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A study of lignocellulosic biomass pyrolysis via the pyrolysis of cellulose, hemicellulose and lignin
06 November 2013,
01:53:33
Publication date: Available online 5
November 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Stylianos D. Stefanidis , Konstantinos G. Kalogiannis , Eleni F. Iliopoulou , Chrysoula M. Michailof , Petros A. Pilavachi , Angelos A. Lappas
In this study, thermogravimetric (TG) analyses, along with thermal and catalytic fast pyrolysis experiments of cellulose, hemicellulose, lignin and their mixtures were carried out in order to investigate their pyrolysis products and whether the prediction of the pyrolysis behavior of a certain lignocellulosic biomass feedstock is possible, when its content in these three constituents is known. We were able to accurately predict the final solid residue of mixed component samples in the TG analyses but the differential thermogravimetric (DTG) curves indicated limited heat transfer when more than one component was present in the pyrolyzed sample. The limited heat transfer did not have a significant effect on the TG curves but it affected the product distribution in the fast pyrolysis experiments, which resulted in inaccurate calculation of the product yields, when using a simple additive law. In addition, the pyrolysis products of each biomass constituent were characterized in order to study their contribution to the yield and composition of the products from whole biomass pyrolysis. An investigation into the pyrolysis reaction pathways of each component was also carried out, using the bio-oil characterization data from this study and data found in the literature.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Stylianos D. Stefanidis , Konstantinos G. Kalogiannis , Eleni F. Iliopoulou , Chrysoula M. Michailof , Petros A. Pilavachi , Angelos A. Lappas
In this study, thermogravimetric (TG) analyses, along with thermal and catalytic fast pyrolysis experiments of cellulose, hemicellulose, lignin and their mixtures were carried out in order to investigate their pyrolysis products and whether the prediction of the pyrolysis behavior of a certain lignocellulosic biomass feedstock is possible, when its content in these three constituents is known. We were able to accurately predict the final solid residue of mixed component samples in the TG analyses but the differential thermogravimetric (DTG) curves indicated limited heat transfer when more than one component was present in the pyrolyzed sample. The limited heat transfer did not have a significant effect on the TG curves but it affected the product distribution in the fast pyrolysis experiments, which resulted in inaccurate calculation of the product yields, when using a simple additive law. In addition, the pyrolysis products of each biomass constituent were characterized in order to study their contribution to the yield and composition of the products from whole biomass pyrolysis. An investigation into the pyrolysis reaction pathways of each component was also carried out, using the bio-oil characterization data from this study and data found in the literature.
Use of Py-GC/MS and PCFC to characterize the surface modification of flax fibers
06 November 2013,
01:53:33
Publication date: Available online 4
November 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): G. Dorez , B. Otazaghine , A. Taguet , L. Ferry , J.M. Lopez-Cuesta
Surface modification of flax fibers with a phosphorous agent in a solvent process have been originally evaluated through thermal degradation using Pyrolysis Combustion Flow Calorimeter and Pyrolysis-Gas Chromatography/Mass Spectrometry. It has been highlighted that these techniques are particularly sensitive to the presence of the phosphonated grafting agent on natural fibers. After treatment, octadecylphosphonic acid (ODPA) was found to be covalently grafted on the flax fibers at a rate of almost 5%. For a better comprehension of the interactions between the phosphonic group and flax, the reactivity of the phosphonic acid function of ODPA with the main components of fibers was assessed. The results showed that ODPA reacts strongly with lignin and at a lower degree with xylan (model for hemicellulose) whereas no reaction with cellulose was evidenced.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): G. Dorez , B. Otazaghine , A. Taguet , L. Ferry , J.M. Lopez-Cuesta
Surface modification of flax fibers with a phosphorous agent in a solvent process have been originally evaluated through thermal degradation using Pyrolysis Combustion Flow Calorimeter and Pyrolysis-Gas Chromatography/Mass Spectrometry. It has been highlighted that these techniques are particularly sensitive to the presence of the phosphonated grafting agent on natural fibers. After treatment, octadecylphosphonic acid (ODPA) was found to be covalently grafted on the flax fibers at a rate of almost 5%. For a better comprehension of the interactions between the phosphonic group and flax, the reactivity of the phosphonic acid function of ODPA with the main components of fibers was assessed. The results showed that ODPA reacts strongly with lignin and at a lower degree with xylan (model for hemicellulose) whereas no reaction with cellulose was evidenced.
