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Florence Epron - One of the best experts on this subject based on the ideXlab platform.
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Effect of the metallic particle size of supported Pt catalysts on Methylcyclopentane hydrogenolysis: Understanding of the ring opening products distribution by a geometric approach
Journal of Catalysis, 2018Co-Authors: Anthony Le Valant, Fabien Drault, Corentin Maleix, Clément Comminges, Romain Beauchet, Yann Batonneau, Laurence Pirault-roy, Catherine Especel, Florence EpronAbstract:Hydrogenolysis of Methylcyclopentane was studied in the presence of supported platinum catalysts, with particle sizes between 0.9 and 2.4 nm. The distribution of ring-opening products (n-hexane, 2-methylpentane, 3-methylpentane), which are virtually the only products at 573 K, mainly depended on the platinum particle size, with no effect of the Methylcyclopentane conversion. This distribution was well described by the selective or non-selective mechanisms previously proposed in the literature except for the smallest particles (d
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relationship between the structural properties of supported bimetallic pt rh catalysts and their performances for Methylcyclopentane ring opening
Journal of Catalysis, 2010Co-Authors: Petrisor Samoila, Catherine Especel, Florence Epron, M Boutzeloit, P MarecotAbstract:Abstract Bimetallic Pt–Rh catalysts supported on alumina and silica were synthesized either by the refilling method or by coimpregnation. They were characterized by transmission electron microscopy (TEM), H 2 chemisorption, temperature-programmed reduction (TPR), Fourier transform infrared (FTIR) of adsorbed CO and the test reaction of cyclohexane dehydrogenation. Varying the preparation procedure and the nature of the support leads to the formation of bimetallic Pt–Rh particles of different size in the range 1.2–2.7 nm. A Pt surface enrichment and the presence of a Pt–Rh alloy were detected by FTIR of adsorbed CO on the largest particles. The catalytic performances of the Pt–Rh systems were evaluated in Methylcyclopentane (MCP) ring opening (RO) under pressure (28.5 bar). All the bimetallic catalysts present an activity much higher than that of the Pt monometallic sample, close to that of the Rh one. At 300 °C, the turnover frequencies are the followings: 115 h −1 for Pt, 4094 h −1 for Rh, between 2264 and 5563 h −1 for the Pt–Rh catalysts whatever the preparation procedure and the nature of the support. On Pt–Rh samples presenting particles with large enough size (>1.7 nm), the RO selectivity at iso-conversion (>50%) is higher than those of monometallic Pt/Al 2 O 3 and Rh/Al 2 O 3 systems, reaching the performances of a monometallic iridium-based sample considered as the most selective catalyst in these conditions. Finally, the refilling method allows obtaining supported Pt–Rh catalysts with the structural properties required to obtain both high activity and RO selectivity during Methylcyclopentane hydrogenolysis.
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Selective ring-opening of Methylcyclopentane on platinum-based bimetallic catalysts
Applied Catalysis A-general, 2009Co-Authors: P. Samoila, Catherine Especel, Florence Epron, M Boutzeloit, Patrice MarecotAbstract:Abstract Several monometallic catalysts supported on alumina were tested in Methylcyclopentane ring-opening under pressure. Among the monometallic catalysts tested (Ru, Re, Rh, Pt and Ir), iridium and rhodium catalysts were the most active but iridium was by far the most selective in ring-opening (RO) products (2-methylpentane, 3-methylpentane and n -hexane), the formation of C1–C5 products being negligible, as already reported in the literature. Thereafter, platinum-based bimetallic catalysts supported on alumina were prepared by redox surface reaction in order to favor the metal–metal interaction. The aim was to obtain bimetallic catalysts leading to selectivity towards RO products similar to that of the iridium catalyst. Two types of modifiers were studied, namely (i) inactive species such as copper and germanium and (ii) active promoters for hydrogenolysis reactions, such as ruthenium and rhodium. It was shown that with inactive metals, the parent platinum catalyst undergoes mainly a dilution of its active phase. An increase of the activity is observed for the Pt-Ru/Al 2 O 3 systems compared to the parent one, but also an increase of the C1–C5 products. On the contrary, the addition of Rh allowed us to increase the activity of the platinum parent catalyst and to obtain bimetallic catalysts with selectivity towards RO products similar to that obtained with iridium in same conditions.
