The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Kenichi Kuroda - One of the best experts on this subject based on the ideXlab platform.
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tetramethylammonium hydroxide thermochemolysis of Guaiacyl syringyl and Guaiacyl dehydrogenation polymers
Organic Geochemistry, 2005Co-Authors: Kenichi Kuroda, Akiko NakagawaizumiAbstract:Abstract Tetramethylammonium hydroxide thermochemolysis of lignin was investigated using Guaiacyl–syringyl and Guaiacyl dehydrogenation polymers. The Guaiacyl–syringyl mixed polymer provided: (1) 1-(3,4-dimethoxyphenyl)-1,2,3-trimethoxypropane isomers ( 11 / 12 ) and 1-(3,4,5-trimethoxyphenyl)-1,2,3-trimethoxypropane isomers ( 15 / 16 ) as β-aryl ether subunit-derived products, (2) 2,3,3′,4′-tetramethoxy-5-(3-methoxyprop-1-enyl)stilbene ( 18 ) and 2,3,3′,4′,5′-pentamethoxy-5-(3-methoxyprop-1-enyl)stilbene ( 22 ) as β-5 subunit-derived products, (3) pinoresinol dimethyl ether ( 21 ), medioresinol dimethyl ether ( 23 ) and syringaresinol dimethyl ether ( 24 ) as β–β subunit-derived products, respectively, and (4) coniferyl alcohol dimethyl ether ( 8 ) and sinapyl alcohol dimethyl ether ( 14 ) from 4- O -linked coniferyl and sinapyl alcohols. The ratio of products stemming from β-aryl ether, β-5, β–β subunits was 23:13:64. The Guaiacyl polymer provided 11 / 12 , 18 , 21 , and 8 , suggesting the same reactions occurring also in the Guaiacyl polymer, although the ratio (31:32:37) of the products from β-aryl ether, β-5, β–β subunits differed.
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Tetramethylammonium hydroxide thermochemolysis of Guaiacyl–syringyl and Guaiacyl dehydrogenation polymers
Organic Geochemistry, 2005Co-Authors: Kenichi Kuroda, Akiko Nakagawa-izumiAbstract:Abstract Tetramethylammonium hydroxide thermochemolysis of lignin was investigated using Guaiacyl–syringyl and Guaiacyl dehydrogenation polymers. The Guaiacyl–syringyl mixed polymer provided: (1) 1-(3,4-dimethoxyphenyl)-1,2,3-trimethoxypropane isomers ( 11 / 12 ) and 1-(3,4,5-trimethoxyphenyl)-1,2,3-trimethoxypropane isomers ( 15 / 16 ) as β-aryl ether subunit-derived products, (2) 2,3,3′,4′-tetramethoxy-5-(3-methoxyprop-1-enyl)stilbene ( 18 ) and 2,3,3′,4′,5′-pentamethoxy-5-(3-methoxyprop-1-enyl)stilbene ( 22 ) as β-5 subunit-derived products, (3) pinoresinol dimethyl ether ( 21 ), medioresinol dimethyl ether ( 23 ) and syringaresinol dimethyl ether ( 24 ) as β–β subunit-derived products, respectively, and (4) coniferyl alcohol dimethyl ether ( 8 ) and sinapyl alcohol dimethyl ether ( 14 ) from 4- O -linked coniferyl and sinapyl alcohols. The ratio of products stemming from β-aryl ether, β-5, β–β subunits was 23:13:64. The Guaiacyl polymer provided 11 / 12 , 18 , 21 , and 8 , suggesting the same reactions occurring also in the Guaiacyl polymer, although the ratio (31:32:37) of the products from β-aryl ether, β-5, β–β subunits differed.