KOH activation of HyperCoal to develop activated carbons for electric double-layer capacitors
06 November 2013,
01:53:33
Publication date: Available online 27
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Xiaoyan Zhao , Shanshan Huang , Jingpei Cao , Shaochen Xi , Xianyong Wei , Junpei Kamamoto , Takayuki Takarada
A series of activated carbons (ACs) was prepared from HyperCoal by conventional and direct KOH activation methods, and was used as electrodes in electric double-layer capacitors (EDLC) using 0.5M TEABF4/PC as the electrolytic solution. The effects of carbonization temperature (CT), activation temperature (AT) and KOH/sample ratio on BET surface area, average pore size and capacitance of ACs were investigated in this study. Nitrogen adsorption isotherms of all ACs indicated that the pores in ACs were mainly micropores. The BET surface area and capacitance decreased with raising CT from 500 to 900°C, while the highest BET surface area of 2540m2 g−1 and maximum capacitance of 46.0Fg−1 were achieved at CT of 500°C and AT of 800°C in conventional activation. On the contrary, in the direct activation, the BET surface area and the capacitance increased with the increase of AT and KOH/sample ratio, getting the maximum value of 2440m2 g−1 and 44.4Fg−1, which is comparable with that of conventional method, at AT of 800°C and KOH/sample ratio of 4.0. Such a procedure provides a cost-effective approach to preparation of high performance activated carbons from HyperCoal for EDLC.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Xiaoyan Zhao , Shanshan Huang , Jingpei Cao , Shaochen Xi , Xianyong Wei , Junpei Kamamoto , Takayuki Takarada
A series of activated carbons (ACs) was prepared from HyperCoal by conventional and direct KOH activation methods, and was used as electrodes in electric double-layer capacitors (EDLC) using 0.5M TEABF4/PC as the electrolytic solution. The effects of carbonization temperature (CT), activation temperature (AT) and KOH/sample ratio on BET surface area, average pore size and capacitance of ACs were investigated in this study. Nitrogen adsorption isotherms of all ACs indicated that the pores in ACs were mainly micropores. The BET surface area and capacitance decreased with raising CT from 500 to 900°C, while the highest BET surface area of 2540m2 g−1 and maximum capacitance of 46.0Fg−1 were achieved at CT of 500°C and AT of 800°C in conventional activation. On the contrary, in the direct activation, the BET surface area and the capacitance increased with the increase of AT and KOH/sample ratio, getting the maximum value of 2440m2 g−1 and 44.4Fg−1, which is comparable with that of conventional method, at AT of 800°C and KOH/sample ratio of 4.0. Such a procedure provides a cost-effective approach to preparation of high performance activated carbons from HyperCoal for EDLC.
Microwave pyrolysis of cellulose at low temperature
06 November 2013,
01:53:33
Publication date: Available online 25
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ahmad Al Shra’ah , Robert Helleur
Microwave pyrolysis of cellulose was successfully achieved at low temperature (200 to 280°C) using a lab-scale microwave synthesis system. Both closed and open microwave setups were developed to measure yields of pyrolysis products and to characterize the bio-oil. The effect of temperature, type of cellulose (crystalline and amorphous), and microwave absorber were examined. Microwave-derived bio-oil compositions were compared to conventional pyrolysis (microfurnace pyrolyzer- GC/MS) under similar heating rates. Maximum bio-oil yield (45%) was obtained from amorphous cellulose at 260°C using an open system. Addition of water significantly increased the bio-oil yield to 52% (amorphous) and to 47% (crystalline) while addition of activated carbon had the effect of increasing gaseous products. Microwave-derived bio-oil products varied in chemical nature and abundance depending on cellulose crystallinity and between open or closed microwave pyrolysis and showed significant differences from conventional pyrolysis bio-oil. High yields of levoglucosan were obtained from amorphous cellulose at 260°C while conventional pyrolysis required a much higher temperature (400°C).
