Large-scale production of titania nano-coated silica-gel beads by fluidized bed chemical vapor deposition

2007 ◽  
Vol 24 (2) ◽  
pp. 347-349 ◽  
Author(s):  
Jaehyeon Park ◽  
Dal Hee Bae ◽  
Seung Yong Lee ◽  
Jini Kwak ◽  
Hai Woong Park ◽  
...  
2016 ◽  
Vol 852 ◽  
pp. 514-519 ◽  
Author(s):  
Xiao Gang Sun ◽  
Zhi Wen Qiu ◽  
Long Chen ◽  
Man Yuan Cai ◽  
Zhi Peng Pang ◽  
...  

Since the first observation of carbon nanotubes (CNTs) in 1991, their synthesis techniques has been extensively investigated. The chemical vapor deposition (CVD) process have attracted much attention because of both their versatility and easy large scale production for CNTs . This paper is focused on a catalytic CVD-based method for synthesis of whisker multiwalled carbon nanotubes (WMWCNTs). The new type of carbon nanotube is similar to the whisker. The morphology of the WMWCNTs are very different from traditional carbon nanotubes prepared by traditional chemical vapor deposition process. The traditional CNTs were twisted and entangled with each other. These suggested that there are a lot of deficiencies on the CNTs and are difficult to disperse in matrix materials. The as-produced WMWCNTs are very straight and not entangled with each other. The line structure means that WMWCNTs are easily dispersed in matrix materials than traditional CNTs which are twined together. The crystallinity of WMWCNTs increased to 96% which was much higher than traditional CNTs after graphitization treatment at 2800°C.


2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
S. A. Manafi ◽  
S. H. Badiee

Carbon nanofibers (CNFs) have been synthesized in high yield (>70%) by catalytic chemical vapor deposition (CCVD) on Co/LiF catalyst using acetylene as carbon source. A novel catalyst support (LiF) is reported for the first time as an alternative for large-scale production of carbon nanofibers while purification process of nanofibers is easier. In our experiment, the sealed furnace was heated at700∘Cfor 0.5 hour (the heating rate was10∘C/min) and then cooled to room temperature in the furnace naturally. Catalytic chemical vapor deposition is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanofibers (CNFs). The obtained sample was sequentially washed with ethanol, dilutes acid, and distilled water to remove residual impurities, amorphous carbon materials, and remaining of catalyst, and then dried at110∘Cfor 24 hours. The combined physical characterization through several techniques, such as high-resolution transmission electron microscope (TEM), scanning electron microscope (SEM), thermogarvimetric analysis (TGA), and zeta-sizer and Raman spectroscopy, allows determining the geometric characteristic and the microstructure of individual carbon nanofibers. Catalytic chemical vapor deposition is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanofibers (CNFs). As a matter of fact, the method of CCVD guarantees the production of CNFs for different applications.


Author(s):  
Mahmoud Reza Hosseini ◽  
Nader Jalili ◽  
Rebecca M. Alway-Cooper

Carbon nanotubes (CNTs) are one of the best candidates for utilizing in the future nanoelectronic devices. However, the semiconductivity property of CNTs varies as diameter and chirality number change. Several nanoelectronic applications require semiconductivity to be of a certain value with little variability. Therefore, it is necessary to reliably produce uniform CNTs with unique diameter and chirality. However, this still remains one of the challenging problems in the large scale production and application of CNTs. In this paper, the effect of fabrication temperature change on CNTs diameter and chirality are experimentally and theoretically studied. Utilizing chemical vapor deposition (CVD) fabrication process and by conducting experimental investigation, it is observed that a CNT possesses a larger diameter at its base compared to the section far away from deposited nanoparticles. Moreover, using MD simulation technique, it is observed that the energy of the CNTs molecular structure will increase by applying higher fabrication temperature. Usually this energy increase is greater in the thicker CNTs. However, the energy increase percentage is found to be affected by the chirality of the CNT. Among CNTs of the same diameter, the armchair conformation has the highest percent increase, followed by the chiral CNTs, and the zigzag nanotube has the lower percent increase. The obtained results can be utilized in a controllable CNTs diameter and chirality design process.


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