Gabriela Tonetto | Universidad Nacional del Sur (original) (raw)

Papers by Gabriela Tonetto

Research paper thumbnail of Isomerization of fatty acids in sunflower oil during heat treatment

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

Research paper thumbnail of Preparation of USY zeolite supported catalysts from V(AcAc)3 and NH4VO3. Catalytic properties for the dehydrogenation of n-butane in oxygen-free atmosphere

The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is d... more The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is discussed. The samples were prepared in order to obtain highly dispersed V-species, avoiding the formation of crystalline vanadia and the destruction of the zeolite framework. Two methods were employed for preparing VO(x)/USY samples: an organic route using V(AcAc)3 and an inorganic route using NH4VO3. The characterization of the samples was performed with XRD, TPR, NH3-TPD, and N2 isotherms. From these results it is concluded that when VO(x) is supported on the surface of USY from acidic aqueous solution of ammonium metavanadate, the destruction of the zeolite framework is accomplished. For higher pH values in the impregnating solution, undesired V2O5 is formed on the USY surface. On the other hand, VO(x)/USY prepared from the organic precursor shows no destruction of the USY structure. In addition, highly dispersed VO(x) are formed, though for relatively high V loadings (6%) an obstruction of the zeolite windows takes place. The samples are tested as catalysts for gas phase dehydrogenation of n-butane to olefins. The catalysts prepared from NH4VO3 are almost inactive for the reaction. On the other hand, both samples prepared from V(AcAc)3 present initial conversion levels in the 8-12% range. However, the selectivity depends on the V loading, the catalysts with 6% loading being the most selective (75%). The catalytic patterns of the samples (activity and selectivity) are in agreement with the physicochemical features of the VO(x)/USY surface.

Research paper thumbnail of Sunflower oil hydrogenation on Pt catalysts: Comparison between conventional process and homogeneous phase operation using supercritical propane

The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 c... more The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 catalyst was modified: (a) with K and (b) by high temperature reduction treatment, in order to observe its influence on the activity and the cis-isomers selectivity. The catalysts were characterized by atomic absorption, H 2 chemisorption, TPR and XRD.

Research paper thumbnail of Hydrogenation of edible oil over Pd-Me/Al2O3 catalysts (Me=Mo, V and Pb)

Journal of Molecular Catalysis A: Chemical, 2005

This work presents the performance of supported Pd and Pd-Me (Me=Mo, V and Pb) catalysts in the h... more This work presents the performance of supported Pd and Pd-Me (Me=Mo, V and Pb) catalysts in the hydrogenation of sunflower oil.The catalysts were prepared using alumina as support, and were following two different methods of preparation: wet impregnating and sol–gel techniques. The samples were characterized by atomic absorption, N2 adsorption isotherm, temperature-programmed reduction and hydrogen chemisorption.For Pd monometallic catalysts prepared

Research paper thumbnail of A combined theoretical and experimental study of the effects of residual chlorine on the behavior of Pd/γ-Al2O3 catalysts for methane oxidation

Journal of Molecular Catalysis A: Chemical, 2001

Studies of the methane oxidation on Pd/γ-Al2O3 catalysts with and without chloride were made. The... more Studies of the methane oxidation on Pd/γ-Al2O3 catalysts with and without chloride were made. The reaction was investigated at temperatures in the range 20–500°C using stoichiometric reactant mixture. Dissociation of methane and oxygen and desorption of carbon dioxide and water on Pd catalysts have been investigated using a Molecular Orbital approach of the Extended Hückel type, including repulsion terms.

Research paper thumbnail of NO decomposition on PdMo/γ-Al2O3 catalysts

Journal of Molecular Catalysis A: Chemical, 2003

Studies of the NO decomposition reaction on Pd/catalysts were made. The catalytic tests revealed ... more Studies of the NO decomposition reaction on Pd/catalysts were made. The catalytic tests revealed that the binary catalyst has different behavior for the NO decomposition, being the principal differences a longer steady state activity and an increase of oxygen evolution at elevated temperatures. Characterization by TPR, hydrogen chemisorption and FT-IR of CO indicated that palladium physicochemical properties are altered by an effective interaction with molybdenum. The results would suggest a decoration effect of Mo over Pd particle. This interaction appears to be responsible for the observed modification in NO activity and selectivity.

