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Aromatic Hydrocarbon Production by the Online Catalytic Cracking of Lignin Fast Pyrolysis Vapors using Mo2N/γ-Al2O3
30 May 2013,
16:58:57
Publication date: Available online 30 May
2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Yan Zheng , Dengyu Chen , Xifeng Zhu
This study investigates the online catalytic cracking of lignin fast pyrolysis vapors using Mo2N/γ-Al2O3 prepared by nitriding an alumina-supported molybdenum oxide precursor with nitrogen hydrogen mixtures though temperature programming. The activity and selectivity of the catalyst toward aromatic hydrocarbons were determined in the pyrolysis-gas chromatography/mass spectrometry system. Results show that the catalyst has a significant function in the pyrolysis process. In the presence of the catalyst, the primary pyrolysis products from lignin are catalytically converted into aromatic products, benzene and toluene, as well as to an insignificant quantities of dimethylbenzene, ethylbenzene, trimethylbenzene, and naphthalene. The highest aromatic hydrocarbon yield of 17.5% is obtained using Mo2N/γ-Al2O3 (the catalyst-to-lignin weight ratio=4) at 700°C; by contrast, this yield is only 1.4% when no catalyst is used. Furthermore, the highest benzene yield of 70.1% is obtained using Mo2N/γ-Al2O3 (catalyst-to-lignin weight ratio=4) at 850°C. Under this condition, the monocyclic aromatic hydrocarbons together contribute >95% of the total aromatic hydrocarbon yield, whereas the selectivity toward naphthalene is only 2.2%.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Yan Zheng , Dengyu Chen , Xifeng Zhu
This study investigates the online catalytic cracking of lignin fast pyrolysis vapors using Mo2N/γ-Al2O3 prepared by nitriding an alumina-supported molybdenum oxide precursor with nitrogen hydrogen mixtures though temperature programming. The activity and selectivity of the catalyst toward aromatic hydrocarbons were determined in the pyrolysis-gas chromatography/mass spectrometry system. Results show that the catalyst has a significant function in the pyrolysis process. In the presence of the catalyst, the primary pyrolysis products from lignin are catalytically converted into aromatic products, benzene and toluene, as well as to an insignificant quantities of dimethylbenzene, ethylbenzene, trimethylbenzene, and naphthalene. The highest aromatic hydrocarbon yield of 17.5% is obtained using Mo2N/γ-Al2O3 (the catalyst-to-lignin weight ratio=4) at 700°C; by contrast, this yield is only 1.4% when no catalyst is used. Furthermore, the highest benzene yield of 70.1% is obtained using Mo2N/γ-Al2O3 (catalyst-to-lignin weight ratio=4) at 850°C. Under this condition, the monocyclic aromatic hydrocarbons together contribute >95% of the total aromatic hydrocarbon yield, whereas the selectivity toward naphthalene is only 2.2%.
