نتایج جستجو برای: green catalysts

تعداد نتایج: 172025  

2008
David M. Knapp

INTRODUCTION Stereoselective chemical reactions have become extremely important in both academic and industrial settings for the synthesis of useful molecules. Catalytic reactions are of particular importance due to their capacity to effect otherwise impossible transformations using substoichiometric quantities of the catalyst. Traditionally, transition metal catalysts have played a central rol...

Journal: :Current opinion in chemical engineering 2021

Green hydrogen produced by water electrolysis in combination with renewable energy is expected to become a key enabler for decarbonization of and transportation sectors as well hard-to-abate industries, contributing the achievement carbon neutrality. Compared conventional alkaline technology, proton exchange membrane (PEMWE) possesses many advantages green production, but currently relies heavi...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2008
Ilkeun Lee Ricardo Morales Manuel A Albiter Francisco Zaera

Colloidal and sol-gel procedures have been used to prepare heterogeneous catalysts consisting of platinum metal particles with narrow size distributions and well defined shapes dispersed on high-surface-area silica supports. The overall procedure was developed in three stages. First, tetrahedral and cubic colloidal metal particles were prepared in solution by using a procedure derived from that...

2016
Chengli Mou Tingshun Zhu Pengcheng Zheng Song Yang Bao-An Song Yonggui Robin Chi

Benzocoumarin is an important structural motif widely found in natural products and synthetic molecules. Traditional methods for the synthesis of benzocoumarins and their derivatives require multiple steps, typically with an intramolecular ester forming reaction to make the lactone ring as the last step. Another major method involves transition metal-catalyzed coupling or carbon-hydrogen bond a...

2016
Pedro N Romano João M A R de Almeida Yuri Carvalho Peter Priecel Eduardo Falabella Sousa-Aguiar Jose A Lopez-Sanchez

Green, inexpensive, and robust copper-based heterogeneous catalysts achieve 100 % conversion and 99 % selectivity in the conversion of furfural to furfuryl alcohol when using cyclopentyl-methyl ether as green solvent and microwave reactors at low H2 pressures and mild temperatures. The utilization of pressurized microwave reactors produces a 3-4 fold increase in conversion and an unexpected enh...

2016
Aazam Monfared Zohreh Esmaeeli

The anticoagulant racemic warfarin is synthesized by the Michael addition of 4-hydroxycoumarin with benzalacetone in the present of equimolar amounts of imidazolium based ionic liquids [bmim] BF4 and [bmim] Br and other reaction solvents such as H2O, pyridine and ammonia in five different tests. Also synthesis of a derivative of warfarin (2-methyl-4-phenyl pyrano [3, 2-c] chromen-5(4H)-one) und...

2013
Tai Sun Zheye Zhang Junwu Xiao Chen Chen Fei Xiao Shuai Wang Yunqi Liu

We report a facile and green method to synthesize a new type of catalyst by coating Pd nanoparticles (NPs) on reduced graphene oxide (rGO)-carbon nanotube (CNT) nanocomposite. An rGO-CNT nanocomposite with three-dimensional microstructures was obtained by hydrothermal treatment of an aqueous dispersion of graphene oxide (GO) and CNTs. After the rGO-CNT composites have been dipped in K₂PdCl₄ sol...

Journal: :Molecules 2015
Zen Maeno Takato Mitsudome Tomoo Mizugaki Koichiro Jitsukawa Kiyotomi Kaneda

Two high-performance Cu catalysts were successfully developed by immobilization of Cu ions in the nanospaces of poly(propylene imine) (PPI) dendrimer and magadiite for the selective C-C coupling of 2,6-dimethylphenol (DMP) to 3,3',5,5'-tetramethyldiphenoquinone (DPQ) with O2 as a green oxidant. The PPI dendrimer encapsulated Cu ions in the internal nanovoids to form adjacent Cu species, which e...

Journal: :Nanoscale 2016
Sixiang Cai Hang Hu Hongrui Li Liyi Shi Dengsong Zhang

Manganese based catalysts are highly active in the NH3-SCR reaction for NOx removal. Unfortunately, manganese oxides can be easily deactivated by sulfur dioxide in the flow gas, which has become the main obstacle for their practical applications. To address this problem, we presented a green and facile method for the synthesis of multi-shell Fe2O3@MnOx@CNTs. The morphology and structural proper...

2010
Shiro Kobayashi

This article is a short comprehensive review describing in vitro polyester synthesis catalyzed by a hydrolysis enzyme of lipase, most of which has been developed for these two decades. Polyesters are prepared by repeated ester bond-formation reactions; they include two major modes, ring-opening polymerization (ROP) of cyclic monomers such as cyclic esters (lactones) and condensation polymerizat...

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