Effect of Temperature on Gravity Assisted Synthesis of Carbon Nanotubes by Spray Pyrolysis

Carbon nanotubes were prepared along the gravity direction in a spray pyrolysis setup over the silica supported Fe-Co-Ni catalyst. The silica supported Fe-Co-Ni catalyst coated by jet nebulized spray pyrolysis method over copper strip was inverted to face downward, so that carbon nanotubes can be prepared along the direction of gravity. From the point of view of green chemistry, instead of commonly used hydrocarbons, a plant based natural precursor, pine oil is used as carbon precursor for preparation of carbon nanotubes. The effect of temperature on yield and morphology of carbon nanotubes grown along gravity was studied. The yield of carbon nanotubes was calculated as mass percentage of catalyst and support. The carbon nanotubes were characterized using XRD, SEM, Raman and TGA techniques. The carbon deposit obtained at 650 ºC contains multi-walled carbon nanotubes in larger quantity with very less amorphous carbon. A narrow, lengthy and well graphitized multi-walled carbon nanotubes were formed when the carbon nanotubes grow along the gravity.