CoMoCAT

Figure 6.60. Illustration of two methods used for the commercial production of SWNTs. Shown are (a) the CoMoCat fluidized bed method using CO as the precursor and a Co/Mo bimetallic catalyst,[84] and (b) the HiPco floating catalyst process using the thermal decomposition of iron pentacarbonyl at pressures of 1-10 atm.[85]...

Figure 13.4 Optical absorption spectrum of a typical CoMoCAT material, obtained by CCVD of CO at 725°C on Co-Mo catalysts at high pressures. This material exhibits a high concentration of the specific (6,5) type. (Reproduced with permission from Y. Tan and D. Resasco, J. Phys. Chem. B 2005,109, 14454.)...

Figure 13.8 Schematic drawings for the different SWNT synthesis methods, (a) Arc discharge (dc). Nanotuhes are collected from the cathode surfaces (indicated hy A) and from the inner wall of the evaporator (indicated hy B). (h) Laser vaporization. The C/Ni/Co target is positioned inside a furnace. The carbon and catalyst vaporization is reaUzed by irradiation with a double laser, in this case, a XeCl and a NdYAG. (c) Fluidized bed CCVD reaction system used in the CoMoCAT process. [Part (a) reproduced with permission from Y. Saito et al, J. Phys. Chem. B 2000, 104, 2495. Part (b) reproduced with permission from A. A. Puietzky et al, Appl. Phys. Lett. 2000, 76, 182.]...

One important aspect in the SWNT production by CCVD method is the reactor design. Large-scale production requires reactor designs amenable to being scaled up. An example of a schematic design is shown in Figure 13.8c for the fluidized bed system employed in the CoMoCAT process. 

Supported Catalyst (CoMoCAT) 6,333,016 (2001) D. Resasco, B. Kitiyanan, J. Harwell, W. Alvarez... 

In a hypothetical CCVD process similar to CoMoCAT, SWNT are produced in a fluidized bed reactor by disproportionation of carbon monoxide (2CO C + CO2). Fresh catalyst is added at a continuous rate (CTl) of 10 kg/h. Before puri-Acation, the black sand product (CT2) contains 30 wt% carbon, while the rest of... 

Figure 11 examines the SWCNT topology compared to the unmodified SPE. The CNTs utilized within the ink are S3mthesized by the CoMoCAT process. 

Acronyms and variables cold crystalhzation (CC) cobalt molybdenum catalyst (CoMoCAT) chemical vapor deposition (CVD) dichlorobenzene (DCB) high-pressure carbon monoxide (HiPCO) isotactic polypropylene (iPP) melt crystalhzation (MC) melt flow index (MFl) poly( -caprolactone) (PCL) polydispersity index (PDD polyethylene (PE) polyethylene oxide (PEO) poly (ethylene-propylene-diene) [P(E-PP-diene)] poly(ethylene 2,6-naphthalate) (PEN) poly(ethylene terephthalate (PET) poly(L-lactic acid) (PLLA) poly(trimethylene terephthalate (PTMT) poly(vinyl alcohol) (PVA) 1,1,2,2-tetrachloroethane (TCE) tetrahydrofuran (THE) weight-average molecular weight = ] number-average molecular weight Avrami exponent for neat polymer = Avrami exponent for CNT composite = Avrami rate constant for neat polymer = Avrami exponent for composite = neat polymer crystalhzation... 

CoMoCAT (fluidized-bed CVD) and HiPCO (high-pressure CO CVD), have recently been developed for the commercial production of SWNTs (Figure 6.79). Though the experimental setup of these methods are significantly more complex than standard hot-walled CVD, these techniques are still considered an extension of... 

The SWCNTs were dispersed in DMF at a concentration of 0.5 g L by bath sonication for 40 min at 40—50 °C. In a typical procedure, 20 mL of this dispersion was filtered and washed on the filter with 10 mL of methanol and 10 mL of water. The solid was transferred into 20 mL of 8 M HNO3 in a glass vial, and the mixture was sonicated in a bath at 40—50 °C for a time ranging firom 30 min to 5 h. The mixture was diluted 1 2 with deionized water and filtered using a 0.45 pm PTFE filter. The solid was washed on the filter with water until the filtrate was neutral, washed with 10 mL of methanol, washed with 10 mL of DMF, and redispersed in 20 mL of DMF by bath sonication for 60 min. The filtrates from CoMoCat and HiPco nanotubes were colorless, but the filtrate from PLV nanotubes was Hght gray. AFM analysis of the PLV filtrate indicated the presence of nanotubes (Tchoul et al., 2007). 

One of the most successful examples is chromatographic separation of SWNTs wrapped with DNA [136,137,139,140]. Quite recently, (6,4), (9,1) and (6,5) SWNTs were obtained in almost pure form by sorting of CoMoCAT SWNTs wrapped with DNA with conventional ion-exchange chromatography [33]. The SWNTs/DNA solution was subjected to a variety of optical analyses such as circular dichroism, photoluminescence and absorption spectroscopies [141-143] as well as investigation of their photo- and electrochem-icalbehaviors [144,145]. The strong interaction between SWNT and DNA was simulated theoretically by molecular dynamics [146] and ab initio calculations [147], and used for nanofabrication of SWNTs [148,149]. 

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