Abstract: Flue gas desulfurization（FGD）by activated coke（AC）is of great potential in the recycling technology. AC
particles with smaller diameter are superior to the one with larger diameter in cost and absorptive mass transfer. Proven by
the tests on AC with different particle diameters，the SO2 adsorption rate of AC increased with the decrease of AC's particle
size both in the fixed-bed and entrained-flow reactors，since the mass transfer resistance of AC with smaller diameter is
lower than that with larger diameter.Taking AC with the same particle size，the adsorption rate of AC in the entrained-flow
reactor was higher than AC in the fixed-bed reactor by two orders of magnitude. Broken into smaller particles，the total
specific pore volume and total specific surface area of AC is greatly increased. The increased specific surface area is mainly
brought by the additional medium and large pores（pore diameter > 2 nm），who improve the diffusion of SO2 on the surface
and inside of AC.The pores also facilitate the migration and storage of the by-products from adsorption process and raise the
adsorption rate of AC.

Key words: activated coke diameter, fixed-bed reactor, entrained-flow reactor, SO2 adsorption, desulfurization technology,
mass transfer resistance, adsorption rate, near-zero emission