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Hydrolysis of triglycerides using solid acid catalysts / Kanokwan Ngaosuwan in Industrial & engineering chemistry research, Vol. 48 N° 10 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4757–4767 Titre : Hydrolysis of triglycerides using solid acid catalysts Type de document : texte imprimé Auteurs : Kanokwan Ngaosuwan, Auteur ; Edgar Lotero, Auteur ; Kaewta Suwannakarn, Auteur Année de publication : 2009 Article en page(s) : pp. 4757–4767 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Triglycerides  Noncatalytic  hydrolysis  Solid  acid Résumé : The commercial production of free fatty acids (FFAs) is carried out through the noncatalytic hydrolysis of triglycerides (TGs) using great amounts of superheated steam in large reactors made of expensive corrosion-resistant materials, making the process energy intensive and costly. In this study, the feasibility of a continuous reaction system using a solid acid for the hydrolysis of TGs at atmospheric pressure has been investigated. This research was to explore the viability of heterogeneous catalyzed hydrolysis of oils and fats for the synthesis of FFAs, a platform reaction of the oleochemical industry and a possible reaction in a novel two-step (hydrolysis−esterification) biodiesel synthesis process using low-cost feedstocks containing >5−15% FFAs. Tricaprylin (TCp) was used as a model compound representing TGs in order to obtain reliable intrinsic kinetics. Using tungstated zirconia (WZ) and the solid acid composite SAC-13 (Nafion resin nanoparticles supported on mesoporous silica) as catalysts, the hydrolysis of TCp was carried out at 110−150 °C in a semibatch reactor with continuous addition of water at low flow rates capable of achieving 100% selectivity of the carboxylic acid side chains on the triglyceride to HCp. The characteristics of the catalysts played an important role in reaction selectivity, apparent activation energy, and deactivation. Catalyst recycling experiments showed continuous activity loss for both catalysts. Characterization of the used catalysts indicated that deactivation was likely caused by the strong adsorption of bulky reaction intermediates on the catalytic acid sites, blocking reactant accessibility. For WZ, recalcination in air was an effective regeneration method resulting in the recovery of 100% of its original activity. Regeneration by calcination was not possible for SAC-13 due to its temperature sensitivity. Methanol washing of used WZ and SAC-13 catalysts only partially regenerated catalyst activity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013988 [article] Hydrolysis of triglycerides using solid acid catalysts [texte imprimé] / Kanokwan Ngaosuwan, Auteur ; Edgar Lotero, Auteur ; Kaewta Suwannakarn, Auteur . - 2009 . - pp. 4757–4767. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 10 (Mai 2009) . - pp. 4757–4767 Mots-clés : Triglycerides  Noncatalytic  hydrolysis  Solid  acid Résumé : The commercial production of free fatty acids (FFAs) is carried out through the noncatalytic hydrolysis of triglycerides (TGs) using great amounts of superheated steam in large reactors made of expensive corrosion-resistant materials, making the process energy intensive and costly. In this study, the feasibility of a continuous reaction system using a solid acid for the hydrolysis of TGs at atmospheric pressure has been investigated. This research was to explore the viability of heterogeneous catalyzed hydrolysis of oils and fats for the synthesis of FFAs, a platform reaction of the oleochemical industry and a possible reaction in a novel two-step (hydrolysis−esterification) biodiesel synthesis process using low-cost feedstocks containing >5−15% FFAs. Tricaprylin (TCp) was used as a model compound representing TGs in order to obtain reliable intrinsic kinetics. Using tungstated zirconia (WZ) and the solid acid composite SAC-13 (Nafion resin nanoparticles supported on mesoporous silica) as catalysts, the hydrolysis of TCp was carried out at 110−150 °C in a semibatch reactor with continuous addition of water at low flow rates capable of achieving 100% selectivity of the carboxylic acid side chains on the triglyceride to HCp. The characteristics of the catalysts played an important role in reaction selectivity, apparent activation energy, and deactivation. Catalyst recycling experiments showed continuous activity loss for both catalysts. Characterization of the used catalysts indicated that deactivation was likely caused by the strong adsorption of bulky reaction intermediates on the catalytic acid sites, blocking reactant accessibility. For WZ, recalcination in air was an effective regeneration method resulting in the recovery of 100% of its original activity. Regeneration by calcination was not possible for SAC-13 due to its temperature sensitivity. Methanol washing of used WZ and SAC-13 catalysts only partially regenerated catalyst activity. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8013988

