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排序方式: 共有93条查询结果,搜索用时 15 毫秒
61.
Designing a capsule catalyst and its application for direct synthesis of middle isoparaffins 总被引:1,自引:0,他引:1
He J Yoneyama Y Xu B Nishiyama N Tsubaki N 《Langmuir : the ACS journal of surfaces and colloids》2005,21(5):1699-1702
A catalyst in the form of a capsule catalyst was prepared by coating HZSM5 membrane on a preshaped Co/SiO2 catalyst pellet. The capsule catalyst with HZSM5 membrane exhibited excellent selectivity for light hydrocarbon synthesis, especially for isoparaffin synthesis from syngas (CO + H2). Long-chain hydrocarbon formation was totally suppressed by the zeolite membrane. The modification of membrane and core catalyst significantly improved the catalytic properties of these new kinds of capsule catalysts. 相似文献
62.
Tsubaki K Otsubo T Morimoto T Maruoka H Furukawa M Momose Y Shang M Fuji K 《The Journal of organic chemistry》2002,67(23):8151-8156
Several functional groups were introduced on the upper rim of (lower rim free) homooxacalix[3]arene for the first time. The swinging nitrohomooxacalix[3]arene host 1 was fixed in the cone conformation by complexation with n-hexylamine. 相似文献
63.
Electric properties of mixed anionic-nonionic surfactant systems in aqueous solutions above the CMC have been studied in terms of pNa values, electrical conductivities, and dielectric constants; these systems are sodium 3, 6, 9-trioxaicosanoate (ECL) — alkyl polyoxyethylene ethers (CmPOE; m=12, 14, 16, and 18). The degree of ionic dissociation of mixed micelle increases with increasing the number of carbon atoms of the alkyl group in the nonionic surfactant. The electrical conductivity increases with increasing the alkyl chain length in the nonionic surfactant, in spite of the increase of the activation energy for conduction. The size of mixed micelles also increases with increasing alkyl chain length. This may be attributed to the fact that the mixed micelle is formed more easily by a nonionic surfactant including long alkyl chains than for one having shorter alkyl chains. 相似文献
64.
This digest overviews successful synthetic approaches to natural dimeric 1,4-naphthoquinones. Several natural dimeric 1,4-naphthoquinone derivatives have been isolated from natural sources including plants, bacteria, and fungi. They have diverse structures and attractive biological activities. However, it is difficult to construct the dimeric scaffolds efficiently and selectively, because 1,4-naphthoquinones and their derivatives are highly reactive. Efficient and attractive synthetic methodologies to construct unique dimeric 1,4-naphthoquinone skeletons are reviewed. 相似文献
65.
Capsule catalysts composed of pre-shaped core catalysts and layer zeolites have been widely used in the tandem reactions where multiple continuous reactions are combined into one process. They show excellent catalytic performance in heterogeneous catalysis, including the direct synthesis of middle isoparaffins or dimethyl ether from syngas, as compared to the conventional hybrid catalysts. The present review highlights the recent development in the design of capsule catalysts and their catalytic applications in heterogeneous catalysis. The capsule catalyst preparation methods are introduced in detail, such as hydrothermal synthesis method, dual-layer method, physically adhesive method and single crystal crystallization method. Furthermore, several new applications of capsule catalysts in heterogeneous catalytic processes are presented such as in the direct synthesis of liquefied petroleum gas from syngas, the direct synthesis of para-xylene from syngas and methane dehydroaromatization. In addition, the development in the design of multifunctional capsule catalysts is discussed, which makes the capsule catalyst not just a simple combination of two different catalysts, but has some special functions such as changing the surface hydrophobic or acid properties of the core catalysts. Finally, the future perspectives of the design and applications of capsule catalysts in heterogeneous catalysis are provided. 相似文献
66.
Catalytic Oxidation of Dimethyl Ether to Dimethoxymethane over Cs Modified H_3PW_(12)O_(40)/SiO_2 Catalysts 总被引:1,自引:0,他引:1
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The attractive utilization route for one-step catalytic oxidation of dimethyl ether to dimethoxymethane was successfully carried out over the H_3PW_(12)O_(40)(40%)/SiO_2 catalyst,modified by Cs,K,Ni,and V.The Cs modification of H_3PW_(12)O_(40)(40%)/SiO_2 gave the most promising result of 20% dimethyl ether conversion and 34.8% dimethoxymethane selectivity.Dimethoxymethane could be synthe- sized via methoxy groups decomposed from dimethyl ether through the synergistic effect between the acid sites and the redox sites of Cs modified H_3PW_(12)O_(40)(40%)/SiO_2. 相似文献
67.
p-Nitrocalix[6]arene which possibly serves as a potential intermediate to derive functionalized calixarenes was synthesized for the first time. 相似文献
68.
Hideaki Tsubaki Atsushi Sugawara Hiroyuki Takeda Bobak Gholamkhass Kazuhide Koike Osamu Ishitani 《Research on Chemical Intermediates》2007,33(1-2):37-48
Photocatalysis of biscarbonylrhenium complexes cis,trans-[Re(dmbpy)(CO)2(PR3) (PR′3)]+ (dmbpy=4,4′-dimethyl-2,2′-bipyridine: R, R′=Ph (1a +); p-FPh (1b +); R=Ph, R′=OEt (1c +); R, R′=O-i-Pr (1d +)) is reported for the first time. The rhenium complexes with two triarylphosphine ligands (1a +, 1b +) efficiently photocatalyzed CO2 reduction with triethanolamine as a sacrificial donor. On the other hand, the complexes with one or two trialkylphosphite ligand(s) (1c +, 1d +) had low photocatalytic abilities under the same reaction conditions. 相似文献
69.
Tetracosanaphthalenes with diethylaminocarbonylmethoxy side chains were constructed by bottom-up synthesis, and their absolute configurations were determined by an exciton chirality method. 相似文献
70.
Tsubaki K 《Organic & biomolecular chemistry》2007,5(14):2179-2188
Helical oligonaphthalenes were constructed by bottom-up synthesis (repeating dimerization reactions), their absolute configurations were determined by an exciton chirality method and their functions, such as energy transfer, are also reported. 相似文献