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Hero J. Heeres - One of the best experts on this subject based on the ideXlab platform.
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valorization of Humin type byproducts from pyrolytic sugar conversions to biobased chemicals
Journal of Analytical and Applied Pyrolysis, 2020Co-Authors: Shilpa Agarwal, H. Heeres, Peter J. Deuss, Ria M Abdillasantes, Hero J. HeeresAbstract:The pyrolytic sugar fraction, obtained by an aqueous extraction of pyrolysis oil, is an attractive source for sugar-derived platform chemicals. However, solids (Humin) formation occurs to a significant extent during hydrolysis and subsequent acid-catalyzed conversion processes. In this study, we report investigations on possible conversion routes (pyrolysis, liquefaction) of such Humin byproducts to biobased chemicals. Experiments were carried out with a model Humin made from a representative technical pyrolytic sugar and the product was characterized by elemental analysis, GPC, TGA, HPLC, GC-MS, FT-IR and NMR. The obtained Humin sample is soluble in organic solvents (dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and isopropanol (IPA)), in contrast to typical more condensed Humins from glucose and fructose, allowing characterization using NMR and GPC. All analyses reveal that the Humins are oligomeric in nature (M-w of about 900 g/mol) and consist of sugar and furanic fragments linked with among others (substituted) aliphatic, ester units and, in addition, phenolic fragments with methoxy groups. The Humins were used as a feed for catalytic pyrolysis and catalytic liquefaction experiments. Catalytic pyrolysis experiments (mg scale, programmable temperature vaporizer (PTV)-GC-MS, 550 degrees C) with HZSM-5 50 as the catalyst gave benzene-toluene-xylene-naphthalene-ethylbenzene mixtures (BTXNE) in 5.1 wt% yield based on Humin intake. Liquefaction experiments (batch reactor, 350 degrees C, 4 h, isopropanol as both the solvent and hydrogen donor and Pt/CeO2 (4.43 wt% Pt) catalyst) resulted in 80 wt% conversion of the Humin feed to a product oil with considerable amounts of phenolics and aromatics (ca. 24.7 % based on GC detectables in the Humin oil). These findings imply that the techno-economic viability of pyrolysis oil biorefineries can be improved by converting Humin type byproducts to high value, low molecular weight biobased chemicals.
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Valorization of Humin type byproducts from pyrolytic sugar conversions to biobased chemicals
Journal of Analytical and Applied Pyrolysis, 2020Co-Authors: Ria M. Abdilla-santes, Shilpa Agarwal, H. Heeres, Peter J. Deuss, Hero J. HeeresAbstract:Abstract The pyrolytic sugar fraction, obtained by an aqueous extraction of pyrolysis oil, is an attractive source for sugar-derived platform chemicals. However, solids (Humin) formation occurs to a significant extent during hydrolysis and subsequent acid-catalyzed conversion processes. In this study, we report investigations on possible conversion routes (pyrolysis, liquefaction) of such Humin byproducts to biobased chemicals. Experiments were carried out with a model Humin made from a representative technical pyrolytic sugar and the product was characterized by elemental analysis, GPC, TGA, HPLC, GC-MS, FT-IR and NMR. The obtained Humin sample is soluble in organic solvents (dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and isopropanol (IPA)), in contrast to typical more condensed Humins from glucose and fructose, allowing characterization using NMR and GPC. All analyses reveal that the Humins are oligomeric in nature (Mw of about 900 g/mol) and consist of sugar and furanic fragments linked with among others (substituted) aliphatic, ester units and, in addition, phenolic fragments with methoxy groups. The Humins were used as a feed for catalytic pyrolysis and catalytic liquefaction experiments. Catalytic pyrolysis experiments (mg scale, programmable temperature vaporizer (PTV)-GC–MS, 550 °C) with HZSM-5−50 as the catalyst gave benzene-toluene-xylene-naphthalene-ethylbenzene mixtures (BTXNE) in 5.1 wt% yield based on Humin intake. Liquefaction experiments (batch reactor, 350 °C, 4 h, isopropanol as both the solvent and hydrogen donor and Pt/CeO2 (4.43 wt% Pt) catalyst) resulted in 80 wt% conversion of the Humin feed to a product oil with considerable amounts of phenolics and aromatics (ca. 24.7 % based on GC detectables in the Humin oil). These findings imply that the techno-economic viability of pyrolysis oil biorefineries can be improved by converting Humin type byproducts to high value, low molecular weight biobased chemicals.
