Comparative study on the preparation of powdered activated coke for SO₂ adsorption: One-step and two-step rapid activation methods

Activated coke, which is a porous carbonaceous material, can be used in flue gas desulfurization, but its preparation has two primary problems, namely the complex preparation process and the high preparation cost. In this study, two methods were proposed for the rapid preparation of powdered activated coke (PAC), namely one-step rapid activation method and two-step rapid activation method. Shengli (SL) lignite and Jinjie (JJ) bituminous coal were used as raw materials to prepare the PAC in a drop-tube reactor via the two methods. The burn-off, yields and pore structures of the produced PAC using the two methods were compared and analyzed, and their activation mechanisms were speculated. Then, as an evaluation standard method of the SO2 adsorption performance, all samples were tested for their SO2 adsorption capacities for 2 h. Results showed that the pore structure and SO2 adsorption performance of the SL-PACs were much better than those of the JJ-PACs, that is, the PACs prepared from lignite had better properties than that prepared from bituminous coal. Moreover, the PACs prepared using the two-step method had more developed pore structures and higher SO2 adsorption capacities; however, their yields were relatively low. The one-step method has a simpler process, and its investment and operating costs are lower compared to the two-step method.