Documents disponibles écrits par cet auteur

Dilute acid hydrolysis of loblolly pine / Teresita Marzialetti in Industrial & engineering chemistry research, Vol. 47 N°19 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7131–7140 Titre : Dilute acid hydrolysis of loblolly pine : a comprehensive approach Type de document : texte imprimé Auteurs : Teresita Marzialetti, Auteur ; Mariefel B. Valenzuela-Olarte, Auteur ; Carsten Sievers, Auteur Année de publication : 2008 Article en page(s) : p. 7131–7140 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Acid  hydrolysis  Loblolly  pine  Monosaccharides Résumé : A comprehensive study of the acid hydrolysis of the softwood species, Loblolly pine (Pinus taeda), using different hydrolysis conditions is presented. The effect of the type of acid, pH, reaction temperature, and reaction time on hydrolysis products such as monosaccharides (mannose, glucose, galactose, xylose, and arabinose) and the subsequent degradation products, 5-hydroxymethyl-2-furaldehyde (HMF) and 2-furaldehyde (furfural) is reported using a batch reactor. Trifluoroacetic acid (TFA) is found to yield the highest amount of overall soluble monosaccharides (∼70% yield from the hemicelluloses fraction) at 150 °C at pH 1.65. The mineral acids (HCl, H2SO4, HNO3, and H3PO4) gave a slightly lower yield of monosaccharides from hydrolyzed hemicellulose (∼60%). At 200 °C, cellulose is hydrolyzed by the mineral acids as evidenced by higher levels of solid dissolution and higher soluble hexose (relative to pentose) yields. Larger amounts of degradation products are also noted at higher temperatures. Furthermore, an increased amount of HMF and furfural is noted in the liquid product as compared to lower temperatures. TFA was found to be the most “gentle” acid, leading to limited monosaccharide degradation among the acids used. The presence of soluble oligosaccharides in solution after hydrolysis was confirmed by applying a secondary acid hydrolysis to the solid-free liquid hydrolysate. Good closure of mass balances was possible using total organic carbon (TOC) analysis. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800455f [article] Dilute acid hydrolysis of loblolly pine : a comprehensive approach [texte imprimé] / Teresita Marzialetti, Auteur ; Mariefel B. Valenzuela-Olarte, Auteur ; Carsten Sievers, Auteur . - 2008 . - p. 7131–7140. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7131–7140 Mots-clés : Acid  hydrolysis  Loblolly  pine  Monosaccharides Résumé : A comprehensive study of the acid hydrolysis of the softwood species, Loblolly pine (Pinus taeda), using different hydrolysis conditions is presented. The effect of the type of acid, pH, reaction temperature, and reaction time on hydrolysis products such as monosaccharides (mannose, glucose, galactose, xylose, and arabinose) and the subsequent degradation products, 5-hydroxymethyl-2-furaldehyde (HMF) and 2-furaldehyde (furfural) is reported using a batch reactor. Trifluoroacetic acid (TFA) is found to yield the highest amount of overall soluble monosaccharides (∼70% yield from the hemicelluloses fraction) at 150 °C at pH 1.65. The mineral acids (HCl, H2SO4, HNO3, and H3PO4) gave a slightly lower yield of monosaccharides from hydrolyzed hemicellulose (∼60%). At 200 °C, cellulose is hydrolyzed by the mineral acids as evidenced by higher levels of solid dissolution and higher soluble hexose (relative to pentose) yields. Larger amounts of degradation products are also noted at higher temperatures. Furthermore, an increased amount of HMF and furfural is noted in the liquid product as compared to lower temperatures. TFA was found to be the most “gentle” acid, leading to limited monosaccharide degradation among the acids used. The presence of soluble oligosaccharides in solution after hydrolysis was confirmed by applying a secondary acid hydrolysis to the solid-free liquid hydrolysate. Good closure of mass balances was possible using total organic carbon (TOC) analysis. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800455f

Ionic-liquid-phase hydrolysis of pine wood / Carsten Sievers in Industrial & engineering chemistry research, Vol. 48 N°3 (Février 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°3 (Février 2009) . - p. 1277–1286 Titre : Ionic-liquid-phase hydrolysis of pine wood Type de document : texte imprimé Auteurs : Carsten Sievers, Auteur ; Mariefel B. Valenzuela-Olarte, Auteur ; Teresita Marzialetti, Auteur ; Ildar Musin, Auteur Année de publication : 2009 Article en page(s) : p. 1277–1286 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ions  Ionic  liquid  Hemicellulose  Cellulose  --  Depolymerization  Hydrolysis Résumé : Depolymerization of cellulose and hemicellulose from loblolly pine wood is studied in the ionic liquid 1-butyl-3-methylimidazolium chloride, which is capable of dissolving carbohydrates and lignin. In the presence of an acid catalyst, the carbohydrate fraction is converted into water-soluble products under milder conditions than reported for similar reactions in the aqueous phase. The water-soluble products included monosaccharides, oligosaccharides, furfural, and 5-hydroxymethylfurfural (HMF). The lignin fraction is recovered as a solid residue. It is found by 13C CP MAS NMR spectroscopy that chemical modifications of lignin occurred only to a very moderate extent. The influence of the reaction temperature, water content, and acid concentration is investigated. In particular, the presence of water is found to reduce the solubility of carbohydrate but also to be required for its conversion. Under harsh conditions (high temperature, high acid concentration), solid degradation products, so-called humins, form. The main building blocks of humins are sugars that are linked by additional components forming linkages that are more resistant to hydrolysis than glycosidic bonds in carbohydrates. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801174x [article] Ionic-liquid-phase hydrolysis of pine wood [texte imprimé] / Carsten Sievers, Auteur ; Mariefel B. Valenzuela-Olarte, Auteur ; Teresita Marzialetti, Auteur ; Ildar Musin, Auteur . - 2009 . - p. 1277–1286. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°3 (Février 2009) . - p. 1277–1286 Mots-clés : Ions  Ionic  liquid  Hemicellulose  Cellulose  --  Depolymerization  Hydrolysis Résumé : Depolymerization of cellulose and hemicellulose from loblolly pine wood is studied in the ionic liquid 1-butyl-3-methylimidazolium chloride, which is capable of dissolving carbohydrates and lignin. In the presence of an acid catalyst, the carbohydrate fraction is converted into water-soluble products under milder conditions than reported for similar reactions in the aqueous phase. The water-soluble products included monosaccharides, oligosaccharides, furfural, and 5-hydroxymethylfurfural (HMF). The lignin fraction is recovered as a solid residue. It is found by 13C CP MAS NMR spectroscopy that chemical modifications of lignin occurred only to a very moderate extent. The influence of the reaction temperature, water content, and acid concentration is investigated. In particular, the presence of water is found to reduce the solubility of carbohydrate but also to be required for its conversion. Under harsh conditions (high temperature, high acid concentration), solid degradation products, so-called humins, form. The main building blocks of humins are sugars that are linked by additional components forming linkages that are more resistant to hydrolysis than glycosidic bonds in carbohydrates. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801174x