Research On Preparation Of Special Activated Carbon For CH₄Adsorption

Activated carbons were prepared from Guizhou anthracite and Taixi anthraciteby additive method in this study. The preparation process is under the followingprocedures: mixing, extruding, carbonization and activation. The properties of theactivated carbons were characterized by CH4adsorption capacity, iodine number,specific surface area and pore size distribution （PSD）.Guizhou anthracite as raw material, a single factor experimental method whichincluding coconut shell, carbonization temperature and time, activation temperatureand additive was employed to research the influence of preparation conditions onproperties of activated carbon. The results show that alkali metal salt and coconutshell can promote the development of CH4adsorption content. With increasingcarbonization and activation temperature, the amount of CH4adsorption increasesfirstly and then decreases. The optimum preparation conditions for Guizhou anthraciteare97g of coal and coconut shell,3%of additive,16%of coconut shell,650C ofcarbonization temperature,20min of carbonization time and880C of activationtemperature. CH4adsorption content of the activated carbon under the conditions is20.85mL/g.Taixi anthracite as raw material, an orthogonal experimental method wasemployed to investigate the effectiveness of all factors and determine the optimumpreparation conditions. The orthogonal experiment results show that the optimumpreparation conditions are97g of anthracite,3%of composite additives,630C ofcarbonization temperature,20min of carbonization time,910C of activationtemperature and1.5h of activation time. CH4adsorption content of the activatedcarbon under the conditions is22.80mL/g（25C，0.1MPa）. The amount of CH4adsorption of the activated carbon which was prepared from Taxi anthracite is largeand its pore size distribution centralized. Futhermore, study shows that CH4adsorption capacity is independent of iodine number, specific surface area, total porevolume and pore volume of certain pore size. A single factor experimental methodwas employed to research the influnce of preparation conditions which includingadditives, burnoff, carbonization temperature, carbonization time, carbonizationheating rate and activation temperature on properties and PSD of activated carbon. Itis found by single factor experiment that controlling the range of30%-40%of burnoffis benefit to the development of microporous. The optimal activation temperature is880C and the optimal carbonzation temperature is650C. Moreover CH4adsorption capacity decreases with increasing carbonzation heating rate, and3C/min of heatingrate is optimal. CH4adsorption capacity is independent of carbonization time.Optimum preparation conditions for single factor experiment are97g of anthracite,3%of composite additives,30%-40%of burnoff,650C of carbonization temperature,20min of carbonization time,3C/min of carbonzation heating rate and880C ofactivation temperature. CH4adsorption content of the activated carbon under theconditions is24.31mL/g（25C，0.1MPa）.