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•A comparative study of slow and fast pyrolysis was performed.•Fuels tested were native to the southern forests of the United States.•The yields and the compositions of pyrolysis ...products were studied in detail.
Wildland fire, which includes both planned (prescribed fire) and unplanned (wildfire) fires, is an important component of many ecosystems. During wildland fires, low heating rate pyrolysis (slow pyrolysis) occurs during preheating and/or smoldering of plant material. High heating rate pyrolysis (fast pyrolysis) exists in the flame region. Pyrolysis temperature and heating rate play important roles on the yields and the compositions of pyrolysis products. In this work, the effects of pyrolysis temperature and heating rate on the yields and the compositions of pyrolysis products from 14 plant species native to the forests of the southern United States are shown. The slow pyrolysis experiments were performed at a low heating rate of 0.5 °C s−1 and an operating temperature of 500 °C. However, the fast pyrolysis experiments were operated at a high heating rate of 180 °C s−1 and a temperature of 765 °C. The yields and compositions of the pyrolysis products during the slow and fast pyrolysis experiments were analyzed in detail. The results showed that the average tar yield for all plant species (live and dead) was 58 wt% on a dry-ash free (daf) basis for the fast pyrolysis experiments compared to 49 wt% (daf) for the slow pyrolysis experiments, an increase of 9 wt%. The average gas yields for the slow and fast pyrolysis of the plants were 20 and 22 wt% (daf), respectively. The average volatile yield increased from 69 wt% (daf) at the low heating rate experiments to 80 wt% (daf) for the high heating rate experiments. The major light gas species for both the slow and fast pyrolysis experiments (wt% basis) were CO, CO2, CH4, and H2, with higher yields of CO observed in the high heating rate experiments and higher yields of CO2 in the slow pyrolysis experiments. The slow pyrolysis experiments led to formation of aliphatic and 1-ring aromatic compounds with large number of attachments on their rings, such as phenol, 1,2-benzenediol, 2-methoxy phenol, etc. In the fast pyrolysis experiments, phenol was still one of the major products. However, in contrast with the slow pyrolysis experiments, 1- to 5-ring aromatic compounds with very few attachments, such as fluorene, anthracene, phenanthrene, fluoranthene, pyrene, etc. were major tar compounds during the fast pyrolysis experiments.
Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating ...rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.
New Y(III) and La(III) complexes with 4-bpy (4,4'-bipyridine) and trichloro- or dibromoacetates with the formulae: Y(4-bpy).sub.2(CCl.sub.3COO).sub.3 x H.sub.2O I, La(4-bpy).sub.1.5 ...(CCl.sub.3COO).sub.3 x 2H.sub.2O II, Y(4-bpy).sub.1.5(CHBr.sub.2COO).sub.3 x 3H.sub.2O III, and La(4-bpy)(CHBr.sub.2COO).sub.3 x H.sub.2O IV were prepared and characterized by chemical, elemental analysis, and IR spectroscopy. Conductivity studies (in methanol, dimethyloformamide, and dimethylsulfoxide) were also described. They are small, crystalline substances. The way of metalligand coordination was discussed. The thermal properties of complexes in the solid state were studied by TG-DTG techniques under dynamic flowing air atmosphere. TG-FTIR system was used to analyze principal volatile thermal decomposition and fragmentation products evolved during pyrolysis in dynamic flowing argon atmosphere for La(III) compounds. Keywords Y(III) and La(III) complexes * 4,4'-Bipyridine * Trichloroacetates * Dibromoacetates * TG-DTG * TG-FTIR * IR spectra
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•Macroalgae and microalgae are excellent pyrolysis feedstock.•Chemical constituents of algae are important criteria as feedstock.•Advanced pyrolysis derived products show higher ...energy content and better yield.•Technological limitations associated with each technique have been detailed.
