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Effect of alkaline catalysts on hydrothermal conversion of glycerin into lactic acid / Zheng Shen in Industrial & engineering chemistry research, Vol. 48 N° 19 (Octobre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8920–8925 Titre : Effect of alkaline catalysts on hydrothermal conversion of glycerin into lactic acid Type de document : texte imprimé Auteurs : Zheng Shen, Auteur ; Fangming Jin, Auteur ; Yalei Zhang, Auteur Année de publication : 2009 Article en page(s) : pp. 8920–8925 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Glycerin  Hydrothermal  treatment  Alkaline  catalysts  Lactic  acid Résumé : Hydrothermal treatment of glycerin was carried out at 300 °C by using eight alkaline catalysts, including hydroxides of alkali metals, alkaline-earth metals, and aluminum. All alkaline catalysts promoted the formation of lactic acid or lactate salts from glycerin, except for Al(OH)3. The alkali-metal hydroxides were more effective than alkaline-earth-metal hydroxides on the catalysis of hydrothermal reactions. On the hydrothermal conversion of glycerin into lactic acid, the catalytic effectiveness followed the sequence of KOH > NaOH > LiOH for alkali-metal hydroxides, and Ba(OH)2 > Sr(OH)2 > Ca(OH)2 > Mg(OH)2 for alkaline-earth hydroxides. An excellent lactic acid yield of 90% was attained on hydrothermal conversion of glycerin at 300 °C with KOH or NaOH as a catalyst. KOH was superior to NaOH as a catalyst since it worked at a lower concentration or within a shorter reaction time to obtain the same lactic acid yield. The hydrothermal conversion of glycerin depended not only on the hydroxide ion concentration but also on the metal ions of catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900937d [article] Effect of alkaline catalysts on hydrothermal conversion of glycerin into lactic acid [texte imprimé] / Zheng Shen, Auteur ; Fangming Jin, Auteur ; Yalei Zhang, Auteur . - 2009 . - pp. 8920–8925. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 19 (Octobre 2009) . - pp. 8920–8925 Mots-clés : Glycerin  Hydrothermal  treatment  Alkaline  catalysts  Lactic  acid Résumé : Hydrothermal treatment of glycerin was carried out at 300 °C by using eight alkaline catalysts, including hydroxides of alkali metals, alkaline-earth metals, and aluminum. All alkaline catalysts promoted the formation of lactic acid or lactate salts from glycerin, except for Al(OH)3. The alkali-metal hydroxides were more effective than alkaline-earth-metal hydroxides on the catalysis of hydrothermal reactions. On the hydrothermal conversion of glycerin into lactic acid, the catalytic effectiveness followed the sequence of KOH > NaOH > LiOH for alkali-metal hydroxides, and Ba(OH)2 > Sr(OH)2 > Ca(OH)2 > Mg(OH)2 for alkaline-earth hydroxides. An excellent lactic acid yield of 90% was attained on hydrothermal conversion of glycerin at 300 °C with KOH or NaOH as a catalyst. KOH was superior to NaOH as a catalyst since it worked at a lower concentration or within a shorter reaction time to obtain the same lactic acid yield. The hydrothermal conversion of glycerin depended not only on the hydroxide ion concentration but also on the metal ions of catalysts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900937d

Hydrogen-transfer reduction of ketones into corresponding alcohols using formic acid as a hydrogen donor without a metal catalyst in high-temperature water / Zheng Shen in Industrial & engineering chemistry research, Vol. 49 N° 13 (Juillet 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 13 (Juillet 2010) . - pp. 6255–6259 Titre : Hydrogen-transfer reduction of ketones into corresponding alcohols using formic acid as a hydrogen donor without a metal catalyst in high-temperature water Type de document : texte imprimé Auteurs : Zheng Shen, Auteur ; Yalei Zhang, Auteur ; Fangming Jin, Auteur Année de publication : 2010 Article en page(s) : pp. 6255–6259 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hydrothermal  reactions  Hydrogen  transferring  Ketones Résumé : In hydrothermal reactions at 260−300 °C, ketones can be reduced into corresponding alcohols by hydrogen transferring from another alcohols or formic acid without a metal catalyst. When using formic acid as a hydrogen donor, the yield of alcohols at respective better conditions was considerably high at a much lower ratio of hydrogen source to ketones compared to traditional Meerwein−Poundrof−Verley (MPV) reduction, reaching 60% for isopropanol from acetone and 70% for lactic acid from pyruvic acid. The proposed possible mechanism for the hydrogen transfer reduction of ketones in high-temperature water (HTW) is similar to the pathway elucidated in the traditional MPV reduction via a transition state. Rather than metal-alkoxides catalysts in MPV reduction, water molecules in HTW as a catalyst may directly participate in the transition state by making a hydrogen-bond ring network with three molecules, that is, ketone, formic acid, and water. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100598a [article] Hydrogen-transfer reduction of ketones into corresponding alcohols using formic acid as a hydrogen donor without a metal catalyst in high-temperature water [texte imprimé] / Zheng Shen, Auteur ; Yalei Zhang, Auteur ; Fangming Jin, Auteur . - 2010 . - pp. 6255–6259. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 13 (Juillet 2010) . - pp. 6255–6259 Mots-clés : Hydrothermal  reactions  Hydrogen  transferring  Ketones Résumé : In hydrothermal reactions at 260−300 °C, ketones can be reduced into corresponding alcohols by hydrogen transferring from another alcohols or formic acid without a metal catalyst. When using formic acid as a hydrogen donor, the yield of alcohols at respective better conditions was considerably high at a much lower ratio of hydrogen source to ketones compared to traditional Meerwein−Poundrof−Verley (MPV) reduction, reaching 60% for isopropanol from acetone and 70% for lactic acid from pyruvic acid. The proposed possible mechanism for the hydrogen transfer reduction of ketones in high-temperature water (HTW) is similar to the pathway elucidated in the traditional MPV reduction via a transition state. Rather than metal-alkoxides catalysts in MPV reduction, water molecules in HTW as a catalyst may directly participate in the transition state by making a hydrogen-bond ring network with three molecules, that is, ketone, formic acid, and water. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100598a