ABSTRACT
I. Introduction ................................................................................................ 2 II. Preparation and Variables .......................................................................... 6 A. Effect of Precursor ............................................................................... 6 B. Effect of Activating Agent: NaOH versus KOH .................................. 7 C. Effect of Contacting Method ............................................................. 11 D. Effect of Hydroxide/Precursor Ratio ................................................. 13 E. Effect of Heat Treatment .................................................................... 16 F. Effect of Nitrogen Flow Rate ............................................................. 21 G. Additional Issues ................................................................................ 23 III. Singular Characteristics of Porosity Developed by Alkaline
Hydroxide Activation ............................................................................... 24 IV. Reactions Occurring During Activation .................................................. 31 A. Reaction Products .............................................................................. 32 B. Variables Affecting Reaction Kinetics .............................................. 35 a. Inuence of Hydroxide/Carbon Ratio .......................................... 36 b. Inuence of Heat Treatment Temperature (HTT)........................ 36 c. Inuence of N2 Flow Rate ............................................................ 37 C. Inuence of Precursor Reactivity ...................................................... 38 D. Inuence of Precursor Structural Order ............................................ 41 V. Applications of KOH/NAOH-Activated Carbons .................................... 43 A. Removal of VOC at Low Concentrations .......................................... 44 B. SO2 Removal ...................................................................................... 47 C. CO2 and CH4 Separation .................................................................... 48 D. CH4 and H2 Storage ............................................................................ 49 E. Electrical Double-Layer Capacitors ................................................... 52 F. Space Cryocoolers .............................................................................. 53 VI. Concluding Remarks ................................................................................ 54 Acknowledgments ............................................................................................... 56 References ........................................................................................................... 56
Activated carbon (AC) is the collective name for a group of porous materials, consisting mostly of carbon, that exhibit appreciable apparent surface area and micropore volume (MPV) [1-4]. They are solids with a wide variety of pore size distributions (PSDs) and micropore size distributions (MPSDs), which can be prepared in different forms, such as powders, granules, pellets, bers, cloths, and others. Owing to these features and their special chemical characteristics, they can be used for very different applications, for example, liquid-and gas-phase treatments and energy storage [1-7]. Considering the variety of elds in which AC is being used, it is extremely important to develop a suitable characterization for it. This will enable determination of the effect that its porous structure has on a given application, which will permit control and performance optimization, which in turn will facilitate the discovery of new applications. For this purpose, the three steps depicted in Figure 1.1 are needed. This gure emphasizes that characterization is one of the three essential steps that should not be omitted to optimize both the preparation of ACs and their applications.
