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Andreas Martin - One of the best experts on this subject based on the ideXlab platform.
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the impact of reaction pressure on the catalytic performance of the pd sb tio2 catalyst in the acetoxylation of toluene into Benzyl Acetate
Chemcatchem, 2013Co-Authors: Neetika Madaan, V. Narayana Kalevaru, Jörg Radnik, Bernhard Lücke, Margamartina Pohl, Suresh Gatla, Angelika Bruckner, Andreas MartinAbstract:The acetoxylation of toluene in the presence of acetic acid and oxygen was performed over a PdSb/TiO2 catalyst at 210 °C and at various reaction pressures (1–10 bar). A remarkable improvement in the catalytic performance and a significant shortening of the induction period were found with an increase in pressure. At a pressure of 6 bar, the highest toluene conversion of 75 % and 100 % selectivity for Benzyl Acetate were observed. This result could be due to both the restructuring of the catalyst surface and to the formation of active PdSb particles of desired size, composition, and shape during the course of the induction period. Samples of the most-active and spent catalysts were studied by ex situ and in situ XRD, XPS, and TEM.
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Palladium-catalysed vapour phase aerobic acetoxylation of toluene to Benzyl Acetate
Catalysis Today, 2009Co-Authors: V. Narayana Kalevaru, Abdohadi Benhmid, Jörg Radnik, Bernhard Lücke, M.-m. Pohl, Andreas MartinAbstract:Abstract Supported Pd–Sb acetoxylation catalysts with different Pd and Sb amounts as well as varying supports were prepared by impregnation technique. The contents of Pd and Sb are varied over a wide range, for instance Pd is varied from 0.5 to 20 wt% by keeping Sb content at 8 wt%. In a similar way, Sb content is varied from 4 to 20 wt% by keeping Pd loading constant at 10 wt%. Four different supports such as TiO2, γ-Al2O3, SiO2 and ZrO2 are applied at constant Pd (10 wt%) and Sb (8 wt%) contents. Catalytic performance of these solids is evaluated for the gas phase acetoxylation of toluene to Benzyl Acetate (BA) at T = 210 °C and p = 2 bar. XPS revealed a considerable loss of both Pd and Sb in the near-surface region in the used catalysts. TEM showed that Pd particles exhibit spherical morphology and their size increased dramatically in the spent catalysts compared to their corresponding fresh ones. Monometallic catalysts showed very poor acetoxylation performance but high total oxidation, which results in an increase of the yield of COx up to ca. 50%. However, combination of both Pd and Sb was found to suppress total oxidation and thereby enhance the acetoxylation performance with high BA selectivity of ≥85%. Catalytic activity was observed to increase continuously with increase in Pd loading. The catalyst with the highest Pd loading (20 wt% Pd) displayed the best performance (toluene conversion = > 90%, BA yield = > 75%). The activity is however decreasing with time-on-stream due to coke deposits. Nevertheless, the deactivated samples can be regenerated in air to restore their maximum activity. Nature of support, content of co-components showed strong influence on the catalytic performance.
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direct synthesis of Benzyl Acetate and optimisation of reaction conditions for the gas phase acetoxylation of toluene
Catalysis Today, 2006Co-Authors: Abdohadi Benhmid, Bernhard Lücke, Andreas Martin, K. V. Narayana, M.-m. PohlAbstract:Abstract TiO2 supported Pd-Sb catalysts were prepared by impregnation method and tested for the selective vapour phase acetoxylation of toluene to Benzyl Acetate (BA). Investigations were carried out to optimise reaction variables such as effects of reaction temperature, acetic acid/toluene mole ratio, O2/toluene mole ratio, contact time, etc. to obtain better performance of the catalysts. Additionally, the influence of Sb/Pd ratio on catalytic performance was also checked under optimised reaction conditions. The activity of the catalysts was found to increase continuously with increasing Sb/Pd ratio up to 0.7 and then decreased with further increase in Sb/Pd ratio to 1.75. The catalyst with Sb/Pd ratio of 0.7 exhibited the best performance among all other catalysts of this series giving a conversion of toluene as high as ca. 68% with BA selectivity of 85%. All these catalysts were observed to deactivate with time on stream due to considerable amount of coke deposition. However, these catalysts can be regenerated in air and reused for more number of cycles with consistent performance.