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Catalytic pyrolysis of recalcitrant, insoluble Humin byproducts from C6 sugar biorefineries
Journal of Analytical and Applied Pyrolysis, 2017Co-Authors: Shilpa Agarwal, Daan S. Van Es, Hero J. HeeresAbstract:Abstract Humins are solid by-products formed during the acid-catalysed conversions of C-6 sugars to platform chemicals like hydroxymethylfurfural and levulinic acid. We here report an experimental study on the liquefaction/depolymerisation of Humins using catalytic pyrolysis. Synthetic Humins (SH) and crude industrial Humins (CIH, including purified industrial (PIH) samples) from the acid-catalysed conversion of C-6 sugars to HMF/LA were tested. Thermal degradation patterns of both Humin types vary significantly. Major thermal decomposition of the industrial Humins was observed between 50 and 650 °C (weight loss approx. 66 wt%), whereas, major weight loss was observed between 200 and 800 °C for the synthetic Humins (47 wt%). A series of catalytic pyrolysis tests with synthetic Humins and different zeolites were performed using a PTV-GC/MS (Humin to catalyst wt ratio of 0.2, 550 °C). Best results were obtained using HZSM-5 (SiO 2 /Al 2 O 3 = 50). For quantitative analysis, a gram scale pyrolysis unit was used, giving a product oil (9–11 wt% on Humin intake) with approximately 1.5 and 10 wt% aromatics from synthetic and crude industrial Humins, respectively. GPC data on the product oils clearly shows the breakdown of the Humin structure into low molecular weight species. The HHV value of the liquid products (up to 41 MJ kg −1 ) is considerably higher than that of the crude industrial Humin feed (21–24 MJ kg −1 ).
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Exploratory catalyst screening studies on the liquefaction of model Humins from C6 sugars
RSC Advances, 2017Co-Authors: Yuliang Wang, Shilpa Agarwal, Zhenchen Tang, Hero J. HeeresAbstract:A catalyst screening study is reported on the liquefaction of Humins, the solid byproducts from C6 sugar biorefineries for levulinic acid and 5-hydroxymethylfurfural production. Experiments were carried out in a batch reactor using an artificial model of Humin derived from glucose with isopropanol (IPA) as the solvent at 400 °C for a 3 h batchtime. Initial studies using noble metal catalysts (Rh, Pt, Pd, Ru) on a carbon support revealed that Pt was the best catalyst in terms of Humin conversion (77%) and amounts of alkylphenolics and aromatics in the product oil (GCxGC-FID). Subsequent support screening studies (TiO2, ZrO2, CeO2) were performed using Pt as the active metal and the results were compared with Pt/C. Detailed liquid product analysis (GPC, GC-MS, GCxGC) including blank reactions in the absence of Humins revealed that the Humins are mainly converted to monomeric alkylphenolics and aromatics oligomers (GPC) and (GC). IPA was shown not to be inert and is converted to acetone and hydrogen, and the latter is the hydrogen source for the various metal catalysed hydrogenolysis and hydro(deoxy)genation reactions. In addition, acetone is converted to aldolcondensation products (like methylisobutylketone, MIBK) and hydrogenation products derived thereof. The best results were obtained with Pt/C when considering Humin conversion. However, Pt/CeO2 was shown to be more attractive when considering the amounts of alkylphenolics in the product oils (20.4 wt% based on Humin intake).
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Catalytic Liquefaction of Humin Substances from Sugar Biorefineries with Pt/C in 2-Propanol
ACS Sustainable Chemistry & Engineering, 2016Co-Authors: Yuehu Wang, Shilpa Agarwal, Hero J. HeeresAbstract:The catalytic liquefaction of Humins, the solid byproduct from the conversion of C6 sugars (glucose, fructose) to 5-hydroxymethylfurfural (HMF) and levulinic acid (LA), using a supported Pt/C catalyst in isopropanol (IPA) as the solvent was investigated. At bench mark conditions (400 °C, 7 h, 27 wt % catalyst on Humin intake, 21 wt % Humin on total intake (IPA and Humins)), about 60% of the Humins was converted to a Humin oil. This oil was analyzed in detail (GC-MS, GCxGC-FID, GPC) and shown to consist of a mixture of monomers and oligomers belonging to various product classes (alkylphenolics, aromatics, aliphatic hydrocarbons). IPA was shown to be reactive under the prevailing reaction conditions and acts as a hydrogen donor for the Humin depolymerization/hydrodeoxygenation reactions. A systematic study according to a central composite design (19 experiments) was performed to optimize the reaction conditions (T, Humin intake, catalyst intake, and batch time) to obtain the highest Humin conversion and alk...
