LI Xuankun, SI Zhichun, LIU Liping, WENG Duan, WU Xiaodong, RAN Rui, KANG Feiyu
With the increasingly stringent exhaust emission standard and the mature application of exhaust treatment technics, fuel evaporation has become the main source of vehicle emission. Canister containing formed active carbon is the key part of automotive fuel evaporator to reduce emission and reuse fuel vapor significantly. Formed active carbon needs to have a large surface area and large effective pore volume (pore size of 2~5 nm) for high working capacity, high structural strength, fast adsorption and desorption of fuel, which are typically obtained by chemical and physical-chemical activation methods. Chemical and physical methods are common in preparation of activate carbon, chemical activation may produce pollution, which leads to environment problems, although to develop a preferable structure of pore, the physical activation costs a large amount of energy and investment, and the pore structure by this method is relatively poor. Chemi-physical methods can combine the benefits of both physical and chemical activations to decrease the pollution and produce high quality activate carbon. Activation and formation are the main processes for preparation of formed activate carbon; the precursor can change into activate carbon through the activation, and then have the solid shape and structural strength after formation. The integration of formation and activation is the development trend of preparation of formed activated carbon. The performance, characterization, preparation and related mechanisms, and the application in VOCs removal of formed active carbon are reviewed.