PAHs emission from the pyrolysis of Western Chinese coal
30 May 2013,
16:58:57
Publication date: Available online 30 May
2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Jie Dong , Zhu Cheng , Fan Li
Several organic and inorganic pollutants are released during coal utilization such as polycyclic aromatic hydrocarbons (PAHs). PAHs, due to their carcinogenic properties pose potential health hazards. The current work focus on the behaviour of the 16 PAHs during pyrolysis process, an important step of all coal thermal conversion including combustion, gasification, and carbonization. The experiments were performed using a CDS -5250 pyroprobe which could be heated fast. The pyroprobe was coupled with GC-MS (Thermo DSQII/FOCUS GC) and the pyrolysis products were analyzed in-situ. The emissions of the 16 USEPA priority-controlled polycyclic aromatic hydrocarbons from Western Chinese coal were measured under different pyrolysis conditions. The results showed that the emission concentrations of PAHs reach a maximum at a pyrolysis temperature of 800°C. Emission concentrations of PAHs decreased with increasing rates of pyrolysis heating. PAHs emmissions increased gradually with coal rank under the same pyrolysis conditions. A correlation between the yield of PAHs; coal rank and maceral was also demonstrated. Also in this study, the variety trend of the each specie of 16 PAHs with pyrolysis temperature were observed and the reasons were disccussed.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Jie Dong , Zhu Cheng , Fan Li
Several organic and inorganic pollutants are released during coal utilization such as polycyclic aromatic hydrocarbons (PAHs). PAHs, due to their carcinogenic properties pose potential health hazards. The current work focus on the behaviour of the 16 PAHs during pyrolysis process, an important step of all coal thermal conversion including combustion, gasification, and carbonization. The experiments were performed using a CDS -5250 pyroprobe which could be heated fast. The pyroprobe was coupled with GC-MS (Thermo DSQII/FOCUS GC) and the pyrolysis products were analyzed in-situ. The emissions of the 16 USEPA priority-controlled polycyclic aromatic hydrocarbons from Western Chinese coal were measured under different pyrolysis conditions. The results showed that the emission concentrations of PAHs reach a maximum at a pyrolysis temperature of 800°C. Emission concentrations of PAHs decreased with increasing rates of pyrolysis heating. PAHs emmissions increased gradually with coal rank under the same pyrolysis conditions. A correlation between the yield of PAHs; coal rank and maceral was also demonstrated. Also in this study, the variety trend of the each specie of 16 PAHs with pyrolysis temperature were observed and the reasons were disccussed.
Exposure to valproic acid and 5,7-dimethoxycoumarin induces pheomelanogenesis in the human melanoma G-361 cells, as demonstrated by Py-GC/MS/MS study
30 May 2013,
16:58:57
Publication date: Available online 27 May
2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ewa Chodurek , Anna Dzierżęga-Lęcznar , Slawomir Kurkiewicz , Krystyna Stępień
Melanogenesis is one of the main markers of the differentiation of normal and neoplastically transformed melanocytes. Valproic acid (VPA) and 5,7-dimethoxycoumarin (DMC), the potential anti-cancer drugs with differentiating activity, were reported to enhance melanin synthesis in melanoma cells. The aim of this study was to examine if the stimulation with VPA and DMC affects the structure of melanin synthesized by the human melanoma G-361 cell line. G-361 cells were cultured with VPA, DMC, and a mixture of the two agents for 7 days. Melanin isolated from the treated and untreated cells were pyrolysed, and the thermal degradation products were analyzed by gas chromatography/tandem mass spectrometry with a triple quadrupole instrument operating in a multiple reaction monitoring mode. After the stimulation with VPA and DMC, the sulfur containing pyrolytic markers of pheomelanin were detected among the thermal degradation products of the pigment isolated from the tumor cells. The levels of pheomelanin markers were the highest after the cell treatment with the combination of both agents. No sulfur compounds were present in the pyrolysate of melanin from the untreated control cells. We have concluded that VPA and DMC are able to induce pheomelanogenesis, and thus alter the structure of melanin produced in the human melanoma G-361 cells.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Ewa Chodurek , Anna Dzierżęga-Lęcznar , Slawomir Kurkiewicz , Krystyna Stępień
Melanogenesis is one of the main markers of the differentiation of normal and neoplastically transformed melanocytes. Valproic acid (VPA) and 5,7-dimethoxycoumarin (DMC), the potential anti-cancer drugs with differentiating activity, were reported to enhance melanin synthesis in melanoma cells. The aim of this study was to examine if the stimulation with VPA and DMC affects the structure of melanin synthesized by the human melanoma G-361 cell line. G-361 cells were cultured with VPA, DMC, and a mixture of the two agents for 7 days. Melanin isolated from the treated and untreated cells were pyrolysed, and the thermal degradation products were analyzed by gas chromatography/tandem mass spectrometry with a triple quadrupole instrument operating in a multiple reaction monitoring mode. After the stimulation with VPA and DMC, the sulfur containing pyrolytic markers of pheomelanin were detected among the thermal degradation products of the pigment isolated from the tumor cells. The levels of pheomelanin markers were the highest after the cell treatment with the combination of both agents. No sulfur compounds were present in the pyrolysate of melanin from the untreated control cells. We have concluded that VPA and DMC are able to induce pheomelanogenesis, and thus alter the structure of melanin produced in the human melanoma G-361 cells.