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ahmad Al Shra’ah , Robert Helleur
Microwave pyrolysis of cellulose was successfully achieved at low temperature (200 to 280°C) using a lab-scale microwave synthesis system. Both closed and open microwave setups were developed to measure yields of pyrolysis products and to characterize the bio-oil. The effect of temperature, type of cellulose (crystalline and amorphous), and microwave absorber were examined. Microwave-derived bio-oil compositions were compared to conventional pyrolysis (microfurnace pyrolyzer- GC/MS) under similar heating rates. Maximum bio-oil yield (45%) was obtained from amorphous cellulose at 260°C using an open system. Addition of water significantly increased the bio-oil yield to 52% (amorphous) and to 47% (crystalline) while addition of activated carbon had the effect of increasing gaseous products. Microwave-derived bio-oil products varied in chemical nature and abundance depending on cellulose crystallinity and between open or closed microwave pyrolysis and showed significant differences from conventional pyrolysis bio-oil. High yields of levoglucosan were obtained from amorphous cellulose at 260°C while conventional pyrolysis required a much higher temperature (400°C).
Characterization of the products from the pyrolysis of sewage sludge in 1kg/h rotating cylinder reactor
06 November 2013,
01:53:33
Publication date: Available online 24
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): M.M. Pedroza , J.F. Sousa , G.E.G. Vieira , M.B.D. Bezerra
The objectives of this study were to produce and characterize bio-fuels through the thermal treatment of sewage sludge in an 1kg/h. rotating cylinder reactor. The experimental procedure was divided into three parts: (a) initial test using the temperatures of 450, 500, 550, 600 and 650°C while the nitrogen flow, the centrifuge rotation and biomass flow were kept constant, (b) 24–1 fractional experimental design and (c) experiments exclusively for the characterization of gaseous fraction, using the temperatures of 500, 550 and 600°C. The maximum liquid yield was 10.5% obtained at the temperature of 500°C, inert gas of 200mL/min, biomass flow of 22g/min and centrifuge rotation of 20Hz. The maximum char yield was 61.9%, obtained at 500°C, inert gas of 100mL/min, biomass flow of 4g/min and centrifuge rotation frequency of 20Hz. The highest phase gas yield was 23.3%, obtained at 600°C, inert flow rate of 200mL/min, biomass flow rate of 22g/min and rotation frequency of 30Hz. The bio-oil had the following characteristics: pH between 6.80 and 6.84, density between 1.05 and 1.09g/mL, viscosity between 2.5 and 3.1 cSt and High Heating Value between 16.91 and 17.85MJ/kg. Non-oxygenated aliphatic (55%) and aliphatic oxygenated hydrocarbons (27%) were found in the bio-oil. The main components detected in the gas phase were H2, CO, CO2 and CH4. Hydrogen was the main constituent, with a yield of 46.2% at 600°C. Among the hydrocarbons formed, methane was predominant (16.6%) at 500°C. The results show that increasing the temperature from 500 to 600°C favors the increase in the gaseous phase and reduction of solid and liquid fractions.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): M.M. Pedroza , J.F. Sousa , G.E.G. Vieira , M.B.D. Bezerra
The objectives of this study were to produce and characterize bio-fuels through the thermal treatment of sewage sludge in an 1kg/h. rotating cylinder reactor. The experimental procedure was divided into three parts: (a) initial test using the temperatures of 450, 500, 550, 600 and 650°C while the nitrogen flow, the centrifuge rotation and biomass flow were kept constant, (b) 24–1 fractional experimental design and (c) experiments exclusively for the characterization of gaseous fraction, using the temperatures of 500, 550 and 600°C. The maximum liquid yield was 10.5% obtained at the temperature of 500°C, inert gas of 200mL/min, biomass flow of 22g/min and centrifuge rotation of 20Hz. The maximum char yield was 61.9%, obtained at 500°C, inert gas of 100mL/min, biomass flow of 4g/min and centrifuge rotation frequency of 20Hz. The highest phase gas yield was 23.3%, obtained at 600°C, inert flow rate of 200mL/min, biomass flow rate of 22g/min and rotation frequency of 30Hz. The bio-oil had the following characteristics: pH between 6.80 and 6.84, density between 1.05 and 1.09g/mL, viscosity between 2.5 and 3.1 cSt and High Heating Value between 16.91 and 17.85MJ/kg. Non-oxygenated aliphatic (55%) and aliphatic oxygenated hydrocarbons (27%) were found in the bio-oil. The main components detected in the gas phase were H2, CO, CO2 and CH4. Hydrogen was the main constituent, with a yield of 46.2% at 600°C. Among the hydrocarbons formed, methane was predominant (16.6%) at 500°C. The results show that increasing the temperature from 500 to 600°C favors the increase in the gaseous phase and reduction of solid and liquid fractions.
