Micro-nano hierarchal web of activated carbon fibers for catalytic gas adsorption and reaction

Abstract

A hierarchal web of activated carbon fibers is synthesized in which carbon nanofibers (CNF) are grown on micro activated carbon fibers (ACF) used as a substrate. A bed of ACF was first impregnated with nickel nitrate hexahydrate which was subsequently reduced to metallic nickel. Catalytic chemical vapor deposition (CVD) was then carried out at 1023 K using benzene as carbon source, which resulted in the growth of CNF. Conditions of hierarchal web formation were optimized by employing two different types of reactors^-a perforated tube reactor with radially outward flow of gases and a perforated disc reactor providing a parallel flow. Both of these configurations were used for carrying out reduction and CVD. Our results show that relatively larger amount and uniformity of CNF could be obtained using the perforated disc reactor. Various analytical techniques including atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to characterize the carbon web. The resulting ACF web is a hierarchical structure, which was tested for its NO removal capability by reduction. We found these carbon structures to be more efficient compared to the original ACF or ACF impregnated with metal.