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•CO2 and Pt catalyst affect condensable species generated via food waste pyrolysis.•Less condensable species are generated with Pt catalyst and CO2.•More non-condensable gases are ...generated with Pt catalyst and CO2.•Simultaneous use of CO2 and Pt catalyst most affects pyrolytic product distribution.
In this study, a method of disposing food waste is introduced via catalytic pyrolysis under CO2 condition. The catalyst and CO2 hindered the generation of condensable compounds, leading to enhancing non-condensable gas generation. However, they did not affect the amount of solid residues left after the thermal reaction. The amount of condensable cyclic compounds was reduced when the catalyst and/or CO2 were used. The enhancement of non-condensable gas production and reduction of cyclic compounds formation were maximized when the Pt catalyst and CO2 were simultaneously applied to the pyrolysis of food waste. For instance, approximately 67.3 % less cyclic compounds, including benzene derivatives, were generated at 700 °C in the presence of the catalyst under a CO2 atmosphere compared to non-catalytic conditions without CO2. The results suggest that a CO2-assisted catalytic pyrolysis is as environmentally benign disposal method for food waste.
•Future directions on co-pyrolysis of biomass and waste plastics are highlighted.•Overview of recent progress in co-pyrolysis of biomass and waste plastics worldwide.•Overview of co-pyrolysis of ...biomass and waste plastics in China.•Co-pyrolysis synergistic mechanism of biomass and plastic wastes was examined.
Continuous growth of human population and industrialization has increased the energy demands all over the world and this has resulted in a number of energy related challenges including depletion of fossil fuels, environmental pollution, and shortage of electricity supply. These challenges made it imperative to develop and maximize the abundant renewable energy resources, particularly the biomass via upgrading thermochemical conversion routes such as co-pyrolysis. This review paper presents an overview of previous studies, recent advances, and future directions on co-pyrolysis of biomass and waste plastics for high-grade biofuel production particularly in China and elsewhere worldwide. This paper also discussed the advantages of the co-pyrolysis process, co-pyrolysis product yields, co-pyrolysis mechanisms of biomass with plastics, and synergistic effects between them during co-pyrolysis, as well as the effects of some operating parameters especially the biomass mixing ratio and pyrolysis temperature on co-pyrolysis yields. The result of this critical review showed that co-pyrolysis of biomass with waste plastics is more beneficial than the normal biomass pyrolysis alone, and that it is also a simple, effective, and optional solution to increase the energy security of a nation, achieve effective waste management, and reduce dependency on fossil fuels.
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.
Pyrolysis property is an important safety issue for asphalt materials. It is important to study the asphalt pyrolysis properties for selecting flame-retarding technology to improve the fire safety of ...asphalt materials. Differential scanning calorimeter–thermogravimetry–Fourier-transform infrared spectroscopy was used to analyze the main pyrolysis temperature range, thermal effects, and emitted volatiles of saturates, aromatics, resins and asphaltenes (SARA) fractions. The microscopic morphology, the elemental compositions and their contents of each SARA fraction pyrolysis residues were tested by environmental scanning electron microscope–energy-dispersive spectrometer. The results indicate that main pyrolysis temperature range of SARA fractions is 250–550 °C, of which saturates have the lowest initial pyrolysis temperature, successively followed by aromatics, resins and asphaltenes. Also, SARA fraction pyrolysis processes are mainly endothermic reactions. The main volatiles in the pyrolysis of SARA fractions are alkanes and a small amount of CO, CO
2
and SO
2
. Finally, the morphology and their elemental compositions of pyrolysis residues of SARA fractions are different. Among them, the proportion of O element is decreased from saturates to aromatics, resins and asphaltenes while the proportion of C is basically increased.
The continuous growth of population and the steady improvement of people's living standards have accelerated the generation of massive food waste. Untreated food waste has great potential to harm the ...environment and human health due to bad odor release, bacterial leaching, and virus transmission. However, the application of traditional disposal techniques like composting, landfilling, animal feeding, and anaerobic digestion are difficult to ease the environmental burdens because of problems such as large land occupation, virus transmission, hazardous gas emissions, and poor efficiency. Pyrolysis is a practical and promising route to reduce the environmental burden by converting food waste into bioenergy. This paper aims to analyze the characteristics of food waste, introduce the production of biofuels from conventional and advanced pyrolysis of food waste, and provide a basis for scientific disposal and sustainable management of food waste. The review shows that co-pyrolysis and catalytic pyrolysis significantly impact the pyrolysis process and product characteristics. The addition of tire waste promotes the synthesis of hydrocarbons and inhibits the formation of oxygenated compounds efficiently. The application of calcium oxide (CaO) exhibits good performance in the increment of bio-oil yield and hydrocarbon content. Based on this literature review, pyrolysis can be considered as the optimal technique for dealing with food waste and producing valuable products.
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•Pyrolysis is an effective method to convert food waste into valuable products.•Tire waste is currently the optimal co-feedstock for the pyrolysis of food waste.•CaO exhibits the best catalytic effect in the pyrolysis of food waste.•Small distributed plants are more economical and feasible in developing countries.
