Biomass pyrolysis has been a popular research topic due to versatility in products: char, bio-oil, and syngas. What makes the biomass pyrolysis so important is that it provides product options such as fuels or green chemicals. In the case of biomass pyrolysis, lignocellulosic materials undergo thermal degradation in the absence of oxidative environment at atmospheric pressure during a definite residence time, which produces solid char, bio-oil, and syngas. If the bio-oil is going to be used as a fuel source or to be processed for producing chemicals, it requires an upgrading. Catalytic pyrolysis is the most promising method to improve the quality of bio-oil. The present study presents an updated review on catalytic pyrolysis of biomass for the production of upgraded bio-oil. In this context, this review considers recent advances in catalysts and catalytic pyrolysis process.
Pyrolysis of olive pomace and copyrolysis of olive pomace with RDF blends were investigated by TGA. To see the effect of heating rate on pyrolysis behavior and kinetic parameters of olive pomace, TG and DTG curves were obtained at three different heating rates (10, 20, and 30°C min−1) between 20°C and 800°C. The results showed that activation energy decreased as the heating rate was increased. In the pyrolysis profile of olive pomace, weight loss was observed almost in one stage where two peaks overlapped between temperatures 170–372°C, having a highest peak at 342°C. In the case of olive pomace‐RDF blends, copyrolysis experiments were conducted under N2 atmosphere at a heating rate of 10°C min−1 from 20°C to 800°C. The pyrolysis profile of the blends presented three peaks (except moisture removal) meaning three consecutive reactions: cellulose‐hemicellulose decomposition, plastics decomposition and CaCO3 decomposition. Lignin decomposition comprised all the stages. Because of its high activation energy, using olive pomace alone in the pyrolysis reaction required a high temperature operation or long reaction time in the reactor. Blending it with RDF decreased the activation energy, decreased the peak temperatures, increased the number of pyrolysis stages (decomposition of plastics and inorganic carbonate based additives), and increased the time required for higher conversion rates. RDF which had a high ash content and low calorific value was found as more useful as a fuel when it was blended with olive pomace. Lower activation energies observed in the relevant decomposition stages indicated that the reaction became faster upon blending. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 649–656, 2014
This study compares the pyrolysis and combustion characteristics with the kinetics of wood sawdust and its hydrochar. Wood sawdust hydrochar was obtained by the hydrothermal treatment of wood sawdust (biomass/water: 1 g/4 mL) at 220°C, where the residence time was set as 90 min. After hydrothermal carbonization, carbon content and heating value were both increased by 14%. Pyrolysis and combustion of wood sawdust and its hydrochar were performed by thermogravimetric analysis at 10, 20, 30, and 40°C/min. Kissinger–Akahira–Sunose (KAS) method, Friedman method, Flynn–Wall–Ozawa (FWO) method, and Kissinger method were used for analyzing the pyrolysis data. For combustion, only KAS and FWO methods were used to determine the kinetic parameters. As compared to wood sawdust pyrolysis, average activation energy of hydrochar pyrolysis was lower (150.36 kJ/mol by using KAS method, 153.05 kJ/mol by using FWO method). Based on mean activation energies, pyrolysis reaction of hydrochar was more favorable than its combustion. In combustion, average activation energy of hydrochar combustion reaction was higher; indicating that combustion of wood sawdust was more favorable.
Biomass energy gains importance constantly in order to increase energy security, diversity and develop the rural economy. Most of the existing biomass energy power plants in Turkey use solid waste, it is extremely important to encourage the use of agricultural residues in these facilities. In this study, agricultural residues were examined under two headings: primary residues (PR) are the residues left in the field after harvest (corn stalk, wheat straw, etc.), and secondary residues (SR) are the residues after the products are processed in the factory (almond shell, corn cob, etc.) When calculating the amount of agricultural residues, special uses such as soil protection, animal feeding, heating purposes are taken into account. The most cultivated products across 81 provinces in Turkey are listed and the residues are concentrated on products with high calorific value. The amount of primary and secondary residues belonging to these agricultural products was extracted and mapped based on provinces. Then the energy potential of these residues was calculated. The total amount of PR and SR produced in Turkey is 39 412 683 tonnes and 6 803 787 tonnes. By assuming the total efficiency of the power plant as 30% and the capacity factor of the biomass power plant as 0.65, the power to be obtained from only PRs will be 2 438.5 MW and from only SR will be 830 MW in the total of 81 provinces. Based on AHP method, cost is the most important criterion in the selection of pretreatment before transportation.
Hydrothermal pretreatment was applied to wood sawdust, Trakya lignite and wood sawdust-Trakya lignite mixture (50%, wt) individually. Changes in fuel properties and thermochemical conversion characteristics of each were observed. In addition, the synergistic effect of biomass on coal with hydrothermal pretreatment of the mixture was investigated. After hydrothermal pretreatment, where the optimum conditions were 230 °C and 90 minutes, fixed carbon percentage and heating value increased and ash content decreased in all fuels. Compared to lignite and wood sawdust, a fuel with higher elemental carbon content, lower oxygen percentage and higher calorific value was obtained when the mixture was co-hydrothermally pretreated. Hydrothermal pretreatment applied to the mixture modified the structural properties and volatiles of the mixture. For this reason, the reactivity of the hydrothermal pretreated mixture in pyrolysis and combustion reactions increased, and the peak temperatures at which the mass loss rate was maximum were shifted to higher.
Öz Çalışma, atıktan türetilmiş yakıtın (ATY) yapısındaki kül oluşturan elementlerin su ve farklı konsantrasyonlarda asit çözeltileri ile özütlenerek yakıtın modifiye edilmesini ve bu demineralizasyon işleminin yakıtın temel özelliklerine (elementel analiz, ısıl değer, piroliz ve yanma karakteristikleri) etkisinin incelenmesini içermektedir. Su, HCl (%2, %5 ve %10) ve HNO3 (%2, %5 ve %10) çözeltileri ile yapılan özütlemelerden sonra kurutulan ATY'ların yakıt özelliklerine bakıldığında, özütlemenin, yakıt özelliklerinden kül içeriğini, elementel bileşimini, piroliz kademelerini, tutuşma sıcaklığı ve tükenme sıcaklığını etkilediği görülmüştür. Özütleme işleminin gerçekleştiği karıştırma süresinin etkin bir parametre olmadığı belirlenmiştir. Fakat özütlemenin su, HCl ya da HNO3 çözeltileri ile gerçekleştirilmesinin ve özellikle asit konsantrasyonunun yakıtın özelliklerinde etkin bir parametre olduğu gözlemlenmiştir. Özütleme işleminde kullanılan asit çözeltisinin türüne ve konsantrasyonuna bağlı olarak kül içeriğinin %34'ten %14'e kadar indiği (%5 HCl çözeltisi); ısıl değerin %13 oranında arttığı (%5 ve %10 HCl çözeltisi); karbon yüzdesinin ise %38 oranında arttığı (%10 HCl çözeltisi) gözlemlenmiştir. Asit çözeltileriyle yapılan özütleme sonrası ATY'ların pirolizinin iki adımda gerçekleştiği, tutuşma sıcaklıklarının 4-24°C ötelendiği, tükenme sıcaklığının ise 32-140°C azaldığı tespit edilmiştir.
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