André Amblès - One of the best experts on this subject based on the ideXlab platform.
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Comparison between humic substances from soil and peats using TMAH and TEAAc thermochemolysis
Organic Geochemistry, 2006Co-Authors: Coralie Deport, Laurent Lemée, André AmblèsAbstract:Humic substances, mainly humic acids and Humin, from a calcic peat (MP), an acid peat (CAL) and a calcic soil (MAT) were investigated. Important differences in the relative abundance of the various organic fractions were observed between the four samples. As shown by the HU/FA + HA ratio, the calcic peat contains the most humified organic matter, the degree of humification decreasing with pH. The organic matter in MAT was much less humified due to cultivation. Bulk information from spectroscopy showed similarities between the various humic acids and the various Humins in the four samples: the presence of ester and ether groups, a marked aliphatic character and the presence of aromatic moieties. The major products of TMAH thermochemolysis were aromatic compounds derived from lignin, tannins and bark, and fatty acids of bacterial or plant origin, as the methyl esters (FAMEs). The compounds were mainly incorporated via ester or ether bonds and n-alkene/n-alkane doublets in the pyrolysate of CAL arose from resistant aliphatic biopolymers. The study of FAME distributions indicated that the bacterial contribution was higher in humic acids than in Humin for all the samples. This contribution was much higher in MAT, as shown by prominent iso- and anteiso-C15 carboxylic acids and the presence of α-hydroxyacids. Bifunctional linear dicarboxylic acids were also incorporated into the humic structure (MAT and CAL), contributing to alkyl bridges. The C21–C33 n-alkanes with a Gaussian distribution found in MAT and MP samples were initially retained in the humic structure via non-covalent bonds. TEAAc thermochemolysis showed that a fraction of the aliphatic acids (with a different distribution) was not covalently bound, having been sterically trapped in the humic structure. Trapped fatty acid methyl esters were minor.
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lipid constituents of peat humic acids and Humin distinction from directly extractable bitumen components using tmah and teaac thermochemolysis
Organic Geochemistry, 2005Co-Authors: Cédric Guignard, Laurent Lemée, André AmblèsAbstract:Humic acids and Humin from an acidic peat were investigated using solid state 13C NMR and pyrolysis with tetramethylammonium hydroxide (TMAH) and tetraethylammonium acetate (TEAAc). The degradation products were compared with the solvent extractable lipids. The latter appeared to originate mostly from plant material, whereas the products derived from the humic fractions showed a more complex structure, partly inherited from natural insoluble material. The major products of TMAH thermochemolysis were aromatic compounds derived from lignin moieties, hydrocarbons and fatty acid methyl esters (FAMEs) partly incorporated via ester or ether bonds. Aliphatic hydrocarbons were present as n-alkene/n-alkane doublets with a Gaussian distribution in the C17–C35 range. These unsaturated and saturated hydrocarbons arose from resistant biopolymers. Bifunctional aliphatic compounds were also incorporated into the humic structure, contributing to alkyl bridges. Thermochemolysis of Humin produced more aliphatic structures than did humic acids. The application of TEAAc thermochemolysis allowed identification of a wide range of products initially retained in the humic macromolecules via non-covalent bonds, thereby indicating that weak bonds such as hydrogen bonds play a key role in the structure of humic substances. The association of thermochemolysis using TMAH and TEAAc thus allows covalently-bound fatty acids, trapped fatty acids and trapped fatty acid methyl esters present in the structure of humic acids or Humin to be distinguished.