Climate change issues are calling for advanced methods to produce materials and fuels in a carbon–neutral and circular way. For instance, biomass pyrolysis has been intensely investigated during the ...last years. Here we review the pyrolysis of algal and lignocellulosic biomass with focus on pyrolysis products and mechanisms, oil upgrading, combining pyrolysis and anaerobic digestion, economy, and life cycle assessment. Products include oil, gas, and biochar. Upgrading techniques comprise hot vapor filtration, solvent addition, emulsification, esterification and transesterification, hydrotreatment, steam reforming, and the use of supercritical fluids. We examined the economic viability in terms of profitability, internal rate of return, return on investment, carbon removal service, product pricing, and net present value. We also reviewed 20 recent studies of life cycle assessment. We found that the pyrolysis method highly influenced product yield, ranging from 9.07 to 40.59% for oil, from 10.1 to 41.25% for biochar, and from 11.93 to 28.16% for syngas. Feedstock type, pyrolytic temperature, heating rate, and reaction retention time were the main factors controlling the distribution of pyrolysis products. Pyrolysis mechanisms include bond breaking, cracking, polymerization and re-polymerization, and fragmentation. Biochar from residual forestry could sequester 2.74 tons of carbon dioxide equivalent per ton biochar when applied to the soil and has thus the potential to remove 0.2–2.75 gigatons of atmospheric carbon dioxide annually. The generation of biochar and bio-oil from the pyrolysis process is estimated to be economically feasible.
We have quantified the influence of different pyrolysis temperature and feedstocks types on thirty six compositional characteristics of biochar. The properties of biochar were principally influenced ...more by the feedstocks type than pyrolytic temperature. Higher porosity and surface area illustrated its soil structural modification and nutrient retention capacity along with their utilization for wastewater adsorbents. The total carbon content in all the biochar increased upto 10.14% with the increase in pyrolysis temperature. The produced biochar can replace the conventional fossil fuels due to their high fixed carbon. The cation exchange capacity of biochar augmented with rise in pyrolysis temperature. But the dissolved organic carbon reduced exponentially with increase in temperature. At low temperature pyrolysis the polarity index tends to increase and vice-versa. All the biochar has a potential to alleviate soil boron deficiency due to its higher concentration. Therefore, dissimilar properties of biochar can be produced by selecting the right feedstock type and standardizing specific pyrolytic temperature, depending on the necessity for environmental application in a specific crisis.
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•Compositional heterogeneity can meet the necessity for environmental application in a specific crisis.•Total carbon (53.30–74.10) in biochar can be used for purification and adsorption due to low sulphur content.•Low atomic O/C (0.04) and H/C (0.28) ratio reflects favourable fuel quality.•Well-established total pores volume (1.37–3.99 cm3 g−1) might promote the methanogenesis procedure.
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•Optimized parameters for stepwise pyrolysis are systematically investigated.•Low-temperature pyrolysis section is beneficial to biomass decomposition.•High-temperature pyrolysis ...section realizes the deoxygenation of intermediates.•Stepwise pyrolysis improves both the bio-oil yield and hydrocarbons selectivity.
Stepwise pyrolysis is recognized as a promising method in converting biomass into sustainable bio-oils. However, a systematic study on the stepwise parameters (e.g., low- and high-pyrolysis temperatures, duration, atmosphere) is still lacking. Herein, the stepwise catalytic fast pyrolysis (CFP) of cotton stove over ZSM-5 was conducted, aiming to reveal the impact of aforementioned parameters on bio-oils production. Results showed that the low-temperature pyrolysis benefitted the decomposition of biomass, while the high-temperature counterpart favored the upgrading of bio-oil. The combination of a low-temperature pyrolysis (400 ℃ for 2 min) and high-temperature pyrolysis (600 ℃ for 3 min) led to a satisfied hydrocarbons selectivity (35.8 area%) and bio-oil yield (11.4 wt%). This was superior to the one-step pyrolysis conducted at 600 ℃ for 5 min, which decreased the values to 32.2 area% and 11.2 wt%, respectively. The CO2 introduction into N2 atmosphere in stepwise pyrolysis further enhanced the hydrocarbon-rich bio-oil production, and a maximum bio-oil yield of 15.9 wt% was obtained in 100 vol% CO2, while the highest hydrocarbons selectivity of 51.8 area% was reached in 80 vol% CO2. This work confirmed the advantages of stepwise pyrolysis for producing high-quality bio-oils and provided a reference for pyrolysis in CO2 atmosphere.
Forsterite (Mgsub.2SiOsub.4) materials have been used in the industrial applications of refractory materials, bone grafting materials, and microwave dielectric materials. In order to avoid the ...formation of the secondary phase of MgO or MgSiOsub.3, spray pyrolysis with the precursors of magnesium nitrate hydrate and tetraethyl orthosilicate has been applied to synthesized Mgsub.2SiOsub.4 powders. In this study, three typical morphologies of smooth solid sphere, rough hollow sphere, and concaved hollow sphere were observed using scanning electron microscopy and transmission electron microscopy. The experimental results suggested that morphology and particle size distribution are strongly influenced by the calcination temperature. Finally, the corresponding powder formation mechanisms were proposed and discussed.
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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.