Research paper thumbnail of Steam promoted mesoporosity in USY zeolites: structural properties and 1,2,4-TMB reactivity

Journal of Molecular Catalysis A: Chemical, 2004

ABSTRACT This work addresses the potential effects of steaming in the case of dealumination of Y ... more ABSTRACT This work addresses the potential effects of steaming in the case of dealumination of Y zeolites. With this end, the interaction between 1,2,4-trimethylbenzene (1,2,4-TMB) and ultrastable Y zeolite (USY) is analyzed. The zeolite is modeled using the complete exposed USY structure of one unit cell constituted by eight sodalite cages, 16 hexagonal prisms bridging the sodalite cages and the formed supercage.The MM2 method is considered to evaluate the steric energies in a model of the window including the six surrounding complete sodalite cages. The Parametrized Model revision 3 (PM3) method is also used to analyze the changes in enthalpy upon 1,2,4-TMB adsorption and reaction on each cage. Finally, several calculations on the adsorption of the 1,2,4-TMB on different sodalite cages are effected using the Extended Hückel method and this to complete the description about the interactions between the crystalline USY and 1,2,4-TMB molecules.Calculation results reported in this work support the high probability of carbocation formation and overall reaction in fragments removed from the zeolite. This partially destroyed zeolite display some relaxation of the original structure and allows extra accessibility of TMB to the acidic sites.

Research paper thumbnail of Partial hydrogenation of sunflower oil: Use of edible modifiers of the cis/trans-selectivity

Journal of Molecular Catalysis A: Chemical, 2009

ABSTRACT The partial hydrogenation of sunflower oil with minimum trans-isomer formation is studie... more ABSTRACT The partial hydrogenation of sunflower oil with minimum trans-isomer formation is studied, using a Pd/γ-alumina catalyst modified with promoters apt for human consumption: ethyl benzoate and magnesium glycinate. It was found that the hydrogenation rate diminishes with the additions of the modifiers.Regarding the cis/trans-selectivity, significant differences were found: ethyl benzoate promoted the formation of trans-isomers, whereas magnesium glycinate diminished it. The results can be interpreted in terms of different effects: change in the electron density of palladium, which affects the relative adsorption strength of the reactant, intermediates and hydrogen, and a block of part of the surface by the modifiers. Theoretical calculations were performed to support this hypothesis.

Research paper thumbnail of Performance of Pd-Mo/γ-Al2O3 catalysts for the selective reduction of NO by methane

Journal of Molecular Catalysis A: Chemical, 2003

Pd-Mo/γ-Al2O3 catalysts were prepared by wet impregnation using organometallic precursors. The pe... more Pd-Mo/γ-Al2O3 catalysts were prepared by wet impregnation using organometallic precursors. The performance of these catalysts in the selective catalytic reduction of NO by methane (denoted NO–CH4) was compared with corresponding palladium- and molybdenum-supported catalysts prepared by the same method.Characterization by TPR, hydrogen chemisorption and FTIR of CO and NO showed evidence of palladium–molybdenum interaction. The experimental results indicated an encapsulation

Research paper thumbnail of Revisiting the hydrogenation of sunflower oil over a Ni catalyst

Journal of Food Engineering, 2007

In the present paper the performance of commercial Ni catalyst in edible oil hydrogenation is eva... more In the present paper the performance of commercial Ni catalyst in edible oil hydrogenation is evaluated under different operating conditions. Particularly, the influence of mass transport resistance on the trans-isomers selectivity is analyzed. Initially a series of experiments aim to analyze the effect of four process variables (reaction temperature, hydrogen bubbling device, agitation rate and stirrer design) on catalyst activity and selectivity to trans-isomers. These experiments are conducted in diffusional regimes. A simpler set of experiments is carried out operating under conditions that allow the authors to neglect some diffusional resistances although those associated to the catalyst are still present. In the first case activity and selectivity appear to be independent of the hydrogen bubbling system and the catalyst loading. The whole set of data analyzed in terms of the C18:1/C18:2 0 ratio as a function of the C18:2/C18:2 0 ratio shows that the former, a sort of selectivity, depends on the agitation regime. The formation of trans-isomers however, appears to be a function of the reaction extent only.

