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Selected papers from the latest issue:
Production of char from vacuum pyrolysis of South-African sugar cane bagasse and its characterization as activated carbon and biochar
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
Marion Carrier, Ailsa G. Hardie, Ümit Uras, Johann Görgens, Johannes (Hansie) Knoetze
The potential of vacuum pyrolysis to convert sugar cane bagasse into char materials for wastewater treatment and soil amendment is the focus of this research paper. Vacuum pyrolysis produces both bio-oil and char in similar quantities. Vacuum pyrolysis has the potential to produce high quality chars for wastewater treatment and soil amendment directly during the conversion process, with no further upgrading required. In the present study, chars with the required porous structure was obtained directly from the vacuum pyrolysis process, making it very efficient as adsorbent both in terms of methylene blue (MB) adsorption with a N2-BET surface area of 418 m2 g−1. Further steam activation of the chars benefited the development of meso- and macroporosity, although this upgrading step was not essential to achieve the required performance of char as an MB adsorbent. The development of large pores during the vacuum pyrolysis favoured physisorption of MB, rather than chemisorption. The chemical nature of the vacuum pyrolysis char resulted in a slightly acidic surface (pH 6.56). The biochar from vacuum pyrolysis can be considered as a highly beneficial soil amendment, as it would enhance soil nutrient and water holding capacity, due to its high cation exchange capacity (122cmolckg−1) and high surface area. It is also a good source of beneficial plant macro- and micronutrients and contains negligible levels of toxic elements
Source:Journal of Analytical and Applied Pyrolysis
Marion Carrier, Ailsa G. Hardie, Ümit Uras, Johann Görgens, Johannes (Hansie) Knoetze
The potential of vacuum pyrolysis to convert sugar cane bagasse into char materials for wastewater treatment and soil amendment is the focus of this research paper. Vacuum pyrolysis produces both bio-oil and char in similar quantities. Vacuum pyrolysis has the potential to produce high quality chars for wastewater treatment and soil amendment directly during the conversion process, with no further upgrading required. In the present study, chars with the required porous structure was obtained directly from the vacuum pyrolysis process, making it very efficient as adsorbent both in terms of methylene blue (MB) adsorption with a N2-BET surface area of 418 m2 g−1. Further steam activation of the chars benefited the development of meso- and macroporosity, although this upgrading step was not essential to achieve the required performance of char as an MB adsorbent. The development of large pores during the vacuum pyrolysis favoured physisorption of MB, rather than chemisorption. The chemical nature of the vacuum pyrolysis char resulted in a slightly acidic surface (pH 6.56). The biochar from vacuum pyrolysis can be considered as a highly beneficial soil amendment, as it would enhance soil nutrient and water holding capacity, due to its high cation exchange capacity (122cmolckg−1) and high surface area. It is also a good source of beneficial plant macro- and micronutrients and contains negligible levels of toxic elements
An understanding of the porosity of residual coal/char/ash samples from AN AIR-BLOWN PACKED BED reactor operating on inertinite-rich lump coal
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
J.R. Bunt, F.B. Waanders, A. Nel, L. Dreyer, P.W.A. van Rensburg
The thermal treatment of coal causes a development of internal porosity of the resultant char due to the changes in the coal char pores, i.e. the opening of original closed pores, the formation of new pores, and an increase in pore size of existing and newly formed pores. Furthermore, the porosity formed during de-volatilisation causes changes in pore structural characteristics such as: density, pore size distribution, total open pore volume, porosities and average pore diameter. Much research has been conducted in this area, but was mainly focused on fine particle sizes (<1mm) and vitrinite-rich coals, particularly from the Northern hemisphere. The objective of this study was to obtain an understanding of both the macro and micro-porosity development within the de-volatilisation zone of a packed bed consisting of lump inertinite-rich coal (75mm x 6mm) from the Highveld coalfield in South Africa. This was achieved by generating samples in an air-blown packed bed reactor and conducting proximate, CO2 reactivity, mercury intrusion porosimetry, and BET CO2 surface area analyses on the dissected coal/char/ash samples. From mercury-intrusion porosimetry results obtained for the de-volatilisation reaction zone of the reactor, it was found that although the percentage macro-porosity and average pore diameter increased by 11% and 77% respectively (which confirms pore development), that these developments do not enlarge the surface area, and thus has no significant contribution on the reactivity of the coal/char. On the other hand, the micro-pore surface area, pore volume and pore diameter were all found to increase during de-volatilisation, resulting in an increase in the coal char reactivity. The micro-porosity is thus generally responsible for the largest internal surface area during de-volatilisation, which enables increased reactivity. The CO2 gasification reactivity (at 1000 ˚C) increased from 3.8 to 4.5 hr−1 in the first stage of de-volatilisation, and then decreased to 3.8 hr−1 in a slower de-volatilisation regime. This is due to the maximum pore expansion and volatile matter evolution reached at 4.5 hr−1, before coalescence and pore shrinkage occur with a further increase in temperature within the slower de-volatilisation region of the reactor. During de-volatilisation there is thus both an increase and decrease in reactivity which might suggest two distinct intermediate zones within the de-volatilisation zone.