Molecular Characteristics of Vermicompost and Their Relationship to Preservation of Inoculated Nitrogen-Fixing Bacteria
30 May 2013,
16:58:57
Publication date: Available online 27 May
2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Dariellys Martinez-Balmori , Fábio Lopes Olivares , Riccardo Spaccini , Kamilla Pereira Aguiar , Marcelo Francisco Araújo , Natália Oliveira Aguiar , Fernando Guridi , Luciano Pasqualoto Canellas
The chemical nature of organic matter during the process of vermicomposting of cattle manure and filter cake from a sugar factory was characterized by thermochemolysis. The pyrolysates were mainly constituted of lignin moieties from propanoic acid units and short-chain (<C20) fatty acids (as methyl esters); alkanes, alkenes, terpenes and steroids were minor compounds. Nitrogen containing compounds were noticeable in filter cake vermicompost (VC) as were carbohydrate moieties. Despite thermochemolysis had shown low sensitivity for carbohydrates, the presence of a number of carbohydrate derivatives was indicative of extensive biological transformation of organic matter during vermicomposting. A high content of long-chain alcohols was found only in filter cake VC. At the end of VC maturation, the content of hydrophobic compounds (lignins plus fatty acids) in filter cake residues was higher than in cattle manure. This mature VC exhibited the highest natural density of culturable diazotrophic bacteria compared to cattle manure VC (approximately 104 times cells g−1 VC), and when the diazotrophic bacterium Herbaspirillum seropedicae was introduced to both types of VC, the population numbers were higher in filter cake VC at 10 months of storage after inoculation. We found an apparent relationship between molecular characteristics of organic matter and the harboring or preservation of diazotrophic bacteria introduced to VC, which is a step toward understanding the relationship between the molecular characteristics of organic matter and the microbial activities.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Dariellys Martinez-Balmori , Fábio Lopes Olivares , Riccardo Spaccini , Kamilla Pereira Aguiar , Marcelo Francisco Araújo , Natália Oliveira Aguiar , Fernando Guridi , Luciano Pasqualoto Canellas
The chemical nature of organic matter during the process of vermicomposting of cattle manure and filter cake from a sugar factory was characterized by thermochemolysis. The pyrolysates were mainly constituted of lignin moieties from propanoic acid units and short-chain (<C20) fatty acids (as methyl esters); alkanes, alkenes, terpenes and steroids were minor compounds. Nitrogen containing compounds were noticeable in filter cake vermicompost (VC) as were carbohydrate moieties. Despite thermochemolysis had shown low sensitivity for carbohydrates, the presence of a number of carbohydrate derivatives was indicative of extensive biological transformation of organic matter during vermicomposting. A high content of long-chain alcohols was found only in filter cake VC. At the end of VC maturation, the content of hydrophobic compounds (lignins plus fatty acids) in filter cake residues was higher than in cattle manure. This mature VC exhibited the highest natural density of culturable diazotrophic bacteria compared to cattle manure VC (approximately 104 times cells g−1 VC), and when the diazotrophic bacterium Herbaspirillum seropedicae was introduced to both types of VC, the population numbers were higher in filter cake VC at 10 months of storage after inoculation. We found an apparent relationship between molecular characteristics of organic matter and the harboring or preservation of diazotrophic bacteria introduced to VC, which is a step toward understanding the relationship between the molecular characteristics of organic matter and the microbial activities.
