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Mathematical modeling of rubber tire pyrolysis
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Augustine Quek, Rajasekhar Balasubramanian
This article provides a critical review of past efforts over the last three decades at modeling the pyrolysis and gas activation of waste tires. The various forms of the Arrhenius kinetic rate equation as well as other forms of mathematical descriptions related to pyrolysis of waste tires are reviewed. In addition to reaction kinetics, other aspects of the tire pyrolysis such as heat and mass transfer, and reactor-specific models are also reviewed. Both one-step/component and multi-step/component pyrolysis models are discussed in the review. The multi-component models are based on the actual chemical components such as natural rubber and other additives. Kinetic constants reported in the literature are also analyzed.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Augustine Quek, Rajasekhar Balasubramanian
This article provides a critical review of past efforts over the last three decades at modeling the pyrolysis and gas activation of waste tires. The various forms of the Arrhenius kinetic rate equation as well as other forms of mathematical descriptions related to pyrolysis of waste tires are reviewed. In addition to reaction kinetics, other aspects of the tire pyrolysis such as heat and mass transfer, and reactor-specific models are also reviewed. Both one-step/component and multi-step/component pyrolysis models are discussed in the review. The multi-component models are based on the actual chemical components such as natural rubber and other additives. Kinetic constants reported in the literature are also analyzed.
Efficient preparation of carbon papers by pyrolysis of iodine-treated Japanese paper
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Mutsumasa Kyotani, Satoshi Matsushita, Shin-ichi Kimura, Kazuo Akagi
A novel carbon paper has been prepared by pyrolysis from traditional Japanese paper called washi in Japan, which is mainly composed of cellulose microfibers. The washi was iodine-treated before pyrolysis. The effect of iodine-treatment on pyrolysis of the washi was investigated using thermogravimetric analysis. The structural and electrical properties of the carbon papers were also investigated using Raman scattering, X-ray diffraction, electron microscopy, and resistivity measurements. The iodine-treatment prevents cellulose from thermally decomposing and is effective in increasing the carbon yield and retaining its fibrillar structure. Porous carbon papers consisting of many micro and nanofibrils were prepared by the pyrolysis of the iodine-treated washi at 800°C. Those prepared at 800°C and then heat-treated at higher temperatures than 1800°C show electrical conductivities of 3Scm−1 and 24–27Scm−1. The degree of crystallinity and the electrical conductivity of the papers are improved by the heat treatment at higher temperatures.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Mutsumasa Kyotani, Satoshi Matsushita, Shin-ichi Kimura, Kazuo Akagi
A novel carbon paper has been prepared by pyrolysis from traditional Japanese paper called washi in Japan, which is mainly composed of cellulose microfibers. The washi was iodine-treated before pyrolysis. The effect of iodine-treatment on pyrolysis of the washi was investigated using thermogravimetric analysis. The structural and electrical properties of the carbon papers were also investigated using Raman scattering, X-ray diffraction, electron microscopy, and resistivity measurements. The iodine-treatment prevents cellulose from thermally decomposing and is effective in increasing the carbon yield and retaining its fibrillar structure. Porous carbon papers consisting of many micro and nanofibrils were prepared by the pyrolysis of the iodine-treated washi at 800°C. Those prepared at 800°C and then heat-treated at higher temperatures than 1800°C show electrical conductivities of 3Scm−1 and 24–27Scm−1. The degree of crystallinity and the electrical conductivity of the papers are improved by the heat treatment at higher temperatures.
BET, TG–DTG, FT-IR, SEM, iodine number analysis and preparation of activated carbon from acorn shell by chemical activation with ZnCl2
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Cafer Saka
Activated carbons were produced from acorn shell by chemical activation with zinc chloride (ZnCl2) at 600°C in N2 atmosphere and their characteristics were investigated. The effects of activation temperature, duration time, impregnation concentration of agent and impregnation time were examined. Adsorption capacity was demonstrated with BET and iodine number. The obtained activated carbons were characterized by measuring their porosities and pore size distributions. BET surface area of the best produced activated carbon was 1289m2/g. The surface chemical characteristics of activated carbons were determined by FT-IR spectroscopic method. The microstructure of the produced activated carbons was examined by scanning electron microscopy (SEM). Thermal gravimetry (TG) and derivative thermal gravimetry (DTG) analysis of produced activated carbon was carried out.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Cafer Saka
Activated carbons were produced from acorn shell by chemical activation with zinc chloride (ZnCl2) at 600°C in N2 atmosphere and their characteristics were investigated. The effects of activation temperature, duration time, impregnation concentration of agent and impregnation time were examined. Adsorption capacity was demonstrated with BET and iodine number. The obtained activated carbons were characterized by measuring their porosities and pore size distributions. BET surface area of the best produced activated carbon was 1289m2/g. The surface chemical characteristics of activated carbons were determined by FT-IR spectroscopic method. The microstructure of the produced activated carbons was examined by scanning electron microscopy (SEM). Thermal gravimetry (TG) and derivative thermal gravimetry (DTG) analysis of produced activated carbon was carried out.