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Highly efficient Pd–Sb–TiO2 catalysts for the vapour phase acetoxylation of toluene to Benzyl Acetate
Journal of Catalysis, 2005Co-Authors: Abdohadi Benhmid, Jörg Radnik, Bernhard Lücke, M.-m. Pohl, Andreas Martin, K. V. Narayana, S. Bischoff, Matthias SchneiderAbstract:Abstract A series of Pd–Sb–TiO 2 (anatase) catalysts has been prepared over a wide range of Pd loadings from 0.5 to 20 wt% and tested for the selective vapour-phase acetoxylation of toluene to Benzyl Acetate at a reaction temperature of 210 °C and a pressure of 2 bar. The catalysts were characterised by nitrogen adsorption, XRD, XPS, and TEM. The BET surface areas and pore volumes were observed to decrease considerably with increasing Pd content of the catalysts. XPS revealed that there is loss of both Pd and Sb in the surface region in the used catalysts. The particle size of Pd (measured by TEM) is found to increase dramatically in the used catalysts compared with the fresh ones. Pd particle size is observed to exhibit a strong influence on the catalytic performance of the catalysts. The activity of the catalysts was found to increase continuously with increasing Pd loading, which is associated with an increase in the Pd particle size of the catalysts. The catalyst with 20 wt% Pd has been found to display the best performance, giving conversion of toluene as high as ca. 92 mol% with a Benzyl Acetate selectivity of 85%. Nevertheless, the solids were observed to deactivate with time on stream due to a considerable amount of coke deposition on the surface. However, the catalysts can be regenerated in air and reused for more number of cycles with consistent performance.
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highly active and selective pd cu tio2 catalyst for the direct synthesis of Benzyl Acetate by gas phase acetoxylation of toluene
Chemistry Letters, 2004Co-Authors: Abdohadi Benhmid, Bernhard Lücke, Andreas Martin, K. V. Narayana, Margamartina PohlAbstract:Extremely high Benzyl Acetate selectivity (ca. 94%) at a toluene conversion of ca. 60% was achieved over Pd-Cu-TiO 2 catalyst for the first time by gas phase acetoxylation of toluene with good long-term stability.
Paul K. Boss - One of the best experts on this subject based on the ideXlab platform.
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Grape Contribution to Wine Aroma: Production of Hexyl Acetate, Octyl Acetate, and Benzyl Acetate during Yeast Fermentation Is Dependent upon Precursors in the Must
Journal of agricultural and food chemistry, 2012Co-Authors: Eric G. Dennis, Robert A. Keyzers, Curtis M. Kalua, Suzanne M. Maffei, Emily L. Nicholson, Paul K. BossAbstract:Wine is a complex consumer product produced predominately by the action of yeast upon grape juice musts. Model must systems have proven ideal for studies of the effects of fermentation conditions on the production of certain wine volatiles. To identify grape-derived precursors to Acetate esters, model fermentation systems were developed by spiking precursors into model must at different concentrations. Solid-phase microextraction-gas chromatgraphy mass spectrometry analysis of the fermented wines showed that a variety of grape-derived aliphatic alcohols and aldehydes are precursors to Acetate esters. The C6 compounds hexan-1-ol, hexenal, (E)-2-hexen-1-ol, and (E)-2-hexenal are all precursors to hexyl Acetate, and octanol and Benzyl alcohol are precursors to octyl Acetate and Benzyl Acetate, respectively. In these cases, the postfermentation concentration of an Acetate ester increased proportionally with the prefermentation concentration of the respective precursor in the model must. Determining viticultural or winemaking methods to alter the prefermentation concentration of precursor compounds or change the precursor-to-Acetate ester ratio will have implications upon the final flavor and aroma of wines.
