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Improving the stability of cobalt fischer − tropsch catalysts by boron promotion / Mark Saeys in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 11098-11100 Titre : Improving the stability of cobalt fischer − tropsch catalysts by boron promotion Type de document : texte imprimé Auteurs : Mark Saeys, Auteur ; Kong Fei Tan, Auteur ; Jie Chang, Auteur Année de publication : 2011 Article en page(s) : pp. 11098-11100 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fischer  Tropsch  catalyst  Stability Résumé : Supported Co catalysts exhibit favorable activity and selectivity for Fischer―Tropsch synthesis (FTS) but deactivate slowly. To explore deactivation by carbon deposition, the stability of various forms of deposited carbon was evaluated using density functional theory (DFT). A surface carbide and graphene islands were calculated to be thermodynamically stable. Two forms of deposited carbon are also distinguished experimentally after 200 h of FTS. On the basis of this mechanistic insight, boron was proposed as a promoter to enhance the stability of Co catalysts. DFT calculations indicate that boron and carbon display similar binding preferences, and boron could selectively block the deposition of resilient carbon deposits. To evaluate the theoretical predictions, supported 20 wt % Co catalysts were promoted with 0.5 wt % boron and tested under realistic FTS conditions. Boron promotion was found to reduce the deactivation rate 6-fold, without affecting selectivity and activity. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23448007 [article] Improving the stability of cobalt fischer − tropsch catalysts by boron promotion [texte imprimé] / Mark Saeys, Auteur ; Kong Fei Tan, Auteur ; Jie Chang, Auteur . - 2011 . - pp. 11098-11100. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 11098-11100 Mots-clés : Fischer  Tropsch  catalyst  Stability Résumé : Supported Co catalysts exhibit favorable activity and selectivity for Fischer―Tropsch synthesis (FTS) but deactivate slowly. To explore deactivation by carbon deposition, the stability of various forms of deposited carbon was evaluated using density functional theory (DFT). A surface carbide and graphene islands were calculated to be thermodynamically stable. Two forms of deposited carbon are also distinguished experimentally after 200 h of FTS. On the basis of this mechanistic insight, boron was proposed as a promoter to enhance the stability of Co catalysts. DFT calculations indicate that boron and carbon display similar binding preferences, and boron could selectively block the deposition of resilient carbon deposits. To evaluate the theoretical predictions, supported 20 wt % Co catalysts were promoted with 0.5 wt % boron and tested under realistic FTS conditions. Boron promotion was found to reduce the deactivation rate 6-fold, without affecting selectivity and activity. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23448007

Selective separation of wood components based on hansen’s theory of solubility / Huaming Yu in Industrial & engineering chemistry research, Vol. 50 N° 12 (Juin 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 12 (Juin 2011) . - pp. 7513-7519 Titre : Selective separation of wood components based on hansen’s theory of solubility Type de document : texte imprimé Auteurs : Huaming Yu, Auteur ; Jia Hu, Auteur ; Jie Chang, Auteur Année de publication : 2011 Article en page(s) : pp. 7513-7519 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Solubility  Wood Résumé : A new method for selective separation of wood components is presented. Based on Hansen's theory of solubility, ionic liquid (IL) 1-butyl-3-methylimidazolium bromine ([Bmin]Br) was mixed with aqueous ethanol HBr the acid catalyst in the degradation of wood components, was found to form in situ by ion exchange between IL and organic acid. The hydrogen bonding capacity of the mixture was enhanced as the presence of IL, which led to the promotion of the solubilization of lignin and other products from carbohydrates hydrolysis. The data showed that, variations of the IL concentration caused cellulose to be separated from pine wood with a purity of more than 94%, or to be hydrolyzed and converted into saccharides together with hemicellulose. Because of the complete hydrolysis of hemicellulose, the cross-linked matrix oflignin and hemicellulose was destroyed, which led to the isolation of lignin with a high purity of about 93%. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24239067 [article] Selective separation of wood components based on hansen’s theory of solubility [texte imprimé] / Huaming Yu, Auteur ; Jia Hu, Auteur ; Jie Chang, Auteur . - 2011 . - pp. 7513-7519. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 12 (Juin 2011) . - pp. 7513-7519 Mots-clés : Solubility  Wood Résumé : A new method for selective separation of wood components is presented. Based on Hansen's theory of solubility, ionic liquid (IL) 1-butyl-3-methylimidazolium bromine ([Bmin]Br) was mixed with aqueous ethanol HBr the acid catalyst in the degradation of wood components, was found to form in situ by ion exchange between IL and organic acid. The hydrogen bonding capacity of the mixture was enhanced as the presence of IL, which led to the promotion of the solubilization of lignin and other products from carbohydrates hydrolysis. The data showed that, variations of the IL concentration caused cellulose to be separated from pine wood with a purity of more than 94%, or to be hydrolyzed and converted into saccharides together with hemicellulose. Because of the complete hydrolysis of hemicellulose, the cross-linked matrix oflignin and hemicellulose was destroyed, which led to the isolation of lignin with a high purity of about 93%. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24239067

Synthesis, characterization, and catalytic activity of phosphorus modified H - ZSM - 5 catalysts in selective ethanol dehydration / Kanaparthi Ramesh in Industrial & engineering chemistry research, Vol. 49 N° 9 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4080-4090 Titre : Synthesis, characterization, and catalytic activity of phosphorus modified H - ZSM - 5 catalysts in selective ethanol dehydration Type de document : texte imprimé Auteurs : Kanaparthi Ramesh, Auteur ; Jie Chang, Auteur ; Yi-Fan Han, Auteur Année de publication : 2010 Article en page(s) : pp. 4080-4090 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Dehydration  Catalyst  Catalyst  activity Résumé : Phosphorus (P) modified H-ZSM-5 catalysts were prepared by wet impregnation method by varying P loadings from 0 to 7.43 wt % using phosphoric acid (H3PO4) as the P source. The catalysts were tested for ethanol dehydration in the temperature range of 523—723 K. The P-modified catalysts were found to be highly active and selective toward ethylene at 673 K and atmospheric pressure. In addition, the P-modified catalysts were found to be extremely stable more than 200 h without any sign of deactivation. However, the selectivity was found to be strongly dependent on several factors such as P content, reaction temperature, and space velocity (WHSV). The P-modified ZSM-5 catalysts were also found to be highly active for the dehydration of aqueous ethanol solutions (10 wt %) showing very high ethylene selectivity (above 98%) at significantly lower temperature 623 K. The catalysts were thoroughly characterized using various methods, including N2 physisorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric differential thermal analysis (TG-DTA), 1H, 27Al, and 31P magic angle spinning nuclear magnetic resonance (MAS NMR), and amonia temperature programmed desorption (NH3-TPD). 27Al MAS NMR spectra suggest that P addition facilitate the breaking of Si―O―Al bond that lead to a partial dealumination. NH3-TPD results indicate that total acidity as well as density of high strength acid sites were decreased with P loading. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=22732897 [article] Synthesis, characterization, and catalytic activity of phosphorus modified H - ZSM - 5 catalysts in selective ethanol dehydration [texte imprimé] / Kanaparthi Ramesh, Auteur ; Jie Chang, Auteur ; Yi-Fan Han, Auteur . - 2010 . - pp. 4080-4090. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4080-4090 Mots-clés : Dehydration  Catalyst  Catalyst  activity Résumé : Phosphorus (P) modified H-ZSM-5 catalysts were prepared by wet impregnation method by varying P loadings from 0 to 7.43 wt % using phosphoric acid (H3PO4) as the P source. The catalysts were tested for ethanol dehydration in the temperature range of 523—723 K. The P-modified catalysts were found to be highly active and selective toward ethylene at 673 K and atmospheric pressure. In addition, the P-modified catalysts were found to be extremely stable more than 200 h without any sign of deactivation. However, the selectivity was found to be strongly dependent on several factors such as P content, reaction temperature, and space velocity (WHSV). The P-modified ZSM-5 catalysts were also found to be highly active for the dehydration of aqueous ethanol solutions (10 wt %) showing very high ethylene selectivity (above 98%) at significantly lower temperature 623 K. The catalysts were thoroughly characterized using various methods, including N2 physisorption, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric differential thermal analysis (TG-DTA), 1H, 27Al, and 31P magic angle spinning nuclear magnetic resonance (MAS NMR), and amonia temperature programmed desorption (NH3-TPD). 27Al MAS NMR spectra suggest that P addition facilitate the breaking of Si―O―Al bond that lead to a partial dealumination. NH3-TPD results indicate that total acidity as well as density of high strength acid sites were decreased with P loading. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=22732897