Thermal stability characterization of n-alkanes from determination of produced aromatics
30 May 2013,
16:58:57
Publication date: Available online 24 May
2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Xiaomei Qin , Hai Chi , Wenjun Fang , Yongsheng Guo , Li Xu
The thermal stability of n-nonane and n-undecane, as the model endothermic hydrocarbon fuels, was evaluated by determining the content change of produced aromatics during the thermal cracking process. The 1H nuclear magnetic resonance spectroscopy (1H NMR), along with the high-performance liquid chromatography (HPLC) and the gas chromatography/mass spectrometry (GC/MS) analyses, is mainly considered to follow the formation of aromatics in the liquid cracking residues of the n-alkanes. The results of the aromatic contents obtained from these three analytical methods show satisfactory agreements. The 1H NMR method also gives the olefin content and the branching index of the liquid residues. The changes of the aromatics, olefins and branching index against the temperature directly reflect the thermal stability of the n-alkanes. Based on the results from 1H NMR, HPLC and GC/MS, a scheme of the formation of aromatics from the thermal cracking of n-alkanes is discussed.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Xiaomei Qin , Hai Chi , Wenjun Fang , Yongsheng Guo , Li Xu
The thermal stability of n-nonane and n-undecane, as the model endothermic hydrocarbon fuels, was evaluated by determining the content change of produced aromatics during the thermal cracking process. The 1H nuclear magnetic resonance spectroscopy (1H NMR), along with the high-performance liquid chromatography (HPLC) and the gas chromatography/mass spectrometry (GC/MS) analyses, is mainly considered to follow the formation of aromatics in the liquid cracking residues of the n-alkanes. The results of the aromatic contents obtained from these three analytical methods show satisfactory agreements. The 1H NMR method also gives the olefin content and the branching index of the liquid residues. The changes of the aromatics, olefins and branching index against the temperature directly reflect the thermal stability of the n-alkanes. Based on the results from 1H NMR, HPLC and GC/MS, a scheme of the formation of aromatics from the thermal cracking of n-alkanes is discussed.
Pyrolysis reactions of coniferyl alcohol as a model of the primary structure formed during lignin pyrolysis
30 May 2013,
16:58:57
Publication date: Available online 21 May
2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Takeo Kotake , Haruo Kawamoto , Shiro Saka
It has been suggested that cinnamyl alcohol-type structures are formed during lignin primary pyrolysis using model dimers. In this article, the pyrolysis reactions of trans-coniferyl alcohol (CA) bearing a guaiacyl moiety were studied under N2 at temperatures in the range of 200–350°C, with particular emphasis on the evaporation/degradation processes. Some (less than 15%) of the CA evaporated without undergoing any degradation reactions, whereas large portions of the CA were converted to polymerization products together with monomers (up to ∼15% in total) with various side-chains. The cis-isomer of CA and 4-vinylguaiacol with a C2 side-chain were also identified. Methylation of the phenolic OH group of CA substantially reduced the formation of polymerization products, whereas the influence of the methylation on the side-chain-converted monomers was limited. Since the methylated CA was not effective for quinine methide formation, quinine methide and radical pathways were indicated as more important reaction mechanisms for the polymerization and side-chain-conversion processes, respectively. These results suggest that CA, if it was formed through pyrolytic cleavage of lignin β-ether linkages, tended to be degraded before it could be recovered through evaporation. Furthermore, the recovery of different monomers suggested the process was greatly dependent on the relative evaporation/degradation efficiencies.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Takeo Kotake , Haruo Kawamoto , Shiro Saka
It has been suggested that cinnamyl alcohol-type structures are formed during lignin primary pyrolysis using model dimers. In this article, the pyrolysis reactions of trans-coniferyl alcohol (CA) bearing a guaiacyl moiety were studied under N2 at temperatures in the range of 200–350°C, with particular emphasis on the evaporation/degradation processes. Some (less than 15%) of the CA evaporated without undergoing any degradation reactions, whereas large portions of the CA were converted to polymerization products together with monomers (up to ∼15% in total) with various side-chains. The cis-isomer of CA and 4-vinylguaiacol with a C2 side-chain were also identified. Methylation of the phenolic OH group of CA substantially reduced the formation of polymerization products, whereas the influence of the methylation on the side-chain-converted monomers was limited. Since the methylated CA was not effective for quinine methide formation, quinine methide and radical pathways were indicated as more important reaction mechanisms for the polymerization and side-chain-conversion processes, respectively. These results suggest that CA, if it was formed through pyrolytic cleavage of lignin β-ether linkages, tended to be degraded before it could be recovered through evaporation. Furthermore, the recovery of different monomers suggested the process was greatly dependent on the relative evaporation/degradation efficiencies.
