Woody biomass can be converted into green fuels by advanced conversion technologies such as gasification and pyrolysis. Due to the complexity of woody biomass, the thermochemical decomposition ...mechanisms are complex and the knowledge of pyrolysis kinetics is mandatory for optimization of the process and reactor design of commercial scale biorefineries. Pyrolysis kinetics of short rotation coppice (SRC) poplar biomass (nine different clones) was studied using non-isothermal thermogravimetry. By using differential thermogravimetry data, obtained for heating rates of 10–50 K/min, the Kissinger model-free methodology showed activation energies in the range 108–320 kJ/mol, similar to those reported in the literature for cellulose pyrolysis. Isoconversional approaches of Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) obtained similar values of activation energy (81–301 kJ/mol and 90–306 kJ/mol, respectively. The kinetics parameters obtained by the FWO and KAS methods were higher than data reported in the literature for other biomasses, and a correlation between activation energy and the lignin content of the biomass samples was found. The pyrolysis activation energy seems to have no significant effect on the pyrolysis product yields, probably because, under the tested conditions (fixed bed reactor, 773 K), pyrolysis was controlled by mass and/or heat transfer limitations instead of kinetics control.
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•SRC poplar biomass pyrolysis kinetics were evaluated by TGA and model-free methods.•Different poplar genotypes presented analogous kinetics behaviours.•Activation energies from Kissinger method were similar to that of cellulose.•Higher activation energy values were correlated to higher biomass lignin content.•Activation energies had no significant effect on pyrolysis in a fixed bed reactor.
The elucidation of the biomass pyrolysis characteristics will provide valuable guidance for the design of pyrolysis devices. The pyrolysis kinetics characteristics of lignocellulosic biomass were ...studied by thermogravimetric analysis, and the main influencing factors, including biomass particle size, heating rate, and metal ion, were investigated. With a decrease in the particle size of rice straw and pine sawdust, the initial and final pyrolysis temperatures and the temperature of the maximum weight loss ratio decreased. Opposite results were obtained for Phoenix tree leaves. Furthermore, the initial release temperature of volatile matter and the temperature corresponding to the peak of the derivative thermogravimetric curves increased with an increase in heating rate. Moreover, the pyrolysis activity of rice straw decreased significantly after deashing but increased with the addition of potassium. The pyrolysis kinetics parameters were calculated by the Coats–Redfern, Doyle, and the distributed activation energy model (DAEM) methods. The apparent activation energy of pyrolysis was the lowest, varying between 30 and 70 kJ/mol, according to the fitting results of the Coats–Redfern method. The apparent activation energies calculated by the DAEM and Doyle methods are similar, and are 67.6, 245.8, and 271.8 kJ/mol for rice straw, pine sawdust and Phoenix tree leaves, respectively.
•A small particle size is beneficial to rice straw and pine sawdust pyrolysis.•Biomass pyrolyzes over a wide temperature range at a high heating rate.•Pyrolysis activity of straw decreases after deashing but increases with potassium.•The Coats-Redfern method, Doyle, and DAEM are evaluated.•Single-stage, first-order reaction kinetic model is decided by Coats–Redfern method.
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•Biochar water and wastewater treatment is reviewed for the first time.•Applications of slow and fast pyrolysis biochars in water treatment are reviewed.•Adsorption capacities for ...organic and inorganic contaminants by biochars are summarized and compared.•Recommendations for further research are made.
Biochar is used for soil conditioning, remediation, carbon sequestration and water remediation. Biochar application to water and wastewater has never been reviewed previously. This review focuses on recent applications of biochars, produced from biomass pyrolysis (slow and fast), in water and wastewater treatment. Slow and fast pyrolysis biochar production is briefly discussed. The literature on sorption of organic and inorganic contaminants by biochars is surveyed and reviewed. Adsorption capacities for organic and inorganic contaminants by different biochars under different operating conditions are summarized and, where possible, compared. Mechanisms responsible for contaminant remediation are briefly discussed. Finally, a few recommendations for further research have been made in the area of biochar development for application to water filtration.
