2011 Vol. 26, No. 5

  Previous Issue | Next Issue 
Research progress in nanofiltration membrane based on carbon nanotubes
ZHAO Bin, ZHANG Lei, WANG Xian-ying, YANG Jun-he, TANG Zhi-hong, YANG Guang-zhi
2011, 26(5): 321-328.
Abstract(3800) PDF(1684)
Abstract:
Carbon nanotubes (CNTs) possess atomically smooth inner surface and nanoscale pores, which lead to extremely high permeability and selectivity as nanofiltration membranes. In this review, preparation methods, permeation properties, merits and limitations of several typical membranes based on CNTs are introduced, such as buckypaper membranes, random distributed CNT/polymer composite membranes, and vertically-aligned CNT/polymer composite membranes. It is suggested that nanofiltration membranes based on vertically-aligned CNTs may be promising since they could make a full use of the characteristics of CNTs.
Effect of high temperature treatment on the microstructure andmechanical properties of binary layer textured 2D C/C composites
LI Wei, LI He-jun, ZHANG Shou-yang, WEI Jian-feng, WANG Jie, LI Zhao-qian
2011, 26(5): 328-334.
Abstract(2817) PDF(1274)
Abstract:
X-ray diffraction (XRD), scaning electron micrsocopy and transmission electron microscopy were used to study the changes of the pyrolytic carbon microstructure and fiber-matrix interface of binary layer textured 2D C/C composites before and after heat treatment. The XRD results show that the d002 decreased and the graphitization degree increased significantly with the increase of heat treatment temperature. No obvious change of the fracture surface morphology and lattice fringes of the inner layer, which correspond to low textured pyrolytic carbon, was observed. However, the lattice fringes of the outer layer (high textured pyrolytic carbon) are regularly parallel, and the density of microcracks in the outer layer increases obviously after heat treatment. These microcracks make cracks propagate and deviate easily, leading to an increase of the toughness of the C/C composites. Moreover, the weakening of the fiber-matrix interface bonding is another mechanism for the toughness enhancement. The results of three point bending tests confirmed the proposed mechanism.
Nickel/Carbon composite materials based on expanded graphite
.M. Afanasov, O.I. Lebedev, B.A. Kolozhvary A.V. Smirnov|　G. Van Tendeloo
2011, 26(5): 335-340. doi: 10.1016/S1872-5805(11)60085-1
Abstract(2578) PDF(1262)
Abstract:
Monolithic nickel/carbon (Ni/C) composites were prepared from coal tar pitch-impregnated compressed expanded graphite pre-decorated with NiO particles (EGNiO) by pyrolysis at 550℃ and subsequent steam activation at 800℃. The microstructural arrangement of the Ni-comprising nanoparticles in the composites was investigated using transmission electron microscopy. The specific surface area and porosity of the composites were analyzed by nitrogen adsorption. The catalytic activity of the composites was compared with the material obtained by the conventional H2 treatment of EGNiO using hydrocracking of 2,2,3-trimethylpentane as a model reaction.
Synthesis of carbon nanofiber/carbon-foam composite for catalyst support in gas-phase catalytic reactions
2011, 26(5): 341-346. doi: 10.1016/S1872-5805(11)60086-3
Abstract(2859) PDF(1104)
Abstract:
A carbon foam was prepared by self-bubbling using mesophase pitch as a precursor. To improve its specific surface area, the carbon foam was oxidized with 65 mass% HNO3, and then a layer of carbon nanofibers (CNFs) was grown on the pore walls using chemical vapor deposition. The specific surface area and thermal conductivity of the carbon foam and CNF/carbon foam composite are 40 and 198m2/g and 107 and 125W/mK, respectively. This CNF/carbon-foam composite can be used as a catalyst support for gas-phase catalytic reactions.
Preparation and characterization of a composite of gold nanoparticles and single-walled carbon nanotubes and its potential for heterogeneous catalysis
Anne E. Shanahan, |　James A. Sullivan, Mary McNamara, Hugh J. Byrne
2011, 26(5): 347-355. doi: 10.1016/S1872-5805(11)60087-5
Abstract(2861) PDF(1098)
Abstract:
A single-walled carbon nanotube-supported gold nanoparticle composite was prepared and characterized by X-ray diffraction, scanning transmission electron microscopy/scanning electron microscopy/transmission electron microscopy, energy-dispersive X-ray analysis, atomic absorption spectroscopy, nitrogen adsorption, Raman spectroscopy, and ultraviolet-visible spectroscopy. The Au particles were found to be crystalline, with a well-defined and narrow particle-size distribution, centered around 7nm. The activity and selectivity of the composite for solventless aerobic oxidation of a secondary alcohol were examined, and a conversion efficiency of 95% was obtained.
Synthesis of carbon microfibers by chemical vapor deposition during the catalytic decomposition of turpentine oil
Kanchan Saxena, Pramod Kumar, V. K. Jain
2011, 26(5): 356-360. doi: 10.1016/S1872-5805(11)60088-7
Abstract(2758) PDF(1211)
Abstract:
Carbon microfibers were synthesized by chemical vapor deposition during the decomposition of turpentine oil in the presence of nickel sulfate as a catalyst precursor on a graphite host. The fibers were separated from graphite and metal impurities by acid treatment, followed by several washes with deionized water. These fibers have a diameter of approximately 3-5μm and they were studied by optical and scanning electron microscopy. A sponge-like morphology of the microfibers due to self-assembly was observed.
Preparation of a carbon nanotube/carbon fiber hybrid and its wettability with epoxy
AN Feng, LU Chun-xiang, GUO Jin-hai, HE Shu-qing, LU Hui-bin, YANG
2011, 26(5): 361-367.
Abstract(2704) PDF(1193)
Abstract:
A carbon nanotube/carbon fiber (CNT/CF) hybrid was prepared via an aerosol-assisted chemical vapor deposition (AACVD) method using acetylene as carbon source and ferrocene as catalyst. The morphology and microstructure of the CNT/CF hybrid were characterized by SEM and TEM. It was found that CNTs were uniformly and densely grown onto CFs at 750-800℃ for 30min. Results obtained from single fiber tests showed that the tensile strength of the CNT/CF hybrid decreased by 13% after AACVD at 750-800℃ for 30min compared to that of CFs, however, the tensile degradation was less than 10% after AACVD at 750℃ for 5 to 40min. The wettability of the hybrid with epoxy resin was improved compared with that of the original CFs
Preparation and properties of MWCNT/Lyocell carbon fibers
LU Jiang, YANG Ge-sheng, SHAO Hui-li, HU Xue-chao
2011, 26(5): 368-374.
Abstract(2016) PDF(1149)
Abstract:
Multi-walled carbon nanotube (MWCNT)/Lyocell composite fibers were prepared and used as a precursor of carbon fibers to improve the mechanical properties of Lyocell-based carbon fibers. The structure and properties of the samples were investigated by wide angle XRD (WAXD), SEM, TGA and tensile tester. WAXD patterns showed that the composite precursor still had a cellulose II crystal structure. TGA curves showed that the thermal stability of the composite precursor was improved by the addition of the MWCNTs and the yield of the resulting carbon fibers could be increased. The SEM results showed that the surface and the cross-section of MWCNT/Lyocell composite fibers were smooth and round, which can meet the requirements of a carbon fiber precursor. MWCNTs were dispersed uniformly in the resulting carbon fibers. Compared with pure Lyocell-based carbon fibers, the tenacity and modulus of Lyocell-based composite carbon fibers containing 1% MWCNTs were increased by 70% and 116%, respectively.
Effect of biological template consolidation on the microstructure and
properties of SnO2/C bio-morphic materials
HE Xin-hai, QI Le-hua, WANG Jun-bo, YANG Min-ge, SHEN Ming-qian, CHANG We
2011, 26(5): 375-380.
Abstract(2288) PDF(1187)
Abstract:
Ramie fibers were treated by different finishing processes including water washing, NaOH soaking and oxidative bleaching. The three kinds of finished Ramie fibers as soft carbon precursor were chopped to 10-20mm and blended with phenolic resin as hard carbon precursor with a weight ratio of fibers to resin of 1∶1 and 6mass% toluene sulfochloride as a hardening reagent. The blends were hot-pressed at 130℃ and carbonized at 800℃. The three carbon plates were repeatedly impregnated with Sn(OH)4 sol to a weight ratio of Sn(OH)4/carbon of 0.5, followed by carbothermal reduction at 560℃ in vacuum to prepare SnO2/C bio-morphic materials. The effect of finishing processes on the phase composition and morphology of SnO2/C bio-morphic materials were analyzed by X-ray diffraction and scanning electron microscopy. In addition, the wear rates of the bio-morphic samples were tested using a home-made abrader. It was found that the microstructure and wear resistance of the SnO2/C bio-morphic materials are significantly different and could be effectively controlled through the finishing process.
Simulation of chemical vapor infiltration of propylene into C/C composites
LIU Yu-tai, BAI Rui-cheng, LI Hong, ZHANG Jia-bao, REN Mu-su, SUN Jin-liang
2011, 26(5): 381-388.
Abstract(2023) PDF(1104)
Abstract:
Chemical vapor infiltration of propylene into C/C composites was studied by numeric simulation and an improved model for homogeneous gas-phase reactions of propylene pyrolysis was proposed. The model consists of 34 elementary reactions of 16 species. Then a bipore model for describing the changes of the pore topology with the progress of densification and a computer code for simulation of surface reactions by other authors were coupled together to predict the process. The numerical simulation showed that the density distribution of C/C composites is dependent on residence time of gas, densification temperature and densification time. There are two infiltration stages (rapid densification of micro-pores and successive densification of macro-pores) which act closely with the concentration distributions of main homogeneous pyrolytic products of propylene. Among them the concentration distribution of benzene seems most apparently to influence the densification speed and C/C density uniformity. The infiltration would be terminated when the benzene rich region becomes narrow, and the surface crusting of C/C appears. The present model is validated by comparing the predicted densities with the experimental ones.
Preparation of hollow carbon spheres by carbonization of polystyrene/polyaniline core-shell polymer particles
DAI Xiao-ying, ZHANG Xin, MENG Yi-fei|　SHEN Pei-kang
2011, 26(5): 389-395.
Abstract(1946) PDF(1885)
Abstract:
Hollow carbon spheres were synthesized using sulfonated polystyrene (PS) spheres as a core template and aniline monomer as carbon source. The spheres prepared were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier infrared spectrometry, and thermogravimetry. The results showed that the as-prepared hollow carbon spheres were uniform in diameter with a shell thickness of 35nm. The morphology, diameter, and wall thickness of the hollow carbon spheres can be tuned by varying the sulfonation rate of the PS core template. Sulfonation modification of PS spheres for 8h was appropriate to prepare hollow carbon spheres. Owing to the presence of enough sulfonic acid groups on PS surface, the difference in the decomposition temperature between the PANI shells and the PS core was increased, resulting in the formation of the hollow carbon spheres with good sphericity and thick carbon shells by carbonizing sulfonated PS/PANI core-shell polymer spheres.
Preparation of activated carbons from lignin by NaOH activation and processing optimization
JIANG Li, MA Fei, | 　LIANG Guo-bing, LI Ting
2011, 26(5): 396-400.
Abstract(1951) PDF(1389)
Abstract:
Activated carbons（ACs）were prepared from lignin by NaOH activation. The influence of NaOH/lignin ratio, activation temperature and time on Brunauer-Emmett-Teller (BET) surface areas of ACs was investigated. Based on experimental optimization methods including the central composite design and response surface methodology, optimized parameters were found and the maximum BET surface area of ACs was 1437.20m2/g when lignin was activated at 751℃ for 57min with a NaOH/lignin ratio of 2.06.

Address： 27 Taoyuan South Road, Yingze District, Taiyuan City, Shanxi Province, ChinaPostCode：030001

Phone/Fax：0351-2025254

Email： tcl@sxicc.ac.cn

Copyright © 2021 Editorial Office of New Carbon Materials. All Rights Reserved This system consists of Beijing Renhe Information Technology Co. Ltd   百度统计