نتایج جستجو برای: natural catalyst
تعداد نتایج: 524102 فیلتر نتایج به سال:
Anodic deposition of a robust iridium-based water-oxidation catalyst from organometallic precursors†
Artificial photosynthesis, modeled on natural light-driven oxidation of water in Photosystem II, holds promise as a sustainable source of reducing equivalents for producing fuels. Few robust wateroxidation catalysts capable of mediating this difficult four-electron, four-proton reaction have yet been described. We report a new method for generating an amorphous electrodeposited material, princi...
The oxidation state of palladium in a model Pd/ ACZ three-way catalyst was monitored by synchronous XANES and mass spectrometry during two consecutive heating (to 850 C) and cooling (to 100 C) cycles under stoichiometric conditions simulating exhaust after treatment of a natural gas engine. During heating in the first cycle, PdO reduction occurred around 500 C and the initial fully oxidized sta...
As stock of crude oil is limited, new resources for fuel and petrochemicals are required to be developed. Natural gas or biogas can be easily converted into methanol which can be converted into gasoline and olefins. This study uses zeolite catalyst (ZSM-5) and its modification by Ni to convert methanol to hydrocarbons (MTH). Catalysts are studied at different temperatures and at different loadi...
We report our studies on the use of two catalyst systems, based on the ligands BrettPhos (1) and RuPhos (2), which provide the widest scope for Pd-catalyzed C-N cross-coupling reactions to date. Often low catalyst loadings and short reaction times can be used with functionalized aryl and heteroaryl coupling partners. The reactions are highly robust and can be set up and performed without the us...
A concise and expeditious approach to the total synthesis of broussonone A, a p-quinol natural compound, has been developed. The key features of the synthesis include the Grubbs II catalyst mediated cross metathesis of two aromatic subunits, and a chemoselective oxidative dearomatizationin the presence of two phenol moieties. Especially, optimization associated with the CM reaction of ortho-alk...
The research in the field of asymmetric carbene organic catalysis has primarily focused on the activation of carbon atoms in non-aromatic scaffolds. Here we report a reaction mode of carbene catalysis that allows for aromatic aldehyde activation and remote oxygen atom functionalization. The addition of a carbene catalyst to the aldehyde moiety of 2-hydroxyl aryl aldehyde eventually enables dear...
Density functional theory (DFT) has been applied to study potential ammonia borane (AB) dehydrogenation pathways via new bifunctional ruthenium-based catalysts, alongside their computationally-designed iron-based counterparts (i.e., four catalysts), using the wB97XD (dispersion-included) functional. The efficiency of each catalyst was under scrutiny based on the addition of ammonia borane, with...
Due to crude oil is limited, new resources for fuel and petrochemicals are important to be developed. Biogas or NG (Natural Gas) can be easily converted into methanol which can be reacted over zeolite to produce olefins and gasoline. HZSM-5 zeolite catalyst has been used in this study and its modification by (0.5wt%, 1wt%, 2wt% and 4wt %) Ni to convert methanol to hydrocarbons (MTH). Catalysts ...
A variety of organocatalysts were screened for the catalysis of the naphthoquinone monoketal Diels-Alder reaction. In this study we found that Schreiner's thiourea catalyst 10 and Jacobson's thiourea catalyst 12 facilitate the cycloaddition of the sterically hindered naphthoquinone monoketal dienophile 3 with diene 4. The use of thiourea catalysis allowed for the first time the highly selective...
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