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copper catalyst

Abir Goswami, Susnata Pramanik, Michael Schmittel
A catalytically active three-component nanorotor is reversibly self-assembled and disassembled by remote control. When zinc(ii) ions (2 equiv.) are added as an external chemical trigger to the mixture of transmitter [Cu(1)]+ and pre-rotor assembly [(S)·(R)], two equiv. of copper(i) ions translocate from [Cu(1)]+ to the two phenanthroline sites of [(S)·(R)]. As a result, [Zn(1)]2+ forms along with the three-component assembly [Cu2(S)(R)]2+, which is both a nanorotor (k298 = 46 kHz, ΔH‡ = 49.1 ± 0.4 kJ mol-1, ΔS‡ = 9...
March 20, 2018: Chemical Communications: Chem Comm
Lovjeet Singh, Pawan Rekha, Shri Chand
In order to find a better alternative of conventional aqueous ion-exchange method, several Cu/zeolite Y samples were synthesized by different routes and examined for the catalytic wet peroxide oxidation of quinoline aqueous solution in continuous fixed-bed reactor. The characterization of catalysts using ICPMS, XRD, N2 sorption, UV-vis DRS, FESEM and XPS techniques reveals the profound influence of preparation methods on synergy between copper-support interfaces. Aqueous ion-exchange (CuYAIE ) and wet-impregnation (CuYIMP ) methods promoted isolated Cu1+/2+ species; however, large crystallites of CuO were present on the external surface of precipitation-impregnation (CuYPI ) catalyst...
March 15, 2018: Journal of Environmental Management
Qi Liu, Mengdie Xu, Jing Zhao, Zhen Yang, Chenze Qi, Minfeng Zeng, Rui Xia, Xingzhong Cao, Baoyi Wang
In this study, an efficient heterogeneous catalytic material including Pd0 nanoparticles and Cu2+ cations supported on montmorillonite/chitosan (MMT/CS) composite was prepared by solution intercalation and complexion methods. The valence states of Pd (both Pd(0) and Pd(II) coexisting) and Cu (mainly Cu(II)) of the Pd0 /Cu2+ @MMT/CS catalyst were confirmed by the X-ray photoelectron spectroscopy (XPS) characterization. The d001 spacing was enlarged from 1.25 nm (MMT) to 1.94 nm (Pd0 /Cu2+ @MMT/CS). Pd0 /Cu2+ @MMT/CS catalyst had obviously bigger specific surface area (SBET ) and total pore volume (Vp ) than pure MMT...
March 14, 2018: International Journal of Biological Macromolecules
Carolina Petitto, Gérard Delahay
Nitrogen oxides (NOx : NO, NO2 ) are a concern due to their adverse health effects. Diesel engine transport sector is the major emitter of NOx . The regulations have been strengthened and to comply with them, one of the two methods commonly used is the selective catalytic reduction of NOx by NH3 (NH3 -SCR), NH3 being supplied by the in-situ hydrolysis of urea. Efficiency and durability of the catalyst for this process are highly required. Durability is evaluated by hydrothermal treatment of the catalysts at temperature above 800°C...
March 2018: Journal of Environmental Sciences (China)
Hai-Jun Zhang, Alexander W Schuppe, Shi-Tao Pan, Jin-Xiang Chen, Bo-Ran Wang, Timothy R Newhouse, Liang Yin
A mild and operationally simple copper-catalyzed vinylogous aerobic oxidation of ,- and ,-unsaturated esters is described. This method features good yields, broad substrate scope, excellent chemo- and regioselectivity and good functional group tolerance. This method is additionally capable of oxidizing ,- and ,-unsaturated aldehydes, ketones, amides, nitriles and sulfones. Furthermore, the present catalytic system is suitable for bisvinylogous and trisvinylogous oxidation. TMG was found to be crucial in its role as a base, but we also speculate it serves as a ligand to copper(II) triflate to produce the active copper(II) catalyst...
March 16, 2018: Journal of the American Chemical Society
Daniel C Crowley, Denis Lynch, Anita R Maguire
Enantioselective intramolecular Buchner reactions of α-diazoketones can be effected using heterogeneous copper-bis(oxazoline) catalysts in batch or using continuous flow processing in up to 83% ee. The catalyst can be reused up to 7 times without loss of activity. For α-diazoketones 3 and 4, the enantioselection achieved in flow with the immobilized catalyst was comparable with the standard homogeneous catalyzed process.
March 15, 2018: Journal of Organic Chemistry
Jacek Mularski, Barbara Czaplińska, Wioleta Cieślik, Jakub Bebłot, Piotr Bartczak, Rafał Sitko, Jarosław Polański, Robert Musiol
Electrolytic copper is a well-known form of pure, oxygen free copper that is used for industrial applications. In this work, the catalytic potential of this relatively cheap material was studied. The addition of less than 0.015 mol equivalent of copper powder effectively catalysed the one-pot synthesis of triazoles from a diverse range of organic halides and alkynes. Quantitative conversions in aqueous solvents can be achieved within minutes. The heterogenous nature of the catalyst afforded a low level of copper contamination in the products, thus meeting the rigorous criteria of the pharmaceutical industry...