Source:Journal of Analytical and Applied Pyrolysis
J.R. Bunt, F.B. Waanders, A. Nel, L. Dreyer, P.W.A. van Rensburg
The thermal treatment of coal causes a development of internal porosity of the resultant char due to the changes in the coal char pores, i.e. the opening of original closed pores, the formation of new pores, and an increase in pore size of existing and newly formed pores. Furthermore, the porosity formed during de-volatilisation causes changes in pore structural characteristics such as: density, pore size distribution, total open pore volume, porosities and average pore diameter. Much research has been conducted in this area, but was mainly focused on fine particle sizes (<1mm) and vitrinite-rich coals, particularly from the Northern hemisphere. The objective of this study was to obtain an understanding of both the macro and micro-porosity development within the de-volatilisation zone of a packed bed consisting of lump inertinite-rich coal (75mm x 6mm) from the Highveld coalfield in South Africa. This was achieved by generating samples in an air-blown packed bed reactor and conducting proximate, CO2 reactivity, mercury intrusion porosimetry, and BET CO2 surface area analyses on the dissected coal/char/ash samples. From mercury-intrusion porosimetry results obtained for the de-volatilisation reaction zone of the reactor, it was found that although the percentage macro-porosity and average pore diameter increased by 11% and 77% respectively (which confirms pore development), that these developments do not enlarge the surface area, and thus has no significant contribution on the reactivity of the coal/char. On the other hand, the micro-pore surface area, pore volume and pore diameter were all found to increase during de-volatilisation, resulting in an increase in the coal char reactivity. The micro-porosity is thus generally responsible for the largest internal surface area during de-volatilisation, which enables increased reactivity. The CO2 gasification reactivity (at 1000 ˚C) increased from 3.8 to 4.5 hr−1 in the first stage of de-volatilisation, and then decreased to 3.8 hr−1 in a slower de-volatilisation regime. This is due to the maximum pore expansion and volatile matter evolution reached at 4.5 hr−1, before coalescence and pore shrinkage occur with a further increase in temperature within the slower de-volatilisation region of the reactor. During de-volatilisation there is thus both an increase and decrease in reactivity which might suggest two distinct intermediate zones within the de-volatilisation zone.
RMicrostructural analysis of poly(vinylidene fluoride) using benzene derivative pyrolysis products
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
Sung-Seen Choi, Yun-Ki Kim
Poly(vinylidene fluoride) (PVDF) was pyrolyzed, and the pyrolysis products were analyzed using gas chromatography/mass spectrometry (GC/MS) to develop a method for identification of the microstructures of head-to-tail (H-T), tail-to-tail (T-T), and head-to-head-to-tail-to-tail (H-H-T-T) sequences. Key pyrolysis products to determine the relative degrees of the microstructures were benzene derivatives. 1,4-Difluorobenzene, 1,2,4-trifluorobenzene, and 1,3,5-trifluorobenzene were major pyrolysis products as benzene derivatives. 1,3,5-Trifluorobenzene and 1,2,4-trifluorobenzene were formed from two HF-eliminated PVDF by 1,6-HF elimination and 1,6-rearrangement, while 1,4-difluorobenzene was generated from two HF-eliminated PVDF by 1,6-H2 elimination and 1,6-rearrangement. 1,3,5-Trifluorobenzene was generated from the H-T sequence, whereas 1,4-difluorobenzene was formed from the T-T one. 1,2,4-Trifluorobenzene can be formed from the H-H-T-T sequence. Relative component ratios of the H-T, T-T, and H-H-T-T sequences of PVDFs can be estimated by comparing relative abundances of the benzene derivative pyrolysis products
Source:Journal of Analytical and Applied Pyrolysis
Sung-Seen Choi, Yun-Ki Kim