Synthesis of nanosized rubidium ferrite by thermolysis of ferricarboxylate precursors and combustion method
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Manik Gupta, Balwinder S. Randhawa
Nanosized pure rubidium ferrites have been successfully prepared by thermal decomposition of rubidium hexa(carboxylato)ferrate(III) precursors, Rb3[Fe(L)6]·xH2O (L=formate, acetate, propionate, butyrate), in flowing air atmosphere from ambient temperature to 1000°C. Various physico-chemical techniques i.e. simultaneous TG–DTG–DTA, XRD, Transmission Electron Microscope (TEM), IR and Mössbauer spectroscopy etc. have been employed to characterize the intermediates and end products. After dehydration, the anhydrous precursors undergo exothermic decomposition to yield various intermediates i.e. rubidium carbonate/acetate/propionate/butyrate and α-Fe2O3. A subsequent decomposition of these intermediates, followed by solid state reaction, lead to the formation of nanosized rubidium ferrite (RbFeO2). The same nano-ferrite has also been prepared by the combustion method at a comparatively lower temperature and in less time than that of the conventional ceramic method (>1200°C).
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Manik Gupta, Balwinder S. Randhawa
Nanosized pure rubidium ferrites have been successfully prepared by thermal decomposition of rubidium hexa(carboxylato)ferrate(III) precursors, Rb3[Fe(L)6]·xH2O (L=formate, acetate, propionate, butyrate), in flowing air atmosphere from ambient temperature to 1000°C. Various physico-chemical techniques i.e. simultaneous TG–DTG–DTA, XRD, Transmission Electron Microscope (TEM), IR and Mössbauer spectroscopy etc. have been employed to characterize the intermediates and end products. After dehydration, the anhydrous precursors undergo exothermic decomposition to yield various intermediates i.e. rubidium carbonate/acetate/propionate/butyrate and α-Fe2O3. A subsequent decomposition of these intermediates, followed by solid state reaction, lead to the formation of nanosized rubidium ferrite (RbFeO2). The same nano-ferrite has also been prepared by the combustion method at a comparatively lower temperature and in less time than that of the conventional ceramic method (>1200°C).
Characterization of the different fractions obtained from the pyrolysis of rope industry waste
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Marta Andrade, José B. Parra, Marta Haro, Ana S. Mestre, Ana P. Carvalho, Conchi O. Ania
A study of the possibilities of pyrolysis for recovering wastes of the rope's industry has been carried out. The pyrolysis of this lignocellulosic residue started at 250°C, with the main region of decomposition occurring at temperatures between 300 and 350°C. As the reaction temperature increased, the yields of pyrolyzed gas and oil increased, yielding 22wt.% of a carbonaceous residue, 50wt.% tars and a gas fraction at 800°C. The chemical composition and textural characterization of the chars obtained at various temperatures confirmed that even if most decomposition occurs at 400°C, there are some pyrolytic reactions still going on above 550°C. The different pyrolysis fractions were analyzed by GC–MS; the produced oil was rich in hydrocarbons and alcohols. On the other hand, the gas fraction is mainly composed of CO2, CO and CH4. Finally, the carbonaceous solid residue (char) displayed porous features, with a more developed porous structure as the pyrolysis temperature increased.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Marta Andrade, José B. Parra, Marta Haro, Ana S. Mestre, Ana P. Carvalho, Conchi O. Ania
A study of the possibilities of pyrolysis for recovering wastes of the rope's industry has been carried out. The pyrolysis of this lignocellulosic residue started at 250°C, with the main region of decomposition occurring at temperatures between 300 and 350°C. As the reaction temperature increased, the yields of pyrolyzed gas and oil increased, yielding 22wt.% of a carbonaceous residue, 50wt.% tars and a gas fraction at 800°C. The chemical composition and textural characterization of the chars obtained at various temperatures confirmed that even if most decomposition occurs at 400°C, there are some pyrolytic reactions still going on above 550°C. The different pyrolysis fractions were analyzed by GC–MS; the produced oil was rich in hydrocarbons and alcohols. On the other hand, the gas fraction is mainly composed of CO2, CO and CH4. Finally, the carbonaceous solid residue (char) displayed porous features, with a more developed porous structure as the pyrolysis temperature increased.
