Influence of acid treatment on N-doped multi-walled carbon nanotube supports for Fischer–Tropsch performance on cobalt catalyst

• The bamboo-like structure of N-doped CNTs disappeared after acid treatment.
• N doping and acid treatment improve Co dispersion inside the tubes of the NCNTs.
• The acid treatment time influences the support structure and further FT activity.

Nitrogen-doped carbon nanotubes (NCNTs) were acid treated and used as a support for Co catalysts. The effect of acid treatment time on the carbon structure, surface properties and the microstructure of Co catalysts was extensively characterized by BET, XRD, TPR, XPS, TEM and Raman spectroscopy. It was found that acid treatment affected the support structure, the Co reducibility, the Co dispersion and the Fischer–Tropsch (FT) synthesis performance significantly. The graphitization degree, cobalt particle size, cobalt particle location and the number of active sites determined the FT synthesis performance of the Co catalysts.