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Lipid constituents of peat humic acids and Humin. Distinction from directly extractable bitumens using TMAH and TEAAc thermochemolysis
Organic Geochemistry, 2005Co-Authors: Cédric Guignard, Laurent Lemée, André AmblèsAbstract:Humic acids and Humin from an acidic peat were investigated using solid state 13C NMR and pyrolysis with tetramethylammonium hydroxide (TMAH) and tetraethylammonium acetate (TEAAc). The degradation products were compared with the solvent extractable lipids. The latter appeared to originate mostly from plant material, whereas the products derived from the humic fractions showed a more complex structure, partly inherited from natural insoluble material. The major products of TMAH thermochemolysis were aromatic compounds derived from lignin moieties, hydrocarbons and fatty acid methyl esters (FAMEs) partly incorporated via ester or ether bonds. Aliphatic hydrocarbons were present as n-alkene/n-alkane doublets with a Gaussian distribution in the C17–C35 range. These unsaturated and saturated hydrocarbons arose from resistant biopolymers. Bifunctional aliphatic compounds were also incorporated into the humic structure, contributing to alkyl bridges. Thermochemolysis of Humin produced more aliphatic structures than did humic acids. The application of TEAAc thermochemolysis allowed identification of a wide range of products initially retained in the humic macromolecules via non-covalent bonds, thereby indicating that weak bonds such as hydrogen bonds play a key role in the structure of humic substances. The association of thermochemolysis using TMAH and TEAAc thus allows covalently-bound fatty acids, trapped fatty acids and trapped fatty acid methyl esters present in the structure of humic acids or Humin to be distinguished.
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free and esterified aliphatic carboxylic acids in Humin and humic acids from a peat sample as revealed by pyrolysis with tetramethylammonium hydroxide or tetraethylammonium acetate
Organic Geochemistry, 2002Co-Authors: Laurent Grasset, Cédric Guignard, André AmblèsAbstract:Abstract The combination of TMAH thermochemolysis and TEAAc treatment makes it possible to discriminate between the different forms of mono- and dicarboxylic acids present in the structure of Humin and humic acids, that is, “free” uncombined acids, methyl or ethyl esters present as tightly trapped molecules within the matrix, or acids chemically linked to the matrix by ester groups. The results confirm that ester groups are involved in the structure of Humin and humic acids. The cross-linking of moieties originating from microbial metabolism or inherited from higher plants is partly ensured by these chemical groups. On the other hand, significant amounts of fatty monocarboxylic acids and linear dicarboxylic acids are present as free acids in the Humin of the studied sample. Humin contains also fatty acid methyl esters. Free, uncombined α,ω-dicarboxylic acids were only found in Humin.
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Structural characterization of humic substances from an acidic peat using thermochemolysis techniques
Agronomie, 2000Co-Authors: Cédric Guignard, Laurent Lemée, André AmblèsAbstract:The general aim of the present work is a study of the insoluble organic matter (humic acids, Humin) present in an acidic wetland, and more particularly lipidic parts involved in their chemical structure. Humic acids and Humin from an acidic peat bog located at Brennilis (Sphagnum, pH 4.7) in Brittany (France) were characterised by spectroscopic properties (FT-IR and solid state 13C NMR) of their functional groups. Analytical and preparative thermochemolysis (pyrolysis using tetraalkylammonium hydroxide) were also used to investigate humic substances. This technique yielded various ranges of hydrocarbons, fatty acid methyl esters and a,w-dicarboxylic acid methyl esters. In both cases, pyrolysates contained high amounts of polar macromolecular components and aromatic products, mainly derived from lignin moieties, as syringic and p-coumaric units. Our results indicate that structural similarities exist between humic acids and Humin in the Brennilis sample, but important structural differences can be pointed out by thermochemolysis.
Shilpa Agarwal - One of the best experts on this subject based on the ideXlab platform.