Poly(vinylidene fluoride) (PVDF) was pyrolyzed, and the pyrolysis products were analyzed using gas chromatography/mass spectrometry (GC/MS) to develop a method for identification of the microstructures of head-to-tail (H-T), tail-to-tail (T-T), and head-to-head-to-tail-to-tail (H-H-T-T) sequences. Key pyrolysis products to determine the relative degrees of the microstructures were benzene derivatives. 1,4-Difluorobenzene, 1,2,4-trifluorobenzene, and 1,3,5-trifluorobenzene were major pyrolysis products as benzene derivatives. 1,3,5-Trifluorobenzene and 1,2,4-trifluorobenzene were formed from two HF-eliminated PVDF by 1,6-HF elimination and 1,6-rearrangement, while 1,4-difluorobenzene was generated from two HF-eliminated PVDF by 1,6-H2 elimination and 1,6-rearrangement. 1,3,5-Trifluorobenzene was generated from the H-T sequence, whereas 1,4-difluorobenzene was formed from the T-T one. 1,2,4-Trifluorobenzene can be formed from the H-H-T-T sequence. Relative component ratios of the H-T, T-T, and H-H-T-T sequences of PVDFs can be estimated by comparing relative abundances of the benzene derivative pyrolysis products
Classification of forensic soil evidences by application of THM-PyGC/MS and multivariate analysis
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
Choong Sik Lee, Tae Myung Sung, Hyong Seong Kim, Chung Hyun Jeon
The forensic classification of soil samples was carried out by thermally assisted hydrolysis and methylation (THM) of soil organic matters (SOM) using pyrolysis-gas chromatography/mass spectrometry (PyGC/MS). In this work, thirty-three THM derivatives were detected as SOM contained in<3mg soil. The specific ions of the mass spectra were selected to separate and minimize the interference between SOM peaks. SOM data were normalized with the sum of peak areas to correct the amounts of SOM contained in the soil, and the chemometric approach based on principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA) was employed to evaluate and compare the soil classification. The first seven principal components (PCs) accounted for 94.8% of total cumulate variance and these PCs were statistically determined by multiple comparisons (Tamhane's T2 and Dunnett's T3) for the post-hoc test (p-value<0.05) and were used to construct the LDA model. It was determined that multiple comparisons were a statistically good criterion for deciding on the number of PCs for the LDA model. It was also concluded that the discrimination model correctly classified 40 soil samples into six clusters with high accuracy. Furthermore, the eleven marker compounds were investigated according to the loadings of PCs and the normalized data. These results demonstrated that lignin, fatty acid and urea can be used as potentially useful compounds to characterize soil samples for forensic purposes.
Source:Journal of Analytical and Applied Pyrolysis
Choong Sik Lee, Tae Myung Sung, Hyong Seong Kim, Chung Hyun Jeon
The forensic classification of soil samples was carried out by thermally assisted hydrolysis and methylation (THM) of soil organic matters (SOM) using pyrolysis-gas chromatography/mass spectrometry (PyGC/MS). In this work, thirty-three THM derivatives were detected as SOM contained in<3mg soil. The specific ions of the mass spectra were selected to separate and minimize the interference between SOM peaks. SOM data were normalized with the sum of peak areas to correct the amounts of SOM contained in the soil, and the chemometric approach based on principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA) was employed to evaluate and compare the soil classification. The first seven principal components (PCs) accounted for 94.8% of total cumulate variance and these PCs were statistically determined by multiple comparisons (Tamhane's T2 and Dunnett's T3) for the post-hoc test (p-value<0.05) and were used to construct the LDA model. It was determined that multiple comparisons were a statistically good criterion for deciding on the number of PCs for the LDA model. It was also concluded that the discrimination model correctly classified 40 soil samples into six clusters with high accuracy. Furthermore, the eleven marker compounds were investigated according to the loadings of PCs and the normalized data. These results demonstrated that lignin, fatty acid and urea can be used as potentially useful compounds to characterize soil samples for forensic purposes.