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characterization of kenaf hibiscus cannabinus lignin by pyrolysis gas chromatography mass spectrometry in the presence of tetramethylammonium hydroxide
Journal of Analytical and Applied Pyrolysis, 2002Co-Authors: Kenichi Kuroda, Akiko Izumi, Bibhuti B Mazumder, Yoshito Ohtani, Kazuhiko SameshimaAbstract:Abstract Pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) in the presence of tetramethylammonium hydroxide (TMAH) was applied to kenaf ( Hibiscus cannabinus ) fibers in order to clarify the chemical composition of in situ lignin. The core and bast samples obtained from the middle position of variety Chinpi-3 were pyrolyzed at 500 °C for 4 s with TMAH. The core pyrogram revealed peaks retaining the structural attributes of Guaiacyl and syringyl β-aryl ether subunits, and the bast pyrogram was dominated by peaks retaining the structural attributes of syringyl β-aryl ether subunit. Both pyrograms lacked products derived from p -hydroxyphenyl β-aryl ether subunit. Product distribution showed that: (1) the core in situ lignin comprises 1.5 parts of syringyl-, 1 part of Guaiacyl β-aryl ether subunits, and (2) in the bast in situ lignin the syringyl β-aryl ether subunits are present in greater quantities than the Guaiacyl β-aryl ether subunits. The syringyl to Guaiacyl lignin unit (S/G) ratios determined by conventional pyrolysis and alkaline CuO oxidation also supported the TMAH/Py results. 4-Methoxy and 3,4-dimethoxycinnamic acid methyl esters were present in the core pyrolyzate and absent in the bast pyrolyzate. 4-Methoxycinnamic acid methyl ester was present in greater quantities than 3,4-dimethoxycinnamic acid methyl esters.
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Structural Analysis of Lignin by Pyrolysis-Gas Chromatography (IV). Comparison with nitrobenzene oxidation for determination of decayed hardwoods and kraft-cooked hardwoods.
JAPAN TAPPI JOURNAL, 1997Co-Authors: Junji Tanaka, Hiroshi Ohi, Akiko Izumi, Satoshi Suzuki, Kenichi KurodaAbstract:In order to learn the effectiveness of pyrolysis-gas chromatography (Py-GC) on the characterization of chemically or biologically modified lignin, decayed hardwoods and kraft-cooked hardwoods were subjected to Py-GC as a tool for the convenience lignin analysis tool. The selected Guaiacyl pyrolysis products (guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-vinylguaiacol, eugenol, vanillin, rans-isoeugenol and trans-coniferyl alcohol) and their syringyl analogue (syringol, 4-methylsyringol, 4-ethylsyringol 4-vinylsyringol, 4-allylsyringol, syringaldehyde, trans-4-propenylsyringol and trans-sinapyl alcohol), as the main lignin-derived compounds, were determined using each absolute calibration factors to flame ionization detector. The results were compared with those by the alkaline nitrobenzene oxidation.European beech (Fagus silvatica) woods were decayed by a brown-rot fungus (Tyromyces palustris) or a white-rot fungus (Coriolus versicolor), and beech (Fagus crenata) woods were cooked with kraft liquor. Residual lignin contents of wood samples were measured by the Klason lignin methods. Lignin was analyzed by Py-GC and the alkaline nitrobenzene oxidation method quantitatively without isolation from woods. The yields of the pyrolysis products were obtained on the basis of the residual lignin in decayed woods, and changes in the yields and their relative compositions during the decay for 180 days were investigated. The molar ratios of syringyl type pyrolysis products to Guaiacyl ones (S/G ratios) measured by Py-GC were compared with the molar ratios of syringaldehyde to vanillin (S/V ratios) obtained by the nitrobenzene oxidation.(1) In pyrolysis of 180 days-decayed woods by Tyromyces palustris, the yields of trans-coniferyl alcohol and trans-sinapyl alcohol sharply decreased.(2) In those by Coriolus versicolor, the yields of trans-coniferyl alcohol and trans-sinapyl alcohol decreased, and relative compositions of guaiacoland syringol clearly in-creased.(3) For decayed woods by Coriolus versicolor, the yields of syringyl type pyrolysis products decreased more rapidly than those of Guaiacyl ones with increase of decaying days. The S/G ratios measured by Py-GC were in good agreement with the S/V ratios obtained by the nitrobenzene oxidation.(4) In pyrolysis of kraft-cooked woods, the yields of trans-coniferyl alcohol and trans-sinapyl alcohol decreased, and relative compositions of guaiacol and syringol increased. (5) The S/G ratios of residual lignin in kraft-cooked woods decreased with increase of cooking time, and those were in good agreement with the S/V ratios.
