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排序方式: 共有297条查询结果,搜索用时 78 毫秒
1.
Hydrogenation of naphthalene on noble-metal-containing mesoporous MCM-41 aluminosilicates 总被引:2,自引:0,他引:2
S. Albertazzi R. Ganzerla C. Gobbi M. Lenarda M. Mandreoli E. Salatelli P. Savini L. Storaro A. Vaccari 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):261-270
Aromatic saturation of oil fractions is a key process in the refining industry due to increasing demand for cleanest distillates with superior performances. In this study, the behavior of different catalysts containing 1 wt.% of noble-metal inside a mesoporous MCM-41 (Si:Al=20) framework was investigated in the hydrogenation of naphthalene, as preliminary step to investigate bimetallic catalysts. While at atmospheric pressure only Rh and Pd showed a low hydrogenation activity, in the tests performed at 6.0 MPa the catalytic activity grew, exhibiting the following order: Pt>RhPd>>>Ru≈Ir. However, all the catalysts required a large H2 excess, to avoid a decrease in hydrogenation and ring-opening activity, and gave rise to the best performance for a contact time of 6.8 s, favouring at lower values the partial hydrogenation to tetralin and at higher values cracking reactions. Finally, all the catalysts showed low thio-tolerance, with significant deactivation already feeding 100 ppm wt. of dibenzothiophene (DBT), with a partial reversibility only for the Pt-containing catalyst (CAT 3). 相似文献
2.
3.
Jenn-Lin Lin 《中国化学会会志》1984,31(4):395-399
The reaction of 3-(4-phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine (PPDT) and tetraphenylborate (TPB) with cobalt (II) has been studied to determine the optimum conditions for the extraction and quantitative spectrophotometry determination of this metal. The ternary complex is extracted into molten naphthalene at pH 3.6–7.4. The solid naphthalene containing the cobalt associated complex is separated by filtration and dissolved in acetonitrile. Beer's law is obeyed in the concentration range 8–140 μg cobalt in 10 ml of acetonitrile solution. The molar absorptivity and sensitivity are 4.2×103 l·mol?1·cm?1 and 0.01408 μg/cm2, respectively. The other factors such as pH, amounts of reagents and naphthalene, shaking and standing times, and the effect of diverse ions are studied. The method has been applied to the determination of cobalt in iron steel alloys. 相似文献
4.
A series of chiral aromatic imides and diimides were synthesized and their electrochemical, absorption, fluorescent, and chiroptical properties were examined for their potential application as molecular chiroptical switches. These compounds exhibit strong UV-vis absorptions, and can be electrochemically reduced to radical anions that absorb in the near infrared (NIR) region. Further reduction to the dianionic states results in new absorptions in the visible region. The changes in circular dichroism upon redox switching were apparent in the UV-vis region but were absent in the NIR region. 相似文献
5.
多环麝香的分子结构和香气之间的关系 总被引:2,自引:0,他引:2
本文综述了多环麝香的当前进展,并提出了系统的分类方法。对各种多环麝香(茚满型,萘满型,异色满型,氢化引达省型,苊型)香味与分子结构之间关系的研究进行了总结,还作了比较。并描述了多环分子中环上取代基的性质,数量和位置对麝香香味的影响。 相似文献
6.
Mrcia Sousa Bispo Maria das Graas Andrade Korn Elane Santos da Boa Morte Leonardo Sena Gomes Teixeira 《Spectrochimica Acta Part B: Atomic Spectroscopy》2002,57(12):2175-2180
An analytical method for separation and pre-concentration of lead in seawater for determination by inductively coupled plasma optical emission spectrometry has been investigated. Lead was retained in the solid phase (0.5 g) composed of co-precipitated naphthalene and alizarin red. The solid phase quantitatively sorbs Pb(II) at pH 8–9, and the metal was eluted using 5.0 ml of 2 mol l−1 nitric acid. The effect of NaCl, KCl, BaCl2, CaCl2, Na2SO4, MgCl2 and Na3PO4 on the sorption of Pb(II) in the solid phase was studied. A set of solutions containing varying amounts of electrolytes (0.5; 1.0; 3.0 and 5.0% m/v) with Pb (50 μg) was prepared and the recommended procedure applied. The Na3PO4 was found to interfere; the other electrolytes did not interfere up to 5% m/v. A pre-concentration factor of 40 was obtained in this analytical procedure. The limit of detection and limit of quantification for Pb(II) were 53 and 176 μg l−1, respectively. Lead was determined in seawater samples collected in Salvador city, Bahia, Brazil. The precision, expressed as R.S.D., was 1.8–4.6%, and the recovery of lead added to seawater samples was 95–97%. 相似文献
7.
Vânia H.J. Frade 《Tetrahedron letters》2007,48(19):3403-3407
3-(Naphthalen-1-ylamino)propanoic acid was coupled to the amino group of the main and lateral chains of various amino acids in order to evaluate its applicability as a fluorescent derivatising reagent. The resulting amino acid derivatives are strongly fluorescent with a maximum emission of about 415 nm. Condensation of these derivatives with 5-ethylamino-4-methyl-2-nitrosophenol hydrochloride resulted in the corresponding blue benzo[a]phenoxazinium conjugates, also revealing strong fluorescence in ethanol and water at physiological pH and good quantum yields, but with emission wavelengths between 644 and 657 nm, which was preferable in biological assays. 相似文献
8.
Warô Nakanishi Satoko Hayashi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1833-1837
The lone pair-lone pair repulsion plays an important role in the nonbonded P;;;P interaction in naphthalene 1,8-positions. The conformations around P and Se in 8-(PhSe)-1-(Ph 2 P=O)C 10 H 6 are determined by the attractive O;;;Se--C 3c-4e type interaction. The P;;;Se interaction in the 1,8-positions is also discussed. 相似文献
9.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(1-2):103-113
ABSTRACT Crosslinkable silyldihydroarylenes were synthesized starting from 1,4-(dimethylhydrosilyl)dihydronaphthalene and 9,10-(dimethylhydrosilyl) dihydro-anthracene via catalytic addition of the Si-H reactive groups to the unsaturated bond of triethoxyvinylsilane. Subsequent condensation of the alkoxyl groups leads to bridged polysilsequioxanes which could be used to generate protective layers. IR, and 1H-NMR spectral analyses were performed in order to determine the chemical structure of the bis(triethoxysilylethylene)dihydroarylenes. During crosslinking swelling measurements were performed in order to determine the optimal conditions of the process. 相似文献
10.
Samaresh Ghosh & Ajit K. Banthia 《Supramolecular chemistry》2013,25(7):487-494
Novel polyamidoamine (PAMAM) dendrimers (G=0.5–2.5) with a naphthalene core unit have been prepared. They were found to display acid as well as metal ion sensitive fluorescence signal amplification, making them of potential use as chemosensing materials. PAMAM dendritic wedges as well as naphthalene-centered PAMAM dendrimers were characterized by FT-IR, 1H and 13C NMR spectroscopic methods and elemental analysis. 相似文献