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.
Pyrolysis is one of the thermal conversion pathways to convert biomass into biochar. The characteristic of biochar depends on three parameters, i.e., before pyrolysis (drying methods of biomass), ...during pyrolysis (temperature), and after pyrolysis (activation agents). Thermal and non-thermal drying methods remarkably affected the psychochemical properties of biomass. Pyrolysis temperature significantly governed the biochar production. Temperature above 500 °C was required to convert biomass okara into biochar. Activation agent determined the pore characteristic of biochar. FT-IR, XRD, TGA-DSC, SEM, Raman, XRF, CHNOS Analyzer, Surface area analysis, and TEM characterizations of material confirmed that implemented the three parameters simultaneously were essential to achieved different properties of biochar that could be used in environmental remediation or energy-oriented field.
•Non-thermal drying method generate biomass with higher lignocellulose level which led to higher carbon content of biochar.•Simultaneously varying biomass drying method, pyrolysis temperature, and activating agents provided various biochar character.•Acid activated biochar okara pyrolyzed at 800 °C possessed GO-like structure.
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.
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.
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.
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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.
•Scrap tire rubber was successfully pyrolyzed in a two-stage pyrolyzer.•The two-stage pyrolyzer is composed of auger and fluidized bed reactors.•N2 and temperatures of ∼500°C were effective for a ...low-sulfur oil.•A pyrolysis oil contained only 0.55wt.% of sulfur and 0.28wt.% of nitrogen.•A pyrolysis oil from the auger reactor contained 50wt.% dl-limonene.
The aim of this work was to reduce the sulfur content of pyrolysis oil derived from the scrap tire pyrolysis. In this respect, a series of pyrolysis experiments was conducted in both a fluidized bed reactor (one-stage pyrolysis) and a newly developed two-stage pyrolyzer consisting of an auger reactor and a fluidized bed reactor in series (two-stage pyrolysis). The one-stage pyrolysis was carried out at ∼500 and 600°C with different fluidizing gases (N2 and product gas). In the experiments, the pyrolysis oil obtained at ∼500°C had a lower sulfur content than that produced at ∼600°C. N2 was better at producing a low-sulfur pyrolysis oil than product gas. The sulfur contents of the oils obtained from the one-stage pyrolysis ranged from 0.75 to 0.92wt.%. The two-stage pyrolysis was conducted using product gas as the fluidizing medium at different auger reactor temperatures (∼230–450°C) and at a constant fluidized bed reactor temperature (∼510°C). A pyrolysis oil containing only 0.55wt.% of sulfur could be produced at the temperatures of the auger reactor of ∼330°C and fluidized bed reactor of ∼510°C. Moreover, the two-stage pyrolysis could produce an oil with a low nitrogen content (0.28wt.%). A pyrolysis oil obtained from the auger reactor contained dl-limonene up to 50wt.%.
Increasing fossil fuel consumption and global warming has been driving the worldwide revolution towards renewable energy. Biomass is abundant and low-cost resource whereas it requires environmentally ...friendly and cost-effective conversion technique. Pyrolysis of biomass into valuable bio-oil has attracted much attention in the past decades due to its feasibility and huge commercial outlook. However, the complex chemical compositions and high water content in bio-oil greatly hinder the large-scale application and commercialization. Therefore, catalytic pyrolysis of biomass for selective production of specific chemicals will stand out as a unique pathway. This review aims to improve the understanding for the process by illustrating the chemistry of non-catalytic and catalytic pyrolysis of biomass at the temperatures ranging from 400 to 650 °C. The focus is to introduce recent progress about producing value-added hydrocarbons, phenols, anhydrosugars, and nitrogen-containing compounds from catalytic pyrolysis of biomass over zeolites, metal oxides, etc. via different reaction pathways including cracking, Diels-Alder/aromatization, ketonization/aldol condensation, and ammoniation. The potential challenges and future directions for this technique are discussed in deep.
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•Properties of lignocellulosic biomass and its pyrolysis chemistry are extensively reviewed.•Catalytic pyrolysis of lignocellulosic biomass for selective production of valuable chemicals is outlined.•Different catalytic reforming pathways are summarized.•Future research directions and technological challenges are proposed.
Catalytic thermolysis is considered to be an effective process for viscosity reduction, the conversion of high-molecular components of oil (resins and asphaltenes) into light hydrocarbons, and the ...desulfurization of hydrocarbons. In this paper, we conducted non-catalytic and catalytic thermolysis of a heavy oil sample isolated from the Ashalcha oil field (Tatarstan, Russia) at a temperature of 250 °C. Fullerene C60 nanoparticles were applied to promote selective low-temperature thermolytic reactions in the heavy oil, which increase the depth of heavy oil upgrading and enhance the flow behavior of viscous crude oil. In addition, the influence of water content on the performance of heavy oil thermolysis was evaluated. It was found that water contributes to the cracking of high-molecular components such as resins and asphaltenes. The destruction products lead to the improvement of group and fractional components of crude oil. The results of the experiments showed that the content of asphaltenes after the aquatic thermolysis of the heavy oil sample in the presence of fullerene C60 was reduced by 35% in contrast to the initial crude oil sample. The destructive hydrogenation processes resulted in the irreversible viscosity reduction of the heavy oil sample from 3110 mPasup..s to 2081 mPasup..s measured at a temperature of 20 °C. Thus, the feasibility of using fullerene C60 as an additive in order to increase the yield of light fractions and reduce viscosity is confirmed.
The high viscosity of heavy oil is the main challenge hindering its production. Catalytic thermolysis can be an effective solution for the upgrading of heavy oil in reservoir conditions that leads to ...the viscosity reduction of native oil and increases the yield of light fractions. In this study, the thermolysis of heavy oil produced from Ashalchinskoye field was carried out in the presence of FeP and Al(Hsub.2POsub.4) nanocatalysts at a temperature of 250 °C in Nsub.2 gas environment. It was shown that Al(Hsub.2POsub.4)sub.3 and FeP catalysts at a concentration of 0.5% significantly promoted the efficiency of the heavy oil thermolysis and are key controlling factors contributing to the acceleration of chemical reactions. The Al(Hsub.2POsub.4)sub.3 + NiCOsub.3 nanoparticles were active in accelerating the main chemical reactions during upgrading of heavy oil: desulfurization, removal of the side alkyl chains from polyaromatic hydrocarbons, the isomerization of the molecular chain, hydrogenation and ring opening, which led to the viscosity reduction in heavy oil by 42%wt. Moreover, the selectivity of the Al(Hsub.2POsub.4)sub.3 + NiCOsub.3 catalyst relative to the light distillates increased up to 33.56%wt., which is more than two times in contrast to the light distillates of initial crude oil. The content of resins and asphaltenes in the presence of the given catalytic complex was reduced from 34.4%wt. to 14.7%wt. However, FeP + NiCOsub.3 nanoparticles contributed to the stabilization of gasoline fractions obtained after upgraded oil distillation. Based on the results, it is possible to conclude that the thermolysis of heavy oil in the presence of FeP and Al(Hsub.2POsub.4)sub.3 is a promising method for upgrading heavy oil and reducing its viscosity.