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structural analysis of alkaline cooked lignin by pyrolysis gas chromatography evaluation of uniformity in delignification of beech wood chips
Japan Tappi Journal, 1994Co-Authors: Satoshi Suzuki, Hiroshi Ohi, Akiko Izumi, Kenichi Kuroda, Akira YamaguchiAbstract:Uniformity in delignification of beech wood chips was studied by using pyrolysis-gas chromatography (Py-GC).As pyrolysis products of kraft, soda-THAQ (1, 4, 4 a, 9 a-tetrahydroanthraquinone) and sulfite-THAQ pulps, ten compounds (guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, trans-isoeugenol, syringol, 4-methylsyringol, 4-vinylsyringol, syringaldehyde and trans-4-propenylsyringol) were identified. A high correlation between the ratios of syringyl derivatives to Guaiacyl derivatives (S/G) from pyrograms and Klason lignin contents of kraft and soda-THAQ pulps was found. Measuring the S/G ratios enabled to estimate the Klason lignin contents of beech pulps. Ununiformity in delignification of beech wood chips during kraft cooking could be evaluated by measuring the S/G ratios of slices of the chip. As the delignification during alkaline cooking proceeded, relative yields of guaiacol and syringol to those of the other pyrolysis products from residual lignin in pulps increased.To clarify the lignin structure which gives guaiacol and syringol in Py-GC for pulps, lignin model compounds (syringylglycol-β-Guaiacyl ether, syringaresinol) were analyzed under the same pyrolysis conditions (500°C, 4 sec) as those for pulps. Although guaiacol was formed from syringylglycol-β-Guaiacyl ether, syringol was not formed under the present conditions. On the other hand, syringaresinol gave syringol. Py-GC is expected to be a promising method for characterization of residual lignin in alkali pulps.
Luiz C A Barbosa - One of the best experts on this subject based on the ideXlab platform.
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in situ determination of the syringyl Guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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In situ determination of the syringyl/Guaiacyl ratio of residual lignin in pre-bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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in situ determination of the syringyl Guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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Determination of Eucalyptus spp lignin S/G ratio: a comparison between methods
Bioresource Technology, 2010Co-Authors: Cleiton Antônio Nunes, Claudio F Lima, Luiz C A Barbosa, Jorge Luiz Colodette, A.f.g. Gouveia, Flaviano O. SilvérioAbstract:The syringyl/Guaiacyl ratio was determined for six different Eucalyptus spp. wood clones cultivated in four regions in Brazil. The determinants were made by pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and the results were compared with those obtained by alkaline nitrobenzene oxidation method. The S/G ratios were obtained considering all the identified lignin derivatives in the pyrograms and also using two groups of markers. The first group of markers consisted of guaiacol, 4-methylguaiacol, 4-vinylguaiacol, trans-isoeugenol, syringol, 4-methylsyringol, 4-vinylsyringol and trans-4-propenylsyringol compounds as markers. The second group included guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, 4-ethylsyringol, 4-vinylsyringol, syringaldehyde, syringylacetone and trans-4-propenylsyringol. It was observed from the statistical analysis that the values of S/G obtained by Py–GC–MS using the two groups of markers did not differ significantly from those obtained by nitrobenzene oxidation method.
