Documents disponibles écrits par cet auteur

Hydroformylation of 1,4-diacetoxy-2-butene using HRh(CO)(PPh3)3 tethered on alumina as a catalyst / Rashmi Chansarkar in Industrial & engineering chemistry research, Vol. 48 N° 21 (Novembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9479–9489 Titre : Hydroformylation of 1,4-diacetoxy-2-butene using HRh(CO)(PPh3)3 tethered on alumina as a catalyst : kinetic study Type de document : texte imprimé Auteurs : Rashmi Chansarkar, Auteur ; Ashutosh A. Kelkar, Auteur ; Raghunath V. Chaudhari, Auteur Année de publication : 2010 Article en page(s) : pp. 9479–9489 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : 1,4-diacetoxy-2-butene  Kinetic  study Résumé : Hydroformylation of 1,4-diacetoxy-2-butene (DAB) was studied using [HRh(CO)(PPh3)3] complex catalyst tethered on alumina using phosphotungstic acid (PTA) as an anchoring agent, with the aim to understand the product distribution, selectivity, and intrinsic kinetics. It was observed that with the tethered heterogeneous catalyst a simultaneous hydroformylation followed by deacetoxylation steps was possible, which is relevant for combining two steps in the sequence of synthesis of vitamin-A intermediate [2-formyl-4-acetoxy butene (FAB)]. 31P cross-polarization magic angle spinning nuclear magnetic resonance (CP MAS NMR) and infrared (IR) instrumental techniques were found be the most effective techniques to establish the catalyst structure and true heterogeneity. On the basis of the spectroscopic evidence, we postulate the loss of a PPh3 group during tethering to give HRh(CO)(PPh3)2−PTA−Al2O3 as a heterogeneous complex catalyst. Experimental data on the concentration−time and CO/H2 consumption−time profiles were obtained and the effects of DAB concentration, CO partial pressure, H2 partial pressure, and catalyst loading were studied in a 50 mL stirred batch reactor over a temperature range of 338−358 K. The analysis of solid−liquid−gas mass transfer effects was investigated to ensure that the reaction was operating in the kinetic regime. Various models were developed, and the best model was chosen by a model discrimination procedure. The agreement between the model prediction and the experimental data was found to be excellent. The activation energies for the hydroformylation and deacetoxylation steps were found to be 42.5 and 80.2 kJ/mol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900269z [article] Hydroformylation of 1,4-diacetoxy-2-butene using HRh(CO)(PPh3)3 tethered on alumina as a catalyst : kinetic study [texte imprimé] / Rashmi Chansarkar, Auteur ; Ashutosh A. Kelkar, Auteur ; Raghunath V. Chaudhari, Auteur . - 2010 . - pp. 9479–9489. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 21 (Novembre 2009) . - pp. 9479–9489 Mots-clés : 1,4-diacetoxy-2-butene  Kinetic  study Résumé : Hydroformylation of 1,4-diacetoxy-2-butene (DAB) was studied using [HRh(CO)(PPh3)3] complex catalyst tethered on alumina using phosphotungstic acid (PTA) as an anchoring agent, with the aim to understand the product distribution, selectivity, and intrinsic kinetics. It was observed that with the tethered heterogeneous catalyst a simultaneous hydroformylation followed by deacetoxylation steps was possible, which is relevant for combining two steps in the sequence of synthesis of vitamin-A intermediate [2-formyl-4-acetoxy butene (FAB)]. 31P cross-polarization magic angle spinning nuclear magnetic resonance (CP MAS NMR) and infrared (IR) instrumental techniques were found be the most effective techniques to establish the catalyst structure and true heterogeneity. On the basis of the spectroscopic evidence, we postulate the loss of a PPh3 group during tethering to give HRh(CO)(PPh3)2−PTA−Al2O3 as a heterogeneous complex catalyst. Experimental data on the concentration−time and CO/H2 consumption−time profiles were obtained and the effects of DAB concentration, CO partial pressure, H2 partial pressure, and catalyst loading were studied in a 50 mL stirred batch reactor over a temperature range of 338−358 K. The analysis of solid−liquid−gas mass transfer effects was investigated to ensure that the reaction was operating in the kinetic regime. Various models were developed, and the best model was chosen by a model discrimination procedure. The agreement between the model prediction and the experimental data was found to be excellent. The activation energies for the hydroformylation and deacetoxylation steps were found to be 42.5 and 80.2 kJ/mol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900269z

Mass transfer and solubility of CO and H2 in ionic liquid. Case of [Bmim][PF6] with gas-inducing stirrer reactor / Amit Sharma in Industrial & engineering chemistry research, Vol. 48 N° 8 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4075–4082 Titre : Mass transfer and solubility of CO and H2 in ionic liquid. Case of [Bmim][PF6] with gas-inducing stirrer reactor Type de document : texte imprimé Auteurs : Amit Sharma, Auteur ; Carine Julcour, Auteur ; Ashutosh A. Kelkar, Auteur Année de publication : 2009 Article en page(s) : pp. 4075–4082 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ionic  liquids  Solubility  Gas−liquid  mass  transfer  Carbon  monoxide  Hydrogen Résumé : Since the past decade, ionic liquids have gained significant importance as alternative solvents for catalysis applications. Many of the reactions evaluated in ionic liquids employ gases as substrates, and therefore it is important to know their solubility and mass transfer characteristics. This work reports for the first time both the solubility and volumetric gas−liquid mass transfer coefficient kLa for hydrogen and carbon monoxide in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) at three temperatures (293, 323, and 373 K) in relevance to hydroformylation reaction. The experimental data on the volumetric gas−liquid mass transfer coefficient are described by a dimensionless correlation for the bench-scale stirred tanks with gas-inducing impeller. kLa values have also been evaluated for different [Bmim][PF6]−decane emulsions at 373 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801584p [article] Mass transfer and solubility of CO and H2 in ionic liquid. Case of [Bmim][PF6] with gas-inducing stirrer reactor [texte imprimé] / Amit Sharma, Auteur ; Carine Julcour, Auteur ; Ashutosh A. Kelkar, Auteur . - 2009 . - pp. 4075–4082. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4075–4082 Mots-clés : Ionic  liquids  Solubility  Gas−liquid  mass  transfer  Carbon  monoxide  Hydrogen Résumé : Since the past decade, ionic liquids have gained significant importance as alternative solvents for catalysis applications. Many of the reactions evaluated in ionic liquids employ gases as substrates, and therefore it is important to know their solubility and mass transfer characteristics. This work reports for the first time both the solubility and volumetric gas−liquid mass transfer coefficient kLa for hydrogen and carbon monoxide in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]) at three temperatures (293, 323, and 373 K) in relevance to hydroformylation reaction. The experimental data on the volumetric gas−liquid mass transfer coefficient are described by a dimensionless correlation for the bench-scale stirred tanks with gas-inducing impeller. kLa values have also been evaluated for different [Bmim][PF6]−decane emulsions at 373 K. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801584p