Optimization of platinum filament micropyrolyzer for studying primary decomposition in cellulose pyrolysis
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
Frederik Ronsse, Dustin Dalluge, Wolter Prins, Robert C. Brown
In this study, a systematic and quantitative analysis of the yield and composition of primary decomposition products produced during pyrolysis of cellulose using a platinum filament type micropyrolyzer was performed. It demonstrates the importance of proper selection of the operating conditions for the filament type micropyrolyzer. A method was developed to optimize micropyrolysis operational parameters with respect to maximizing the yield of certain primary decomposition products, more specifically, levoglucosan. The results indicate that composition and yield of the pyrolysis vapors are highly sensitive to any parameter which directly or indirectly affects heat transfer during micropyrolysis. In this regard, filament type micropyrolyzers were shown to be more sensitive than microfurnace based micropyrolyzers. Parameters which have to be considered for method development and optimization in filament type micropyrolyzers are sample size, pyrolysis temperature, difference between actual (i.e. sample) and set-point (i.e. filament) temperature, sample particle size and the potential occurrence of cold spots in the system, promoting condensation. With proper parameter selection and optimization, yields in primary decomposition products are similar to microfurnace pyrolyzers with good repeatability
Source:Journal of Analytical and Applied Pyrolysis
Frederik Ronsse, Dustin Dalluge, Wolter Prins, Robert C. Brown
In this study, a systematic and quantitative analysis of the yield and composition of primary decomposition products produced during pyrolysis of cellulose using a platinum filament type micropyrolyzer was performed. It demonstrates the importance of proper selection of the operating conditions for the filament type micropyrolyzer. A method was developed to optimize micropyrolysis operational parameters with respect to maximizing the yield of certain primary decomposition products, more specifically, levoglucosan. The results indicate that composition and yield of the pyrolysis vapors are highly sensitive to any parameter which directly or indirectly affects heat transfer during micropyrolysis. In this regard, filament type micropyrolyzers were shown to be more sensitive than microfurnace based micropyrolyzers. Parameters which have to be considered for method development and optimization in filament type micropyrolyzers are sample size, pyrolysis temperature, difference between actual (i.e. sample) and set-point (i.e. filament) temperature, sample particle size and the potential occurrence of cold spots in the system, promoting condensation. With proper parameter selection and optimization, yields in primary decomposition products are similar to microfurnace pyrolyzers with good repeatability
Molecular characterization of Ulex europaeus biochar obtained from laboratory heat treatment experiments – A pyrolysis–GC/MS study
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
Joeri Kaal, Antonio Martínez Cortizas, Otilia Reyes, Mario Soliño
Gorse species (Ulex sp.) are ubiquitous in the shrublands of NW Spain and have the potential to become key players in an integral biofuel/biochar program in NW Spain. Here we present molecular characterization (using pyrolysis–GC/MS) of a biochar “thermosequence” obtained by laboratory heating of Ulex europaeus wood in a muffle furnace between 200 and 600°C (T CHAR). Low temperature chars (T CHAR ≤350°C) produced significant amounts of pyrolysis products of which the precursor biopolymer could be recognized, while high-temperature chars (T CHAR ≥400°C) produced mainly phenols and monocyclic and polycyclic aromatic hydrocarbons, which are not specific for any biopolymer. Carbohydrate could hardly be recognized at T CHAR ≥350°C. The thermal rearrangement of polyphenols, mainly lignin, was reflected in more detail (1) C3-side chain shortening and probably depolymerization (T CHAR 200–350°C), (2) demethoxylation of syringyl and probably also some guaiacyl lignin (T CHAR 300–400°C), (3) elimination of virtually all remaining methoxyl groups (T CHAR 350–400°C), through dehydroxylation and demethoxylation, (4) almost complete dehydroxylation of lignin and other biopolymers (T CHAR 400–500°C), (5) progressive condensation into polyaromatic structures (T CHAR 300–500°C) and (6) partial elimination of alkyl bridges between (poly)aromatic moieties (T CHAR 450–500°C). These results were supported by Fourier transform infrared spectroscopy (FTIR) of the same samples. We conclude that pyrolysis–GC/MS can be used as a rapid molecular screening method of gorse-derived biochar. Molecular properties elucidation is an essential part of predicting the stability and agronomical behavior of gorse-derived biochar after future implementation in soils.
Source:Journal of Analytical and Applied Pyrolysis
Joeri Kaal, Antonio Martínez Cortizas, Otilia Reyes, Mario Soliño
Gorse species (Ulex sp.) are ubiquitous in the shrublands of NW Spain and have the potential to become key players in an integral biofuel/biochar program in NW Spain. Here we present molecular characterization (using pyrolysis–GC/MS) of a biochar “thermosequence” obtained by laboratory heating of Ulex europaeus wood in a muffle furnace between 200 and 600°C (T CHAR). Low temperature chars (T CHAR ≤350°C) produced significant amounts of pyrolysis products of which the precursor biopolymer could be recognized, while high-temperature chars (T CHAR ≥400°C) produced mainly phenols and monocyclic and polycyclic aromatic hydrocarbons, which are not specific for any biopolymer. Carbohydrate could hardly be recognized at T CHAR ≥350°C. The thermal rearrangement of polyphenols, mainly lignin, was reflected in more detail (1) C3-side chain shortening and probably depolymerization (T CHAR 200–350°C), (2) demethoxylation of syringyl and probably also some guaiacyl lignin (T CHAR 300–400°C), (3) elimination of virtually all remaining methoxyl groups (T CHAR 350–400°C), through dehydroxylation and demethoxylation, (4) almost complete dehydroxylation of lignin and other biopolymers (T CHAR 400–500°C), (5) progressive condensation into polyaromatic structures (T CHAR 300–500°C) and (6) partial elimination of alkyl bridges between (poly)aromatic moieties (T CHAR 450–500°C). These results were supported by Fourier transform infrared spectroscopy (FTIR) of the same samples. We conclude that pyrolysis–GC/MS can be used as a rapid molecular screening method of gorse-derived biochar. Molecular properties elucidation is an essential part of predicting the stability and agronomical behavior of gorse-derived biochar after future implementation in soils.