Alan E Nelson - One of the best experts on this subject based on the ideXlab platform.
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characterization and evaluation of Methylcyclopentane and cyclohexane ring opening over ir zro2 moo3 catalysts
Catalysis Letters, 2008Co-Authors: Zhenhui Wang, Alan E NelsonAbstract:A series of Ir/ZrO2–MoO3 catalysts with different molybdenum concentrations and iridium loadings were synthesized and studied for ring opening of Methylcyclopentane and cyclohexane to n-hexane. X-ray photoelectron spectroscopy (XPS) indicated that molybdenum and zirconium were present mainly in the form of MoO3 and ZrO2, respectively, and temperature programmed desorption (TPD) indicated the acidity was strongly correlated to the MoO3 content. Iridium was incorporated by wet impregnation to a desired loading of 30 and 300 ppmw with the concentration verified by instrumental neutron activation analysis (INAA). The vapor phase conversion of Methylcyclopentane and the liquid phase conversion of cyclohexane were subsequently studied to determine catalytic activity and selectivity. The Ir/ZrO2–MoO3 catalyst with 3.5 at.% molybdenum and 30 ppmw iridium produced an overall relatively high activity and selectivity for the conversion of cyclohexane to n-hexane.
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characterization of monofunctional zro2 moo3 catalysts for Methylcyclopentane conversion
Thermochimica Acta, 2005Co-Authors: Carolyn Kenney, Yadollah Maham, Alan E NelsonAbstract:Abstract A series of ZrO 2 –MoO 3 catalysts with different molybdenum loadings (0–18.7 at.% Mo) prepared by co-precipitation were characterized and evaluated for their performance for Methylcyclopentane (mcp) conversion. The dependence of Mo content on the crystallinity, surface area, and acidic properties of ZrO 2 –MoO 3 is studied and evaluated as a function of molybdenum loading. The monoclinic phase is observed at low Mo loadings, with the tetragonal polymorph of ZrO 2 effectively stabilized at higher Mo loadings. The surface area of ZrO 2 –MoO 3 increases with molybdenum content to a maximum value of 124 m 2 g −1 at a loading of 15.8 at.% Mo, followed by a decrease at higher Mo loadings. Isothermal CO 2 adsorption and ammonia TPD results indicate the strength of basic sites and specific NH 3 desorption decreases with increasing molybdenum content, while TPR indicates ZrO 2 –MoO 3 catalysts are more easily reduced with increasing molybdenum loading. The most active catalyst for mcp conversion (36% conversion) corresponds to a molybdenum loading of 3.2 at.% Mo, which has the highest acidity per surface area of the ZrO 2 –MoO 3 catalysts studied.
Chul Wee Lee - One of the best experts on this subject based on the ideXlab platform.
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catalytic selective ring opening of Methylcyclopentane in the presence of co2
Fuel Processing Technology, 2014Co-Authors: Dipali P Upare, Chul Wee LeeAbstract:Abstract Simple and highly efficient approach for the utilization of carbon dioxide (CO 2 ) in selective ring opening (SRO) of Methylcyclopentane (MCP) over 0.9 wt.% Ir/USY catalyst is described. Ring opening products such as n -hexane, 2-MP and 3-MP were formed during the SRO of MCP in the presence of CO 2 . The influence of CO 2 pressure on the total conversion and ring opening (RO) product selectivity was examined, which highlights the great potential of CO 2 utilization in petroleum industry for SRO process.