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COMPARISON BETWEEN ANALYTICAL PYROLYSIS AND NITROBENZENE OXIDATION FOR DETERMINATION OF SYRINGYL/Guaiacyl RATIO IN Eucalyptus spp. LIGNIN
Bioresources, 2008Co-Authors: Claudio F Lima, Flaviano Oliveira Silvério, Luiz C A Barbosa, Cristiana R. Marcelo, Jorge Luiz ColodetteAbstract:Pyrolysis-gas chromatography/mass spectrometry (Py-GC-MS) was applied to measure the lignin syringyl/Guaiacyl (S/G) ratio in E. dunni, E. grandis, E. nitens, E. urograndis, and E. urophylla woods. A total of 41 compounds were identified, of which 11 were derived from carbohydrates and 30 from lignins. The S/G ratio was calculated on the basis of the areas of peaks recorded in the pyrograms and compared with the results obtained by alkaline nitrobenzene oxidation. The values of S/G found by pyrolysis were similar for all the species using the compounds guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, 4-ethylsyringol, 4vinylsyringol, homosyringaldehyde, acetosyringone, and syringylacetone, as lignin markers. The selected markers were efficient for the determination of S/G ratio in eucalyptus wood by Py-GC-MS. The Py-GC-MS technique produced results that are comparable to the nitrobenzene oxidation method, with the advantage of requiring small wood samples and a short analysis time.
Claudio F Lima - One of the best experts on this subject based on the ideXlab platform.
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in situ determination of the syringyl Guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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In situ determination of the syringyl/Guaiacyl ratio of residual lignin in pre-bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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in situ determination of the syringyl Guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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Determination of Eucalyptus spp lignin S/G ratio: a comparison between methods
Bioresource Technology, 2010Co-Authors: Cleiton Antônio Nunes, Claudio F Lima, Luiz C A Barbosa, Jorge Luiz Colodette, A.f.g. Gouveia, Flaviano O. SilvérioAbstract:The syringyl/Guaiacyl ratio was determined for six different Eucalyptus spp. wood clones cultivated in four regions in Brazil. The determinants were made by pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) and the results were compared with those obtained by alkaline nitrobenzene oxidation method. The S/G ratios were obtained considering all the identified lignin derivatives in the pyrograms and also using two groups of markers. The first group of markers consisted of guaiacol, 4-methylguaiacol, 4-vinylguaiacol, trans-isoeugenol, syringol, 4-methylsyringol, 4-vinylsyringol and trans-4-propenylsyringol compounds as markers. The second group included guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, 4-ethylsyringol, 4-vinylsyringol, syringaldehyde, syringylacetone and trans-4-propenylsyringol. It was observed from the statistical analysis that the values of S/G obtained by Py–GC–MS using the two groups of markers did not differ significantly from those obtained by nitrobenzene oxidation method.
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COMPARISON BETWEEN ANALYTICAL PYROLYSIS AND NITROBENZENE OXIDATION FOR DETERMINATION OF SYRINGYL/Guaiacyl RATIO IN Eucalyptus spp. LIGNIN
Bioresources, 2008Co-Authors: Claudio F Lima, Flaviano Oliveira Silvério, Luiz C A Barbosa, Cristiana R. Marcelo, Jorge Luiz ColodetteAbstract:Pyrolysis-gas chromatography/mass spectrometry (Py-GC-MS) was applied to measure the lignin syringyl/Guaiacyl (S/G) ratio in E. dunni, E. grandis, E. nitens, E. urograndis, and E. urophylla woods. A total of 41 compounds were identified, of which 11 were derived from carbohydrates and 30 from lignins. The S/G ratio was calculated on the basis of the areas of peaks recorded in the pyrograms and compared with the results obtained by alkaline nitrobenzene oxidation. The values of S/G found by pyrolysis were similar for all the species using the compounds guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, 4-ethylsyringol, 4vinylsyringol, homosyringaldehyde, acetosyringone, and syringylacetone, as lignin markers. The selected markers were efficient for the determination of S/G ratio in eucalyptus wood by Py-GC-MS. The Py-GC-MS technique produced results that are comparable to the nitrobenzene oxidation method, with the advantage of requiring small wood samples and a short analysis time.
