Environmental scanning electron microscopy of activated carbon production from anthracite by one-step pyrolysis-activation

Experiments were carried out to produce activated carbons from anthracite using one-step steam pyrolysis-activation. Environmental scanning electron microscopy (ESEM) was used to observe the porosity development in real time. The anthracite samples were heated in different gas atmospheres before steam activation. The ESEM observations showed that the activation agent had a significant effect on the porosity of activated carbon produced from anthracite. The activated carbon produced by steam activation at 850°C for 6 h had the highest surface area and a well-developed porous structure. Substantial activation of anthracite surfaces and formation of extensive porosity occurred under the same conditions but with steam at 270 Pa instead of atmospheric pressure. Air treatment at 300°C for 3 h before steam activation also led to production of activated carbon with well-developed porosity. An important advantage of the activated anthracites produced in this study is their microporous structure with a considerable fraction of pores of molecular dimensions. This indicates that molecular sieve materials can be producted from Pennsylvania anthracite by one-step pyrolysis-activation under appropriate conditions.