March 14, 2018: Scientific Reports
Xiaofeng Lai, Hu Zhao, Yong Zhang, Kai Guo, Yuqiao Xu, Suning Chen, Jian Zhang
Copper oxide nanoparticles (CuO NPs) are widely used as catalysts or semiconductors in material fields. Recent studies have suggested that CuO NPs have adverse genotoxicity and cytotoxicity effects on various cells. However, little is known about the toxicity of CuO NPs following exposure to murine lungs. The purpose of this fundamental research was to investigate whether CuO NPs could induce epithelial cell injury, pulmonary inflammation, and eventually fibrosis in C57BL/6 mice. Our studies showed that CuO NPs aggravated pulmonary inflammation in a dose-dependent manner...
March 14, 2018: Scientific Reports
Mahmoud Nasrollahzadeh, Mohaddeseh Sajjadi, Fatemeh Ghorbannezhad, S Mohammad Sajadi
A3 coupling is one of the few transition-metal catalyzed carbon-carbon bond forming reactions that have been established as a most direct, efficient and atom-economical synthetic approach to afford propargylamine derivatives using various catalysts. A large number of nanosized heterogeneous catalysts for three-component coupling reactions between an aldehyde, an amine, and a terminal alkyne have been popularly introduced as an A3 coupling in the last decade. The coupling product has found a broad application as a key intermediate for a variety of heterocyclic useful compounds and numerous biologically active molecules such as β-lactams, conformationally restricted peptides, isosteres, herbicides, fungicides, indolizines, pyrroles, quinolines and therapeutic drug molecules...
March 14, 2018: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Nihat Ege Sahin, Clement Comminges, Anthony Le Valant, Julien Kiener, Julien Parmentier, Teko Napporn, Georgian Melinte, Ovidiu Ersen, Kouakou Kokoh
Copper supported mesoporous carbon nanocatalysts (Cu/FDU-15) were synthesized using an easy and convenient one-pot soft template method for low overvoltage CO2 electroreduction. The TEM imaging revealed the presence of large Cu nanoparticles (diameter 140 nm) with Cu2O nanoparticles (16 nm) as additional phase. From the electron tomography observations, it was found that the copper particles were placed inside and on the exterior surface of the porous FDU-15 support, providing an accessible surface for electrocatalytic reactions...
March 14, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
He-Min Wang, Hao Zhou, Qing-Song Xu, Tai-Shang Liu, Chen-Lu Zhuang, Mei-Hua Shen, Hua-Dong Xu
A t-BuOCu-initiated reaction sequence of styrene borometalation and intramolecular imine addition has been achieved using a Cu(OTf)2 /dppf combination as catalyst. The product of this reaction cascade is a useful 2,3-disubstituted indoline bearing a versatile boryl moiety and is formed with sole cis-selectivity. To account for the observation of the exclusive formation of cis-stereoisomers, a transition state featuring copper-imine coordination is suggested. The application to the synthesis of antioxidant tetrahydroindenoindoles is described...
March 14, 2018: Organic Letters
Jie Cai, Qiu-Yun Zhang, Fang-Fang Wei, Jin-Shu Huang, Yun-Mei Feng, Hai-Tao Ma, Yutao- Zhang
Copper (II) containing phosphomolybdic acid (PMA) catalysts were synthesized by ion exchange method and characterization using various physico-chemical techniques such as X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), thermogravimetric (TG) and scanning electron microscopy (SEM). The characterization results showed that the Keggin ions were retained in the catalysts and possessed well thermal stability. The catalytic esterification of lauric acid with methanol could be easily achieved about 78...
March 9, 2018: Journal of Oleo Science
Peerawat Charuwat, Gregory Boardman, Charles Bott, John T Novak
  The thermal hydrolysis of saturated (C16:0 and C18:0) and unsaturated fatty acids (C16:1, C18:1, and C18:2) was investigated at 90 °C to 160 °C for 30 min and 8 h durations. Hydrolysis efficiencies were calculated based on mass yield (i.e., mg/g parent compound), which accounted for all C2-C24 by-products. Very little degradation (less than 1%) of long chain fatty acids (LCFAs) was observed from 30 min thermal hydrolysis. At 140 and 160 °C for 8 h, saturated fatty acids degraded uniformly to C2 to C14...