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valorization of Humin type byproducts from pyrolytic sugar conversions to biobased chemicals
Journal of Analytical and Applied Pyrolysis, 2020Co-Authors: Shilpa Agarwal, H. Heeres, Peter J. Deuss, Ria M Abdillasantes, Hero J. HeeresAbstract:The pyrolytic sugar fraction, obtained by an aqueous extraction of pyrolysis oil, is an attractive source for sugar-derived platform chemicals. However, solids (Humin) formation occurs to a significant extent during hydrolysis and subsequent acid-catalyzed conversion processes. In this study, we report investigations on possible conversion routes (pyrolysis, liquefaction) of such Humin byproducts to biobased chemicals. Experiments were carried out with a model Humin made from a representative technical pyrolytic sugar and the product was characterized by elemental analysis, GPC, TGA, HPLC, GC-MS, FT-IR and NMR. The obtained Humin sample is soluble in organic solvents (dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and isopropanol (IPA)), in contrast to typical more condensed Humins from glucose and fructose, allowing characterization using NMR and GPC. All analyses reveal that the Humins are oligomeric in nature (M-w of about 900 g/mol) and consist of sugar and furanic fragments linked with among others (substituted) aliphatic, ester units and, in addition, phenolic fragments with methoxy groups. The Humins were used as a feed for catalytic pyrolysis and catalytic liquefaction experiments. Catalytic pyrolysis experiments (mg scale, programmable temperature vaporizer (PTV)-GC-MS, 550 degrees C) with HZSM-5 50 as the catalyst gave benzene-toluene-xylene-naphthalene-ethylbenzene mixtures (BTXNE) in 5.1 wt% yield based on Humin intake. Liquefaction experiments (batch reactor, 350 degrees C, 4 h, isopropanol as both the solvent and hydrogen donor and Pt/CeO2 (4.43 wt% Pt) catalyst) resulted in 80 wt% conversion of the Humin feed to a product oil with considerable amounts of phenolics and aromatics (ca. 24.7 % based on GC detectables in the Humin oil). These findings imply that the techno-economic viability of pyrolysis oil biorefineries can be improved by converting Humin type byproducts to high value, low molecular weight biobased chemicals.
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Valorization of Humin type byproducts from pyrolytic sugar conversions to biobased chemicals
Journal of Analytical and Applied Pyrolysis, 2020Co-Authors: Ria M. Abdilla-santes, Shilpa Agarwal, H. Heeres, Peter J. Deuss, Hero J. HeeresAbstract:Abstract The pyrolytic sugar fraction, obtained by an aqueous extraction of pyrolysis oil, is an attractive source for sugar-derived platform chemicals. However, solids (Humin) formation occurs to a significant extent during hydrolysis and subsequent acid-catalyzed conversion processes. In this study, we report investigations on possible conversion routes (pyrolysis, liquefaction) of such Humin byproducts to biobased chemicals. Experiments were carried out with a model Humin made from a representative technical pyrolytic sugar and the product was characterized by elemental analysis, GPC, TGA, HPLC, GC-MS, FT-IR and NMR. The obtained Humin sample is soluble in organic solvents (dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and isopropanol (IPA)), in contrast to typical more condensed Humins from glucose and fructose, allowing characterization using NMR and GPC. All analyses reveal that the Humins are oligomeric in nature (Mw of about 900 g/mol) and consist of sugar and furanic fragments linked with among others (substituted) aliphatic, ester units and, in addition, phenolic fragments with methoxy groups. The Humins were used as a feed for catalytic pyrolysis and catalytic liquefaction experiments. Catalytic pyrolysis experiments (mg scale, programmable temperature vaporizer (PTV)-GC–MS, 550 °C) with HZSM-5−50 as the catalyst gave benzene-toluene-xylene-naphthalene-ethylbenzene mixtures (BTXNE) in 5.1 wt% yield based on Humin intake. Liquefaction experiments (batch reactor, 350 °C, 4 h, isopropanol as both the solvent and hydrogen donor and Pt/CeO2 (4.43 wt% Pt) catalyst) resulted in 80 wt% conversion of the Humin feed to a product oil with considerable amounts of phenolics and aromatics (ca. 24.7 % based on GC detectables in the Humin oil). These findings imply that the techno-economic viability of pyrolysis oil biorefineries can be improved by converting Humin type byproducts to high value, low molecular weight biobased chemicals.
