Controllable synthesis of carbon nanotubes via autothermal reforming of ethyl acetate

Controllable synthesis of carbon nanotubes (CNTs) via autothermal reforming of ethyl acetate and waste cooking oil was studied for the first time. The products of the products were characterized by techniques of FESEM, XRD, HRTEM, Raman and XPS. Results revealed that reaction temperature, reaction time and reactants significantly affected the growth of CNTs. Ethyl acetate could be easily catalyzed into CNTs at 600 °C, which contained numerous defects and vacancies. High reaction temperatures led to the formation of CNTs with small diameter. The graphitization and purity of CNTs could be improved by increasing the reaction time. Besides, the amount of CNTs decreased by increasing the reaction time at low reaction temperature (< 600 °C), whereas increased at high reaction temperature (700 and 800 °C). In addition, increasing the amount of O₂ and H₂O in reactants reduced the formation of irregular carbon species and promoted the synthesis of CNTs with ultra-small diameter. Two growth mechanisms for synthesizing CNTs from ethyl acetate via autothermal reforming were proposed: “tip-growth” mechanism and “graphene-to-CNTs” mechanism. Furthermore, the real waste cooking oil was also successfully catalyzed into CNTs.