Simultaneous free fatty acid esterification and triglyceride transesterification using a solid acid catalyst with in situ removal of water and unreacted methanol / Kaewta Suwannakarn in Industrial & engineering chemistry research, Vol. 48 N° 6 (Mars 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2810–2818 Titre : Simultaneous free fatty acid esterification and triglyceride transesterification using a solid acid catalyst with in situ removal of water and unreacted methanol Type de document : texte imprimé Auteurs : Kaewta Suwannakarn, Auteur ; Edgar Lotero, Auteur ; Kanokwan Ngaosuwan, Auteur Année de publication : 2009 Article en page(s) : pp. 2810–2818 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Free  fatty  acids  Simultaneous  esterification  Transesterification  of  triglycerides  Waste  grease Résumé : Waste greases used in biodiesel production contain high concentrations of free fatty acids (FFAs). To efficiently utilize these low-cost feedstocks for biodiesel synthesis, a preliminary acid-catalyzed esterification pretreatment is necessary to reduce their FFA contents. In this study, the use of a three-phase reaction has been investigated for the simultaneous esterification of FFAs and transesterification of triglycerides (TGs) using model mixtures of TGs and FFAs [0−25 wt % lauric acid (HLa) in tricaprylin (TCp)] to simulate waste grease and to permit easy distinction between the reactions. Trans/esterification with methanol was carried out using a commercial tungstated zirconia (WZ) solid catalyst in a well-stirred semibatch reactor at 130 °C operating at atmospheric pressure. Methanol was continuously charged to the reactor. Unreacted methanol and water produced during the reaction were continuously removed by vaporization, thereby favoring esterification. Esterification occurred 4 times faster than transesterification. Under our reaction conditions and in the presence of the catalyst, byproduct water was produced not only from HLa esterification but also from methanol dehydration. Because of the presence of this water, TGs were converted into the ester product by two routes: direct TG transesterification and TG hydrolysis followed by esterification. The catalyst, WZ, underwent 37% deactivation after three 2-h reaction cycles but completely recovered its original activity after a simple recalcination in flowing air. The feasibility of a continuous multiphase process for reducing FFAs in low-cost biodiesel feedstocks has been successfully demonstrated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800889w [article] Simultaneous free fatty acid esterification and triglyceride transesterification using a solid acid catalyst with in situ removal of water and unreacted methanol [texte imprimé] / Kaewta Suwannakarn, Auteur ; Edgar Lotero, Auteur ; Kanokwan Ngaosuwan, Auteur . - 2009 . - pp. 2810–2818. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 2810–2818 Mots-clés : Free  fatty  acids  Simultaneous  esterification  Transesterification  of  triglycerides  Waste  grease Résumé : Waste greases used in biodiesel production contain high concentrations of free fatty acids (FFAs). To efficiently utilize these low-cost feedstocks for biodiesel synthesis, a preliminary acid-catalyzed esterification pretreatment is necessary to reduce their FFA contents. In this study, the use of a three-phase reaction has been investigated for the simultaneous esterification of FFAs and transesterification of triglycerides (TGs) using model mixtures of TGs and FFAs [0−25 wt % lauric acid (HLa) in tricaprylin (TCp)] to simulate waste grease and to permit easy distinction between the reactions. Trans/esterification with methanol was carried out using a commercial tungstated zirconia (WZ) solid catalyst in a well-stirred semibatch reactor at 130 °C operating at atmospheric pressure. Methanol was continuously charged to the reactor. Unreacted methanol and water produced during the reaction were continuously removed by vaporization, thereby favoring esterification. Esterification occurred 4 times faster than transesterification. Under our reaction conditions and in the presence of the catalyst, byproduct water was produced not only from HLa esterification but also from methanol dehydration. Because of the presence of this water, TGs were converted into the ester product by two routes: direct TG transesterification and TG hydrolysis followed by esterification. The catalyst, WZ, underwent 37% deactivation after three 2-h reaction cycles but completely recovered its original activity after a simple recalcination in flowing air. The feasibility of a continuous multiphase process for reducing FFAs in low-cost biodiesel feedstocks has been successfully demonstrated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800889w