Conversion of sugarcane bagasse ash to silica-based catalyst support material for synthesis of carbon nanotubes from benzene

Sugarcane bagasse ash, an abundant agricultural waste with high silica content (68 wt%), was modified through two combined processes of 1 M hydrochloric acid leaching followed by 800 °C calcination for 2 h with a different sequence to tailor its textural properties. Then, the silica-rich powder was utilized as an Fe catalyst support material for carbon nanotube synthesis. The calcined after acid-leached ash (CLA) samples exhibited a higher silica content of 87.5 wt% with a specific surface area of 12.3 m²/g, when compared to the acid-leached after calcined ash (LCA) samples prepared by an opposite treatment sequence. After the hydrothermal treatment with an iron nitrate solution using 20 wt% Fe loading, the Fe supported on the calcined after acid-leached ash (Fe/CLA) catalyst exhibited a higher surface area of 25.4 m²/g with a smaller Fe crystallite size of 31.8 nm. By using benzene as a carbon source through catalytic chemical vapor deposition at 800 °C, the selected Fe/CLA catalyst could provide a remarkable carbon nanotube yield of 7.93 wt% with a uniform diameter of 44.4 nm and high graphitic content based on I G /I D of 1.96. Accordingly, this work demonstrates the potential utilization of sugarcane bagasse ash as a promising Fe catalyst support material for carbon nanotube production from benzene with preliminary economic-environmental outlooks.