Document Type : Article
Chemical Engineering Department, Caspian Faculty of Engineering, College of Engineering, University of Tehran
Nanotechnology Research Center, Research Institute of Petroleum Industry, Tehran, Iran
Chemical Engineering Department, Caspian Faculty of engineering, College of Engineering, University of Tehran
Chemical Engineering, Caspian Faculty of engineering, College of Engineering, University of Tehran
Activated carbon from walnut shell is studied for methane storage in this research. The samples are synthesized by zinc chloride and phosphoric acid, as activating agents. The effect of physical activation, after chemical activation steps, on the final structure of the samples and their total methane storage is examined. The results show that physical activation has an improving effect on the total capacity of the samples activated by phosphoric acid, however; it has a reverse effect on the capacity of zinc chloride activated ones. The experimental data show that the best capacity is obtained at impregnation ratios of 0.7 and 1.2 in the case of phosphoric acid and zinc chloride activated samples, respectively. The best sample is the one activated by phosphoric acid with impregnation ratio of 0.7 and subsequently physically activated by carbon dioxide. It has the BET surface area of 1479 m2/g, average pore diameter of 4.2 nm, total pore volume of 0.84 cm3/g and methane adsorption capacity of 159 cm3/g. The sample shows high stability during successive adsorption/desorption cycles experiment.