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grape contribution to wine aroma production of hexyl Acetate octyl Acetate and Benzyl Acetate during yeast fermentation is dependent upon precursors in the must
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Eric G. Dennis, Robert A. Keyzers, Curtis M. Kalua, Suzanne M. Maffei, Emily L. Nicholson, Paul K. BossAbstract:Wine is a complex consumer product produced predominately by the action of yeast upon grape juice musts. Model must systems have proven ideal for studies of the effects of fermentation conditions on the production of certain wine volatiles. To identify grape-derived precursors to Acetate esters, model fermentation systems were developed by spiking precursors into model must at different concentrations. Solid-phase microextraction–gas chromatgraphy mass spectrometry analysis of the fermented wines showed that a variety of grape-derived aliphatic alcohols and aldehydes are precursors to Acetate esters. The C6 compounds hexan-1-ol, hexenal, (E)-2-hexen-1-ol, and (E)-2-hexenal are all precursors to hexyl Acetate, and octanol and Benzyl alcohol are precursors to octyl Acetate and Benzyl Acetate, respectively. In these cases, the postfermentation concentration of an Acetate ester increased proportionally with the prefermentation concentration of the respective precursor in the model must. Determining viticultur...
Mehmet Bilgin - One of the best experts on this subject based on the ideXlab platform.
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measurements of quaternary liquid liquid equilibrium for water acetic acid propionic acid solvent butyronitrile Benzyl Acetate or methyl isobutyl ketone at 298 15 k
Journal of Chemical & Engineering Data, 2006Co-Authors: Mehmet BilginAbstract:Liquid−liquid equilibrium data of water + acetic acid + propionic acid + solvent (butyronitrile, Benzyl Acetate, and methyl isobutyl ketone (MIBK)) quaternary systems were measured. Complete phase diagrams were obtained by determining solubility curves and tie-line data at 298.15 K. The experimental data were compared with predicted values obtained from the UNIFAC method. Selectivity values for solvent separation efficiency were derived from the tie-line data. A comparison of the extracting capabilities of the solvents was made with respect to distribution coefficients, separation factors, and solvent-free selectivity bases. The reliability of the data was ascertained from Othmer−Tobias plots. We conclude that the performance of the solvents increases in the order of butyronitrile, MIBK, and Benzyl Acetate.
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Measurements of Quaternary Liquid-Liquid Equilibrium for Water + Acetic Acid + Propionic Acid + Solvent (Butyronitrile, Benzyl Acetate, or Methyl Isobutyl Ketone) at 298.15 K
Journal of Chemical & Engineering Data, 2006Co-Authors: Mehmet BilginAbstract:Liquid−liquid equilibrium data of water + acetic acid + propionic acid + solvent (butyronitrile, Benzyl Acetate, and methyl isobutyl ketone (MIBK)) quaternary systems were measured. Complete phase diagrams were obtained by determining solubility curves and tie-line data at 298.15 K. The experimental data were compared with predicted values obtained from the UNIFAC method. Selectivity values for solvent separation efficiency were derived from the tie-line data. A comparison of the extracting capabilities of the solvents was made with respect to distribution coefficients, separation factors, and solvent-free selectivity bases. The reliability of the data was ascertained from Othmer−Tobias plots. We conclude that the performance of the solvents increases in the order of butyronitrile, MIBK, and Benzyl Acetate.
Bernhard Lücke - One of the best experts on this subject based on the ideXlab platform.