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Catalytic pyrolysis of recalcitrant, insoluble Humin byproducts from C6 sugar biorefineries
Journal of Analytical and Applied Pyrolysis, 2017Co-Authors: Shilpa Agarwal, Daan S. Van Es, Hero J. HeeresAbstract:Abstract Humins are solid by-products formed during the acid-catalysed conversions of C-6 sugars to platform chemicals like hydroxymethylfurfural and levulinic acid. We here report an experimental study on the liquefaction/depolymerisation of Humins using catalytic pyrolysis. Synthetic Humins (SH) and crude industrial Humins (CIH, including purified industrial (PIH) samples) from the acid-catalysed conversion of C-6 sugars to HMF/LA were tested. Thermal degradation patterns of both Humin types vary significantly. Major thermal decomposition of the industrial Humins was observed between 50 and 650 °C (weight loss approx. 66 wt%), whereas, major weight loss was observed between 200 and 800 °C for the synthetic Humins (47 wt%). A series of catalytic pyrolysis tests with synthetic Humins and different zeolites were performed using a PTV-GC/MS (Humin to catalyst wt ratio of 0.2, 550 °C). Best results were obtained using HZSM-5 (SiO 2 /Al 2 O 3 = 50). For quantitative analysis, a gram scale pyrolysis unit was used, giving a product oil (9–11 wt% on Humin intake) with approximately 1.5 and 10 wt% aromatics from synthetic and crude industrial Humins, respectively. GPC data on the product oils clearly shows the breakdown of the Humin structure into low molecular weight species. The HHV value of the liquid products (up to 41 MJ kg −1 ) is considerably higher than that of the crude industrial Humin feed (21–24 MJ kg −1 ).
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Exploratory catalyst screening studies on the liquefaction of model Humins from C6 sugars
RSC Advances, 2017Co-Authors: Yuliang Wang, Shilpa Agarwal, Zhenchen Tang, Hero J. HeeresAbstract:A catalyst screening study is reported on the liquefaction of Humins, the solid byproducts from C6 sugar biorefineries for levulinic acid and 5-hydroxymethylfurfural production. Experiments were carried out in a batch reactor using an artificial model of Humin derived from glucose with isopropanol (IPA) as the solvent at 400 °C for a 3 h batchtime. Initial studies using noble metal catalysts (Rh, Pt, Pd, Ru) on a carbon support revealed that Pt was the best catalyst in terms of Humin conversion (77%) and amounts of alkylphenolics and aromatics in the product oil (GCxGC-FID). Subsequent support screening studies (TiO2, ZrO2, CeO2) were performed using Pt as the active metal and the results were compared with Pt/C. Detailed liquid product analysis (GPC, GC-MS, GCxGC) including blank reactions in the absence of Humins revealed that the Humins are mainly converted to monomeric alkylphenolics and aromatics oligomers (GPC) and (GC). IPA was shown not to be inert and is converted to acetone and hydrogen, and the latter is the hydrogen source for the various metal catalysed hydrogenolysis and hydro(deoxy)genation reactions. In addition, acetone is converted to aldolcondensation products (like methylisobutylketone, MIBK) and hydrogenation products derived thereof. The best results were obtained with Pt/C when considering Humin conversion. However, Pt/CeO2 was shown to be more attractive when considering the amounts of alkylphenolics in the product oils (20.4 wt% based on Humin intake).
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Catalytic Liquefaction of Humin Substances from Sugar Biorefineries with Pt/C in 2-Propanol
ACS Sustainable Chemistry & Engineering, 2016Co-Authors: Yuehu Wang, Shilpa Agarwal, Hero J. HeeresAbstract:The catalytic liquefaction of Humins, the solid byproduct from the conversion of C6 sugars (glucose, fructose) to 5-hydroxymethylfurfural (HMF) and levulinic acid (LA), using a supported Pt/C catalyst in isopropanol (IPA) as the solvent was investigated. At bench mark conditions (400 °C, 7 h, 27 wt % catalyst on Humin intake, 21 wt % Humin on total intake (IPA and Humins)), about 60% of the Humins was converted to a Humin oil. This oil was analyzed in detail (GC-MS, GCxGC-FID, GPC) and shown to consist of a mixture of monomers and oligomers belonging to various product classes (alkylphenolics, aromatics, aliphatic hydrocarbons). IPA was shown to be reactive under the prevailing reaction conditions and acts as a hydrogen donor for the Humin depolymerization/hydrodeoxygenation reactions. A systematic study according to a central composite design (19 experiments) was performed to optimize the reaction conditions (T, Humin intake, catalyst intake, and batch time) to obtain the highest Humin conversion and alk...
Hugo Marcelo Zunino - One of the best experts on this subject based on the ideXlab platform.