Preparation, characterization and analyses of carbons with natural and induced calcium compounds for the adsorption of fluoride
06 November 2013,
01:53:33
Publication date: Available online 24
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): L.A. Ramírez-Montoya , V. Hernández-Montoya , A. Bonilla-Petriciolet , Miguel A. Montes-Morán , R. Tovar-Gómez , M.R. Moreno-Virgen
A comparative study of fluoride removal has been made using samples of carbons obtained from single carbonization from pecan nut shells and plum kernels and carbons obtained by impregnation of these wastes, prior to their carbonization, with a calcium acetate solution. The impregnation step was determinant for increasing the ability of carbons to remove fluoride anions from water of carbons prepared from both precursors. The intrinsic calcium content of the precursors left a footprint in the process, with carbons prepared from the higher calcium content precursor (i.e., pecan nut shells) always performing better than the plum kernel carbon counterpart. Outstanding fluoride retention abilities (from 0.5 to 2.5mg of fluoride adsorbed per gram of carbon) were obtained if pecan nut shells are impregnated with a calcium solution of 3151mg/L and carbonized at 800°C (sample denominated IC-PN-25). These results can be associated with the calcium compounds founded in IC-PN-25 which are CaO and CaCO3, according with the X-ray results. Furthermore, dynamic adsorption studies were carried out using beds of carbon denominated IC-PN-25. Reasonably high (0.4) filter usage ratios were obtained in such on-column adsorption studies. Finally, different models were used to fit batch and dynamic adsorption data, with Sips and Yan models fitting better the equilibrium isotherm and breaktrough curve data, respectively, than others.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): L.A. Ramírez-Montoya , V. Hernández-Montoya , A. Bonilla-Petriciolet , Miguel A. Montes-Morán , R. Tovar-Gómez , M.R. Moreno-Virgen
A comparative study of fluoride removal has been made using samples of carbons obtained from single carbonization from pecan nut shells and plum kernels and carbons obtained by impregnation of these wastes, prior to their carbonization, with a calcium acetate solution. The impregnation step was determinant for increasing the ability of carbons to remove fluoride anions from water of carbons prepared from both precursors. The intrinsic calcium content of the precursors left a footprint in the process, with carbons prepared from the higher calcium content precursor (i.e., pecan nut shells) always performing better than the plum kernel carbon counterpart. Outstanding fluoride retention abilities (from 0.5 to 2.5mg of fluoride adsorbed per gram of carbon) were obtained if pecan nut shells are impregnated with a calcium solution of 3151mg/L and carbonized at 800°C (sample denominated IC-PN-25). These results can be associated with the calcium compounds founded in IC-PN-25 which are CaO and CaCO3, according with the X-ray results. Furthermore, dynamic adsorption studies were carried out using beds of carbon denominated IC-PN-25. Reasonably high (0.4) filter usage ratios were obtained in such on-column adsorption studies. Finally, different models were used to fit batch and dynamic adsorption data, with Sips and Yan models fitting better the equilibrium isotherm and breaktrough curve data, respectively, than others.