Research paper thumbnail of Preparation of USY zeolite supported catalysts from V(AcAc)3 and NH4VO3. Catalytic properties for the dehydrogenation of n-butane in oxygen-free atmosphere

Journal of Colloid and Interface Science, 2005

The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is d... more The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is discussed. The samples were prepared in order to obtain highly dispersed V-species, avoiding the formation of crystalline vanadia and the destruction of the zeolite framework. Two methods were employed for preparing VO(x)/USY samples: an organic route using V(AcAc)3 and an inorganic route using NH4VO3. The characterization of the samples was performed with XRD, TPR, NH3-TPD, and N2 isotherms. From these results it is concluded that when VO(x) is supported on the surface of USY from acidic aqueous solution of ammonium metavanadate, the destruction of the zeolite framework is accomplished. For higher pH values in the impregnating solution, undesired V2O5 is formed on the USY surface. On the other hand, VO(x)/USY prepared from the organic precursor shows no destruction of the USY structure. In addition, highly dispersed VO(x) are formed, though for relatively high V loadings (6%) an obstruction of the zeolite windows takes place. The samples are tested as catalysts for gas phase dehydrogenation of n-butane to olefins. The catalysts prepared from NH4VO3 are almost inactive for the reaction. On the other hand, both samples prepared from V(AcAc)3 present initial conversion levels in the 8-12% range. However, the selectivity depends on the V loading, the catalysts with 6% loading being the most selective (75%). The catalytic patterns of the samples (activity and selectivity) are in agreement with the physicochemical features of the VO(x)/USY surface.

Research paper thumbnail of Desulfurization of FCC Gasoline: Novel Catalytic Processes with Zeolites

International Journal of Chemical Reactor Engineering, 2000

Page 1. INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING Volume 6 2008 Review R1 Desulfuriza... more Page 1. INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING Volume 6 2008 Review R1 Desulfurization of FCC Gasoline: Novel Catalytic Processes with Zeolites Lisette Jaimes∗ Gabriela M. Tonetto† Marıa Lujan Ferreira‡ Hugo de Lasa∗∗ ...

Research paper thumbnail of Kinetics of the Hydrogenation of Sunflower Oil over Alumina Supported Palladium Catalyst

International Journal of Chemical Reactor Engineering, 2000

The present work studies the sunflower oil hydrogenation on supported palladium catalysts, by ana... more The present work studies the sunflower oil hydrogenation on supported palladium catalysts, by analyzing the surface kinetics and the mass transfer limitations of products and reactants. Initially, a simplified model was studied. This model took into account only the consecutive hydrogenation of linoleic acid (diene), to reach the production of oleic (monoene) and stearic (saturated) acids. Using the adjusted values of the kinetic constants and the activation energies of the hydrogenation obtained with this model, a new scheme was investigated considering the geometric isomerization reactions (cis-trans). The diene hydrogenation constant was larger than that of the monoene. This fact confirms the higher reaction rate of the diene hydrogenation in comparison with that of the monoene. With respect to the isomerization rates, these have an activation energy superior to that of the monoene hydrogenation, and slightly superior to the diene hydrogenation activation energy. This fact verifies the influence of temperature on the formation of trans-isomers.

Research paper thumbnail of Influence of the Preparation Method and Metal Precursor Compound on Alumina-Supported Pd Catalysts

International Journal of Chemical Reactor Engineering, 2000

Research paper thumbnail of Modeling Fluid Catalytic Cracking in a Novel CREC Riser Simulator: Adsorption Parameters under Reaction Conditions

International Journal of Chemical Reactor Engineering, 2000

Abstract The complexity of a heavy gas oil feedstock and the multitude of reaction pathways have ... more Abstract The complexity of a heavy gas oil feedstock and the multitude of reaction pathways have limited previous attempts to model fluid catalytic cracking (FCC). The demand for more detailed kinetic information motivates the use of pure components to first elucidate the ...