Co-pyrolysis of sophora wood (SW) and polyvinyl chloride (PVC) was conducted in a microwave reactor at different temperatures and different mixing ratios, and the transformation and distribution of ...chlorine in pyrolysis products were investigated. Microwave pyrolysis is a simple and efficient technique with better heating uniformity and process controllability than conventional heating. Compared with PVC pyrolysis, the addition of SW significantly reduced CO2 yield and greatly increased the yield of CO. The yield and quality of pyrolysis oil were effectively improved by SW, and the content of chlorine-containing compounds in the oil was suppressed to <1% at low temperatures (<550 °C). Co-pyrolysis of SW and PVC reduced the chlorine emissions from 59.07% to 28.09% and promoted the retention of chlorine in char (from 0.33% to 4.72%). Cellulose, hemicellulose, and lignin were co-pyrolyzed with PVC to investigate their effects on chlorine distribution. The experiments demonstrated that lignin had the most significant effects on reducing gas phase chlorine emission and achieving chlorine immobilization, and chlorine mainly existed in the form of sodium chloride in the char of lignin-PVC co-pyrolysis. Hence co-pyrolysis of lignocellulosic biomass and PVC provides a practical pathway for utilization of PVC waste in an environmentally friendly manner, realizing efficient chlorine retention and significantly reducing chlorine-related emissions.
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•Microwave co-pyrolysis of PVC and biomass was comprehensively investigated.•The Cl in gas was reduced from 59.07 to 28.09% due to the addition of biomass.•Lignin has the best Cl retention compared with cellulose and hemicellulose.•Cl in char was mainly fixed by lignin of biomass in the form of inorganic salts.•Cl-containing compounds in the oil was suppressed to <1% at <550 °C.
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•The discussion emphasizes the use of biomass wastes in the co-pyrolysis process.•The co-pyrolysis can significantly improve the quantity and quality of pyrolysis oil.•Co-pyrolysis ...technique is more profitable than the pyrolysis of biomass alone.•By using this method, the volume of biomass wastes can be easily controlled.
The oil produced by the pyrolysis of biomass has potential for use as a substitute for fossil fuels. However, the oil needs to be upgraded since it contains high levels of oxygen, which causes low caloric value, corrosion problems, and instability. Generally, upgrading the pyrolysis oil involves the addition of a catalyst, solvent and large amount hydrogen, which can cost more than the oil itself. In this regard, the co-pyrolysis technique offers simplicity and effectiveness in order to produce a high-grade pyrolysis oil. Co-pyrolysis is a process which involves two or more materials as feedstock. Many studies have shown that the use of co-pyrolysis is able to improve the characteristics of pyrolysis oil, e.g. increase the oil yield, reduce the water content, and increase the caloric value of oil. Besides, the use of this technique also contributed to reduce the production cost and solve some issues on waste management. This article tried to review the co-pyrolysis process through several points of view, including the process mechanism, feedstock, the exploration on co-pyrolysis studies, co-pyrolysis phenomena, characteristics of byproducts, and economic assessment. Additionally, several outlooks based on studies in the literature are also presented in this paper.
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•The relationships between lignin structure and pyrolysis activity were evaluated.•Mild acidolysis lignin shows high purity and is representative of native lignin.•Py-GC/MS of four ...lignins isolated from softwood, hardwood, and herbaceous crops.•The pyrolyzed phenolic compounds varies significantly with different lignin sources.•Herbaceous grass lignin produces 4-vinylphenol as the main pyrolysis product.
Understanding the structure activity relationships between lignin and its pyrolysis products is of great significance toward thermochemical conversion of lignin. Herein, mild acidolysis lignins (MALs) isolated from softwood (pine), hardwood (eucalyptus), and herbaceous feedstocks (corn stalk and bamboo) were characterized and their activities toward fast pyrolysis were comparably evaluated. A detailed characterization of lignin structure demonstrates that eucalyptus MAL contains both guaiacyl (G) and syringyl (S) units, whereas pine MAL is enriched in G units. In addition to G, S, and p-hydroxyphenyl (H) units, corn stalk and bamboo MALs consist of tricin and hydroxycinnamic acids (ferulic and p-coumaric acids). Moreover, lignins from those plants are extensively acylated at the Cγ of the lignin side chain with p-coumarate groups. The results of fast pyrolysis of different lignin sources reveal a diverse range of aromatic compounds due to varying selective fractures on the linkages of lignin. Notably, herbaceous MALs afford higher amounts of phenolic compounds, among which 4-vinylphenol is the main pyrolysis product, suggesting the efficient cleavage of C–O linkages coupling with decarboxylation reaction in lignin. This work demonstrates the essential role for the insights gained in the characterization of lignin structure, which will guide for the rational design of thermochemical process toward lignin valorization into phenol compounds via fast pyrolysis.
