Reaction and diffusion controlling during activation process and its impact on pore structure of spherical activated carbon.

[Display omitted] • High specific surface area of activated carbon was obtained with low burn-off. • Pore structure of samples was affected by reaction rate and diffusion controlling. • Proper limitation of reaction rate was useful for diffusion of steam. • Reaction rate and diffusion of steam were controlled by simple method. In this paper, activation reaction, together with diffusion of activation reagent (H 2 O) through samples, were both controlled during activation process of spherical activated carbon (SAC) by simple methods, pore structure of the obtained SAC was analyzed to show the influence of controlling process. Results showed that proper limitation of reaction rate might give more chance for steam to diffuse through samples, and thus more specific surface area (mainly caused by micropores) could be obtained with less burn-off. Additionally, if the diffusion of steam was limited during activation process, though the pore diameter of SAC could be widened, excessive pore corrosion might lead to high inefficient burn-off and low specific surface area. Further studies indicated that, even using same controlling condition, SAC with different diameters had different pore structure or specific surface area, which could be attributed to difficult diffusion of steam into samples with large sizes. [ABSTRACT FROM AUTHOR]