionally, the sizes of poly(acrylic acid) chains (hydrodynamic radius) in the solution as a function of pH were determined based on viscosity measurements. It was demonstrated that under specific pH conditions the prepared activated carbons exhibit high adsorptive affinity for PAA chains (reaching about 265 mg/g). Furthermore, it was also proved that these adsorbents can be successfully regenerated (using an appropriate desorbing agent) and reused. Therefore the low-cost activated carbons can be used for simultaneous removal of undesirable low-molecular polymers and surfactants from wastewaters.

Thermal Decomposition and Combustion of Peat Fuel

The thermal decomposition of peat in a drop tube furnace was studied under conditions typical of the low-temperature combustion chambers of industrial heat-generating plants, and the combustion of peat charcoal was examined on a thermogravimetric analyzer with dynamic heating. It was established that the thermal properties of peat are well combined with the properties of woody biomass, primarily, with coniferous wood (spruce and pine). The main differences are that the process of peat pyrolysis occurred in a wider temperature range and two extremum points at temperatures of 277 and 320°C were observed in this case.

Thermal effects investigation during biomass slow pyrolysis in a fixed bed reactor

The desire to increase the role of renewable biomass resources in the energy sector sets the task of finding promising areas for its resource-efficient use. Pyrolytic conversion (pyrolysis) of biomass can be considered as one of such directions. The efficiency of pyrolysis depends on the possibility of its implementation in the autothermal mode. In this regard, the purpose of this work is to study the thermal conversion of biomass in the process of slow low-temperature pyrolysis in relation to its implementation in a fixed bed reactor. Physical experiment methods, differential thermal analysis and electron scanning microscopy were used in the work. As a result of the study, it was shown that in the process of straw and peat low-temperature pyrolysis (heating rate of 10 °C/min) a thermal exothermic decomposition effect was observed when the reactor was heated to 500 °C. This effect led to an increase in the rate of heating of the biomass bed. Moreover, in the case of straw pyrolysis, the temperature in the bed began to exceed the temperature of the reactor wall (up to 55–60 °C) when heated above 303 °C. The total values of the exothermic effect of straw and peat pyrolysis in the temperature range of 170–600 °C were 1,475 kJ/kg and 862 kJ/kg, respectively (based on the dry mass of the feedstock). The scanning microscopy method shows the change in the biomass structure during the pyrolytic decomposition process.

Thermal degradation of peat-based activated carbons covered with mixed adsorption layers of PAA polymer and SDS surfactant

The thermal behaviour of activated carbons obtained from peat and modified with poly(acrylic acid) - PAA films was examined. Additionally, the effect of anionic surfactant – sodium dodecyl sulfate (SDS) presence in the adsorption layer was determined. Three samples of activated carbons were analyzed: (1) sample N - obtained by pyrolysis of peat followed by steam activation, (2) sample N9C - obtained by physical activation of sample N with carbon dioxide and (3) sample N9K - obtained by chemical activation of sample N with potassium carbonate. TG, DTG and DSC coupled with FTIR and QMS spectrometry enable not only specification of thermal stability of examined systems, but also determination of main gaseous products of their thermal decomposition. The obtained results indicate that polymer/surfactant adsorption influences significantly the thermal degradation of used carbon materials.

Экспериментальное исследование СВЧ-пиролиза торфа

The work is devoted to the study of the destruction of the top sphagnum peat layer due to microwave radiation. For the analysis of physical and chemical processes, a laboratory setup was created on the basis of a coaxial resonator-reactor having a geometry that ensures a uniform distribution of the microwave field in the reactor volume. An industrial magnetron having a frequency of 2.45 GHz and a power of up to 1 kW was used as a source of microwave radiation. In laboratory studies with a relatively small amount of peat (~ 100 g), the advantage of the created setup consists in the ability to quickly achieve the necessary temperature for the pyrolysis reaction at a relatively low level of microwave power (~ 100 W) in these experiments. The analysis of the products obtained during the reaction was carried out using a gas chromatography mass spectrometer. The research was aimed at creating highly-efficient environmentallyfriendly technologies for processing biofuels characterised by a high yield of combustible gases suitable for further use in industrial power plants, as well as for obtaining a resinous fraction for the production of light hydrocarbons and a carbon residue for modern highly efficient sorbents. On the basis of the experimental setup, studies were carried out on soft microwave pyrolysis of peat at a temperature of 250 °C under constant removal of gaseous reaction products. Samples of solid, liquid and gas phases presenting valuable carbon residues, oily fractions and a pyrolysis gas, respectively, were obtained and analysed. The article examines the possibility for industrial application of reaction products. The chemical composition of the r eaction products during both microwave and “traditional” pyrolysis with thermal heating is compared. The composition of the gases released during microwave pyrolysis is characterised by the absence of heavy toxic gases often accompanying the process of “traditional” thermal pyrolysis. Reducing the amount of toxic gases improves the environmental component of production. This circumstance indicates the prospects of microwave pyrolysis for industrial processing of organic materials. The authors declare no conflict of interests regarding the publication of this article.

Experimental study of the dynamics of microwave pyrolysis of peat

The work is devoted to the study of the effect of high-power microwave radiation on sphagnum peat. To implement the microwave pyrolysis process, a laboratory unit based on a coaxial resonator has been created. An industrial magnetron with a frequency of 2.45 GHz was used as a source of microwave radiation. Samples of gas, liquid and solid phases were obtained and analyzed. Studies of soft microwave pyrolysis in conditions of constant removal of gaseous reaction products were carried out. A comparative analysis of the products obtained in microwave pyrolysis and pyrolysis with thermal heating was performed. The aim of the research is to create highly efficient environmentally friendly technologies for processing biofuels with a high yield of combustible gases, suitable for further use in power plants, as well as the production of resinous fraction and carbon residue.