The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Siegfried Blechert - One of the best experts on this subject based on the ideXlab platform.
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unexpected results of a Turnover Number ton study utilising ruthenium based olefin metathesis catalysts
Advanced Synthesis & Catalysis, 2005Co-Authors: Simon Maechling, Mirko Zaja, Siegfried BlechertAbstract:A Turnover Number (TON) study of ruthenium-based metathesis catalysts has been conducted for ring-closing metathesis (RCM) in dilute solution. Unexpectedly the results indicate that 1 s t generation metathesis catalysts can give higher TON in RCM of simple unsubstituted terminal olefins than their second generation counterparts. In particular, the 1 s t generation Hoveyda-Grubbs catalyst showed unexpectedly high activity, particularly when compared to the 2 n d generation catalysts.
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Unexpected Results of a Turnover Number (TON) Study Utilising Ruthenium‐Based Olefin Metathesis Catalysts
Advanced Synthesis & Catalysis, 2005Co-Authors: Simon Maechling, Mirko Zaja, Siegfried BlechertAbstract:A Turnover Number (TON) study of ruthenium-based metathesis catalysts has been conducted for ring-closing metathesis (RCM) in dilute solution. Unexpectedly the results indicate that 1 s t generation metathesis catalysts can give higher TON in RCM of simple unsubstituted terminal olefins than their second generation counterparts. In particular, the 1 s t generation Hoveyda-Grubbs catalyst showed unexpectedly high activity, particularly when compared to the 2 n d generation catalysts.
Simon Maechling - One of the best experts on this subject based on the ideXlab platform.
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unexpected results of a Turnover Number ton study utilising ruthenium based olefin metathesis catalysts
Advanced Synthesis & Catalysis, 2005Co-Authors: Simon Maechling, Mirko Zaja, Siegfried BlechertAbstract:A Turnover Number (TON) study of ruthenium-based metathesis catalysts has been conducted for ring-closing metathesis (RCM) in dilute solution. Unexpectedly the results indicate that 1 s t generation metathesis catalysts can give higher TON in RCM of simple unsubstituted terminal olefins than their second generation counterparts. In particular, the 1 s t generation Hoveyda-Grubbs catalyst showed unexpectedly high activity, particularly when compared to the 2 n d generation catalysts.
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Unexpected Results of a Turnover Number (TON) Study Utilising Ruthenium‐Based Olefin Metathesis Catalysts
Advanced Synthesis & Catalysis, 2005Co-Authors: Simon Maechling, Mirko Zaja, Siegfried BlechertAbstract:A Turnover Number (TON) study of ruthenium-based metathesis catalysts has been conducted for ring-closing metathesis (RCM) in dilute solution. Unexpectedly the results indicate that 1 s t generation metathesis catalysts can give higher TON in RCM of simple unsubstituted terminal olefins than their second generation counterparts. In particular, the 1 s t generation Hoveyda-Grubbs catalyst showed unexpectedly high activity, particularly when compared to the 2 n d generation catalysts.
Mirko Zaja - One of the best experts on this subject based on the ideXlab platform.
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unexpected results of a Turnover Number ton study utilising ruthenium based olefin metathesis catalysts
Advanced Synthesis & Catalysis, 2005Co-Authors: Simon Maechling, Mirko Zaja, Siegfried BlechertAbstract:A Turnover Number (TON) study of ruthenium-based metathesis catalysts has been conducted for ring-closing metathesis (RCM) in dilute solution. Unexpectedly the results indicate that 1 s t generation metathesis catalysts can give higher TON in RCM of simple unsubstituted terminal olefins than their second generation counterparts. In particular, the 1 s t generation Hoveyda-Grubbs catalyst showed unexpectedly high activity, particularly when compared to the 2 n d generation catalysts.
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Unexpected Results of a Turnover Number (TON) Study Utilising Ruthenium‐Based Olefin Metathesis Catalysts
Advanced Synthesis & Catalysis, 2005Co-Authors: Simon Maechling, Mirko Zaja, Siegfried BlechertAbstract:A Turnover Number (TON) study of ruthenium-based metathesis catalysts has been conducted for ring-closing metathesis (RCM) in dilute solution. Unexpectedly the results indicate that 1 s t generation metathesis catalysts can give higher TON in RCM of simple unsubstituted terminal olefins than their second generation counterparts. In particular, the 1 s t generation Hoveyda-Grubbs catalyst showed unexpectedly high activity, particularly when compared to the 2 n d generation catalysts.
