Uniformly Carbon-Covered Alumina and Its Surface Characteristics

Li, Lin; Lin, Wei; Zhu, Yucheng; Zhao, BY; Xie, YC; Jia, GQ; Li, C

doi:10.1021/la047097d

Cited by 65 publications

(66 citation statements)

References 38 publications

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“…In such an atmosphere the carbon support provides the carbon source for the carburization. This can efficiently suppress the formation of detrimental carbonaceous deposits on the surface of the carbide, which usually occurs when the carburization proceeds in a CH 4 /H 2 atmosphere [9]. Unfortunately, difficulties in controlling the pore sizes of the carbon have hindered its utilization as a catalyst support for N 2 H 4 decomposition.…”

Section: Introductionmentioning

confidence: 99%

Carbon-covered Alumina: A Superior Support of Noble Metal-like Catalysts for Hydrazine Decomposition

2007

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Carbon-covered alumina (CCA) were synthesized from mesoporous alumina and a series of carbon sources (including sucrose, furfuryl alcohol, and benzene). They had structural properties of alumina and surface characteristics of carbon. When they were used as supports for molybdenum carbide, nitride, and phosphide catalysts, significantly higher activities were obtained in hydrazine decomposition as compared to those supported on the conventional alumina. The difference in the interactions of catalytic active sites with the CCA and with the alumina supports was preliminarily deemed to be the main cause of the better performance of CCA supported catalysts. Carbon contents on alumina and carbon sources were found to be important for CCA to be a good support. Carbon deposited on alumina in a near monolayer form showed the best activities. In contrast with sucrose and furfuryl alcohol, benzene as the carbon source readily yielded CCA supports with a hydrophobic surface, which resulted in relatively low dispersions of metal and, in turn, decreased activity of the supported catalysts.

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Section: Introductionmentioning

confidence: 99%

Carbon-covered Alumina: A Superior Support of Noble Metal-like Catalysts for Hydrazine Decomposition

2007

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“…2 (insert). Two peaks that were assigned to the D and G bands were observed at 1318 and 1607 cm -1 , respectively, and are due to the sp 2 carbon species (Zheng et al 2008;Lin et al 2005b). These two peaks are common for various forms of disordered, noncrystalline and amorphous carbons observed in the Raman spectra.…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…The D (disorder) band is related to the breathing modes of the sp 2 carbon atoms in the ring, while the G band is due to bond stretching of the sp 2 carbon atoms. The widths, dispersions and intensities of these peaks are different for various carbons and hence provide powerful information for differentiating carbon species (Lin et al 2005b). The D peak can be fitted into three peaks which are observed at 1165, 1318 and 1386 cm -1 .…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…The G band was observed at 1607 cm -1 , and this is an indication that the carbon layer on the CCAs was possibly related to conjugate olefinic species or polycyclic aromatic hydrocarbons. This peak usually appears at lower wavelengths of 1582 cm -1 when the carbon layer is crystalline graphite (Lin et al 2005b). This means that the carbon layer deposited on the alumina surface is not crystalline.…”

Section: Raman Spectroscopymentioning

confidence: 99%

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Synthesis and characterization of carbon-covered alumina (CCA) supported TiO2 nanocatalysts with enhanced visible light photodegradation of Rhodamine B

Mahlambi

Mishra

et al. 2012

Nanotechnology for Sustainable Development

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The anatase phase of titania (TiO 2 ) nanophotocatalysts was prepared using a modified sol gel process and thereafter embedded on carbon-covered alumina supports. The carbon-covered alumina (CCA) supports were prepared via the adsorption of toluene 2,4-diisocyanate (TDI) on the surface of the alumina. TDI was used as the carbon source for the first time for the carbon-covered alumina support system. The adsorption of TDI on alumina is irreversible; hence, the resulting organic moiety can undergo pyrolysis at high temperatures resulting in the formation of a carbon coating on the surface of the alumina. The TiO 2 catalysts were impregnated on the CCA supports. X-ray diffraction analysis indicated that the carbon deposited on the alumina was not crystalline and also showed the successful impregnation of TiO 2 on the CCA supports. In the Raman spectra, it could be deduced that the carbon was rather a conjugated olefinic or polycyclic hydrocarbons which can be considered as molecular units of a graphitic plane. The Raman analysis of the catalysed CCAs showed the presence of both the anatase titania and D and G band associated with the carbon of the CCAs. The scanning electron microscope micrographs indicated that the alumina was coated by a carbon layer and the energy dispersive X-ray spectra showed the presence of Al, O and C in the CCA samples, with the addition of Ti for the catalyst impregnated supports. The Brunauer Emmet and Teller surface area analysis showed that the incorporating of carbon on the alumina surface resulted in an increase in surface area, while the impregnation with TiO 2 resulted in a further increase in surface area. However, a decrease in the pore volume and diameter was observed. The photocatalytic activity of the nanocatalysts was studied for the degradation of Rhodamine B dye. The CCA-TiO 2 nanocatalysts were found to be more photocatalytically active under both visible and UV light irradiation compared to the free TIO 2 nanocatalysts.