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balance and distribution of sulphur in volcanic ash derived soils in chile
Soil Biology & Biochemistry, 2002Co-Authors: Maria Aguilera, Maria De La Luz Mora, Gilda Borie, Pedro Peirano, Hugo Marcelo ZuninoAbstract:Abstract Sulphur distribution with an insight in S-organic fractions was studied in volcanic-ash derived soils of Chile (Typic Dystrandepts, Palehumult) by isolating each fraction and measuring S directly by instrumental elemental analysis. S-pattern followed closely C and N distribution in these soils. Light organic-S forms accounted for more than 40% of total S in soil, indicating that this S-form is the actual vehicle through which mineralization to S-SO4 occurs. The role of this type of S-molecules, especially of those with lower molecular weight, needs to be clarified regarding its direct availability for plant roots. In younger Andisol soils, the main fraction of organic S was linked to high molecular weight Humins (20–34%). In Ultisol soil, apparently a final degradation step occurs where organic soluble-S has almost disappeared and S is nearly exclusively represented by S in humic acid (HA), fulvic acid (FA) and Humin (H).
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n pool in volcanic ash derived soils in chile and its changes in deforested sites
Soil Biology & Biochemistry, 2002Co-Authors: Gilda Borie, Pedro Peirano, Hugo Marcelo Zunino, Silvia Maria AguileraAbstract:Abstract Changes in N-distribution patterns in volcanic-ash of Chile after deforestation of a primary forest were measured. There is a clear tendency towards the depletion of N linked to high molecular weight fractions (Humin, humic acid fractions) after the disturbance. These changes are illustrated schematically in relation to N input and output and to rhizosphere behavior after deforestation. N-pool and its pattern distribution within soil organic macromolecules is postulated to be a good indicator of N-dynamics in soils, which could be applied to detect soil deterioration processes. As an experimental model, it is proposed to characterize organic-N as N-fulvic, N-humic, N-Humin and light organic-N.
Cédric Guignard - One of the best experts on this subject based on the ideXlab platform.
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lipid constituents of peat humic acids and Humin distinction from directly extractable bitumen components using tmah and teaac thermochemolysis
Organic Geochemistry, 2005Co-Authors: Cédric Guignard, Laurent Lemée, André AmblèsAbstract:Humic acids and Humin from an acidic peat were investigated using solid state 13C NMR and pyrolysis with tetramethylammonium hydroxide (TMAH) and tetraethylammonium acetate (TEAAc). The degradation products were compared with the solvent extractable lipids. The latter appeared to originate mostly from plant material, whereas the products derived from the humic fractions showed a more complex structure, partly inherited from natural insoluble material. The major products of TMAH thermochemolysis were aromatic compounds derived from lignin moieties, hydrocarbons and fatty acid methyl esters (FAMEs) partly incorporated via ester or ether bonds. Aliphatic hydrocarbons were present as n-alkene/n-alkane doublets with a Gaussian distribution in the C17–C35 range. These unsaturated and saturated hydrocarbons arose from resistant biopolymers. Bifunctional aliphatic compounds were also incorporated into the humic structure, contributing to alkyl bridges. Thermochemolysis of Humin produced more aliphatic structures than did humic acids. The application of TEAAc thermochemolysis allowed identification of a wide range of products initially retained in the humic macromolecules via non-covalent bonds, thereby indicating that weak bonds such as hydrogen bonds play a key role in the structure of humic substances. The association of thermochemolysis using TMAH and TEAAc thus allows covalently-bound fatty acids, trapped fatty acids and trapped fatty acid methyl esters present in the structure of humic acids or Humin to be distinguished.