Feng Deng - One of the best experts on this subject based on the ideXlab platform.
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boosting the Turnover Number of core shell al zsm 5 b zsm 5 zeolite for methanol to propylene reaction by modulating its gradient acid site distribution and low consumption diffusion
Catalysis Science & Technology, 2019Co-Authors: Yanliang Zhai, Shaolong Zhang, Yunshan Shang, Yu Song, Wenxuan Wang, Luoming Zhang, Yanjun Gong, Feng DengAbstract:Herein, a specific core–shell MFI zeolite was designed for the methanol to propylene (MTP) reaction. The core–shell structure of Al-ZSM-5@B-ZSM-5 and Al-ZSM-5@silicalite-1 were easily obtained via a two-step procedure, in which Al-ZSM-5 aggregate acted as the core and B-ZSM-5 or silicalite-1 as the shell. Their core–shell structures, acidity distribution and pore properties were characterized systemically, and new insights were gained into the synergetic effect of acid property and diffusion on the MTP reaction. The Al-ZSM-5@B-ZSM-5 zeolite exhibited a superior catalytic performance with a lifetime of 350 h (WHSV = 3 h−1), propylene selectivity of 49% and high Turnover Number of 4.3 × 106, while for the Al-ZSM-5 core, the corresponding values were 210 h, 43% and 5.2 × 105, respectively. Al-ZSM-5@silicalite-1 displayed the second best performance with the values of 250 h, 45% and 2.9 × 106, respectively. Gradient strong acid reduction from the core to the shell via the epitaxial growth of the silicalite-1 or B-ZSM-5 shell combined with an appropriate strong/weak acid ratio plays a vital role in inhibiting the hydrogen transfer reaction and thus gives a low consumption of propylene and low coke deposition. For the hydrogen transfer reaction of alkenes to form alkanes and aromatics, strong acid sites are required. Moreover, the acid sites originally existing on the external surface of the Al-ZSM-5 core were converted into internal acid sites due to the formation of an interface zone in the core–shell zeolite, possessing micropore characteristics, which in turn improve the shape selectivity and suppress coke deposition. Especially, the Al-ZSM-5@B-ZSM-5 zeolite displayed more weak acid sites and few strong acid sites on its shell surface, which are beneficial for the low formation of external coke and also account for the highest utilization of acid sites in the MTP reaction, high propylene selectivity and long lifetime.
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Boosting the Turnover Number of core–shell Al-ZSM-5@B-ZSM-5 zeolite for methanol to propylene reaction by modulating its gradient acid site distribution and low consumption diffusion
Catalysis Science & Technology, 2019Co-Authors: Yanliang Zhai, Shaolong Zhang, Yunshan Shang, Yu Song, Wenxuan Wang, Luoming Zhang, Yanjun Gong, Feng DengAbstract:Herein, a specific core–shell MFI zeolite was designed for the methanol to propylene (MTP) reaction. The core–shell structure of Al-ZSM-5@B-ZSM-5 and Al-ZSM-5@silicalite-1 were easily obtained via a two-step procedure, in which Al-ZSM-5 aggregate acted as the core and B-ZSM-5 or silicalite-1 as the shell. Their core–shell structures, acidity distribution and pore properties were characterized systemically, and new insights were gained into the synergetic effect of acid property and diffusion on the MTP reaction. The Al-ZSM-5@B-ZSM-5 zeolite exhibited a superior catalytic performance with a lifetime of 350 h (WHSV = 3 h−1), propylene selectivity of 49% and high Turnover Number of 4.3 × 106, while for the Al-ZSM-5 core, the corresponding values were 210 h, 43% and 5.2 × 105, respectively. Al-ZSM-5@silicalite-1 displayed the second best performance with the values of 250 h, 45% and 2.9 × 106, respectively. Gradient strong acid reduction from the core to the shell via the epitaxial growth of the silicalite-1 or B-ZSM-5 shell combined with an appropriate strong/weak acid ratio plays a vital role in inhibiting the hydrogen transfer reaction and thus gives a low consumption of propylene and low coke deposition. For the hydrogen transfer reaction of alkenes to form alkanes and aromatics, strong acid sites are required. Moreover, the acid sites originally existing on the external surface of the Al-ZSM-5 core were converted into internal acid sites due to the formation of an interface zone in the core–shell zeolite, possessing micropore characteristics, which in turn improve the shape selectivity and suppress coke deposition. Especially, the Al-ZSM-5@B-ZSM-5 zeolite displayed more weak acid sites and few strong acid sites on its shell surface, which are beneficial for the low formation of external coke and also account for the highest utilization of acid sites in the MTP reaction, high propylene selectivity and long lifetime.