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selective ring opening of Methylcyclopentane and methylcyclohexane over iridium bifunctional catalysts supported on surface modified γ al 2 o 3 sio 2 and ultra stable y zeolites
Catalysis Letters, 2011Co-Authors: Nageswara R Rao, Nansuk You, Songhun Yoon, Dipali Pravin Upare, Yongki Park, Chul Wee LeeAbstract:Selective ring opening of Methylcyclopentane (MCP) and methylcyclohexane (MCH) over a series of Iridium catalysts supported on γ-alumina, silica and ultra-stable Y (USY) zeolites was investigated. The acid density of the supports was modified by co impregnation of potassium in small quantities and its effect on conversion, yield and selectivity was evaluated. USY zeolites showed 26.9–38.1 and 27.5–33.7% of conversion with ring opening selectivities between 56.4–63.8 and 94.3–97.7% for MCP and MCH, respectively. Whereas on silica, the conversions were 10.7–16.6 and 10.4–14.0% with 96.9–99.0 and 93.3–99.1% selectivity. Interestingly, potassium acted as a promoter in case of USY zeolites while suppressed of activity of Ir supported on γ-alumina and silica. The reaction conditions such as temperature, pressure, contact time and the feed/catalyst ratio were optimized. The evaluation of catalysts’ activity and selectivity towards ring opening of MCP and MCH is of great importance in understanding which catalyst modification could be effective in treatment of gasoline/diesel feed stocks for improving octane/cetane rating and fuel quality. Selective ring opening of Methylcyclopentane and methylcyclohexane over a series of Iridium catalysts supported on surface modified by co impregnation of potassium of γ-alumina, silica and USY zeolites was investigated and its effect on conversion, yield and selectivity was evaluated.
J Perezramirez - One of the best experts on this subject based on the ideXlab platform.
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hydrogenolysis of Methylcyclopentane over the bimetallic ir au γ al2o3 catalysts
Applied Surface Science, 2007Co-Authors: R J Chimentao, Gustavo Paim Valenca, Francesc Medina, J PerezramirezAbstract:Abstract The gas-phase hydrogenolysis of Methylcyclopentane (MCP) was investigated over the bimetallic Ir–Au/γ-Al 2 O 3 catalysts. The bimetallic systems containing the atomic Au/Ir ratios in the range of 0.125–8 and a fixed total metal content of 8 wt.%, were prepared by the sequential impregnation (SI) and co-impregnation (CI) methods. The corresponding monometallic Ir/γ-Al 2 O 3 and Au/γ-Al 2 O 3 catalysts were also prepared. The materials were characterized by ICP, XRD, N 2 adsorption, TEM, and H 2 chemisorption. Highly dispersed Ir nanoparticles were obtained in all cases, while the size of Au nanoparticles increased (up to 50 nm) upon the increasing Au content in the catalyst. The monometallic gold catalyst did not adsorb H 2 . The incorporation of Au increased the amount of irreversible adsorbed H 2 in the Ir–Au/γ-Al 2 O 3 catalysts with respect to the monometallic ones. The products obtained in the MCP hydrogenolysis were 2-methylpentane (2-MP), 3-methylpentane (3-MP) and n -hexane ( n -H). The initial rate (molecules of MCP reacted s −1 g Ir −1 ) increased with the Au content. The deactivation was lower for bimetallic catalysts, particularly for the CI ones. The addition of Au played a significant effect on chemisorption and catalytic properties of Ir.
Catherine Especel - One of the best experts on this subject based on the ideXlab platform.
