scholarly journals Comparison of the catalytic activity for the Suzuki–Miyaura reaction of (η5-Cp)Pd(IPr)Cl with (η3-cinnamyl)Pd(IPr)(Cl) and (η3-1-t-Bu-indenyl)Pd(IPr)(Cl)

2015 ◽  
Vol 11 ◽  
pp. 2476-2486 ◽  
Author(s):  
Patrick R Melvin ◽  
Nilay Hazari ◽  
Hannah M C Lant ◽  
Ian L Peczak ◽  
Hemali P Shah
Keyword(s):  
Catalytic Activity ◽  
Comparative Studies ◽  
Active Species ◽  
Highly Active ◽  
Supported Pd

Complexes of the type (η3-allyl)Pd(L)(Cl) and (η3-indenyl)Pd(L)(Cl) are highly active precatalysts for the Suzuki–Miyaura reaction. Even though allyl and indenyl ligands are similar to cyclopentadienyl (Cp) ligands, there have been no detailed comparative studies exploring the activity of precatalysts of the type (η5-Cp)Pd(L)(Cl) for Suzuki–Miyaura reactions. Here, we compare the catalytic activity of (η5-Cp)Pd(IPr)(Cl) (IPr = 1,3-bis(2,6-diisopropylphenyl)-1,3-dihydro-2H-imidazol-2-ylidene, Cp) with two commercially available catalysts (η3-cinnamyl)Pd(IPr)(Cl) (Cin) and (η3-1-t-Bu-indenyl)Pd(IPr)(Cl) ( tBu Ind). We show that Cp gives slightly better catalytic activity than Cin, but significantly inferior activity than tBu Ind. This order of activity is rationalized by comparing the rates at which the precatalysts are activated to the monoligated Pd(0) active species along with the tendency of the starting precatalysts to comproportionate with monoligated Pd(0) to form inactive Pd(I) dimers. As part of this work the Cp supported Pd(I) dimer (μ-Cp)(μ-Cl)Pd2(IPr)2 (Cp Dim ) was synthesized and crystallographically characterized. It does not readily disproportionate to form monoligated Pd(0) and consequently Cp Dim is a poor catalyst for the Suzuki–Miyaura reaction.

Highly Active and Selective PtSnM1/γ-Al2O3 Catalyst for Direct Propane Dehydrogenation

2021 ◽  
Vol 43 (3) ◽  
pp. 342-342
Author(s):  
Arshid M Ali Arshid M Ali ◽  
Abdulrahim A Zahrani Abdulrahim A Zahrani ◽  
Muhammad A Daous Muhammad A Daous ◽  
Muhammad Umar Seetharamulu Podila and Lachezar A Petrov Muhammad Umar Seetharamulu Podila and Lachezar A Petrov
Keyword(s):  
Catalytic Activity ◽  
Coke Formation ◽  
Protective Layer ◽  
Catalytic Performance ◽  
Active Species ◽  
Propane Dehydrogenation ◽  
Propane Conversion ◽  
Feed Composition ◽  
Highly Active ◽  
Al2o3 Catalyst

This study is aimed to understand the role of alkaline earth elements (AEE) to the catalytic performance of PtSnM1/γ-Al2O3catalystfor the direct propane dehydrogenation (where M1 = Mg, Ca, Sr, Ba). All the catalysts were prepared by using wet impregnation.The overall catalytic performance of all the catalysts was studied at different reaction temperatures, feed composition ratios and GHSV. The best operating reaction conditions were575and#186;C, feed composition ratio of C3H8:H2:N2 = 1.0:0.5:5.5 and GHSV of 3800h-1. An optimal addition of “Ca” to PtSn//γ-Al2O3 catalyst, enhanced the catalytic activity of PtSnM1/γ-Al2O3 catalyst in comparison to other studied AEE. This catalyst had shown the highest propane conversion (~ 55.8 %) with 95.7 % propylene selectivity and least coke formation (7.11 mg.g-1h-1). In general, the increased catalytic activity of PtSnM1/γ-Al2O3 is attributed to the reduced coking extent during the reaction. In addition, the enhanced thermal stability of the PtSnCa/γ-Al2O3catalystis because of the protective layer betweenγ-Al2O3 and active metal, which allows the formation of active species such as PtSn, PtCa2 and Pt2Al phases?