Research paper thumbnail of Catalytic Conversion of 1,2,4-Trimethylbenzene in a CREC Riser Simulator. A Heterogeneous Model with Adsorption and Reaction Phenomena

Industrial & Engineering Chemistry Research, 2003

ABSTRACT The aim of the present work is the development of a heterogeneous kinetic model for the ... more ABSTRACT The aim of the present work is the development of a heterogeneous kinetic model for the isomerization and disproportionation of 1,2,4-TMB. With this end, experiments are conducted in a novel CREC riser simulator loaded with an FCC catalyst. FCC catalysts were prepared using HY zeolites having different crystallite sizes, namely,0.4 and 0.9 μm. The observed distributions of products are reviewed considering potential shape-selectivity effects and hindered diffusion of products. The adopted modeling strategy allows for the calculation, with little ambiguity, of adsorption constants; heats of adsorption; and kinetic constants, such as energies of activation and preexponential factors.

Research paper thumbnail of Catalytic Desulfurization of Gasoline via Dehydrosulfidation

Industrial & Engineering Chemistry Research, 2006

This study presents a potentially attractive route for the desulfurization of gasoline via cataly... more This study presents a potentially attractive route for the desulfurization of gasoline via catalytic dehydrosulfidation, removal of hydrogen sulfide from sulfur-containing molecules. The proposed study involves thermodynamic calculations and experimentation in a fluidized riser simulator at the Chemical Reaction Engineering Centre (CREC) at the University of Western Ontario. A ZSM-5 catalyst was used because of its demonstrated performance for the dehydration of methanol, a parent reaction with an expected similar reaction network. The catalyst was characterized using several techniques, including (a) BET (surface area), (b) ammonia temperature-programmed desorption (concentration of acid sites), and (c) SEM-EDX (sodium content) at various stages of catalyst preparation. The catalytic dehydrodesulfidation reaction was studied using a model compound (ethyl mercaptan, EM) in n-octane (n-C 8 ) to represent sulfur-contaminated gasoline. The experimental data obtained were successfully fitted using a kinetic model representing the rate of disappearance of the sulfur-containing species.

Research paper thumbnail of Hydrogenation of sunflower oil over different palladium supported catalysts: Activity and selectivity

Chemical Engineering Journal, 2009

Six palladium catalysts were prepared using different precursors (palladium acetylacetonate, pall... more Six palladium catalysts were prepared using different precursors (palladium acetylacetonate, palladium nitrate and tetraamminepalladium nitrate) and supports (␣-Al 2 O 3 , ␥-Al 2 O 3 , ZSM-5, and MCM-22). The samples were characterized by atomic absorption spectroscopy, N 2 adsorption isotherms, XRD, H 2 chemisorption, transmission electron microscopy and temperature programmed reduction. The activity and selectivity of the catalysts were investigated in the hydrogenation of sunflower oil and compared to a commercial Ni catalyst.

Research paper thumbnail of Palladium catalyst on anodized aluminum monoliths for the partial hydrogenation of vegetable oil

Chemical Engineering Journal, 2011

The present work explores the viability of introducing improvements to the conventional process o... more The present work explores the viability of introducing improvements to the conventional process of hydrogenation using structured catalysts. Monolithic catalysts of anodized aluminum were prepared and characterized. They were impregnated with palladium and used as monolithic stirrers in the sunflower oil hydrogenation reaction at 100 • C and 413 kPa.

Research paper thumbnail of Sunflower oil hydrogenation on Pt catalysts: Comparison between conventional process and homogeneous phase operation using supercritical propane

Catalysis Today, 2008

The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 c... more The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 catalyst was modified: (a) with K and (b) by high temperature reduction treatment, in order to observe its influence on the activity and the cis-isomers selectivity. The catalysts were characterized by atomic absorption, H 2 chemisorption, TPR and XRD.

