Activation of Canadian Coals in a Fixed-Bed Reactor: Effect of the Particle Size on Product Quality

Three Canadian coals, namely, Bienfait lignite, Montgomery sub-bituminous C, and Coal Valley high volatile bituminous C were activated in a fixed-bed reactor. For each coal, two different sizes of particles in the ranges of 0−1.25 mm (fines) and 1.25−2.5 mm (granules) along with cylindrical pellets of 3.18 mm in diameter and 7 ± 2 mm long were activated. The qualities of the products were determined by measuring iodine and methylene blue numbers, specific Brunauer−Emmett−Teller (BET) surface areas, bulk densities, and ash contents. The specific surface areas and iodine and methylene blue numbers of bituminous coal products were lower than the values obtained with the lignite and sub-bituminous coals, although the product yields were higher. Products obtained from pellets were found to have superior quality compared to that obtained from fines. The ash content of the feed coal influences the quality of the product activated carbon. It was established that a first-order reaction between steam and coal pellets occurred in the process. The activation energies for the process were also determined.