Flaviano Oliveira Silvério - One of the best experts on this subject based on the ideXlab platform.
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in situ determination of the syringyl Guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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In situ determination of the syringyl/Guaiacyl ratio of residual lignin in pre-bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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in situ determination of the syringyl Guaiacyl ratio of residual lignin in pre bleached eucalypt kraft pulps by analytical pyrolysis
Journal of Analytical and Applied Pyrolysis, 2015Co-Authors: Claudio F Lima, Marcela N N Silva, Luiz C A Barbosa, Jorge Luiz Colodette, Flaviano Oliveira SilvérioAbstract:Abstract Pyrolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS) was used for evaluating the syringyl/Guaiacyl (S/G) ratios of residual lignins in oxygen pre-bleached kraft pulps from 24 Eucalyptus wood clones. The optimization of the method showed that the best conditions were achieved when pyrolysis is carried out at 550 °C, using a 60 m length SPB-1701 capillary column and the mass spectrometer operating in SIM mode. Pulp pyrograms were analyzed and the compounds produced by pyrolysis of residual lignins identified by mass spectrometry. A total of 18 compounds were identified, being nine derived from Guaiacyl units and nine derived from syringyl lignin. The S/G ratios were calculated using the relative area of S-lignin (syringol, 4-methylsyringol, 4-vinylsyringol and trans -4-(prop-2-enyl) syringol) and G-lignin (guaiacol, 4-methylguaiacol, 4-vinylguaiacol and trans -isoeugenol) as lignin markers. These studies showed that Py-GC/MS-SIM is an efficient tool to characterizing the chemical composition of residual lignin in oxygen pre-bleached Eucalyptus pulps.
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COMPARISON BETWEEN ANALYTICAL PYROLYSIS AND NITROBENZENE OXIDATION FOR DETERMINATION OF SYRINGYL/Guaiacyl RATIO IN Eucalyptus spp. LIGNIN
Bioresources, 2008Co-Authors: Claudio F Lima, Flaviano Oliveira Silvério, Luiz C A Barbosa, Cristiana R. Marcelo, Jorge Luiz ColodetteAbstract:Pyrolysis-gas chromatography/mass spectrometry (Py-GC-MS) was applied to measure the lignin syringyl/Guaiacyl (S/G) ratio in E. dunni, E. grandis, E. nitens, E. urograndis, and E. urophylla woods. A total of 41 compounds were identified, of which 11 were derived from carbohydrates and 30 from lignins. The S/G ratio was calculated on the basis of the areas of peaks recorded in the pyrograms and compared with the results obtained by alkaline nitrobenzene oxidation. The values of S/G found by pyrolysis were similar for all the species using the compounds guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, 4-ethylsyringol, 4vinylsyringol, homosyringaldehyde, acetosyringone, and syringylacetone, as lignin markers. The selected markers were efficient for the determination of S/G ratio in eucalyptus wood by Py-GC-MS. The Py-GC-MS technique produced results that are comparable to the nitrobenzene oxidation method, with the advantage of requiring small wood samples and a short analysis time.
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comparison between analytical pyrolysis and nitrobenzene oxidation for determination of syringyl Guaiacyl ratio in eucalyptus spp lignin
Bioresources, 2008Co-Authors: Claudio F Lima, Flaviano Oliveira Silvério, Luiz C A Barbosa, Cristiana R. Marcelo, Jorge Luiz ColodetteAbstract:Pyrolysis-gas chromatography/mass spectrometry (Py-GC-MS) was applied to measure the lignin syringyl/Guaiacyl (S/G) ratio in E. dunni, E. grandis, E. nitens, E. urograndis, and E. urophylla woods. A total of 41 compounds were identified, of which 11 were derived from carbohydrates and 30 from lignins. The S/G ratio was calculated on the basis of the areas of peaks recorded in the pyrograms and compared with the results obtained by alkaline nitrobenzene oxidation. The values of S/G found by pyrolysis were similar for all the species using the compounds guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, 4-ethylsyringol, 4vinylsyringol, homosyringaldehyde, acetosyringone, and syringylacetone, as lignin markers. The selected markers were efficient for the determination of S/G ratio in eucalyptus wood by Py-GC-MS. The Py-GC-MS technique produced results that are comparable to the nitrobenzene oxidation method, with the advantage of requiring small wood samples and a short analysis time.
