MgO catalyst

1614

CARBON 47 (2009) 1613– 1616

infiltration (CVI), and the relationship between density and infil-

Dynamic adsorption of phenol at 30 °C on activated bamboo

tration time was investigated. The flexural strength was deter-

charcoal was investigated. Effects of phenol initial concentration

mined by a three-point bend test. The microstructure and

and adsorbent size on kinetics were discussed. Three models

fracture-surface morphology of the composites were observed

were used to study the adsorption kinetics. It was found that a

by polarized light microscopy and scanning electron microscopy

pseudo-second-order equation provided the best correlation to

respectively. Results show that the bulk density reaches 1.47 g/

the data. The initial adsorption rates derived from the model

cm3 for a 96 h densification, a significant improvement in densifi-

increased with concentration and decreased with size. An

cation efficiency compared with other precursors. A high-tex-

intraparticle diffusion was the rate-controlling step for the

tured carbon matrix, consisting of rough laminar pyrocarbon,

adsorption of phenol on activated bamboo charcoal.

can be easily obtained. The C/C composites exhibit a pseudo-plas-

[New Carbon Materials 2008;23(4):326–30.]

tic failure behavior. Ethanol is a new promising precursor for the densification of C/C composites.

doi:10.1016/j.carbon.2008.12.011

[New Carbon Materials 2008;23(4):314–8.] doi:10.1016/j.carbon.2008.12.009 Theoretical and experimental evidence of a metal-carbon synergism for the catalytic growth of carbon nanotubes by chemical Synthesis of thin-walled carbon nanotubes from methane by changing the Ni/Mo ratio in a Ni/Mo/MgO catalyst Qiang Znang, Yi Liu, Ling Hu, Wei-zhong Qian, Guo-hua Luo, Fei Wei Beijing Key Laboratory of Green Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China Thin-walled carbon nanotubes (CNTs) were prepared from methane decomposition using Ni/Mo/MgO as catalysts loaded with 1% mole fraction of Ni and smaller proportion of Mo. The relationship between CNT diameter and Ni/Mo ratio was studied by SEM, TEM, XRD and Raman spectroscopy. The particle size and the active phase of the catalyst could be modulated by the Ni/Mo ratio. With decreasing Ni/Mo ratio, a NiMo alloy was first formed, and then an isolated Mo phase was formed on the catalyst, as characterized by TEM and XRD. The NiMo alloy, with very small size, was responsible for the growth of thin-walled CNTs, whereas, the Mo phase was related to the formation of largediameter thick-walled CNTs. The thin-walled CNTs with outer diameter of 3.0 nm and inner diameter of 1.3 nm could be obtained with high selectivity, a narrow diameter distribution, and high purity by controlling the Ni/Mo ratio at 6. Raman spectra confirmed the formation of thin-walled CNTs with few defects.

vapor deposition Gui-xiang Dua,b, Zhi-rong Kangc, Jin-ling Songa,b, Jiang-hong Zhaoa, Chang Songa,b, Zhen-ping Zhua a

State Key Laboratory of Coal Conversion, Institute of Coal Chemistry,

Chinese Academy of Sciences, Taiyuan 030001, China b

Graduate School of Chinese Academy of Sciences, Beijing 100049,

China c

Department of mathematics, Taiyuan University of Technology, Taiy-

uan 030024, China The nucleation and growth of carbon nanotubes (CNTs) using chemical vapor deposition with a metal-carbon catalyst have been studied experimentally and theoretically. Results suggest that the nucleation and growth of multiwalled CNTs are not due to the metal alone, but that carbon nuclei (once formed) also contribute to radial and axial growth. Metal particles mainly promote the nucleation and growth of the innermost carbon shell(s), and catalyze the ordering of the carbon atoms to form graphene structures. The intrinsic difference between multiwalled CNT formation and single-walled CNT formation seems to be associated with a self-catalytic function of carbon nuclei. [New Carbon Materials 2008;23(4):331–8.] doi:10.1016/j.carbon.2008.12.012

The formation of thin-walled CNTs was mainly attributed to a rapid surface diffusion and precipitation of carbon on the small metal alloy crystallites.

Effect of temperature, carbon fibers, and silica fume on the

[New Carbon Materials 2008;23(4):319–25.]

mechanical properties of lightweight concretes Harun Tanyildizi

doi:10.1016/j.carbon.2008.12.010

Department of Construction Education, Firat University, Elazig, Turkey The effect of temperature, and carbon fiber and silica fume

Adsorption kinetics of activated bamboo charcoal for phenol Jiang-tao Zhua, Zheng-hong Huanga,b, Fei-yu Kanga, Jin-he Fuc, Yong-de Yuec a

Lab of Advanced Materials, Department of Materials Science and

Engineering, Tsinghua University, Beijing 100084, China b

Key Laboratory of Carbon Materials, Institute of Coal Chemistry,

contents on the mechanical properties (compressive and flexural strength) of lightweight concretes was investigated. Samples containing silica fume (mass fractions of 0% and 10%) and carbon fibers (mass fractions of 0%, 0.5%, 1%, and 2%) were prepared. The compressive and flexural strengths of the samples were determined after they had been exposed to high temperatures (400, 600, and 800 °C). The Taguchi method was used to determine

Chinese Academy of Sciences, Taiyuan, Shanxi 030001, China

the optimum conditions and to reduce the number of experi-

c

ments. The significance of the three factors affecting the

International Center for Bamboo and Rattan, Beijing 100102, China