Synthetic Fuel Production From Cottonseed: Fast Pyrolysis And A Tga/Ft-Ir/Ms Study
06 November 2013,
01:53:33
Publication date: Available online 24
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): ESİN Apaydin-Varol , BAŞAK BURCU Uzun , EYLEM Önal , AYŞE E. Pütün
This study investigates the thermal decomposition behavior of cotton seed via TGA/FT-IR/MS and the quantification/characterization of liquid products from fast pyrolysis. Thermal degradation of the biomass sample has occurred in four steps, corresponding to the removal of moisture, decomposition of cellulose, hemicellulose and lignin and it was completed at about 700°C. The main gaseous products evolved were CO2, light hydrocarbons and H2O. For the fast pyrolysis experiments, particular investigated process variables were temperature (400-700°C), heating rate (5–700°Cmin−1) and nitrogen gas flow rate (100–800 cm3min−1). Maximum oil yield was attained at 500°C with a yield of 49.5% under 200 cm3min−1 nitrogen flow rate and at a heating rate of 300°Cmin−1. Bio-oil obtained at optimum conditions are separated into its fractions by column chromatography. The oil and its sub-fractions were characterized by elemental analysis, FT-IR, and GC/MS. The char was characterized with elemental analysis and FT-IR techniques. The aliphatic sub-fraction of the obtained bio-oil contains predominantly straight chain of n-alkanes and alkenes. According to the chemical characterization, the bio-oil can be utilized as conventional liquid fuels.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): ESİN Apaydin-Varol , BAŞAK BURCU Uzun , EYLEM Önal , AYŞE E. Pütün
This study investigates the thermal decomposition behavior of cotton seed via TGA/FT-IR/MS and the quantification/characterization of liquid products from fast pyrolysis. Thermal degradation of the biomass sample has occurred in four steps, corresponding to the removal of moisture, decomposition of cellulose, hemicellulose and lignin and it was completed at about 700°C. The main gaseous products evolved were CO2, light hydrocarbons and H2O. For the fast pyrolysis experiments, particular investigated process variables were temperature (400-700°C), heating rate (5–700°Cmin−1) and nitrogen gas flow rate (100–800 cm3min−1). Maximum oil yield was attained at 500°C with a yield of 49.5% under 200 cm3min−1 nitrogen flow rate and at a heating rate of 300°Cmin−1. Bio-oil obtained at optimum conditions are separated into its fractions by column chromatography. The oil and its sub-fractions were characterized by elemental analysis, FT-IR, and GC/MS. The char was characterized with elemental analysis and FT-IR techniques. The aliphatic sub-fraction of the obtained bio-oil contains predominantly straight chain of n-alkanes and alkenes. According to the chemical characterization, the bio-oil can be utilized as conventional liquid fuels.
Terpenoid composition and chemotaxonomic aspects of Miocene amber from the Koroglu Mountains, Turkey
06 November 2013,
01:53:33
Publication date: Available online 24
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Oluwadayo O. Sonibare , Ru-Jin Huang , Dorrit E. Jacob , Yunyun Nie , Eike Kleine-Benne , Thorsten Hoffmann , Stephen F. Foley
A recently discovered fossil resin from Koroglu Mountain in Turkey has been analyzed by gas chromatography-mass spectrometry and pyrolysis gas chromatography-mass spectrometry to determine its structural class and botanical origin. The sesqui- and diterpenoids contained in the amber extract were used as chemosystematic markers when compared with terpenoids in extant conifers. The pyrolysis products were dominated by labdanoid derived bicyclic products together with succinic acid indicating Class Ia type amber. The biomarker compositions of the resin comprise mainly sesqui- and diterpenoids, and lack triterpenoids. This distribution suggests a gymnosperm, and more specifically a conifer source. The exclusive presence of abietane- and labdane- type diterpenoids together with the absence of phenolic diterpenoids strongly suggest that the resin was derived from Pinaceae. However, the presence of methyl-16,17-dinor callitrisate in the pyrolysate also suggests that Cupressaceae cannot be excluded as a possible source for the amber.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Oluwadayo O. Sonibare , Ru-Jin Huang , Dorrit E. Jacob , Yunyun Nie , Eike Kleine-Benne , Thorsten Hoffmann , Stephen F. Foley
A recently discovered fossil resin from Koroglu Mountain in Turkey has been analyzed by gas chromatography-mass spectrometry and pyrolysis gas chromatography-mass spectrometry to determine its structural class and botanical origin. The sesqui- and diterpenoids contained in the amber extract were used as chemosystematic markers when compared with terpenoids in extant conifers. The pyrolysis products were dominated by labdanoid derived bicyclic products together with succinic acid indicating Class Ia type amber. The biomarker compositions of the resin comprise mainly sesqui- and diterpenoids, and lack triterpenoids. This distribution suggests a gymnosperm, and more specifically a conifer source. The exclusive presence of abietane- and labdane- type diterpenoids together with the absence of phenolic diterpenoids strongly suggest that the resin was derived from Pinaceae. However, the presence of methyl-16,17-dinor callitrisate in the pyrolysate also suggests that Cupressaceae cannot be excluded as a possible source for the amber.