Bhalchandra M. Bhanage - One of the best experts on this subject based on the ideXlab platform.
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Palladacycle-Catalyzed Carbonylative Suzuki—Miyaura Coupling with High Turnover Number and Turnover Frequency.
ChemInform, 2015Co-Authors: Prashant Gautam, Bhalchandra M. BhanageAbstract:This work reports the carbonylative Suzuki–Miyaura coupling of aryl iodides catalyzed by palladacycles. More importantly, the palladacycles have been used to generate high Turnover Numbers (TON’s) and Turnover frequencies (TOF’s). A range of aryl iodides can be coupled with arylboronic acids, generating TON’s in the range of 106 to 107 and TOF’s in the range of 105 to 106 h–1. Comparison of the palladacycles with a conventional palladium source shows their superiority in generating high TON’s and TOF’s.
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palladacycle catalyzed carbonylative suzuki miyaura coupling with high Turnover Number and Turnover frequency
Journal of Organic Chemistry, 2015Co-Authors: Prashant Gautam, Bhalchandra M. BhanageAbstract:This work reports the carbonylative Suzuki–Miyaura coupling of aryl iodides catalyzed by palladacycles. More importantly, the palladacycles have been used to generate high Turnover Numbers (TON’s) and Turnover frequencies (TOF’s). A range of aryl iodides can be coupled with arylboronic acids, generating TON’s in the range of 106 to 107 and TOF’s in the range of 105 to 106 h–1. Comparison of the palladacycles with a conventional palladium source shows their superiority in generating high TON’s and TOF’s.
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Palladacycle-Catalyzed Carbonylative Suzuki–Miyaura Coupling with High Turnover Number and Turnover Frequency
2015Co-Authors: Prashant Gautam, Bhalchandra M. BhanageAbstract:This work reports the carbonylative Suzuki–Miyaura coupling of aryl iodides catalyzed by palladacycles. More importantly, the palladacycles have been used to generate high Turnover Numbers (TON’s) and Turnover frequencies (TOF’s). A range of aryl iodides can be coupled with arylboronic acids, generating TON’s in the range of 106 to 107 and TOF’s in the range of 105 to 106 h–1. Comparison of the palladacycles with a conventional palladium source shows their superiority in generating high TON’s and TOF’s
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Chemical Fixation of Carbon Dioxide to Propylene Carbonate Using Smectite Catalysts with High Activity and Selectivity
Catalysis Letters, 2002Co-Authors: Shin-ichiro Fujita, Bhalchandra M. Bhanage, Yutaka Ikushima, Masayuki Shirai, Kazuo Torii, Masahiko AraiAbstract:The reaction of propylene oxide and carbon dioxide to propylene carbonate was carried out using Mg-, Ni- and Mg-Ni-containing smectite catalysts which contain different amounts of alkali atoms such as sodium, potassium and lithium. These catalysts are highly active and selective for this reaction. The catalytic activity strongly depends on the elemental composition of the catalyst used. Particularly the amount of alkali atoms incorporated in the catalyst is the most important factor governing the catalytic performance. The most active catalyst among those prepared in the present study shows a Turnover Number of 105 mmol/g for the propylene carbonate formation, which is the highest Turnover Number compared with those reported so far (10 mmol/g) for the title reaction.
