Potassium Oxalate as an Alternative Activating Reagent of Corn Starch-Derived Porous Carbons for Methane Storage

Fossil fuels are a main source of energy but also the major contributor to global warming. Therefore, the needs for alternative renewable and sustainable energy sources such as natural gas is increasing; nevertheless, for practical use, efficient gas storage materials of alternative fuels are essential. Activated carbons (ACs) are a promising candidate as gas storage materials due to their narrow micropore size distribution and high porosity. Appropriate selection of the activating reagents is key factor for the preparation of high-performance ACs. Recently, potassium hydroxide is the most widely used activating reagent, but its application for plant-scale production is reluctant by its toxicity and high corrosiveness. Hence, in this study, the less corrosive and easy manageable potassium oxalate salt was used as an alternative reagent to prepare ACs from corn starch, for methane storage. The products were characterized based on their N-2 adsorption-desorption isotherms at 77 K and on their specific surface area and pore size distributions, respectively calculated via the Brunauer-Emmett-Teller (BET) equation and the non-local density functional (NLDFT) theory. The methane storage capacities and adsorption cycles were investigated with a high-pressure adsorption instrument operating at 298 K and 35 bar.