Effect of calcium on the activation characteristics and pore structure of phenolic resin-based carbon spheres

Phenolic resin-based activated carbon spheres (PACS) with high mesopore volume were successfully prepared by the addition of calcium nitrate into the novolac-type phenolic resin. N2 adsorption was used to characterize the pore structure of the prepared PACS. The results shows that the calcium enhances the burning rate of the carbon spheres and reduced the micropore surface area with little influence on their pore size distribution. The calcium-containing activated carbon spheres have preponderant mesopores 3-4 nm in size and a high mesopore ratio. Continued activation increased the number of mesopores larger than 4 nm; but had little effect on the 3-4 nm size mesopores, which indicted different mechanisms for mesopore evolution in calcium-containing activated carbon spheres.