Review of analytical strategies in the production and upgrading of bio-oils derived from lignocellulosic biomass
06 November 2013,
01:53:33
Publication date: Available online 20
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Pankaj K. Kanaujia , Y.K. Sharma , M.O. Garg , Deependra Tripathi , Raghuvir Singh
Lignocellulosic biomass is a promising source of renewable energy and valuable chemicals. It is abundant in several forms which may be pyrolyzed to give gases, condensates and char. The condensed liquid obtained through pyrolysis is popularly called bio-oil from which valuable chemicals may be derived in a well defined manner. Chemically, this liquid is a complex mixture of simple organic, inorganic and macromolecular compounds formed through thermo-chemical breakdown of lignocellulosic biomass. High oxygen content is responsible for its low gross calorific value which renders it useless for fuel applications however; upgrading processes aimed at reducing oxygenates potentially increase its usage at par with fossil fuels. Fast and efficient analytical methods have revealed huge amount of informations from biomass and pyrolysis liquids hence a key component in organizing research in this area. Owing to the high compositional complexity and diversity in bio-oils originating from different sources, generalized analytical procedures are very difficult to formulate. However, tools of analytical chemistry have helped in understanding the underlying mechanisms involved in production and upgrading of bio-oils at molecular levels. With the possibility of commercial large scale production plants coming up in Europe, concerns with bio-oil quality, stability and upgrading rely strongly on analytical approaches. With this review we have tried to present outcomes of important research related to chemical analysis of bio-oils. The discussion is intended to summarize role of prominent analytical techniques in the chemical characterization of bio-oils. On this basis, optimum sample preparation strategies have also been proposed along with the rationale behind analysis with conclusions.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Pankaj K. Kanaujia , Y.K. Sharma , M.O. Garg , Deependra Tripathi , Raghuvir Singh
Lignocellulosic biomass is a promising source of renewable energy and valuable chemicals. It is abundant in several forms which may be pyrolyzed to give gases, condensates and char. The condensed liquid obtained through pyrolysis is popularly called bio-oil from which valuable chemicals may be derived in a well defined manner. Chemically, this liquid is a complex mixture of simple organic, inorganic and macromolecular compounds formed through thermo-chemical breakdown of lignocellulosic biomass. High oxygen content is responsible for its low gross calorific value which renders it useless for fuel applications however; upgrading processes aimed at reducing oxygenates potentially increase its usage at par with fossil fuels. Fast and efficient analytical methods have revealed huge amount of informations from biomass and pyrolysis liquids hence a key component in organizing research in this area. Owing to the high compositional complexity and diversity in bio-oils originating from different sources, generalized analytical procedures are very difficult to formulate. However, tools of analytical chemistry have helped in understanding the underlying mechanisms involved in production and upgrading of bio-oils at molecular levels. With the possibility of commercial large scale production plants coming up in Europe, concerns with bio-oil quality, stability and upgrading rely strongly on analytical approaches. With this review we have tried to present outcomes of important research related to chemical analysis of bio-oils. The discussion is intended to summarize role of prominent analytical techniques in the chemical characterization of bio-oils. On this basis, optimum sample preparation strategies have also been proposed along with the rationale behind analysis with conclusions.