Algal biomass including macroalgae and microalgae show great potential as pyrolysis feedstock in generating energy-dense and valuable pyrolytic products such as bio-oil, biochar and bio-syngas. The chemical constituents of macroalgae and microalgae show great variations, especially their lipid, carbohydrate and protein contents, which could affect the qualities of the pyrolytic products. From the established conventional pyrolysis, the products produced from both macroalgae and microalgae show moderate energy contents (<34 MJ/kg). The review identifies the issues associated with development of conventional pyrolysis such as flash and intermediate pyrolysis. To enhance the production of biofuels from algal biomass, advanced or non-conventional pyrolysis techniques have been employed. Catalytic pyrolysis on algal biomass could reduce the nitrogenates and oxygenates in the biofuels. On top of that, co-pyrolysis with suitable feedstock shows great enhancement on the bio-oil yield. As for hydropyrolysis of algal biomass, their generated biofuels can produce up to 48 MJ/kg with high yield of bio-oil up to 50 wt%, comparable to conventional fuels. Microwave-assisted pyrolysis of algal biomass greatly shortens the processing time through advanced heating; however, favours the formation of bio-syngas by improving the yield up to 84 wt% depending on the feedstock used. Therefore, formation of biofuel fraction suitable for energy generation highly depends on the selected pyrolysis technologies.
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•Evolution of functionalities of the biochar from poplar pyrolysis was studied.•Pyrolysis temperature governs structure and functionalities of the biochar.•Decarboxylation dominates ...above 350 °C while decarbonylation dominated above 450 °C.•Drastic fusion of the ring structures in biochar occurred from 550 to 650 °C.•High pyrolysis temperature created more defective structures in biochar.
This study studied the change of functionalities in the biochar formed in pyrolysis of poplar wood in a wide range of temperature. The in situ Diffuse Reflectance Infrared Fourier transform spectroscopy characterization indicated that aldehydes and ketones functionalities formation initiated at 100 °C, dominated at 300 to 500 °C. Carboxyl group was less stable than carbonyls. Cellulose crystal in poplar decomposed slightly at 300 °C and significantly at 350 °C. The temperature from 250 to 350 °C significantly affected biochar yields, while the drastic fusion of the ring structures in biochar occurred from 550 to 650 °C, making biochar more aliphatic while less more aromatic. High pyrolysis temperature also created more defective structures in the biochar and favored the absorption of the CO2 generated during the pyrolysis. The results provide the reference information for understanding the structural configuration and evolution of the functionalities during in pyrolysis of poplar biomass.
Surface area and porosity are important physical properties of biochar, playing a crucial role in many biochar applications, such as wastewater treatment and soil remediation. The production of ...engineered biochar with highly porous structure and large surface area has received extensive attention. This paper comprehensively reviewed the effects of biomass and pyrolysis parameters on the surface area and porosity of biochar. The composition of biomass feedstock and pyrolysis temperature are the major influencing factors. It is suggested that the lignocellulosic biomass is an outstanding candidate, wood and woody biomass in particular. Besides, moderate temperatures (400–700 °C) are suitable for the development of the pore structure. Further improvement can be implemented by additional treatments. Activation is the most widely used and effective way to promote biochar surface area and porosity, especially the chemical activation. Enhancement can also be achieved by using other treatment methods, such as carbonaceous materials coating, ball milling, and templating. Future research should focus on upgrading or developing treatment technology to achieve enhanced functionality and porous structure of biochar simultaneously.
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•Biomass feedstock and pyrolysis temperature are two key influencing factors.•The lignocellulosic biomass is a preferable candidate.•Moderate temperature (400–700 °C) is more suitable.•Chemical activation is the most effective additional treatment.•Future research should focus on functionalizing and reforming porous structure simultaneously.
In this study some literature data on the pyrolysis characteristics of biomass under inert atmosphere were structured and analyzed, constituting a guide to the conversion behavior of a fuel particle ...within the temperature range of 200–1000 °C. Data is presented for both pyrolytic product distribution (yields of char, total liquids, water, total gas and individual gas species) and properties (elemental composition and heating value) showing clear dependencies on peak temperature. Empirical relationships are derived from the collected data, over a wide range of pyrolysis conditions and considering a variety of fuels, including relations between the yields of gas-phase volatiles and thermochemical properties of char, tar and gas. An empirical model for the stoichiometry of biomass pyrolysis is presented, where empirical parameters are introduced to close the conservation equations describing the process. The composition of pyrolytic volatiles is described by means of a relevant number of species: H
2O, tar, CO
2, CO, H
2, CH
4 and other light hydrocarbons. The model is here primarily used as a tool in the analysis of the general trends of biomass pyrolysis, enabling also to verify the consistency of the collected data. Comparison of model results with the literature data shows that the information on product properties is well correlated with the one on product distribution. The prediction capability of the model is briefly addressed, with the results showing that the yields of volatiles released from a specific biomass are predicted with a reasonable accuracy. Particle models of the type presented in this study can be useful as a submodel in comprehensive reactor models simulating pyrolysis, gasification or combustion processes.