Evolution of gaseous products from biomass pyrolysis in the presence of phosphoric acid
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
Songlin Zuo, Zhiliang Xiao, Jianxiao Yang
Slow pyrolysis experiments of China fir (Cunninghamia lanceolata) wood were performed in a vertical tubular furnace at various heating rates. The raw material was pretreated by impregnation with phosphoric acid solutions of various concentrations for given times. The evolution of the gaseous products CO, CO2, H2 and CH4 was analyzed online by using gas spectrometry to investigate the effect of phosphoric acid on the pyrolytic gaseous products of biomass. The addition of phosphoric acid was shown to significantly reduce the pyrolysis temperature necessary for the production of CO, CO2 and H2 gases, and the pyrolysis variables exerted an influence on the amount of the gases released. Moreover, phosphoric acid appreciably depressed the CO, CO2 and CH4 production, and promoted H2, especially when a higher heating rate was employed. This suggested that phosphoric acid catalyzed both the primary thermal decomposition of biopolymers and the secondary reactions that took place among the pyrolytic vapor products.
Source:Journal of Analytical and Applied Pyrolysis
Songlin Zuo, Zhiliang Xiao, Jianxiao Yang
Slow pyrolysis experiments of China fir (Cunninghamia lanceolata) wood were performed in a vertical tubular furnace at various heating rates. The raw material was pretreated by impregnation with phosphoric acid solutions of various concentrations for given times. The evolution of the gaseous products CO, CO2, H2 and CH4 was analyzed online by using gas spectrometry to investigate the effect of phosphoric acid on the pyrolytic gaseous products of biomass. The addition of phosphoric acid was shown to significantly reduce the pyrolysis temperature necessary for the production of CO, CO2 and H2 gases, and the pyrolysis variables exerted an influence on the amount of the gases released. Moreover, phosphoric acid appreciably depressed the CO, CO2 and CH4 production, and promoted H2, especially when a higher heating rate was employed. This suggested that phosphoric acid catalyzed both the primary thermal decomposition of biopolymers and the secondary reactions that took place among the pyrolytic vapor products.
Influence of impregnated metal on the pyrolysis conversion of biomass constituents
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
François-Xavier Collard, Joël Blin, Ammar Bensakhria, Jérémy Valette
When impregnated in biomass, metal precursors display catalytic activity that results in a significant decrease in tar production and increases hydrogen formation during pyrolysis. The aim of this work was to assess the effect of nickel and iron salts on the pyrolysis mechanisms of the main constituents of biomass. Samples of metal-impregnated cellulose, hemicelluloses (beech wood xylan) and lignin were pyrolyzed. Beech wood samples with different metal contents (0.10, 0.26 and 0.65mmol/gwood) were also tested to compare the effects of iron and nickel in the biomass. As a result of metal impregnation, significant changes in the yields of pyrolysis products, in the concentration of tar compounds (determined by GC-MS) and in the composition of the gaseous fraction were obtained. The results showed that in cellulose, xylan and lignin, impregnated iron catalyzed rearrangement reactions leading to an increase in char yield and a decrease in tar formation. Impregnated nickel also catalyzed charring reactions in microcrystalline cellulose and in lignin, but promoted the depolymerization of amorphous xylan resulting in a 27-fold increase in furfural yields. Nickel was more efficient than iron in the rearrangement of the aromatic rings in the matrix, which contributed to the large increase in hydrogen production observed with nickel-impregnated samples (+472% for nickel-impregnated lignin). Based on these results, it was possible to explain the changes in pyrolysis yields obtained from beech wood after metal impregnation. The comparison of the catalytic effect of the two metals on biomass constituents explained the higher char yield and tar decrease obtained with iron-impregnated wood on one hand, and the higher aromatic tar reduction and hydrogen production increase obtained with nickel-impregnated wood on the other hand
