Synthesis and characterization of monometallic cobalt catalyst supported on kaolin for the production of carbon nanotubes

This study focuses on the synthesis and the optimization of a monometallic cobalt catalyst on kaolin as support for carbon nanotube production using the catalytic chemical vapour deposition method. The catalyst was prepared by a wet impregnation method. Cobalt has been dispersed onto kaolin support and the catalyst production parameters such as the mass of support, the stirring speed, the drying temperature and the drying time have been optimized using full factorial experimental design. The highest catalyst yield of 72.5% has been obtained at an operating temperature of 110 °C, 7 rpm stirring speed, 7 h drying time, and mass of support of 8 g. A statistical analysis has showed that the mass of the catalyst support had the most significant effect on the yield. The as-produced catalyst has been dried at 110 °C and 120 °C for 5 h to 7 h and calcined at 500 °C for 14 h with an the optimum percentage yield obtained of 72.5 %. The catalyst had a specific surface area of 269.5 m² /g and has been thermally stable up to 1000 °C. The highest yield of carbon nanotube has been obtained at a production temperature of 850 °C. The analyses of the carbon nanotube have indicated that it had an average diameter of 47 nm; specific surface area, pore volume and pore size have been 454.6 m² /g, 0.1573 cm³ /g, and 33.35 nm respectively. Thermo-gravimetric analysis has indicated that the carbon nanotube produced has been stable up to 700 °C. Fourier transform infrared spectroscopy analysis has revealed the presence of functional groups such as alkynes. The various analyses conducted have showed that kaolin is suitable for catalyst synthesis for carbon nanotube growth.