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the impact of reaction pressure on the catalytic performance of the pd sb tio2 catalyst in the acetoxylation of toluene into Benzyl Acetate
Chemcatchem, 2013Co-Authors: Neetika Madaan, V. Narayana Kalevaru, Jörg Radnik, Bernhard Lücke, Margamartina Pohl, Suresh Gatla, Angelika Bruckner, Andreas MartinAbstract:The acetoxylation of toluene in the presence of acetic acid and oxygen was performed over a PdSb/TiO2 catalyst at 210 °C and at various reaction pressures (1–10 bar). A remarkable improvement in the catalytic performance and a significant shortening of the induction period were found with an increase in pressure. At a pressure of 6 bar, the highest toluene conversion of 75 % and 100 % selectivity for Benzyl Acetate were observed. This result could be due to both the restructuring of the catalyst surface and to the formation of active PdSb particles of desired size, composition, and shape during the course of the induction period. Samples of the most-active and spent catalysts were studied by ex situ and in situ XRD, XPS, and TEM.
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Palladium-catalysed vapour phase aerobic acetoxylation of toluene to Benzyl Acetate
Catalysis Today, 2009Co-Authors: V. Narayana Kalevaru, Abdohadi Benhmid, Jörg Radnik, Bernhard Lücke, M.-m. Pohl, Andreas MartinAbstract:Abstract Supported Pd–Sb acetoxylation catalysts with different Pd and Sb amounts as well as varying supports were prepared by impregnation technique. The contents of Pd and Sb are varied over a wide range, for instance Pd is varied from 0.5 to 20 wt% by keeping Sb content at 8 wt%. In a similar way, Sb content is varied from 4 to 20 wt% by keeping Pd loading constant at 10 wt%. Four different supports such as TiO2, γ-Al2O3, SiO2 and ZrO2 are applied at constant Pd (10 wt%) and Sb (8 wt%) contents. Catalytic performance of these solids is evaluated for the gas phase acetoxylation of toluene to Benzyl Acetate (BA) at T = 210 °C and p = 2 bar. XPS revealed a considerable loss of both Pd and Sb in the near-surface region in the used catalysts. TEM showed that Pd particles exhibit spherical morphology and their size increased dramatically in the spent catalysts compared to their corresponding fresh ones. Monometallic catalysts showed very poor acetoxylation performance but high total oxidation, which results in an increase of the yield of COx up to ca. 50%. However, combination of both Pd and Sb was found to suppress total oxidation and thereby enhance the acetoxylation performance with high BA selectivity of ≥85%. Catalytic activity was observed to increase continuously with increase in Pd loading. The catalyst with the highest Pd loading (20 wt% Pd) displayed the best performance (toluene conversion = > 90%, BA yield = > 75%). The activity is however decreasing with time-on-stream due to coke deposits. Nevertheless, the deactivated samples can be regenerated in air to restore their maximum activity. Nature of support, content of co-components showed strong influence on the catalytic performance.
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direct synthesis of Benzyl Acetate and optimisation of reaction conditions for the gas phase acetoxylation of toluene
Catalysis Today, 2006Co-Authors: Abdohadi Benhmid, Bernhard Lücke, Andreas Martin, K. V. Narayana, M.-m. PohlAbstract:Abstract TiO2 supported Pd-Sb catalysts were prepared by impregnation method and tested for the selective vapour phase acetoxylation of toluene to Benzyl Acetate (BA). Investigations were carried out to optimise reaction variables such as effects of reaction temperature, acetic acid/toluene mole ratio, O2/toluene mole ratio, contact time, etc. to obtain better performance of the catalysts. Additionally, the influence of Sb/Pd ratio on catalytic performance was also checked under optimised reaction conditions. The activity of the catalysts was found to increase continuously with increasing Sb/Pd ratio up to 0.7 and then decreased with further increase in Sb/Pd ratio to 1.75. The catalyst with Sb/Pd ratio of 0.7 exhibited the best performance among all other catalysts of this series giving a conversion of toluene as high as ca. 68% with BA selectivity of 85%. All these catalysts were observed to deactivate with time on stream due to considerable amount of coke deposition. However, these catalysts can be regenerated in air and reused for more number of cycles with consistent performance.