Chemical composition of bio-oil produced by co-pyrolysis of biopolymer/polypropylene mixtures with K2CO3 and ZnCl2 addition
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Piotr Rutkowski
The chemical composition of liquid products of cellulose and lignin co-pyrolysis with polypropylene at 450°C with and without the potassium carbonate or zinc chloride as an catalyst was investigated. The yield of liquid products of pyrolysis was in the range of 26–45wt% and their form was liquid or semi-solid highly depending on the composition of sample and pyrolysis conditions. The potassium carbonate and zinc chloride addition to blends has also influenced the range of samples decomposition as well as the chemical composition of resulted bio-oils. All bio-oils from biopolymer and polypropylene mixtures were three-phase (water, oil and solid). While zinc chloride acted as catalyst, all bio-oils obtained from biopolymer and polypropylene mixtures were yellow liquids with well-separated water and oil phases. All analyses proved that the structure and quality of bio-oil strongly depends on both the composition of the blend and the presence of the additive. The FT-IR and GC–MS analyses of oils showed that oxygen functionalities and hydrocarbons contents highly depend on the composition of biomass/polypropylene mixture. Results confirmed the significant removal and/or transformation of oxygen containing organic compounds, i.e. levoglucosan, 1,6-anhydro-β-d-glucofuranose and phenol derivatives due to the zinc chloride presence during pyrolysis process. All analyses showed that zinc chloride as catalyst was generally much more effective for removal of hydroxyl and methoxy groups than was potassium carbonate. It was demonstrated in this study that catalysts used in present work lead to the increased char yield and improved the fuel quality of bio-oil.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Piotr Rutkowski
The chemical composition of liquid products of cellulose and lignin co-pyrolysis with polypropylene at 450°C with and without the potassium carbonate or zinc chloride as an catalyst was investigated. The yield of liquid products of pyrolysis was in the range of 26–45wt% and their form was liquid or semi-solid highly depending on the composition of sample and pyrolysis conditions. The potassium carbonate and zinc chloride addition to blends has also influenced the range of samples decomposition as well as the chemical composition of resulted bio-oils. All bio-oils from biopolymer and polypropylene mixtures were three-phase (water, oil and solid). While zinc chloride acted as catalyst, all bio-oils obtained from biopolymer and polypropylene mixtures were yellow liquids with well-separated water and oil phases. All analyses proved that the structure and quality of bio-oil strongly depends on both the composition of the blend and the presence of the additive. The FT-IR and GC–MS analyses of oils showed that oxygen functionalities and hydrocarbons contents highly depend on the composition of biomass/polypropylene mixture. Results confirmed the significant removal and/or transformation of oxygen containing organic compounds, i.e. levoglucosan, 1,6-anhydro-β-d-glucofuranose and phenol derivatives due to the zinc chloride presence during pyrolysis process. All analyses showed that zinc chloride as catalyst was generally much more effective for removal of hydroxyl and methoxy groups than was potassium carbonate. It was demonstrated in this study that catalysts used in present work lead to the increased char yield and improved the fuel quality of bio-oil.