Research paper thumbnail of Isomerization of fatty acids in sunflower oil during heat treatment

Latin American applied research Pesquisa aplicada latino americana = Investigación aplicada latinoamericana

Research paper thumbnail of Preparation of USY zeolite supported catalysts from V(AcAc)3 and NH4VO3. Catalytic properties for the dehydrogenation of n-butane in oxygen-free atmosphere

The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is d... more The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is discussed. The samples were prepared in order to obtain highly dispersed V-species, avoiding the formation of crystalline vanadia and the destruction of the zeolite framework. Two methods were employed for preparing VO(x)/USY samples: an organic route using V(AcAc)3 and an inorganic route using NH4VO3. The characterization of the samples was performed with XRD, TPR, NH3-TPD, and N2 isotherms. From these results it is concluded that when VO(x) is supported on the surface of USY from acidic aqueous solution of ammonium metavanadate, the destruction of the zeolite framework is accomplished. For higher pH values in the impregnating solution, undesired V2O5 is formed on the USY surface. On the other hand, VO(x)/USY prepared from the organic precursor shows no destruction of the USY structure. In addition, highly dispersed VO(x) are formed, though for relatively high V loadings (6%) an obstruction of the zeolite windows takes place. The samples are tested as catalysts for gas phase dehydrogenation of n-butane to olefins. The catalysts prepared from NH4VO3 are almost inactive for the reaction. On the other hand, both samples prepared from V(AcAc)3 present initial conversion levels in the 8-12% range. However, the selectivity depends on the V loading, the catalysts with 6% loading being the most selective (75%). The catalytic patterns of the samples (activity and selectivity) are in agreement with the physicochemical features of the VO(x)/USY surface.

Research paper thumbnail of Sunflower oil hydrogenation on Pt catalysts: Comparison between conventional process and homogeneous phase operation using supercritical propane

The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 c... more The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 catalyst was modified: (a) with K and (b) by high temperature reduction treatment, in order to observe its influence on the activity and the cis-isomers selectivity. The catalysts were characterized by atomic absorption, H 2 chemisorption, TPR and XRD.

Research paper thumbnail of Hydrogenation of edible oil over Pd-Me/Al2O3 catalysts (Me=Mo, V and Pb)

Journal of Molecular Catalysis A: Chemical, 2005

This work presents the performance of supported Pd and Pd-Me (Me=Mo, V and Pb) catalysts in the h... more This work presents the performance of supported Pd and Pd-Me (Me=Mo, V and Pb) catalysts in the hydrogenation of sunflower oil.The catalysts were prepared using alumina as support, and were following two different methods of preparation: wet impregnating and sol–gel techniques. The samples were characterized by atomic absorption, N2 adsorption isotherm, temperature-programmed reduction and hydrogen chemisorption.For Pd monometallic catalysts prepared

Research paper thumbnail of A combined theoretical and experimental study of the effects of residual chlorine on the behavior of Pd/γ-Al2O3 catalysts for methane oxidation

Journal of Molecular Catalysis A: Chemical, 2001

Studies of the methane oxidation on Pd/γ-Al2O3 catalysts with and without chloride were made. The... more Studies of the methane oxidation on Pd/γ-Al2O3 catalysts with and without chloride were made. The reaction was investigated at temperatures in the range 20–500°C using stoichiometric reactant mixture. Dissociation of methane and oxygen and desorption of carbon dioxide and water on Pd catalysts have been investigated using a Molecular Orbital approach of the Extended Hückel type, including repulsion terms.

Research paper thumbnail of NO decomposition on PdMo/γ-Al2O3 catalysts

Journal of Molecular Catalysis A: Chemical, 2003

Studies of the NO decomposition reaction on Pd/catalysts were made. The catalytic tests revealed ... more Studies of the NO decomposition reaction on Pd/catalysts were made. The catalytic tests revealed that the binary catalyst has different behavior for the NO decomposition, being the principal differences a longer steady state activity and an increase of oxygen evolution at elevated temperatures. Characterization by TPR, hydrogen chemisorption and FT-IR of CO indicated that palladium physicochemical properties are altered by an effective interaction with molybdenum. The results would suggest a decoration effect of Mo over Pd particle. This interaction appears to be responsible for the observed modification in NO activity and selectivity.

