Titanium Complexes of Silicon-Bridged Cyclopentadienyl−Phenoxy Ligands Modified with Fused-Thiophene: Synthesis, Characterization, and Their Catalytic Performance in Copolymerization of Ethylene and 1-Hexene

2009 ◽  
Vol 28 (24) ◽  
pp. 6915-6926 ◽  
Author(s):  
Taichi Senda ◽  
Hidenori Hanaoka ◽  
Yoshiya Okado ◽  
Yoshiaki Oda ◽  
Hayato Tsurugi ◽  
...  
Keyword(s):  
Catalytic Performance ◽  
Titanium Complexes

Ligand Migration in the Reaction of Titanium Complexes with AlMe3

2007 ◽  
Vol 72 (4) ◽  
pp. 541-559 ◽  
Author(s):  
Michał J. Kobyłka ◽  
Lucjan B. Jerzykiewicz ◽  
Jasson T. Patton ◽  
Szymon Przybylak ◽  
Józef Utko ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Catalytic Performance ◽  
Active Species ◽  
Titanium Complexes ◽  
Propene Polymerization ◽  
Ligand Migration ◽  
High Yields ◽  
Titanium Compounds ◽  
Insight Into ◽  
Gaining Insight

Five different titanium compounds cis-[Ti(η2-hbo)2(OEt)2]·0.5toluene (1), cis-[TiCl2(η2-thp)2] (2), [TiCl2(edbp)2] (3), [Ti2(μ-OMe)2(edbp)2(Me)2] (6), [Ti2(μ-OMe)2(edbp)2(OMe)2] (7) (Hhbo = 2-(2-hydroxyfenyl)benzoxazole, Hthp = tetrahydropyran-2-methanol, H2edbp = 2,2'-ethylidenebis(4,6-di-tert-butylphenol)), have been prepared and tested in combination with MAO as catalysts for propene polymerization and ethene and oct-1-ene copolymerization with the aim of gaining insight into the structure of the active species. Investigation of the 1/AlMe3 or 2/AlMe3 systems resulted in isolation of [Al(η2-hbo)2(Me)] (4) and [Al2(μ2-η2-thp)2(Me)4] (5) in high yields. This indicates that the trimethylaluminum contained in MAO abstracts ligands from 1 or 2, affecting thus the catalytic performance of the 1,2/MAO catalysts. In contrast, compound 3 reacted with MAO affording methylated product 6. Accordingly, the 3/MAO catalyst differed from the above ones, furnishing at 70 °C e.g., narrow molecular weight polypropylene (Mn = 454 000; Mw/Mn = 2.49; Tm = 158.2 °C).

Novel titanium complexes bearing two chelating phenoxy-imine ligands and their catalytic performance for ethylene polymerization

2007 ◽  
Vol 21 (4) ◽  
pp. 268-274 ◽  
Author(s):  
Junquan Sun ◽  
Zhengzai Cheng ◽  
Yujing Nie ◽  
H. Schumann ◽  
M. Hummert
Keyword(s):  
Ethylene Polymerization ◽  
Catalytic Performance ◽  
Titanium Complexes ◽  
Imine Ligands

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

Optimizing electron density of nickel sulfide electrocatalysts through sulfur vacancy engineering for alkaline hydrogen evolution

2020 ◽  
Vol 8 (35) ◽  
pp. 18207-18214
Author(s):  
Dongbo Jia ◽  
Lili Han ◽  
Ying Li ◽  
Wenjun He ◽  
Caichi Liu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Electron Density ◽  
Rational Design ◽  
Nickel Sulfide ◽  
Catalytic Performance ◽  
Sulfide Catalysts ◽  
Sulfur Vacancy

A novel, rational design for porous S-vacancy nickel sulfide catalysts with remarkable catalytic performance for alkaline HER.

Catalytic Resonance Theory: Parallel Reaction Pathway Control

2019 ◽  
Author(s):  
M. Alexander Ardagh ◽  
Manish Shetty ◽  
Anatoliy Kuznetsov ◽  
Qi Zhang ◽  
Phillip Christopher ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Active Site ◽  
Active Sites ◽  
Reaction Pathway ◽  
Control Strategies ◽  
Oscillation Amplitude ◽  
Catalytic Performance ◽  
Parallel Reaction ◽  
Resonance Theory ◽  
Static Conditions

Catalytic enhancement of chemical reactions via heterogeneous materials occurs through stabilization of transition states at designed active sites, but dramatically greater rate acceleration on that same active site is achieved when the surface intermediates oscillate in binding energy. The applied oscillation amplitude and frequency can accelerate reactions orders of magnitude above the catalytic rates of static systems, provided the active site dynamics are tuned to the natural frequencies of the surface chemistry. In this work, differences in the characteristics of parallel reactions are exploited via selective application of active site dynamics (0 < ΔU < 1.0 eV amplitude, 10<sup>-6</sup> < f < 10<sup>4</sup> Hz frequency) to control the extent of competing reactions occurring on the shared catalytic surface. Simulation of multiple parallel reaction systems with broad range of variation in chemical parameters revealed that parallel chemistries are highly tunable in selectivity between either pure product, even when specific products are not selectively produced under static conditions. Two mechanisms leading to dynamic selectivity control were identified: (i) surface thermodynamic control of one product species under strong binding conditions, or (ii) catalytic resonance of the kinetics of one reaction over the other. These dynamic parallel pathway control strategies applied to a host of chemical conditions indicate significant potential for improving the catalytic performance of many important industrial chemical reactions beyond their existing static performance.

Fabrication and Excellent Catalytic Performance of Three-dimensional Ordered Mesoporous Molybdenum Oxides

2014 ◽  
Vol 29 (2) ◽  
pp. 124-130 ◽  
Author(s):  
Yu-Cheng DU ◽  
Guang-Wei ZHENG ◽  
Qi MENG ◽  
Li-Ping WANG ◽  
Hai-Guang FAN ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Catalytic Performance ◽  
Molybdenum Oxides ◽  
Ordered Mesoporous ◽  
Excellent Catalytic Performance
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