Pressurized physical activation: A simple production method for activated carbon with a highly developed pore structure

Activated carbon (AC) is produced by a physical or chemical activation process. Physical activation methods are commonly adopted in industry because of their low production costs, but the insufficiency of activating agent diffusibility into core parts of the particles and microdomains of carbon materials causes a lower activation yield and degree of pore development, compared with chemical activation methods. To increase the activating agent diffusibility and corresponding degree of pore development, we propose a novel pressurized physical activation method. Pressurization afforded remarkable increases in specific surface area and total pore volume of the prepared AC, compared with atmospheric pressure. Additionally, in AC prepared by this method, pore size distribution analysis revealed characteristic development of micropores of about 1.6 nm; such micropores did not appear in AC under conventional atmospheric physical activation. Furthermore, observations of particles and their microdomains showed that pressurization increased the activating agent diffusibility in carbon particles, but not at the microdomain level. This innovative pressurized physical activation can produce AC with highly developed pores (specific surface area >2600 m²/g) and a unique pore size distribution due to the improved activating agent diffusibility in carbon particles.