Highly Active Oxygen Evolution Electrocatalysts Based on Cobalt Amide Imidate Imidazolate Frameworks

2019 ◽  
Author(s):  
Alberto Bucci ◽  
Suvendu Sekhar Mondal ◽  
Vlad Martin-Diaconescu ◽  
Alexandr Shafir ◽  
Julio Lloret-Fillol
Keyword(s):  
Particle Size ◽  
Catalytic Activity ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Solvothermal Method ◽  
Active Species ◽  
Active Oxygen ◽  
Ex Situ ◽  
Highly Active ◽  
Small Change

<p>A family of three imidazolate-based Co-MOFs, IFP-5, -8 and -10 (Imidazolate Framework Potsdam), with different peripheral group –R (-Me, -OMe and –OEt, respectively) have been synthesized by a solvothermal method and tested toward oxygen evolution reaction (OER). Remarkably, IFP-8 presents low overpotentials (319 mV at 10 mA/cm<sup>2</sup>, and 490 mV at 500 mA/cm<sup>2</sup>) and extraordinary stability during 120 h, even when used as a catalyst toward overall water splitting reaction. An integrated <i>ex-situ</i> spectroscopic study, based on PXRD, EXAFS, and ATR, allows the identification of the active species and the factors that rule the catalytic activity. Indeed, it was found that the performances are highly affected by the nature of the -R group, because this small change strongly influences the conversion of the initial MOF to the active species. As a consequence, the remarkable activity of IFP-8 can be ascribed to the formation of Co(O)OH phase of few nanometers particle size (3-10 nm) during the electrocatalytic oxygen evolution. </p>

Highly Active Oxygen Evolution Electrocatalysts Based on Cobalt Amide Imidate Imidazolate Frameworks

2019 ◽  
Author(s):  
Alberto Bucci ◽  
Suvendu Sekhar Mondal ◽  
Vlad Martin-Diaconescu ◽  
Alexandr Shafir ◽  
Julio Lloret-Fillol
Keyword(s):  
Particle Size ◽  
Catalytic Activity ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Solvothermal Method ◽  
Active Species ◽  
Active Oxygen ◽  
Ex Situ ◽  
Highly Active ◽  
Small Change

<p>A family of three imidazolate-based Co-MOFs, IFP-5, -8 and -10 (Imidazolate Framework Potsdam), with different peripheral group –R (-Me, -OMe and –OEt, respectively) have been synthesized by a solvothermal method and tested toward oxygen evolution reaction (OER). Remarkably, IFP-8 presents low overpotentials (319 mV at 10 mA/cm<sup>2</sup>, and 490 mV at 500 mA/cm<sup>2</sup>) and extraordinary stability during 120 h, even when used as a catalyst toward overall water splitting reaction. An integrated <i>ex-situ</i> spectroscopic study, based on PXRD, EXAFS, and ATR, allows the identification of the active species and the factors that rule the catalytic activity. Indeed, it was found that the performances are highly affected by the nature of the -R group, because this small change strongly influences the conversion of the initial MOF to the active species. As a consequence, the remarkable activity of IFP-8 can be ascribed to the formation of Co(O)OH phase of few nanometers particle size (3-10 nm) during the electrocatalytic oxygen evolution. </p>

Invasive species in the flora of Ukraine. I. The group of highly active species

Geo&Bio ◽  
2019 ◽  
Vol 2019 (17) ◽  
pp. 116-135 ◽  
Author(s):  
Vira V. Protopopova ◽  
◽  
Myroslav Shevera
Keyword(s):  
Invasive Species ◽  
Active Species ◽  
Highly Active

Deactivation of arenetitanium(II) bromoalane complexes in the cyclotrimerization of butadiene

1986 ◽  
Vol 51 (12) ◽  
pp. 2751-2759 ◽  
Author(s):  
Jindřich Poláček ◽  
Helena Antropiusová ◽  
Lidmila Petrusová ◽  
Karel Mach
Keyword(s):  
Catalytic Activity ◽  
Catalytic System ◽  
Model System ◽  
Highly Active ◽  
Catalytic Stability

The C6H6.Ti(II)(AlBr4)2 (Ib) catalyst deactivates during the butadiene cyclotrimerization to give a solid containing all titanium (mostly as TiBr3) and a mixture of AlBr3 and RAlBr2 compounds dissolved in benzene. The residual cationic catalytic activity of the deactivated Ib system is due to presence of AlBr3. In contrast to TiCl3, the deactivated Ib system and the model system TiBr3 + AlBr3 are not activated by the addition of EtAlCl2 in the presence of butadiene: the highly active benzenetitanium(II) system is re-constituted only after reduction of TiBr3 with Et3Al followed by the addition of EtAlCl2. The addition of Et2AlBr to Ib accelerates the deactivation of the system. Deactivation products of this system contain mainly Ti(II) species which forms benzenetitanium(II) catalytic system after addition of EtAlCl2. All the EtAlCl2 reactivated systems produce (Z, E, E)-1,5,9-cyclododecatriene with high catalytic stability and considerable selectivity (>90%). This behaviour points to the catalysis by benzenetitanium(II) chloroalane complexes containing only low amount of bromine atoms and ethyl groups.

scholarly journals ZnCDs/ZnO@ZIF-8 Zeolite Composites for the Photocatalytic Degradation of Tetracycline