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study of the hydrodeoxygenation of carbonyl carboxylic and Guaiacyl groups over sulfided como gamma al2o3 and nimo gamma al2o3 catalysts 1 catalytic reaction schemes
Applied Catalysis A-general, 1994Co-Authors: Etienne Laurent, Bernard DelmonAbstract:The elimination of specific oxygenated groups of biomass-derived pyrolysis oils (bio-oils) is necessary for improving their stability. These are mainly unsaturated groups like alkene, carbonyl and carboxylic functions, as well as Guaiacyl groups. For practical applications, it is desirable that the reactions are performed selectively in order to avoid excessive hydrogen consumption. The reactions must be done at relatively low temperature in order to limit competitive thermal condensation reactions. In this study, model oxygenated compounds were used, namely 4-methylacetophenone, diethyldecanedioate and guaiacol. They were tested simultaneously in one reaction test in the presence of sulfided cobalt-molybdenum and nickel-molybdenum supported on gamma-alumina catalysts in a batch system. Their reactivity and conversion scheme were determined. The ketonic group is easily and selectively hydrogenated into a methylene group at temperatures higher than 200 degrees C. Carboxylic groups are also hydrogenated to methyl groups, but a parallel decarboxylation occurs at comparable rates. A temperature around 300 degrees C is required for the conversion of carboxylic groups as well as for the conversion of the Guaiacyl groups. The main reaction scheme of guaiacol is its transformation in hydroxyphenol which is subsequently converted to phenol. But in batch reactor conditions, guaiacol gives a high proportion of heavy products. CoMo and NiMo catalysts have comparable activities and selectivities. However, the NiMo catalyst has a higher decarboxylating activity than CoMo and also leads to a higher proportion of heavy products during the conversion of guaiacol.
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Study of the Hydrodeoxygenation of Carbonyl, Carboxylic and Guaiacyl Groups Over Sulfided Como/gamma-al2o3 and Nimo/gamma-al2o3 Catalysts .1. Catalytic Reaction Schemes
Applied Catalysis A: General, 1994Co-Authors: Etienne Laurent, Bernard DelmonAbstract:The elimination of specific oxygenated groups of biomass-derived pyrolysis oils (bio-oils) is necessary for improving their stability. These are mainly unsaturated groups like alkene, carbonyl and carboxylic functions, as well as Guaiacyl groups. For practical applications, it is desirable that the reactions are performed selectively in order to avoid excessive hydrogen consumption. The reactions must be done at relatively low temperature in order to limit competitive thermal condensation reactions. In this study, model oxygenated compounds were used, namely 4-methylacetophenone, diethyldecanedioate and guaiacol. They were tested simultaneously in one reaction test in the presence of sulfided cobalt-molybdenum and nickel-molybdenum supported on gamma-alumina catalysts in a batch system. Their reactivity and conversion scheme were determined. The ketonic group is easily and selectively hydrogenated into a methylene group at temperatures higher than 200 degrees C. Carboxylic groups are also hydrogenated to methyl groups, but a parallel decarboxylation occurs at comparable rates. A temperature around 300 degrees C is required for the conversion of carboxylic groups as well as for the conversion of the Guaiacyl groups. The main reaction scheme of guaiacol is its transformation in hydroxyphenol which is subsequently converted to phenol. But in batch reactor conditions, guaiacol gives a high proportion of heavy products. CoMo and NiMo catalysts have comparable activities and selectivities. However, the NiMo catalyst has a higher decarboxylating activity than CoMo and also leads to a higher proportion of heavy products during the conversion of guaiacol.
