Innovative one-step preparation of activated carbon from low-rank coals activated with oxidized pellets

Abstract

The research proposed an innovative, efficient, and clean process which used low-rank coals and oxidized pellets as carbon-based feedstocks and activators for one-step preparation of activated carbon with direct reduction iron as co-production. The co-effect between low-rank coals and oxidized pellets was disclosed. The properties characterization of activated carbon was comprehensively analyzed as well. The results indicated that semi-coke can be produced via the pyrolysis and carbonization of low-rank coal, which is the raw material of activated carbon and the reductant of oxidized pellets. Meanwhile, CO2, generated circularly via the reduction of iron oxides, acts as the activating agent of semi-coke to produce activated carbon. Furthermore, CO, generated via gasification reaction of carbon, can act as the main reductant for the reduction of iron oxides. Under the optimum conditions of SF coal as carbon-based feedstock, activated temperature of 850 °C for 140 min with C/Fe of 2.0, one-step prepared activated carbon, characterised by specific surface area of 370.42 m2 g−1, iodine sorption value of 685.67 mg g−1, compressive strength of 234.67 N·per−1, can be obtained with direct reduction iron as co-production processing metallization ratio of 86.96%. Compared with commercial activated carbon, the new SF activated carbon possesses a more superior microstructure, higher graphitization degree, preferable composition, and content of functional groups for its better adsorption property and compressive strength.