Zeolite Surface As a Catalyst Support Material for Synthesis of Single-Walled Carbon Nanotubes

Abstract

Preparation of high-quality single-walled carbon nanotubes (SWNTs) has been advanced by controlling several parameters including the catalyst and the catalyst support material. Although zeolite has been frequently used as a catalyst support material for the synthesis of SWNTs, detailed surface properties of previously employed zeolites, and thus their role as a catalyst support material, have not been 2 sufficiently clarified yet. In this study, a clean b-plane surface of silicalite-1, which is a siliceous MFItype zeolite, was used as a model substrate for the synthesis of SWNTs. The amount of active cobalt used for SWNT generation was smaller than the initially sputtered amount, and XPS measurements revealed diffusion of cobalt into the zeolite framework. The diffused cobalt was found to interact strongly with the silica framework of zeolite. The diffusion coefficient of cobalt in silicalite-1 zeolite was estimated to be one order of magnitude larger than that in thermally oxidized SiO 2 formed on a Si substrate. This difference was ascribed to the microporous structure and lower density of zeolite. In this study, the state of the cobalt catalyst and the interaction between cobalt and the crystalline zeolite substrate is presented and discussed.

Synthesis, characterizations and catalytic allylic oxidation of limonene to carvone of cobalt doped mesoporous silica templated by reed leaves

“…In addition, it is seen that the low angle XRD pattern of the sample at 2θ of 0-6°shows several diffraction lines in distinct peak in the low 2θ of region. It is clearly indicated that the sample possesses a mesoporous structure [30], which is in agreement with the result of N 2 adsorption/desorption measurement.…”

Solvent-free hierarchization of zeolites by carbochlorination

“…Zeolites are microporous, crystalline aluminosilicates that are widely used as heterogeneous catalysts, 1-4 catalyst supports, 5,6 ion-exchangers, 7 molecular sieve membranes, 8,9 in the catalytic conversion of biomass [10][11][12] and many more advanced applications. 13 Their nal performance in all of the mentioned applications strongly depends on the accessibility of the active sites, which is largely affected by pore size and pore connectivity.…”

Sintering‐Resistant Metal Catalysts Supported on Concave‐Convex Surface of TiO2 Nanoparticle Assemblies

“…Owing to the unique surface structure derived from their fine primary particles, the TiO 2 nanoparticle assemblies show excellent dispersion ability of Au nanoparticles on their rough surface. [15][16][17][18][19][20][21] Metal oxides are the most commonly used supports, because they not only have high heat tolerance and mechanical strength required for very high temperatureÀhigh pressure reactions, but also provide a wide surface area for dilution effect to occur that releases reaction heat. [1][2][3][4][5][6][7][8][9][10][11] To obtain good dispersibility of NPs, the surface of metal NPs are directly modified with organic materials or the NPs are mixed with dispersion media such as fatty acids and amines with long alkyl chains.…”

“…[1][2][3][4][5][6][7][8][9][10][11] To obtain good dispersibility of NPs, the surface of metal NPs are directly modified with organic materials or the NPs are mixed with dispersion media such as fatty acids and amines with long alkyl chains. [15][16][17][18][19][20][21] Metal oxides are the most commonly used supports, because they not only have high heat tolerance and mechanical strength required for very high temperatureÀhigh pressure reactions, but also provide a wide surface area for dilution effect to occur that releases reaction heat. [15][16][17][18][19][20][21] Metal oxides are the most commonly used supports, because they not only have high heat tolerance and mechanical strength required for very high temperatureÀhigh pressure reactions, but also provide a wide surface area for dilution effect to occur that releases reaction heat.…”

“…[12][13][14] In the case of heterogeneous catalysts, the dispersion media are called "supports." [15][16][17][18][19][20][21] Metal oxides are the most commonly used supports, because they not only have high heat tolerance and mechanical strength required for very high temperatureÀhigh pressure reactions, but also provide a wide surface area for dilution effect to occur that releases reaction heat. It is also believed that the metal oxide surface affords electronic effect on their catalytic activity of supported metal NPs.In the case of exothermic catalytic reactions, the temperature of catalysts, especially that of the catalyst surface, becomes notably high.…”