Mechanism studies on β-d-glucopyranose pyrolysis by density functional theory methods
06 November 2013,
01:53:33
Publication date: Available online 19
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Yayun Zhang , Chao Liu , Hui Xie
In order to understand the pyrolysis mechanism of cellulose, the pyrolysis of β-d-glucopyranose as cellulose unit model compound was investigated by employing density function theory methods at B3LYP level with 6-31G(d,p) basis set. Two series of pyrolytic reactions containing seven possible pathways were proposed after several pathways were analyzed in detail. All the reactants, transition states, intermediates and products were optimized, also the standard thermodynamic and kinetic parameters in each reaction pathway were calculated. The calculation results indicate that the reactions of pathways 1–5 are endothermic, but ones of pathways 6–7 are exothermic. All the pathways can occur spontaneously above 400K and 1atm. We also obtain five better reaction pathways from two modes of reaction pathways. Among these five pathways, hydroxyacetaldehyde (HAA), acetol, formic acid, acetic acid and furfural are generated in pathway 2, 4, 7, 6 and 3 with the activation energy of 258.9, 291.1, 295.7, 321.5 and 360.6kJ/mol, respectively. Both thermodynamic and kinetic analyses support reaction pathways 2 and 4 as major reaction channels. It can be inferred that HAA, acetol and 5-hydroxymethylfurfural are the main products among small molecular products during cellulose pyrolysis. The formation of formic acid, acetic acid and furfural are difficult than that of former main products. The above results are in accordance with the related experimental results.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Yayun Zhang , Chao Liu , Hui Xie
In order to understand the pyrolysis mechanism of cellulose, the pyrolysis of β-d-glucopyranose as cellulose unit model compound was investigated by employing density function theory methods at B3LYP level with 6-31G(d,p) basis set. Two series of pyrolytic reactions containing seven possible pathways were proposed after several pathways were analyzed in detail. All the reactants, transition states, intermediates and products were optimized, also the standard thermodynamic and kinetic parameters in each reaction pathway were calculated. The calculation results indicate that the reactions of pathways 1–5 are endothermic, but ones of pathways 6–7 are exothermic. All the pathways can occur spontaneously above 400K and 1atm. We also obtain five better reaction pathways from two modes of reaction pathways. Among these five pathways, hydroxyacetaldehyde (HAA), acetol, formic acid, acetic acid and furfural are generated in pathway 2, 4, 7, 6 and 3 with the activation energy of 258.9, 291.1, 295.7, 321.5 and 360.6kJ/mol, respectively. Both thermodynamic and kinetic analyses support reaction pathways 2 and 4 as major reaction channels. It can be inferred that HAA, acetol and 5-hydroxymethylfurfural are the main products among small molecular products during cellulose pyrolysis. The formation of formic acid, acetic acid and furfural are difficult than that of former main products. The above results are in accordance with the related experimental results.
From new simple aliphatic to aromatic heterocycles built from 2-chloroethylisocyanate
06 November 2013,
01:53:33
Publication date: Available online 19
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ana Julieta Pepino , Walter José Peláez , Gustavo Alejandro Argüello
New routes for gas phase thermal reactions of 2-chloroethylisocyanate are presented. They can be tuned by simply changing the material of the reactor and the temperature. Many interesting products are formed, including pyrazines and novel imidazolidine-2-ones. A comprehensive analysis that included high level ab-initio calculations has been carried out. Beyond the general agreement found with experimental results, the most relevant information is that, irrespective of the material of the reactor, all the products can be explained through a common unique key intermediate.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ana Julieta Pepino , Walter José Peláez , Gustavo Alejandro Argüello
New routes for gas phase thermal reactions of 2-chloroethylisocyanate are presented. They can be tuned by simply changing the material of the reactor and the temperature. Many interesting products are formed, including pyrazines and novel imidazolidine-2-ones. A comprehensive analysis that included high level ab-initio calculations has been carried out. Beyond the general agreement found with experimental results, the most relevant information is that, irrespective of the material of the reactor, all the products can be explained through a common unique key intermediate.
