Abstract. This paper presents the effects of acid treatment on the activity, product selectivity and life span of iron Fischer–Tropsch (FT) catalysts supported on carbon nanotubes (CNTs). Two different types of CNTs with low surface area (25 m2/g) and high surface area (170 m2/g) were prepared and treated with 35 wt% HNO3 at 25 8C and 110 8C for 16 h. Fe/CNTs were prepared using incipie…