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“…Oxidative annealing of TiC is another method reported to prepare carbon-modified titania, but the expensive material makes this method unpractical [4]. Recently, a simple process has been developed by our group for the preparation of uniform carbon-covered alumina (CCA) [5,6] and titania (CCT) [7] via pyrolysis of sucrose highly dispersed on the surface of alumina and titania. The carbon content can be easily controlled by tuning the sucrose content in the precursors.…”

mentioning

confidence: 99%

Effect of carbon content on photocatalytic activity of C/TiO2 composite

Zhou

Zhu

et al. 2007

Front. Chem. China

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different methods reported to prepare C/TiO 2 responsive to visible light. Kisch and co-workers [2] prepared carboncontaining titania (CCT) by a modified sol-gel process using different alkoxide precursors, but the content of carbon is obviously difficult to be controlled. Carbon-doped titania can also be prepared by oxidation of a titanium metal sheet in a natural gas flame [3], but this method shows poor reproducibility and expedience. Oxidative annealing of TiC is another method reported to prepare carbon-modified titania, but the expensive material makes this method unpractical [4]. Recently, a simple process has been developed by our group for the preparation of uniform carbon-covered alumina (CCA) [5,6] and titania (CCT) [7] via pyrolysis of sucrose highly dispersed on the surface of alumina and titania. The carbon content can be easily controlled by tuning the sucrose content in the precursors. Additionally, this simple method has good reproducibility. It is proved that the as-prepared C/TiO 2 shows unique surface properties and ability to adsorb pollutant in the aqueous solution. For the model pollutant, methylene blue (MB), it is found that the adsorption capacity of C/TiO 2 catalysts is much higher than that of the mixture of corresponding titania and carbon with the same composition, or the summation of their respective adsorption capacity. Carbon covering the surface of titania can inhibit the phase transformation of TiO 2 during calcination, that is, titania in the as-prepared C/TiO 2 catalyst can maintain its anatase phase at high temperature and not be transformed to rutile phase. Photocatalytic tests show that under UV illumination, the kinetics of the elimination of MB in the suspension of CCT powders follows an apparent first-order rate as in pure titania suspension, but the rate constant is much higher than that of pure titania, even commercial Degussa P-25 TiO 2 . Under visible light illumination, CCT shows similar kinetic features for the photodegradation of the dyes to that under UV illumination, different from the apparent zero-order rate of pure titania. The detection of the products of MB degradation, and the absorption spectra of MB solution after the photocatalytic reaction proved that MB is decomposed over CCT samples under visible light illumination, whereas it is simply bleached over pure titania at the same condition. In the previous work, the effect of calcination temperature on the Abstract A series of carbon-covered titania (CCT) were prepared via pyrolysis of sucrose highly dispersed on titania surface in flowing N 2 . The samples were characterized by XRD, BET, DTA-TG, UV-Vis, and their photocatalytic properties were evaluated with two model pollutants, methylene blue (MB) and rhodamine B (RB), at room temperature. The effect of carbon content on photocatalytic activity of the C/TiO 2 composite was investigated. It was found that the effect of carbon content is different for different pollutants or different light sources. For three tested samples, under UV illumination CCT01 h...

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Uniformly Carbon-Covered Alumina and Its Surface Characteristics

Cited by 65 publications

References 38 publications

Carbon-covered Alumina: A Superior Support of Noble Metal-like Catalysts for Hydrazine Decomposition

Carbon-covered Alumina: A Superior Support of Noble Metal-like Catalysts for Hydrazine Decomposition

Synthesis and characterization of carbon-covered alumina (CCA) supported TiO2 nanocatalysts with enhanced visible light photodegradation of Rhodamine B

Effect of carbon content on photocatalytic activity of C/TiO2 composite

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