High-pressure pyrolysis of n-heptane: Effect of initiators
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Jyoti Prasad Chakraborty, Deepak Kunzru
Pyrolysis of n-heptane was carried out in a tubular reactor, in presence of three initiators viz., di-tert-butyl peroxide (DTBP), diisopropylamine (DIPA) and triethylamine (TEA), in the temperature range of 773–953K, pressure range of 0.1–2.93MPa and mole ratio of 0.005–0.03mole initiator per mole of n-heptane. Influence of temperature, pressure and space time on the conversion and product distribution was studied. All the initiators increased the conversion. This was primarily due to the initiative release of organic radicals after breaking of the weak CN or OO bonds. The product distribution was marginally affected, especially at low conversions. TEA was found out to be the best initiator and the kinetic parameters for n-heptane pyrolysis in the presence of TEA (mole ratio 0.03) were determined at 2.93MPa and 773–813K. The activation energy and pre-exponential factors, determined using a non-linear optimization technique, were 156.8kJmol−1 and 1.01×109 s−1, respectively.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Jyoti Prasad Chakraborty, Deepak Kunzru
Pyrolysis of n-heptane was carried out in a tubular reactor, in presence of three initiators viz., di-tert-butyl peroxide (DTBP), diisopropylamine (DIPA) and triethylamine (TEA), in the temperature range of 773–953K, pressure range of 0.1–2.93MPa and mole ratio of 0.005–0.03mole initiator per mole of n-heptane. Influence of temperature, pressure and space time on the conversion and product distribution was studied. All the initiators increased the conversion. This was primarily due to the initiative release of organic radicals after breaking of the weak CN or OO bonds. The product distribution was marginally affected, especially at low conversions. TEA was found out to be the best initiator and the kinetic parameters for n-heptane pyrolysis in the presence of TEA (mole ratio 0.03) were determined at 2.93MPa and 773–813K. The activation energy and pre-exponential factors, determined using a non-linear optimization technique, were 156.8kJmol−1 and 1.01×109 s−1, respectively.
Effects of heat treatment on physicochemical properties of cerium based nickel system
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
N.M. Deraz
Cerium based nickel catalysts synthesized by impregnation method have been characterized by XRD and TEM techniques. These catalysts can be described as a mixture of nickel oxide and ceria modified by the insertion of a part of nickel in the ceria lattice. The surface and catalytic properties of Ni/Ce mixed oxide solids were determined by nitrogen adsorption at 77K and catalytic conversion of isopropanol at different temperatures. The results revealed that the heat treatment brought about different modifications in the structural, morphological, surface and catalytic properties of the as synthesized catalysts. From the characterization of the as prepared catalysts, it was concluded that the as prepared catalysts contain highly dispersed NiO, well crystalline NiO and CeO2 and also Ni–Ce–O solid solution. This treatment led to a slightly increase in the crystallite size of ceria particles. On the other hand, the increase in the heat treatment resulted in an increase in the crystallite size, lattice constant and unit cell volume of nickel oxide. The formation of Ni–Ce–O solid solution with subsequent creation of oxygen vacancies increase as the heat treatment increases. However, the specific surface area, total pore volume and catalytic activity of the investigated system decrease as the preparation temperature increases from 500 to 700°C. The sintering activation energy of NiO and ceria were found to be 2.8 and 12.7kJ/mol, respectively.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
N.M. Deraz
Cerium based nickel catalysts synthesized by impregnation method have been characterized by XRD and TEM techniques. These catalysts can be described as a mixture of nickel oxide and ceria modified by the insertion of a part of nickel in the ceria lattice. The surface and catalytic properties of Ni/Ce mixed oxide solids were determined by nitrogen adsorption at 77K and catalytic conversion of isopropanol at different temperatures. The results revealed that the heat treatment brought about different modifications in the structural, morphological, surface and catalytic properties of the as synthesized catalysts. From the characterization of the as prepared catalysts, it was concluded that the as prepared catalysts contain highly dispersed NiO, well crystalline NiO and CeO2 and also Ni–Ce–O solid solution. This treatment led to a slightly increase in the crystallite size of ceria particles. On the other hand, the increase in the heat treatment resulted in an increase in the crystallite size, lattice constant and unit cell volume of nickel oxide. The formation of Ni–Ce–O solid solution with subsequent creation of oxygen vacancies increase as the heat treatment increases. However, the specific surface area, total pore volume and catalytic activity of the investigated system decrease as the preparation temperature increases from 500 to 700°C. The sintering activation energy of NiO and ceria were found to be 2.8 and 12.7kJ/mol, respectively.