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•Pyrolysis is a feedstock-flexible conversion technique for waste valorisation.•Various types of reactors and potential feedstocks for pyrolysis are reviewed.•Derived pyrolytic ...products in different phases have desirable properties.•Catalytic pyrolysis and co-pyrolysis are methods with high product selectivity.•Waste management using pyrolysis leads to positive environmental impact.
Pyrolysis is a thermo-chemical decomposition process that converts organic or inorganic materials into solid, liquid and gaseous products. The pyrolysis process involves multiple complex chemical reactions, and the derived products are highly dependent on the pyrolysis operating parameters and type of feedstock. In the present review, progress on the state-of-the-art pyrolysis technology, feedstock and properties of the end products are thoroughly reviewed. The potential application of the pyrolysis products in the industries is discussed: solid leftover can be upgraded and used as a bio-adsorbant, soil amendment, fertilizer or solid fuel; pyrolysis liquid can be used as a bio-chemical source or upgraded into liquid fuel; gaseous products can be used as recirculating gas for the pyrolysis environment or burnt as fuel for heat and power generation. Despite the potential of pyrolysis in processing agricultural or industrial wastes, studies regarding the economic feasibility and environment sustainability of scaled-up pyrolysis plant are scarce. A comprehensive overview on the type of pyrolysis reactor technology, potential feedstock and the properties of the derived products is presented. Further, the sustainability of the technology is assessed from the aspects of energy balance, environment and economics. In spite of the potential benefits to the environment and recovery of valuable products, there are several challenges that need to be addressed to ensure the sustainability and commercialibility of the pyrolysis technologies.
Thermochemical conversion of agricultural by-products into hydrogen-rich syngas is a technology that offers both economic and environmental benefits. In this work, we investigated a biochar-supported ...nickel-based catalyst for the catalytic pyrolysis of straw biomass to produce hydrogen-rich syngas. The by-product, straw biochar, was used as a material for synthesizing fresh catalysts, achieving a closed-loop process. We explored gas yields under various conditions. The highest yields of CO and H2, reaching 0.52 L/g and 0.48 L/g, respectively, were obtained under the conditions of a pyrolysis temperature of 900 °C, a residence time of 20 min, a calcination temperature of 400 °C, a nickel loading of 15 wt%, and a citric acid to potassium hydroxide ratio of 1:4. The catalysts were characterized using XRD, H2-TPR, SEM, and TEM. The results demonstrated that biochar provides excellent support and synergy, enabling the catalyst to function at high temperatures and offering antioxidative protection to the active metals during the thermal process. Overall, this catalytic pyrolysis process, aiming for green and efficient conversion, achieved high yields of syngas and hydrogen.
•Biochar provides anti-oxidation protection for active metals.•Biochar-supported Ni catalyst shows high load capacity and synergy.•Utilizing biochar byproduct to synthesize fresh catalyst, enhancing syngas yield.
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•Pressurized pyrolysis/co-pyrolysis of OS and SWR was investigated.•SWR/OS pressurized co-pyrolysis with BA aided in the formation H2 and CH4.•The OS chars obtained under ...high-pressure has serious melting phenomenon.•The LHV of syngas increased about 8.5 times after the catalytic process.
Oil sludge (OS) and waste tires were studied widely with pyrolysis technology. However, the influence and characteristics of OS and waste tires were not studied with the pressurized co-pyrolysis technology. The pressurized pyrolysis of OS, combined with pressurized co-pyrolysis of side wall rubber (SWR), and catalytic cracking over bottom ash (BA) and SWR char (SWRC), were studied. First, the influence of pressure and temperature on the product distribution of OS pyrolysis was investigated. Then, the effect of the SWR/OS ratio on the pressurized co-pyrolysis product distribution was tested. Finally, the influence of BA on the product distribution of SWR/OS co-pyrolysis under high pressure was evaluated. The OS char obtained under high pressure exhibited serious melting phenomena, whose catalytic effect on the SWR pyrolysis in the pressurized co-pyrolysis process was investigated with TG-FTIR and SEM. The high activity and CO2 adsorption effect of bottom ash were confirmed. The CH4 content in the SWR/OS5/5 gas reached 45.55 vol%. The single ring aromatics concentration reached 57.11% in the SWR/OS6/4 oil. The naphthalene concentration reached 39.31% with the SWRC catalyst.