Transformation of sulfur during pyrolysis of inertinite-rich coals and correlation with their characteristics
30 May 2013,
16:58:57
Publication date: Available online 21 May
2013
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Meijun Wang , Yongfeng Hu , Jiancheng Wang , Liping Chang , Hui Wang
Sulfur transformation of inertinite-rich coals, which were sampled from three Western China coal mines, Xinjiang Hami (HM), Ningxia Lingwu (LW) and Shendong (SD), during pyrolysis is studied through measuring the release of H2S and COS gases by gas chromatography with flame photometric detector and through analyzing the sulfur forms in raw coals and chars from pyrolysis by X-ray absorption spectroscopy (XAS). It is revealed that the transformation of sulfur during coal pyrolysis is closely linked with coal properties, such as the vitrinite/inertinite ratio, alkaline mineral contents (especially calcium compounds) and H/C atomic ratio for three inertinite-rich coals. Comparisons are performed with a coal sample taken from Pingsuo (PS) coal mine located in North China, of which the properties are significantly different. The maximal release temperature of sulfur-containing gases for the pyrolysis of inertinite-rich coal is higher than that of the PS coal. The release of the S-containing gases in inertinite-rich coals has a maximal temperature interval around 600°C and this is associated with the conversions of inorganic sulfur species, such as pyrite transforming to FeS observed by the XAS in chars of these coals. During the process of pyrolysis, the organic sulfur compounds in inertinite-rich coal can be oxidized to form sulfoxide-like species due to the decomposition of oxygen-containing function groups in the coal matrix, but the active sulfur in PS coal can react with fresh char to form relatively stable thiophene structures. The formation of COS during the pyrolysis of inertinite-rich coals is mainly due to secondary reactions between H2S with CO and/or CO2.
Source:Journal of Analytical and Applied Pyrolysis
Author(s): Meijun Wang , Yongfeng Hu , Jiancheng Wang , Liping Chang , Hui Wang
Sulfur transformation of inertinite-rich coals, which were sampled from three Western China coal mines, Xinjiang Hami (HM), Ningxia Lingwu (LW) and Shendong (SD), during pyrolysis is studied through measuring the release of H2S and COS gases by gas chromatography with flame photometric detector and through analyzing the sulfur forms in raw coals and chars from pyrolysis by X-ray absorption spectroscopy (XAS). It is revealed that the transformation of sulfur during coal pyrolysis is closely linked with coal properties, such as the vitrinite/inertinite ratio, alkaline mineral contents (especially calcium compounds) and H/C atomic ratio for three inertinite-rich coals. Comparisons are performed with a coal sample taken from Pingsuo (PS) coal mine located in North China, of which the properties are significantly different. The maximal release temperature of sulfur-containing gases for the pyrolysis of inertinite-rich coal is higher than that of the PS coal. The release of the S-containing gases in inertinite-rich coals has a maximal temperature interval around 600°C and this is associated with the conversions of inorganic sulfur species, such as pyrite transforming to FeS observed by the XAS in chars of these coals. During the process of pyrolysis, the organic sulfur compounds in inertinite-rich coal can be oxidized to form sulfoxide-like species due to the decomposition of oxygen-containing function groups in the coal matrix, but the active sulfur in PS coal can react with fresh char to form relatively stable thiophene structures. The formation of COS during the pyrolysis of inertinite-rich coals is mainly due to secondary reactions between H2S with CO and/or CO2.
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