March 1, 2018: Water Environment Research: a Research Publication of the Water Environment Federation
Ruben Palacio, Sebastian Torres, Sébastien Royer, Anne Sophie Mamede, Diana López, Diana Hernández
Ceria supported copper oxide catalysts were produced by a deposition-precipitation method, at a high copper loading (up to >25 wt%). These materials demonstrated excellent properties for glycerol selective conversion to lactic acid, with a conversion reaching up to 87% with a selectivity to lactic acid of 74% (8 h reaction, 220 °C, under N2 pressure). These catalysts also exhibited high stability upon 5 successive reaction cycles. The formation of a crystalline CuO phase was demonstrated in the nanocomposites at a high Cu loading, with elongated shaped particles formed on the cerium oxide surface...
March 7, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Timo Wendling, Eugen Risto, Thilo Krause, Lukas J Goossen
A copper(I) catalyst enables the insertion of carbon dioxide into alkyne C-H bonds using a suitable organic base with which hydrogenation of the resulting carboxylate salt with regeneration of the base becomes thermodynamically feasible. In the presence of catalytic copper(I) chloride / 4,7-diphenyl-1,10-phenanthroline, polymer-bound triphenylphosphine, and 2,2,6,6-tetramethyl¬piperidine as the base, terminal alkynes undergo carboxylation at 15 bar CO2 and room temperature. After filtration, the ammonium alkynecarboxylate can be hydrogenated to the primary alcohol and water at a rhodium / molybdenum catalyst, regenerating the amine base...
March 5, 2018: Chemistry: a European Journal
Dan Ren, Jinhuan Fong, Boon Siang Yeo
Copper electrodes have been shown to be selective toward the electroreduction of carbon dioxide to ethylene, carbon monoxide, or formate. However, the underlying causes of their activities, which have been attributed to a rise in local pH near the surface of the electrode, presence of atomic-scale defects, and/or residual oxygen atoms in the catalysts, etc., have not been generally agreed on. Here, we perform a study of carbon dioxide reduction on four copper catalysts from -0.45 to -1.30 V vs. reversible hydrogen electrode...
March 2, 2018: Nature Communications
Keijiro Ohshimo, Kengo Akimoto, Masato Ogawa, Wataru Iwasaki, Hiroaki Yamamoto, Masahide Tona, Keizo Tsukamoto, Motoyoshi Nakano, Fuminori Misaizu
The inertness of metal clusters in air is important for their application to novel materials and catalysts. The adsorption reactivity of copper clusters with O2 has been discussed in connection with the electronic structure of clusters because of its importance in electron transfer from the cluster to O2 . Mass spectrometry was used to observe the reaction of Cun + + O2 (n = 13-60) in the gas phase. For O2 adsorption on Cun + , the relative rate constants of the n = 15, 21, 41, and 49 clusters were clearly lower than those with other n...
March 1, 2018: Journal of Physical Chemistry. A
Qiangqiang Sun, Yujuan Dong, Zenglin Wang, Shiwei Yin, Chuan Zhao
Developing highly active electrocatalysts with low cost and high efficiency for hydrogen evolution reactions (HERs) is of great significance for industrial water electrolysis. Herein, a 3D hierarchically structured nanotubular copper-doped nickel catalyst on nickel foam (NF) for HER is reported, denoted as Ni(Cu), via facile electrodeposition and selective electrochemical dealloying. The as-prepared Ni(Cu)/NF electrode holds superlarge electrochemical active surface area and exhibits Pt-like electrocatalytic activity for HER, displaying an overpotential of merely 27 mV to achieve a current density of 10 mA cm-2 and an extremely small Tafel slope of 33...
February 27, 2018: Small
Rong Zhang, Zheng Liu, Qiujun Peng, Yijun Zhou, Lanting Xu, Xianhua Pan
A CuCl catalyzed C-N cross-coupling reaction using commercially available 1H-indazoles with diaryliodonium salts is described. The methodology features ample structural versatility, affording 2-substituted-2H-indazole in good yields and complete N(2)-regiocontrol. Furthermore, the utility of the reaction was demonstrated in the synthesis of a known estrogen receptor β agonist. Mechanistic studies using density functional theory calculations suggested that the complete regioselectivity can be attributed to the only weak base TfO- in our system which could not deprotonate indazoles, and the catalyst oxidation process would be the rate-determining step...
February 26, 2018: Organic & Biomolecular Chemistry
Zhaojun Wen, Xinping Duan, Menglin Hu, Yanning Cao, Linmin Ye, Lilong Jiang, Youzhu Yuan
In this study, the effects of copper (Cu) additive on the catalytic performance of Ag/SBA-15 in complete soot combustion were investigated. The soot combustion performance of bimetallic Ag-Cu/SBA-15 catalysts was higher than that of monometallic Ag and Cu catalysts. The optimum catalytic performance was acquired with the 5Ag1 -Cu0.1 /SBA-15 catalyst, on which the soot combustion starts at Tig =225°C with a T50 =285°C. The temperature for 50% of soot combustion was lower than that of conventional Ag-based catalysts to more than 50°C (Aneggi et al...
February 2018: Journal of Environmental Sciences (China)
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