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Highly efficient Pd–Sb–TiO2 catalysts for the vapour phase acetoxylation of toluene to Benzyl Acetate
Journal of Catalysis, 2005Co-Authors: Abdohadi Benhmid, Jörg Radnik, Bernhard Lücke, M.-m. Pohl, Andreas Martin, K. V. Narayana, S. Bischoff, Matthias SchneiderAbstract:Abstract A series of Pd–Sb–TiO 2 (anatase) catalysts has been prepared over a wide range of Pd loadings from 0.5 to 20 wt% and tested for the selective vapour-phase acetoxylation of toluene to Benzyl Acetate at a reaction temperature of 210 °C and a pressure of 2 bar. The catalysts were characterised by nitrogen adsorption, XRD, XPS, and TEM. The BET surface areas and pore volumes were observed to decrease considerably with increasing Pd content of the catalysts. XPS revealed that there is loss of both Pd and Sb in the surface region in the used catalysts. The particle size of Pd (measured by TEM) is found to increase dramatically in the used catalysts compared with the fresh ones. Pd particle size is observed to exhibit a strong influence on the catalytic performance of the catalysts. The activity of the catalysts was found to increase continuously with increasing Pd loading, which is associated with an increase in the Pd particle size of the catalysts. The catalyst with 20 wt% Pd has been found to display the best performance, giving conversion of toluene as high as ca. 92 mol% with a Benzyl Acetate selectivity of 85%. Nevertheless, the solids were observed to deactivate with time on stream due to a considerable amount of coke deposition on the surface. However, the catalysts can be regenerated in air and reused for more number of cycles with consistent performance.
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highly active and selective pd cu tio2 catalyst for the direct synthesis of Benzyl Acetate by gas phase acetoxylation of toluene
Chemistry Letters, 2004Co-Authors: Abdohadi Benhmid, Bernhard Lücke, Andreas Martin, K. V. Narayana, Margamartina PohlAbstract:Extremely high Benzyl Acetate selectivity (ca. 94%) at a toluene conversion of ca. 60% was achieved over Pd-Cu-TiO 2 catalyst for the first time by gas phase acetoxylation of toluene with good long-term stability.
Abdohadi Benhmid - One of the best experts on this subject based on the ideXlab platform.
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Palladium-catalysed vapour phase aerobic acetoxylation of toluene to Benzyl Acetate
Catalysis Today, 2009Co-Authors: V. Narayana Kalevaru, Abdohadi Benhmid, Jörg Radnik, Bernhard Lücke, M.-m. Pohl, Andreas MartinAbstract:Abstract Supported Pd–Sb acetoxylation catalysts with different Pd and Sb amounts as well as varying supports were prepared by impregnation technique. The contents of Pd and Sb are varied over a wide range, for instance Pd is varied from 0.5 to 20 wt% by keeping Sb content at 8 wt%. In a similar way, Sb content is varied from 4 to 20 wt% by keeping Pd loading constant at 10 wt%. Four different supports such as TiO2, γ-Al2O3, SiO2 and ZrO2 are applied at constant Pd (10 wt%) and Sb (8 wt%) contents. Catalytic performance of these solids is evaluated for the gas phase acetoxylation of toluene to Benzyl Acetate (BA) at T = 210 °C and p = 2 bar. XPS revealed a considerable loss of both Pd and Sb in the near-surface region in the used catalysts. TEM showed that Pd particles exhibit spherical morphology and their size increased dramatically in the spent catalysts compared to their corresponding fresh ones. Monometallic catalysts showed very poor acetoxylation performance but high total oxidation, which results in an increase of the yield of COx up to ca. 50%. However, combination of both Pd and Sb was found to suppress total oxidation and thereby enhance the acetoxylation performance with high BA selectivity of ≥85%. Catalytic activity was observed to increase continuously with increase in Pd loading. The catalyst with the highest Pd loading (20 wt% Pd) displayed the best performance (toluene conversion = > 90%, BA yield = > 75%). The activity is however decreasing with time-on-stream due to coke deposits. Nevertheless, the deactivated samples can be regenerated in air to restore their maximum activity. Nature of support, content of co-components showed strong influence on the catalytic performance.
