Preparation of activated carbon cloths from viscous rayon. Part II: physical activation processes

Activated carbon cloths were prepared from viscous rayon by a two-step acti vation process (carbonization followed by activation) and a single-step act ivation process (simultaneous carbonization and activation), and were compa red in terms of gasification rate, development of porosity and changes in b reaking strength. Direct activation of the precursor takes place with a hig her rate than char activation, the final products of the former process exh ibiting slightly lower micropore volume and surface area. The effect of usi ng carbon dioxide or steam as the activating agent was also analyzed, the f ormer producing a continuous development of narrow microporosity and slight widening only above 30% activation, and the latter a widening of micropore s as from the car ly stages of the process. (C) 2000 Elsevier Science Ltd. All rights reserved.