Oil sands bitumen (OSB) is the key component of extracted oil sands, thus further investigation of the mechanism of OSB pyrolysis reaction would be helpful for the development and application of oil ...sands pyrolysis process. First, chemical structure parameters and thermogravimetric (TG) behavior of OSB were experimentally investigated by 13C NMR spectroscopy and TG analysis, respectively, to initially evaluate the correlation between chemical structure parameters and pyrolytic behavior. Further, the ATR–FTIR spectroscopy technology was used to experimentally characterize and calculate the structural parameters of OSB at different pyrolysis final temperatures, and the main thermal evolution rules of different functional groups during the pyrolysis reaction were obtained. Based on this result and by using the model fitting method, the pyrolysis of OSB was found to be a parallel reaction. Moreover, the kinetic calculation results obtained by Straink method and distributed activated energy model method also supported this result. The correlation between chemical structure parameters and activation energy was analyzed, and it was found that the degree of aromatization Y-factor could be used to characterize the pyrolysis reaction activity. Finally, this study proposed a simplified mechanistic model of chemical structure evolution during OSB pyrolysis.
•Pyrolysis mechanism studied by experimental characterization combined with kinetics.•Study of the thermal evolution of OSB chemical structure by ATR-FTIR.•The pyrolysis kinetics of oil sands bitumen are obtained by different models.•The main reaction stage of OSB pyrolysis is classified as a parallel reaction.•Proposed a simplified pyrolysis mechanism model of OSB chemical structure evolution.
In this work, the conversion of sugarcane bagasse into fuel was studied as a low cost source material. The conversion was carried out experimentally in a batch pyrolysis reactor. Two pyrolysis ...methods were compared; namely, fast pyrolysis and slow or conventional pyrolysis. This comparison was based on the thermal decomposition of biomass into fuel and on the product yields. Since the yields are affected by the type of pyrolysis and the operating temperature of the reactor, the comparisons have been conducted at three fixed temperature values of 753, 853 and 953 K. The results revealed that the conventional pyrolysis produce more syngas yield with the increases of temperature. In the case of fast pyrolysis, it was observed that losses and solid yield increase with temperature increase. Moreover, it was found that the highest losses in both cases are less than 15% and that it was higher in conventional pyrolysis. Gases released during the thermal decomposition of biomass were identified as H2, CO, CO2, CH4 and some light molecular weight of hydrocarbons, such as C2H4 and C2H6. The low temperature was favored for the production of methane other than hydrogen for both processes, while high temperature was favored for the production of hydrogen. The produced H2 can be used in typical fuel cells.
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•A comparison between two-type pyrolyses for syngas from bagasse is presented.•Fast pyrolysis at high temperature favors the production of hydrogen.•Slow pyrolysis favors syngas production while fast pyrolysis favors char production.•Maximum value obtained of H2 is 45 vol% at 953 K, while for CH4 is 30 vol% at 853 K.
Many facets of our civilization's contemporary life are related to the use of electrical and electronic equipment (EEE). EEE replacement is becoming more common as the need for high-performance EEE ...grows and technical advancement accelerates. As a result, a massive quantity of electronic waste (e-waste) is generated. One way of recycling e-waste is through pyrolysis, which is a thermochemical method used to recover polymers and concentrate metals into a solid residue. Additionally, this technique may be modified or integrated with other technologies to reduce the number of organic halides produced by harmful brominated flame retardants (BFRs), often used as additives in these materials. This article provides a comprehensive review in the context of pyrolysis of e-waste and its sustainability. The structure and components of the five significant types of e-waste, including printed circuit boards (PCBs), lithium-ion batteries (LIBs), tantalum capacitors (TCs), light-emitting diodes (LEDs), and liquid crystal displays (LCDs), are first discussed. Then five methods of e-waste pyrolysis, including vacuum pyrolysis, catalytic pyrolysis, co-pyrolysis, microwave pyrolysis, and plasma pyrolysis, have been carefully studied and the merits and demerits of each method are presented. In the following, the sustainability of the pyrolysis process is examined from three perspectives: economic, environmental, and social. In the end, ongoing challenges of e-waste pyrolysis and recommendations for future directions are also addressed. E-waste pyrolysis is still not completely industrialized. However, it can be said that it is a sustainable method, and the suitability of this method has been proven on the laboratory scale. It is hoped that we will see the industrialization of this method in industrialized and developing countries in the future.
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•Five methods of e-waste pyrolysis and their sustainability are discussed.•Pyrolysis of PCBs, LIBs, TCs, LCDs, and LEDs are investigated.•Catalytic pyrolysis increases oil quality and reduces halogenated pollutants.•The prospects and challenges of e-pyrolysis have been scrutinized.