Research paper thumbnail of Steam promoted mesoporosity in USY zeolites: structural properties and 1,2,4-TMB reactivity

Journal of Molecular Catalysis A: Chemical, 2004

ABSTRACT This work addresses the potential effects of steaming in the case of dealumination of Y ... more ABSTRACT This work addresses the potential effects of steaming in the case of dealumination of Y zeolites. With this end, the interaction between 1,2,4-trimethylbenzene (1,2,4-TMB) and ultrastable Y zeolite (USY) is analyzed. The zeolite is modeled using the complete exposed USY structure of one unit cell constituted by eight sodalite cages, 16 hexagonal prisms bridging the sodalite cages and the formed supercage.The MM2 method is considered to evaluate the steric energies in a model of the window including the six surrounding complete sodalite cages. The Parametrized Model revision 3 (PM3) method is also used to analyze the changes in enthalpy upon 1,2,4-TMB adsorption and reaction on each cage. Finally, several calculations on the adsorption of the 1,2,4-TMB on different sodalite cages are effected using the Extended Hückel method and this to complete the description about the interactions between the crystalline USY and 1,2,4-TMB molecules.Calculation results reported in this work support the high probability of carbocation formation and overall reaction in fragments removed from the zeolite. This partially destroyed zeolite display some relaxation of the original structure and allows extra accessibility of TMB to the acidic sites.

Research paper thumbnail of Partial hydrogenation of sunflower oil: Use of edible modifiers of the cis/trans-selectivity

Journal of Molecular Catalysis A: Chemical, 2009

ABSTRACT The partial hydrogenation of sunflower oil with minimum trans-isomer formation is studie... more ABSTRACT The partial hydrogenation of sunflower oil with minimum trans-isomer formation is studied, using a Pd/γ-alumina catalyst modified with promoters apt for human consumption: ethyl benzoate and magnesium glycinate. It was found that the hydrogenation rate diminishes with the additions of the modifiers.Regarding the cis/trans-selectivity, significant differences were found: ethyl benzoate promoted the formation of trans-isomers, whereas magnesium glycinate diminished it. The results can be interpreted in terms of different effects: change in the electron density of palladium, which affects the relative adsorption strength of the reactant, intermediates and hydrogen, and a block of part of the surface by the modifiers. Theoretical calculations were performed to support this hypothesis.

Research paper thumbnail of Performance of Pd-Mo/γ-Al2O3 catalysts for the selective reduction of NO by methane

Journal of Molecular Catalysis A: Chemical, 2003

Pd-Mo/γ-Al2O3 catalysts were prepared by wet impregnation using organometallic precursors. The pe... more Pd-Mo/γ-Al2O3 catalysts were prepared by wet impregnation using organometallic precursors. The performance of these catalysts in the selective catalytic reduction of NO by methane (denoted NO–CH4) was compared with corresponding palladium- and molybdenum-supported catalysts prepared by the same method.Characterization by TPR, hydrogen chemisorption and FTIR of CO and NO showed evidence of palladium–molybdenum interaction. The experimental results indicated an encapsulation

Research paper thumbnail of Revisiting the hydrogenation of sunflower oil over a Ni catalyst

Journal of Food Engineering, 2007

In the present paper the performance of commercial Ni catalyst in edible oil hydrogenation is eva... more In the present paper the performance of commercial Ni catalyst in edible oil hydrogenation is evaluated under different operating conditions. Particularly, the influence of mass transport resistance on the trans-isomers selectivity is analyzed. Initially a series of experiments aim to analyze the effect of four process variables (reaction temperature, hydrogen bubbling device, agitation rate and stirrer design) on catalyst activity and selectivity to trans-isomers. These experiments are conducted in diffusional regimes. A simpler set of experiments is carried out operating under conditions that allow the authors to neglect some diffusional resistances although those associated to the catalyst are still present. In the first case activity and selectivity appear to be independent of the hydrogen bubbling system and the catalyst loading. The whole set of data analyzed in terms of the C18:1/C18:2 0 ratio as a function of the C18:2/C18:2 0 ratio shows that the former, a sort of selectivity, depends on the agitation regime. The formation of trans-isomers however, appears to be a function of the reaction extent only.