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direct synthesis of Benzyl Acetate and optimisation of reaction conditions for the gas phase acetoxylation of toluene
Catalysis Today, 2006Co-Authors: Abdohadi Benhmid, Bernhard Lücke, Andreas Martin, K. V. Narayana, M.-m. PohlAbstract:Abstract TiO2 supported Pd-Sb catalysts were prepared by impregnation method and tested for the selective vapour phase acetoxylation of toluene to Benzyl Acetate (BA). Investigations were carried out to optimise reaction variables such as effects of reaction temperature, acetic acid/toluene mole ratio, O2/toluene mole ratio, contact time, etc. to obtain better performance of the catalysts. Additionally, the influence of Sb/Pd ratio on catalytic performance was also checked under optimised reaction conditions. The activity of the catalysts was found to increase continuously with increasing Sb/Pd ratio up to 0.7 and then decreased with further increase in Sb/Pd ratio to 1.75. The catalyst with Sb/Pd ratio of 0.7 exhibited the best performance among all other catalysts of this series giving a conversion of toluene as high as ca. 68% with BA selectivity of 85%. All these catalysts were observed to deactivate with time on stream due to considerable amount of coke deposition. However, these catalysts can be regenerated in air and reused for more number of cycles with consistent performance.
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Highly efficient Pd–Sb–TiO2 catalysts for the vapour phase acetoxylation of toluene to Benzyl Acetate
Journal of Catalysis, 2005Co-Authors: Abdohadi Benhmid, Jörg Radnik, Bernhard Lücke, M.-m. Pohl, Andreas Martin, K. V. Narayana, S. Bischoff, Matthias SchneiderAbstract:Abstract A series of Pd–Sb–TiO 2 (anatase) catalysts has been prepared over a wide range of Pd loadings from 0.5 to 20 wt% and tested for the selective vapour-phase acetoxylation of toluene to Benzyl Acetate at a reaction temperature of 210 °C and a pressure of 2 bar. The catalysts were characterised by nitrogen adsorption, XRD, XPS, and TEM. The BET surface areas and pore volumes were observed to decrease considerably with increasing Pd content of the catalysts. XPS revealed that there is loss of both Pd and Sb in the surface region in the used catalysts. The particle size of Pd (measured by TEM) is found to increase dramatically in the used catalysts compared with the fresh ones. Pd particle size is observed to exhibit a strong influence on the catalytic performance of the catalysts. The activity of the catalysts was found to increase continuously with increasing Pd loading, which is associated with an increase in the Pd particle size of the catalysts. The catalyst with 20 wt% Pd has been found to display the best performance, giving conversion of toluene as high as ca. 92 mol% with a Benzyl Acetate selectivity of 85%. Nevertheless, the solids were observed to deactivate with time on stream due to a considerable amount of coke deposition on the surface. However, the catalysts can be regenerated in air and reused for more number of cycles with consistent performance.
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highly active and selective pd cu tio2 catalyst for the direct synthesis of Benzyl Acetate by gas phase acetoxylation of toluene
Chemistry Letters, 2004Co-Authors: Abdohadi Benhmid, Bernhard Lücke, Andreas Martin, K. V. Narayana, Margamartina PohlAbstract:Extremely high Benzyl Acetate selectivity (ca. 94%) at a toluene conversion of ca. 60% was achieved over Pd-Cu-TiO 2 catalyst for the first time by gas phase acetoxylation of toluene with good long-term stability.
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One-step synthesis of Benzyl Acetate by gas phase acetoxylation of toluene over highly active and selective Pd–Sb–TiO2 catalysts
Chemical communications (Cambridge England), 2004Co-Authors: Abdohadi Benhmid, Andreas Martin, K. V. Narayana, Bernhard LückeAbstract:Significantly high Benzyl Acetate selectivity of 85% at a toluene conversion of ca. 93% was achieved for the first time in a single step by gas phase acetoxylation over highly active and selective Pd–Sb–TiO2 catalysts.