Production of carbon nanotubes using Fe-FSM-16, co-FSM-16 and Ni-FSM-16 type mesoporous catalytic materials by chemical vapor deposition
Taş, Sinem (2011) Production of carbon nanotubes using Fe-FSM-16, co-FSM-16 and Ni-FSM-16 type mesoporous catalytic materials by chemical vapor deposition. [Thesis]
Official URL: http://192.168.1.20/record=b1306614 (Table of Contents)
FSM-16 was synthesized and loaded with 2 and 4 wt % Fe, Co, and Ni by impregnation method. These catalytic materials were tested in the production of carbon nanotubes using the CVD method. The synthesized materials were characterized by XRD, 29Si- NMR, N₂ [Nitrogen] physisorption, and SEM-EDS. The effect of metal concentration on structural characteristics of the mesoporous material was studied. XRD results demonstrated that Fe, Co and Ni modified FSM-16 had hexagonal mesoporous structure. However, both XRD and 29Si-NMR characterization proved, as the metal concentration increased, hexagonal mesoporous structure was partially lost. According to BET results, the surface area, pore volume and pore diameter decreased due to metal impregnation. This was an indication of deterioration of silica matrix. SEM results exhibited the morphological differences between FSM-16 and Fe, Co, and Ni modified FSM-16. Effect of experimental parameters such as metal concentration, reaction temperature and acetylene flow rate for CNTs growth were investigated by using Fe-FSM-16, Co-FSM- 16, and Ni-FSM-16. Synthesized CNTs were characterized by SEM, Raman spectroscopy and TGA. It was found that metal concentration (2-4 wt %), and reaction temparature (500-800ºC [degrees Celsius] were critical for CNTs formation. While each catalyst exhibited high production of CNTs at 700ºC [degrees Celsius] ; and, they were inactive at 500ºC [degrees Celsius]. The diameter of CNTs changed with synthesis temperature, in particular the diameter of the CNTs increased with the reaction temperature. Ni-FSM-16 and Co-FSM-16 showed somewhat lower reactivity in formation CNTs with respect to Fe-FSM-16. Among the catalysts, 4 wt % Fe-FSM-16 improved the formation of CNTs. The effect of acetylene flow rate for CNTs diameters which grown on the 4 wt % Fe-FSM-16 was studied. It was observed that acetylene flow rate did not affect on the diameter of the synthesized CNTs significantly. Diameters of CNTs were almost the same, observed to be in the range of 20-35 nm. Raman measurement indicated that the synthesized products were MWCNTs since no SWCNTs characteristic features appeared in the RBM region. The characterization results demonstrated that CNTs formation with high efficiency was performed by using 4 wt % Fe-FSM-16 with 80 mL/min acetylene flow rate at 700ºC [degrees Celsius] for 30 min.
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