Synergistic effects on co-pyrolysis of lignite and high-sulfur swelling coal
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Jinxia Fei, Jie Zhang, Fuchen Wang, Jie Wang
Co-pyrolysis of a lignite coal and a bituminous coal was carried out on a fixed-bed reactor. The lignite was enriched with calcium, and the bituminous coal featured in high sulfur and strong swelling. Experiments were also conducted for the blends using the acid-washed lignite and/or the acid washed bituminous coal to address the influences of calcium in the lignite on the synergistic behaviors. Calcium in the lignite exhibited some aspects of synergy including the catalytic cracking reactions of tar, the retention of sulfur in the char, and the catalyzed polyaromatization and gasification of char. These synergies impacted the differences in the product distribution and gas composition between the co-pyrolytic results and the additive ones. Moreover, there appeared to be a synergistic effect on the cross-linking reaction of volatile matter, resulting in an increase in the char yield irrespective of coal demineralization. The co-pyrolysis was also observed to destroy the swelling of coal. This synergistically increased the tar yield due to less resistant escaping of tar from the intra-particles of coal.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
Jinxia Fei, Jie Zhang, Fuchen Wang, Jie Wang
Co-pyrolysis of a lignite coal and a bituminous coal was carried out on a fixed-bed reactor. The lignite was enriched with calcium, and the bituminous coal featured in high sulfur and strong swelling. Experiments were also conducted for the blends using the acid-washed lignite and/or the acid washed bituminous coal to address the influences of calcium in the lignite on the synergistic behaviors. Calcium in the lignite exhibited some aspects of synergy including the catalytic cracking reactions of tar, the retention of sulfur in the char, and the catalyzed polyaromatization and gasification of char. These synergies impacted the differences in the product distribution and gas composition between the co-pyrolytic results and the additive ones. Moreover, there appeared to be a synergistic effect on the cross-linking reaction of volatile matter, resulting in an increase in the char yield irrespective of coal demineralization. The co-pyrolysis was also observed to destroy the swelling of coal. This synergistically increased the tar yield due to less resistant escaping of tar from the intra-particles of coal.
Effects of phosphoric acid as additive in the preparation of activated carbon fibers from poly(p-phenylene benzobisoxazole) by carbon dioxide activation
02 April 2012,
12:04:40
Publication year:
2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
M. Beatriz Vázquez-Santos, Amelia Martínez-Alonso, Juan M.D. Tascón
Poly(p-phenylene benzobisoxazole) (PBO) was impregnated with small amounts of H3PO4, and the effects of this additive on the porosity and other characteristics of chars and activated carbon fibers (ACFs) derived from this polymer were investigated. To this end, PBO-AS impregnated with 5, 10 or 15wt.% H3PO4 was pyrolyzed at 850°C, and the resulting chars were physically activated with carbon dioxide at 800°C to different burn-off (BO) degrees. Thermal analysis techniques only detected minor effects of H3PO4 on PBO pyrolysis. The char yield and char reactivity towards CO2 increased following PBO-AS impregnation with H3PO4. Structural (X-ray diffraction), porous textural (CO2 adsorption) and surface chemical (temperature-programmed desorption, X-ray photoelectron spectroscopy) characterizations of the pyrolysis chars indicated that the increase in char reactivity is probably associated with a higher content of oxygenated functionalities. Following CO2 activation, the surface area and pore volume of the obtained ACFs chiefly depended on the BO degree, but impregnation with H3PO4 restricted the pore size to the micropore and narrow mesopore range, thus producing adsorbents with a slightly narrower pore size distribution than in the absence of H3PO4. The results are compared with those previously obtained under equivalent conditions with other high-crystallinity polymers as precursors for ACFs.
Source:Journal of Analytical and Applied Pyrolysis, Volume 95
M. Beatriz Vázquez-Santos, Amelia Martínez-Alonso, Juan M.D. Tascón
Poly(p-phenylene benzobisoxazole) (PBO) was impregnated with small amounts of H3PO4, and the effects of this additive on the porosity and other characteristics of chars and activated carbon fibers (ACFs) derived from this polymer were investigated. To this end, PBO-AS impregnated with 5, 10 or 15wt.% H3PO4 was pyrolyzed at 850°C, and the resulting chars were physically activated with carbon dioxide at 800°C to different burn-off (BO) degrees. Thermal analysis techniques only detected minor effects of H3PO4 on PBO pyrolysis. The char yield and char reactivity towards CO2 increased following PBO-AS impregnation with H3PO4. Structural (X-ray diffraction), porous textural (CO2 adsorption) and surface chemical (temperature-programmed desorption, X-ray photoelectron spectroscopy) characterizations of the pyrolysis chars indicated that the increase in char reactivity is probably associated with a higher content of oxygenated functionalities. Following CO2 activation, the surface area and pore volume of the obtained ACFs chiefly depended on the BO degree, but impregnation with H3PO4 restricted the pore size to the micropore and narrow mesopore range, thus producing adsorbents with a slightly narrower pore size distribution than in the absence of H3PO4. The results are compared with those previously obtained under equivalent conditions with other high-crystallinity polymers as precursors for ACFs.
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