Research paper thumbnail of Preparation of USY zeolite supported catalysts from V(AcAc)3 and NH4VO3. Catalytic properties for the dehydrogenation of n-butane in oxygen-free atmosphere

Journal of Colloid and Interface Science, 2005

The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is d... more The preparation of different samples of vanadia supported on ultrastable zeolite (VO(x)/USY) is discussed. The samples were prepared in order to obtain highly dispersed V-species, avoiding the formation of crystalline vanadia and the destruction of the zeolite framework. Two methods were employed for preparing VO(x)/USY samples: an organic route using V(AcAc)3 and an inorganic route using NH4VO3. The characterization of the samples was performed with XRD, TPR, NH3-TPD, and N2 isotherms. From these results it is concluded that when VO(x) is supported on the surface of USY from acidic aqueous solution of ammonium metavanadate, the destruction of the zeolite framework is accomplished. For higher pH values in the impregnating solution, undesired V2O5 is formed on the USY surface. On the other hand, VO(x)/USY prepared from the organic precursor shows no destruction of the USY structure. In addition, highly dispersed VO(x) are formed, though for relatively high V loadings (6%) an obstruction of the zeolite windows takes place. The samples are tested as catalysts for gas phase dehydrogenation of n-butane to olefins. The catalysts prepared from NH4VO3 are almost inactive for the reaction. On the other hand, both samples prepared from V(AcAc)3 present initial conversion levels in the 8-12% range. However, the selectivity depends on the V loading, the catalysts with 6% loading being the most selective (75%). The catalytic patterns of the samples (activity and selectivity) are in agreement with the physicochemical features of the VO(x)/USY surface.

Research paper thumbnail of Desulfurization of FCC Gasoline: Novel Catalytic Processes with Zeolites

International Journal of Chemical Reactor Engineering, 2000

Page 1. INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING Volume 6 2008 Review R1 Desulfuriza... more Page 1. INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING Volume 6 2008 Review R1 Desulfurization of FCC Gasoline: Novel Catalytic Processes with Zeolites Lisette Jaimes∗ Gabriela M. Tonetto† Marıa Lujan Ferreira‡ Hugo de Lasa∗∗ ...

Research paper thumbnail of Kinetics of the Hydrogenation of Sunflower Oil over Alumina Supported Palladium Catalyst

International Journal of Chemical Reactor Engineering, 2000

The present work studies the sunflower oil hydrogenation on supported palladium catalysts, by ana... more The present work studies the sunflower oil hydrogenation on supported palladium catalysts, by analyzing the surface kinetics and the mass transfer limitations of products and reactants. Initially, a simplified model was studied. This model took into account only the consecutive hydrogenation of linoleic acid (diene), to reach the production of oleic (monoene) and stearic (saturated) acids. Using the adjusted values of the kinetic constants and the activation energies of the hydrogenation obtained with this model, a new scheme was investigated considering the geometric isomerization reactions (cis-trans). The diene hydrogenation constant was larger than that of the monoene. This fact confirms the higher reaction rate of the diene hydrogenation in comparison with that of the monoene. With respect to the isomerization rates, these have an activation energy superior to that of the monoene hydrogenation, and slightly superior to the diene hydrogenation activation energy. This fact verifies the influence of temperature on the formation of trans-isomers.

Research paper thumbnail of Influence of the Preparation Method and Metal Precursor Compound on Alumina-Supported Pd Catalysts

International Journal of Chemical Reactor Engineering, 2000

Research paper thumbnail of Modeling Fluid Catalytic Cracking in a Novel CREC Riser Simulator: Adsorption Parameters under Reaction Conditions

International Journal of Chemical Reactor Engineering, 2000

Abstract The complexity of a heavy gas oil feedstock and the multitude of reaction pathways have ... more Abstract The complexity of a heavy gas oil feedstock and the multitude of reaction pathways have limited previous attempts to model fluid catalytic cracking (FCC). The demand for more detailed kinetic information motivates the use of pure components to first elucidate the ...