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 934
Author(s):  
Yong Cheng ◽  
Xiuxiu Wang ◽  
Yu Mei ◽  
Dan Wang ◽  
Changchun Ji
Keyword(s):  
Catalytic Activity ◽  
Photocatalytic Degradation ◽  
Photocatalytic Performance ◽  
Active Species ◽  
Degradation Efficiency ◽  
Experimental Result ◽  
Porous Nanostructure ◽  
Resultant Material

Considering the photocatalytic performance of CDs, ZnO, and the unique porous nanostructure and stability of ZIF-8, we prepared ZnCDs/ZnO@ZIF-8 zeolite composites. The resultant material represented an enhanced ability for the photodegradation of TC compared with that of ZnCDs and ZnO. The photocatalytic degradation efficiency reached over 85%. The catalytic activity of the composites was maintained after four cycles. The experimental result indicated that ×O2 radical was the active species in the reaction.

Monodisperse-porous cerium oxide microspheres as a new support with appreciable catalytic activity for a composite catalyst in benzyl alcohol oxidation

2021 ◽  
Author(s):  
Kadriye Özlem Hamaloğlu ◽  
Rukiye Babacan Tosun ◽  
Serap Ulu ◽  
Hakan Kayi ◽  
Cengiz Kavaklı ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Benzyl Alcohol ◽  
Cerium Oxide ◽  
Sol Gel ◽  
Alcohol Oxidation ◽  
Pd Nanoparticles ◽  
Composite Catalyst ◽  
Benzyl Alcohol Oxidation ◽  
Supported Pd

A synergistic catalyst in the form of monodisperse-porous CeO2 microspheres supported Pd nanoparticles (Pd NPs) was synthesized. CeO2 microspheres 4 μm in size were obtained by a newly developed “sol-gel...

scholarly journals Highly Dispersed Pd Species Supported on CeO2 Catalyst for Lean Methane Combustion: The Effect of the Occurrence State of Surface Pd Species on the Catalytic Activity

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 772
Author(s):  
Yanxiong Liu ◽  
Changhua Hu ◽  
Longchun Bian
Keyword(s):  
Catalytic Activity ◽  
Oxygen Vacancies ◽  
Methane Combustion ◽  
Pd Nanoparticles ◽  
High Concentration ◽  
Ch4 Combustion ◽  
Highly Active ◽  
Δ Phase ◽  
Occurrence State ◽  
Comprehensive Characterization

The correlation between the occurrence state of surface Pd species of Pd/CeO2 for lean CH4 combustion is investigated. Herein, by using a reduction-deposition method, we have synthesized a highly active 0.5% PdO/CeO2-RE catalyst, in which the Pd nanoparticles are evenly dispersed on the CeO2 nanorods CeO2-R. Based on comprehensive characterization, we have revealed that the uniformly dispersed Pd nanoparticles with a particle size distribution of 2.3 ± 0.6 nm are responsible for the generation of PdO and PdxCe1−xO2−δ phase with –Pd2+–O2−–Ce4+– linkage, which can easily provide oxygen vacancies and facilitate the transfer of reactive oxygen species between the CeO2-R and Pd species. As a consequence, the remarkable catalytic activity of 0.5% Pd/CeO2-RE is related to the high concentration of PdO species on the surface of the catalyst and the synergistic interaction between the Pd species and the CeO2 nanorod.

Migration of Cations in Layered Oxides for Creating Highly Active Interface toward CO Preferential Oxidation

2021 ◽  
Author(s):  
Junfang Ding ◽  
Zhibin Geng ◽  
Liping Li ◽  
Ye Wang ◽  
Ying Zuo ◽  
...  
Keyword(s):  
Active Species ◽  
Advanced Materials ◽  
Layered Oxides ◽  
Preferential Oxidation ◽  
Interlayer Cation ◽  
Crucial Issue ◽  
Co Preferential Oxidation ◽  
Highly Active

Rationally design and integrate the collaborative active species on the interface is a crucial issue for the development of advanced materials. In this work, we present a simple interlayer cation...

Ni, beyond thermodynamic tuning, maintains the catalytic activity of V species in Ni3(VO4)2 doped MgH2

2021 ◽  
Vol 9 (13) ◽  
pp. 8341-8349
Author(s):  
Jiahe Zang ◽  
Shaofei Wang ◽  
Rongrun Hu ◽  
Han Man ◽  
Jichao Zhang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Storage ◽  
Active Species ◽  
Ni Alloy

A bimetallic oxide Ni3(VO4)2 has been synthesized to catalyze the hydrogen storage reaction of MgH2. The formation of the Mg2Ni alloy and the kinetic modulation of V results in a dehydrogenation temperature of 210 °C. The NiV2O4 intermediate active species is also detected.

Sign in / Sign up

Export Citation Format

Share Document