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Lipid constituents of peat humic acids and Humin. Distinction from directly extractable bitumens using TMAH and TEAAc thermochemolysis
Organic Geochemistry, 2005Co-Authors: Cédric Guignard, Laurent Lemée, André AmblèsAbstract:Humic acids and Humin from an acidic peat were investigated using solid state 13C NMR and pyrolysis with tetramethylammonium hydroxide (TMAH) and tetraethylammonium acetate (TEAAc). The degradation products were compared with the solvent extractable lipids. The latter appeared to originate mostly from plant material, whereas the products derived from the humic fractions showed a more complex structure, partly inherited from natural insoluble material. The major products of TMAH thermochemolysis were aromatic compounds derived from lignin moieties, hydrocarbons and fatty acid methyl esters (FAMEs) partly incorporated via ester or ether bonds. Aliphatic hydrocarbons were present as n-alkene/n-alkane doublets with a Gaussian distribution in the C17–C35 range. These unsaturated and saturated hydrocarbons arose from resistant biopolymers. Bifunctional aliphatic compounds were also incorporated into the humic structure, contributing to alkyl bridges. Thermochemolysis of Humin produced more aliphatic structures than did humic acids. The application of TEAAc thermochemolysis allowed identification of a wide range of products initially retained in the humic macromolecules via non-covalent bonds, thereby indicating that weak bonds such as hydrogen bonds play a key role in the structure of humic substances. The association of thermochemolysis using TMAH and TEAAc thus allows covalently-bound fatty acids, trapped fatty acids and trapped fatty acid methyl esters present in the structure of humic acids or Humin to be distinguished.
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free and esterified aliphatic carboxylic acids in Humin and humic acids from a peat sample as revealed by pyrolysis with tetramethylammonium hydroxide or tetraethylammonium acetate
Organic Geochemistry, 2002Co-Authors: Laurent Grasset, Cédric Guignard, André AmblèsAbstract:Abstract The combination of TMAH thermochemolysis and TEAAc treatment makes it possible to discriminate between the different forms of mono- and dicarboxylic acids present in the structure of Humin and humic acids, that is, “free” uncombined acids, methyl or ethyl esters present as tightly trapped molecules within the matrix, or acids chemically linked to the matrix by ester groups. The results confirm that ester groups are involved in the structure of Humin and humic acids. The cross-linking of moieties originating from microbial metabolism or inherited from higher plants is partly ensured by these chemical groups. On the other hand, significant amounts of fatty monocarboxylic acids and linear dicarboxylic acids are present as free acids in the Humin of the studied sample. Humin contains also fatty acid methyl esters. Free, uncombined α,ω-dicarboxylic acids were only found in Humin.
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Structural characterization of humic substances from an acidic peat using thermochemolysis techniques
Agronomie, 2000Co-Authors: Cédric Guignard, Laurent Lemée, André AmblèsAbstract:The general aim of the present work is a study of the insoluble organic matter (humic acids, Humin) present in an acidic wetland, and more particularly lipidic parts involved in their chemical structure. Humic acids and Humin from an acidic peat bog located at Brennilis (Sphagnum, pH 4.7) in Brittany (France) were characterised by spectroscopic properties (FT-IR and solid state 13C NMR) of their functional groups. Analytical and preparative thermochemolysis (pyrolysis using tetraalkylammonium hydroxide) were also used to investigate humic substances. This technique yielded various ranges of hydrocarbons, fatty acid methyl esters and a,w-dicarboxylic acid methyl esters. In both cases, pyrolysates contained high amounts of polar macromolecular components and aromatic products, mainly derived from lignin moieties, as syringic and p-coumaric units. Our results indicate that structural similarities exist between humic acids and Humin in the Brennilis sample, but important structural differences can be pointed out by thermochemolysis.
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Structural characterization of humic substances from an acidic peat using thermochemolysis techniques
Agronomie, 2000Co-Authors: Cédric Guignard, Laurent Lemée, André AmblèsAbstract:The general aim of the present work is a study of the insoluble organic matter (humic acids, Humin) present in an acidic wetland, and more particularly lipidic parts involved in their chemical structure. Humic acids and Humin from an acidic peat bog located at Brennilis (Sphagnum, pH 4.7) in Brittany (France) were characterised by spectroscopic properties (FT-IR and solid state $^{13}$C NMR) of their functional groups. Analytical and preparative thermochemolysis (pyrolysis using tetraalkylammonium hydroxide) were also used to investigate humic substances. This technique yielded various ranges of hydrocarbons, fatty acid methyl esters and $\alpha$,$\omega$-dicarboxylic acid methyl esters. In both cases, pyrolysates contained high amounts of polar macromolecular components and aromatic products, mainly derived from lignin moieties, as syringic and p-coumaric units. Our results indicate that structural similarities exist between humic acids and Humin in the Brennilis sample, but important structural differences can be pointed out by thermochemolysis.