Research paper thumbnail of Catalytic Conversion of 1,2,4-Trimethylbenzene in a CREC Riser Simulator. A Heterogeneous Model with Adsorption and Reaction Phenomena

Industrial & Engineering Chemistry Research, 2003

ABSTRACT The aim of the present work is the development of a heterogeneous kinetic model for the ... more ABSTRACT The aim of the present work is the development of a heterogeneous kinetic model for the isomerization and disproportionation of 1,2,4-TMB. With this end, experiments are conducted in a novel CREC riser simulator loaded with an FCC catalyst. FCC catalysts were prepared using HY zeolites having different crystallite sizes, namely,0.4 and 0.9 μm. The observed distributions of products are reviewed considering potential shape-selectivity effects and hindered diffusion of products. The adopted modeling strategy allows for the calculation, with little ambiguity, of adsorption constants; heats of adsorption; and kinetic constants, such as energies of activation and preexponential factors.

Research paper thumbnail of Catalytic Desulfurization of Gasoline via Dehydrosulfidation

Industrial & Engineering Chemistry Research, 2006

This study presents a potentially attractive route for the desulfurization of gasoline via cataly... more This study presents a potentially attractive route for the desulfurization of gasoline via catalytic dehydrosulfidation, removal of hydrogen sulfide from sulfur-containing molecules. The proposed study involves thermodynamic calculations and experimentation in a fluidized riser simulator at the Chemical Reaction Engineering Centre (CREC) at the University of Western Ontario. A ZSM-5 catalyst was used because of its demonstrated performance for the dehydration of methanol, a parent reaction with an expected similar reaction network. The catalyst was characterized using several techniques, including (a) BET (surface area), (b) ammonia temperature-programmed desorption (concentration of acid sites), and (c) SEM-EDX (sodium content) at various stages of catalyst preparation. The catalytic dehydrodesulfidation reaction was studied using a model compound (ethyl mercaptan, EM) in n-octane (n-C 8 ) to represent sulfur-contaminated gasoline. The experimental data obtained were successfully fitted using a kinetic model representing the rate of disappearance of the sulfur-containing species.

Research paper thumbnail of Hydrogenation of sunflower oil over different palladium supported catalysts: Activity and selectivity

Chemical Engineering Journal, 2009

Six palladium catalysts were prepared using different precursors (palladium acetylacetonate, pall... more Six palladium catalysts were prepared using different precursors (palladium acetylacetonate, palladium nitrate and tetraamminepalladium nitrate) and supports (␣-Al 2 O 3 , ␥-Al 2 O 3 , ZSM-5, and MCM-22). The samples were characterized by atomic absorption spectroscopy, N 2 adsorption isotherms, XRD, H 2 chemisorption, transmission electron microscopy and temperature programmed reduction. The activity and selectivity of the catalysts were investigated in the hydrogenation of sunflower oil and compared to a commercial Ni catalyst.

Research paper thumbnail of Palladium catalyst on anodized aluminum monoliths for the partial hydrogenation of vegetable oil

Chemical Engineering Journal, 2011

The present work explores the viability of introducing improvements to the conventional process o... more The present work explores the viability of introducing improvements to the conventional process of hydrogenation using structured catalysts. Monolithic catalysts of anodized aluminum were prepared and characterized. They were impregnated with palladium and used as monolithic stirrers in the sunflower oil hydrogenation reaction at 100 • C and 413 kPa.

Research paper thumbnail of Sunflower oil hydrogenation on Pt catalysts: Comparison between conventional process and homogeneous phase operation using supercritical propane

Catalysis Today, 2008

The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 c... more The hydrogenation of sunflower oil on TiO 2 supported by Pt catalysts was studied. The Pt/TiO 2 catalyst was modified: (a) with K and (b) by high temperature reduction treatment, in order to observe its influence on the activity and the cis-isomers selectivity. The catalysts were characterized by atomic absorption, H 2 chemisorption, TPR and XRD.