Characterisation of gas evolution and char structural change during pyrolysis of waste CDs
06 November 2013,
01:53:33
Publication date: Available online 18
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ravindra Rajarao , Irshad Mansuri , Renu Dhunna , Rita Khanna , Veena Sahajwalla
The purpose of this study is to determine the characteristics of gas evolution and char structural change during pyrolysis of waste compact disc (CD). A combination of Thermogravimtetry-Fourier Transform Infrared spectroscopy (TG-FTIR) and Thermogravimtetry-Gas Chromatography/Mass Spectrometry (TG-GCMS) techniques are employed for this study. The thermal characteristics, temperature trend of evolving gas species and gas characteristics are investigated by TG-FTIR and TG-GCMS techniques. From the results, the waste CD degradation is divided into three stages (a) main gaseous compounds in first stage (<500°C) are CO2, CO, CH4 and H2O (b) organic species including aromatic hydrocarbons, phenols and its derivatives are evolved between 500 and 600°C. (c) Temperature above 600°C, carbonisation and char formation occurred. The char chemical structure and physical characteristics are investigated by Scanning Electron Microscopy, FTIR spectroscopy, Raman spectroscopy and X-ray diffraction techniques. This fundamental study provides basic insight of waste CD pyrolysis and also indicates that very high valuable carbon product (90% carbon in residue) with good crystallinity is achievable.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ravindra Rajarao , Irshad Mansuri , Renu Dhunna , Rita Khanna , Veena Sahajwalla
The purpose of this study is to determine the characteristics of gas evolution and char structural change during pyrolysis of waste compact disc (CD). A combination of Thermogravimtetry-Fourier Transform Infrared spectroscopy (TG-FTIR) and Thermogravimtetry-Gas Chromatography/Mass Spectrometry (TG-GCMS) techniques are employed for this study. The thermal characteristics, temperature trend of evolving gas species and gas characteristics are investigated by TG-FTIR and TG-GCMS techniques. From the results, the waste CD degradation is divided into three stages (a) main gaseous compounds in first stage (<500°C) are CO2, CO, CH4 and H2O (b) organic species including aromatic hydrocarbons, phenols and its derivatives are evolved between 500 and 600°C. (c) Temperature above 600°C, carbonisation and char formation occurred. The char chemical structure and physical characteristics are investigated by Scanning Electron Microscopy, FTIR spectroscopy, Raman spectroscopy and X-ray diffraction techniques. This fundamental study provides basic insight of waste CD pyrolysis and also indicates that very high valuable carbon product (90% carbon in residue) with good crystallinity is achievable.
Thermal analysis and products distribution of dried sewage sludge pyrolysis
06 November 2013,
01:53:33
Publication date: Available online 16
October 2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ningbo Gao , Juanjuan Li , Benyu Qi , Aimin Li , Yue Duan , Ze Wang
Pyrolysis behavior of dried sewage sludge was studied by thermogravimetric–Fourier transforms infrared analysis (TG–FTIR) and differential scanning calorimetry (DSC) to investigate thermal decomposition and kinetics analysis. A tubular pyrolyzer was used to explore the production distribution of dried sewage sludge pyrolysis under different runs. The results showed that two weight loss peaks were presented in pyrolysis reaction in the ranges of 186–296°C and 296–518°C, and the activation energy of each stage was 82.284kJmol−1 and 48.342kJmol−1, respectively. The main gases identified by FTIR analysis were CH4, CO2, CO and organic volatile compounds such as aldehydes, acids, alcohols and phenols. Under fast pyrolysis of dried sewage sludge, the maximum tar yield obtained was 46.14% at the temperature of 550°C. The concentrations of all gases increased steadily with increasing pyrolysis temperature from 450°C to 650°C except for CO2.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ningbo Gao , Juanjuan Li , Benyu Qi , Aimin Li , Yue Duan , Ze Wang
Pyrolysis behavior of dried sewage sludge was studied by thermogravimetric–Fourier transforms infrared analysis (TG–FTIR) and differential scanning calorimetry (DSC) to investigate thermal decomposition and kinetics analysis. A tubular pyrolyzer was used to explore the production distribution of dried sewage sludge pyrolysis under different runs. The results showed that two weight loss peaks were presented in pyrolysis reaction in the ranges of 186–296°C and 296–518°C, and the activation energy of each stage was 82.284kJmol−1 and 48.342kJmol−1, respectively. The main gases identified by FTIR analysis were CH4, CO2, CO and organic volatile compounds such as aldehydes, acids, alcohols and phenols. Under fast pyrolysis of dried sewage sludge, the maximum tar yield obtained was 46.14% at the temperature of 550°C. The concentrations of all gases increased steadily with increasing pyrolysis temperature from 450°C to 650°C except for CO2.
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