Source:Journal of Analytical and Applied Pyrolysis
François-Xavier Collard, Joël Blin, Ammar Bensakhria, Jérémy Valette
When impregnated in biomass, metal precursors display catalytic activity that results in a significant decrease in tar production and increases hydrogen formation during pyrolysis. The aim of this work was to assess the effect of nickel and iron salts on the pyrolysis mechanisms of the main constituents of biomass. Samples of metal-impregnated cellulose, hemicelluloses (beech wood xylan) and lignin were pyrolyzed. Beech wood samples with different metal contents (0.10, 0.26 and 0.65mmol/gwood) were also tested to compare the effects of iron and nickel in the biomass. As a result of metal impregnation, significant changes in the yields of pyrolysis products, in the concentration of tar compounds (determined by GC-MS) and in the composition of the gaseous fraction were obtained. The results showed that in cellulose, xylan and lignin, impregnated iron catalyzed rearrangement reactions leading to an increase in char yield and a decrease in tar formation. Impregnated nickel also catalyzed charring reactions in microcrystalline cellulose and in lignin, but promoted the depolymerization of amorphous xylan resulting in a 27-fold increase in furfural yields. Nickel was more efficient than iron in the rearrangement of the aromatic rings in the matrix, which contributed to the large increase in hydrogen production observed with nickel-impregnated samples (+472% for nickel-impregnated lignin). Based on these results, it was possible to explain the changes in pyrolysis yields obtained from beech wood after metal impregnation. The comparison of the catalytic effect of the two metals on biomass constituents explained the higher char yield and tar decrease obtained with iron-impregnated wood on one hand, and the higher aromatic tar reduction and hydrogen production increase obtained with nickel-impregnated wood on the other hand
Production of bio-oil via fast pyrolysis of agricultural residues from cassava plantations in a fluidised-bed reactor with a hot vapour filtration unit
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis
Adisak Pattiya, Suntorn Suttibak
This article reports experimental results on fast pyrolysis of agricultural residues from cassava plantations, namely cassava rhizome (CR) and cassava stalk (CS), in a fluidised-bed fast pyrolysis reactor unit incorporated with a hot vapour filter. The objective of this research was to investigate the effects of reaction temperatures, biomass particle size and the use of simple hot vapour filtration on pyrolysis product yields and properties. Results showed that the optimum pyrolysis temperatures for CR and CS were 475°C and 469°C, which gave maximum bio-oil yields of 69.1wt% and 61.4wt% on dry biomass basis, respectively. The optimum particle size for bio-oil production in this study was 250–425μm. The use of the hot filter led to a reduction of 6–7wt% of bio-oil yield. Nevertheless, the filtered bio-oils appeared to have a better quality in terms of initial viscosity, solids content, ash content and stability.
Source:Journal of Analytical and Applied Pyrolysis
Adisak Pattiya, Suntorn Suttibak
This article reports experimental results on fast pyrolysis of agricultural residues from cassava plantations, namely cassava rhizome (CR) and cassava stalk (CS), in a fluidised-bed fast pyrolysis reactor unit incorporated with a hot vapour filter. The objective of this research was to investigate the effects of reaction temperatures, biomass particle size and the use of simple hot vapour filtration on pyrolysis product yields and properties. Results showed that the optimum pyrolysis temperatures for CR and CS were 475°C and 469°C, which gave maximum bio-oil yields of 69.1wt% and 61.4wt% on dry biomass basis, respectively. The optimum particle size for bio-oil production in this study was 250–425μm. The use of the hot filter led to a reduction of 6–7wt% of bio-oil yield. Nevertheless, the filtered bio-oils appeared to have a better quality in terms of initial viscosity, solids content, ash content and stability.