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Effect of the metallic particle size of supported Pt catalysts on Methylcyclopentane hydrogenolysis: Understanding of the ring opening products distribution by a geometric approach
Journal of Catalysis, 2018Co-Authors: Anthony Le Valant, Fabien Drault, Corentin Maleix, Clément Comminges, Romain Beauchet, Yann Batonneau, Laurence Pirault-roy, Catherine Especel, Florence EpronAbstract:Hydrogenolysis of Methylcyclopentane was studied in the presence of supported platinum catalysts, with particle sizes between 0.9 and 2.4 nm. The distribution of ring-opening products (n-hexane, 2-methylpentane, 3-methylpentane), which are virtually the only products at 573 K, mainly depended on the platinum particle size, with no effect of the Methylcyclopentane conversion. This distribution was well described by the selective or non-selective mechanisms previously proposed in the literature except for the smallest particles (d
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relationship between the structural properties of supported bimetallic pt rh catalysts and their performances for Methylcyclopentane ring opening
Journal of Catalysis, 2010Co-Authors: Petrisor Samoila, Catherine Especel, Florence Epron, M Boutzeloit, P MarecotAbstract:Abstract Bimetallic Pt–Rh catalysts supported on alumina and silica were synthesized either by the refilling method or by coimpregnation. They were characterized by transmission electron microscopy (TEM), H 2 chemisorption, temperature-programmed reduction (TPR), Fourier transform infrared (FTIR) of adsorbed CO and the test reaction of cyclohexane dehydrogenation. Varying the preparation procedure and the nature of the support leads to the formation of bimetallic Pt–Rh particles of different size in the range 1.2–2.7 nm. A Pt surface enrichment and the presence of a Pt–Rh alloy were detected by FTIR of adsorbed CO on the largest particles. The catalytic performances of the Pt–Rh systems were evaluated in Methylcyclopentane (MCP) ring opening (RO) under pressure (28.5 bar). All the bimetallic catalysts present an activity much higher than that of the Pt monometallic sample, close to that of the Rh one. At 300 °C, the turnover frequencies are the followings: 115 h −1 for Pt, 4094 h −1 for Rh, between 2264 and 5563 h −1 for the Pt–Rh catalysts whatever the preparation procedure and the nature of the support. On Pt–Rh samples presenting particles with large enough size (>1.7 nm), the RO selectivity at iso-conversion (>50%) is higher than those of monometallic Pt/Al 2 O 3 and Rh/Al 2 O 3 systems, reaching the performances of a monometallic iridium-based sample considered as the most selective catalyst in these conditions. Finally, the refilling method allows obtaining supported Pt–Rh catalysts with the structural properties required to obtain both high activity and RO selectivity during Methylcyclopentane hydrogenolysis.
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Selective ring-opening of Methylcyclopentane on platinum-based bimetallic catalysts
Applied Catalysis A-general, 2009Co-Authors: P. Samoila, Catherine Especel, Florence Epron, M Boutzeloit, Patrice MarecotAbstract:Abstract Several monometallic catalysts supported on alumina were tested in Methylcyclopentane ring-opening under pressure. Among the monometallic catalysts tested (Ru, Re, Rh, Pt and Ir), iridium and rhodium catalysts were the most active but iridium was by far the most selective in ring-opening (RO) products (2-methylpentane, 3-methylpentane and n -hexane), the formation of C1–C5 products being negligible, as already reported in the literature. Thereafter, platinum-based bimetallic catalysts supported on alumina were prepared by redox surface reaction in order to favor the metal–metal interaction. The aim was to obtain bimetallic catalysts leading to selectivity towards RO products similar to that of the iridium catalyst. Two types of modifiers were studied, namely (i) inactive species such as copper and germanium and (ii) active promoters for hydrogenolysis reactions, such as ruthenium and rhodium. It was shown that with inactive metals, the parent platinum catalyst undergoes mainly a dilution of its active phase. An increase of the activity is observed for the Pt-Ru/Al 2 O 3 systems compared to the parent one, but also an increase of the C1–C5 products. On the contrary, the addition of Rh allowed us to increase the activity of the platinum parent catalyst and to obtain bimetallic catalysts with selectivity towards RO products similar to that obtained with iridium in same conditions.
