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61.
The sol-gel derived Co-Mn/TiO catalysts for light olefins production 《燃料化学学报》2014,42(2):212-218
In this research work,two 30%(Co-Mn)/TiO2catalysts were prepared using sol-gel(catalyst A)and coprecipitation(catalyst B)methods.The activity and selectivity to C2~4light olefins in Fischer-Tropsch synthesis(FTS)has been studied in a fixed-bed reactor under different operational conditions.These operational conditions were:temperature220~280℃,and total pressure from0.1~0.6 MPa.The optimum operating conditions were investigated after steady state.As the results shown,the catalyst A was more selective to C2~4olefins(58.7%in 260℃)and catalyst B was more selective to C5+hydrocarbons.Characterization of both catalysts was carried out by using X-ray diffraction(XRD),scanning electron microscopy(SEM)and N2adsorption-desorption measurements methods. 相似文献
62.
We investigate the entanglement dynamics in a bipartite atomic system subjected to thermal environment with arbitrary initial pure entangled states. We consider the atoms close together and study the effect of temperature of the reservoir and the interatomic distance on the evolution of entanglement for both initially entangled and unentangled states. We find that we can have long time entanglement even in thermal environment. 相似文献
63.
H. Zazoua A. Saadi K. Bachari D. Halliche C. Rabia 《Research on Chemical Intermediates》2014,40(3):931-946
Layered double hydroxides or hydrotalcite-like compounds with different kinds of metal ions (Mg–Al, Mg–Fe and Mg–Cr) in the brucite-like sheets were prepared by a co-precipitation method with Mg/M3+ molar ratio of ~2. The hydrotalcites were characterized by chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy, temperature programmed reduction, SEM microscopy, and specific surface area measurements. The activity is evaluated for benzaldehyde reaction. The selectivity to benzyl alcohol is always 90 % even though benzaldehyde conversion depends on the nature of the metal active phase and reaction conditions. 相似文献
64.
An efficient and convenient method for the synthesis of 1,4-dihydropyridines from β-dicarbonyl compounds, aldehydes, and ammonium acetate and the synthesis of fused 1,4-dihydropyridines from dimedone in the presence of Preyssler heteropolyacid catalyst are reported under reflux conditions with good to excellent yields. Preyssler heteropolyacid catalyst is easily prepared, stable (up to 300 °C), reusable, efficient, green and inexpensive. 相似文献
65.
Nigel S. Dance William R. McWhinnie Jahangir Mallaki Zahra Monsef-Mirzai 《Journal of organometallic chemistry》1980,198(2):131-143
Evidence for telluronium ylid formation via the salt method is obtained for Ph2Te(CH2COPh)Br, but generally telluronium salts (aryl)2Te(CH2R)X rapidly dissociate in chloroform solution to (aryl)2Te and RCH2X. The relative rates of dissociation of Ph2(CH3)TeX in CHCl3 are: X = I > Br ~ NCS > Cl > PhCOO. Conductivity and 1H NMR data suggest the salts Ph2(CH3)TeX to be covalent and at least dimeric in CHCl3, but more ionic in DMSO and, to a lesser extent, a DMF. IR data indicate association in solid Ph2(CH3)Tel. Kinetic data show that the reaction of CH3I with excess Ph2Te (solvent) affords an equilibrium mixture of ionic and covalent forms of Ph2(CH3)Tel, the ionic species being formed via the covalent one. Spin trapping experiments with phenyl(t-butyl)nitrone indicate that oxidative addition of alkyl halides to Ph2Te and redcutive elimination of CH3SCN from Ph2 (CH3)Te(NCS) proceed via radical pathways. A mechanism is proposed for oxidative addition which involves the preformation of a charge transfer complex of RX (alkyl halide) and diphenyltelluride. 相似文献
66.
The chemical composition of the essential oil obtained from aerial parts of Nepeta graciliflora was analysed, for the first time, by GC–FID and GC–MS. A total of 27 compounds were identified, constituting over 91.44% of oil composition. The oil was strongly characterised by sesquiterpenes (86.72%), with β-sesquiphellandrene (28.75%), caryophyllene oxide (12.15%), α-bisabolol (8.97%), α-bergamotene (8.51%), β-bisabolene (6.33%) and β-Caryophyllene (5.34%) as the main constituents. The in vitro activity of the essential oil was determined against four micro-organisms in comparison with chloramphenicol by the agar well diffusion and broth dilution method. The oil exhibited good activity against all tested organisms. 相似文献
67.
Ibrahim Munkaila Abdullahi Jahangir Masud Polydoros-Chrisovalantis Ioannou Eleftherios Ferentinos Panayotis Kyritsis Manashi Nath 《Molecules (Basel, Switzerland)》2021,26(4)
The cobalt–seleno-based coordination complex, [Co{(SePiPr2)2N}2], is reported with respect to its catalytic activity in oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solutions. An overpotential of 320 and 630 mV was required to achieve 10 mA cm−2 for OER and HER, respectively. The overpotential for OER of this CoSe4-containing complex is one of the lowest that has been observed until now for molecular cobalt(II) systems, under the reported conditions. In addition, this cobalt–seleno-based complex exhibits a high mass activity (14.15 A g−1) and a much higher turn-over frequency (TOF) value (0.032 s−1) at an overpotential of 300 mV. These observations confirm analogous ones already reported in the literature pertaining to the potential of molecular cobalt–seleno systems as efficient OER electrocatalysts. 相似文献
68.
Sohan Md. Sohanur Rahman Hasan Mahedi Hossain Md. Forhad Sajib Salek Ahmed Miah Md. Masum Iqbal Md. Asif Karmakar Sumon Alam Md. Jahangir Khalid-Bin-Ferdaus Khandaker Md. Kabir Ahmad Humayan Rashid Md. Mamunur Talukder Mamunur Rashid Reza Md Abu 《Plasma Chemistry and Plasma Processing》2021,41(3):923-944
Plasma Chemistry and Plasma Processing - Plasma agriculture is an emerging field. In this report, we studied the effect of medium pressure (~?10 torr) low-frequency... 相似文献
69.
Families of parameter dependent univariate and bivariate subdivision schemes are presented in this paper. These families are new variants of the Lane-Riesenfeld algorithm. So the subdivision algorithms consist of both refining and smoothing steps. In refining step, we use the quartic B-spline based subdivision schemes. In smoothing step, we average the adjacent points. The bivariate schemes are the non-tensor product version of our univariate schemes. Moreover, for odd and even number of smoothing steps, we get the primal and dual schemes respectively. Higher regularity of the schemes can be achieved by increasing the number of smoothing steps. These schemes can be nicely generalized to contain local shape parameters that allow the user to adjust locally the shape of the limit curve/surface. 相似文献