Editorial Board
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
Literature survey for a first choice of a fuel-oxidiser couple for hybrid propulsion based on kinetic justifications
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
N. Gascoin, P. Gillard, A. Mangeot, A. Navarro-Rodriguez
Hybrid rocket propulsion presents an increasing demand because of safety and cost reasons. Numerous works cover the main related areas (regression rate, oxidiser injection, grain design and additives in solid reducer). Nevertheless, the use of detailed kinetic studies, either experimentally or numerically, remains scarce. In particular, the auto-ignition and pyrolysis delays, the nature of chemical species impacting the diffusion flame and the rate of heat release are some of the important parameters. They are rarely considered when choosing a reducer–oxidiser couple. Understanding these chemical parameters could help choosing, or later improving, the solid reducers which present low regression speeds (limiting step of hybrid engine due to low combustible gas flow rate). Since detailed chemistry is still a foreign field for hybrid rocket studies, a wide review is first presented to determine how existing chemical works can be of interest for this propulsion technique. Mechanical and thermal characteristics are also considered in addition to combustion ones. Analytical estimation of the requirements to be met by the reducer–oxidiser couple is proposed (combustion heat release and associated heat fluxes, endothermic pyrolysis effect, chemical induction delays). Moreover, the choice of a reducer depends on the operating conditions under which it is used. For this reason, some equilibrium calculations are also provided to investigate the pressure and temperature effects. Amongst sixteen solid reducers, only three are finally selected in a first step (high density polyethylene – HDPE, polymethylmethacrylate – PMMA, hydroxyl terminated polybutadiene – HTPB). A similar work for oxidisers is conducted amongst thirteen compounds and three of them are selected (hydrogen peroxide – H2O2, nitrous oxide – N2O, pure oxygen – O2).
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
N. Gascoin, P. Gillard, A. Mangeot, A. Navarro-Rodriguez
Hybrid rocket propulsion presents an increasing demand because of safety and cost reasons. Numerous works cover the main related areas (regression rate, oxidiser injection, grain design and additives in solid reducer). Nevertheless, the use of detailed kinetic studies, either experimentally or numerically, remains scarce. In particular, the auto-ignition and pyrolysis delays, the nature of chemical species impacting the diffusion flame and the rate of heat release are some of the important parameters. They are rarely considered when choosing a reducer–oxidiser couple. Understanding these chemical parameters could help choosing, or later improving, the solid reducers which present low regression speeds (limiting step of hybrid engine due to low combustible gas flow rate). Since detailed chemistry is still a foreign field for hybrid rocket studies, a wide review is first presented to determine how existing chemical works can be of interest for this propulsion technique. Mechanical and thermal characteristics are also considered in addition to combustion ones. Analytical estimation of the requirements to be met by the reducer–oxidiser couple is proposed (combustion heat release and associated heat fluxes, endothermic pyrolysis effect, chemical induction delays). Moreover, the choice of a reducer depends on the operating conditions under which it is used. For this reason, some equilibrium calculations are also provided to investigate the pressure and temperature effects. Amongst sixteen solid reducers, only three are finally selected in a first step (high density polyethylene – HDPE, polymethylmethacrylate – PMMA, hydroxyl terminated polybutadiene – HTPB). A similar work for oxidisers is conducted amongst thirteen compounds and three of them are selected (hydrogen peroxide – H2O2, nitrous oxide – N2O, pure oxygen – O2).
The relation between dioxin concentration from exhaust gas of diesel engine and chlorine content
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
Wei-Cheng Wang, Wen-Her Lin, Chun-Pao Kuo, Jenn-Yan Wu
In this paper, an experiment has been used to study the effect of pyrolysis stage (from injection to combustion) to dioxin exhaust from diesel engine. The characteristics of diesel fuel pyrolysis have been applied in order to calculate the mean molecular weight in varied temperatures and measure the concentration of inorganic chlorine (HCl). On the other hand, measuring the chlorine content of these particles after diesel pyrolysis enables researchers to find out the pyrolysis temperature that has the lowest possibility to produce dioxin. Additionally, the post-pyrolysis carbon particle diameter has been observed through electronic microscope so as to evaluate the combustion condition of the combustion stage. Result from this study would be helpful for researchers to understand the probability of dioxin formation.
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
Wei-Cheng Wang, Wen-Her Lin, Chun-Pao Kuo, Jenn-Yan Wu
In this paper, an experiment has been used to study the effect of pyrolysis stage (from injection to combustion) to dioxin exhaust from diesel engine. The characteristics of diesel fuel pyrolysis have been applied in order to calculate the mean molecular weight in varied temperatures and measure the concentration of inorganic chlorine (HCl). On the other hand, measuring the chlorine content of these particles after diesel pyrolysis enables researchers to find out the pyrolysis temperature that has the lowest possibility to produce dioxin. Additionally, the post-pyrolysis carbon particle diameter has been observed through electronic microscope so as to evaluate the combustion condition of the combustion stage. Result from this study would be helpful for researchers to understand the probability of dioxin formation.
Cellulose pyrolysis kinetics: An historical review on the existence and role of intermediate active cellulose
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
Jacques Lédé
Cellulose pyrolysis, studied since more than one century, has been the object of a great number of papers. Several related kinetic models have been established in large experimental conditions, from slow to fast pyrolysis. Unfortunately, no actual consensus is reached. The primary formation of intermediate species accompanied or not with phase change phenomena are amongst the main matters of concerns. The purpose of the present review is to report the controversies, well-established knowledges and unresolved questions concerning the existence and role of intermediate species (often called “active cellulose”). After a general discussion, a few research topics are suggested at the end of the paper.
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
Jacques Lédé
Cellulose pyrolysis, studied since more than one century, has been the object of a great number of papers. Several related kinetic models have been established in large experimental conditions, from slow to fast pyrolysis. Unfortunately, no actual consensus is reached. The primary formation of intermediate species accompanied or not with phase change phenomena are amongst the main matters of concerns. The purpose of the present review is to report the controversies, well-established knowledges and unresolved questions concerning the existence and role of intermediate species (often called “active cellulose”). After a general discussion, a few research topics are suggested at the end of the paper.
Detailed kinetic computations and experiments for the choice of a fuel–oxidiser couple for hybrid propulsion
16 March 2012, 09:42:01
Publication year: 2012
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
N. Gascoin, P. Gillard, A. Mangeot, A. Navarro-Rodriguez
The choice of a solid reducer for hybrid propulsion is generally based on the quantity of gaseous combustible it can produce (expressed indirectly by the regression rate). For this reason, the studies focus on the use of additives or on the design of grain while the kinetic aspect is rarely of interest despite the chemistry drives the phenomena (chemical induction delay, heat absorption, and chemical composition). One-step mechanisms are first considered in this paper to quantify the effect of operating conditions on high density polyethylene (HDPE), polymethylmethacrylate (PMMA) and hydroxyl termination polybutadiene (HTPB). Then the chemical composition of pyrolysis products is determined for a large range of operating conditions with highly detailed mechanism for HDPE (1014 species and 7541 reactions). The heating rate applied to the reducer is investigated (from 1Ks−1 to 107 Ks−1). Ethylene is found to be the major pyrolysis product. The timescale found over 1250K and 11.11bar is in agreement with the requirements of hybrid propulsion. The calculated data are compared to experimental ones. Finally, a short combustion study with detailed chemistry (over 700 species and 3000 reactions) is proposed because it impacts directly on the pyrolysis through the generated heat flux. It allows considering the oxidiser decomposition (hydrogen peroxide (H2O2) and nitrous oxide (N2O)). Pure oxygen (O2) is considered as reference data. The effect of atmosphere (inert or oxidative) on the pyrolysis is shown. The kinetic computations of N2O combustion give higher flame temperatures than for H2O2. Ignition times, below a few milliseconds, are obtained for all the reducers over 1250K. Finally, the HDPE/H2O2 and HTPB/N2O couples are found to be the most interesting.
Source:Journal of Analytical and Applied Pyrolysis, Volume 94
N. Gascoin, P. Gillard, A. Mangeot, A. Navarro-Rodriguez
The choice of a solid reducer for hybrid propulsion is generally based on the quantity of gaseous combustible it can produce (expressed indirectly by the regression rate). For this reason, the studies focus on the use of additives or on the design of grain while the kinetic aspect is rarely of interest despite the chemistry drives the phenomena (chemical induction delay, heat absorption, and chemical composition). One-step mechanisms are first considered in this paper to quantify the effect of operating conditions on high density polyethylene (HDPE), polymethylmethacrylate (PMMA) and hydroxyl termination polybutadiene (HTPB). Then the chemical composition of pyrolysis products is determined for a large range of operating conditions with highly detailed mechanism for HDPE (1014 species and 7541 reactions). The heating rate applied to the reducer is investigated (from 1Ks−1 to 107 Ks−1). Ethylene is found to be the major pyrolysis product. The timescale found over 1250K and 11.11bar is in agreement with the requirements of hybrid propulsion. The calculated data are compared to experimental ones. Finally, a short combustion study with detailed chemistry (over 700 species and 3000 reactions) is proposed because it impacts directly on the pyrolysis through the generated heat flux. It allows considering the oxidiser decomposition (hydrogen peroxide (H2O2) and nitrous oxide (N2O)). Pure oxygen (O2) is considered as reference data. The effect of atmosphere (inert or oxidative) on the pyrolysis is shown. The kinetic computations of N2O combustion give higher flame temperatures than for H2O2. Ignition times, below a few milliseconds, are obtained for all the reducers over 1250K. Finally, the HDPE/H2O2 and HTPB/N2O couples are found to be the most interesting.
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