(144e) Investigation of Hydrothermal Carbonization and Chemical Activation Process Conditions on Hydrogen Storage in Loblolly Pine-Derived Superactivated Hydrochars

While the challenge of storing hydrogen in inexpensive and renewable adsorbents is relentlessly pursued by researchers all over the world, application of hydrochar derived from biomass is also gaining attention as it can be subsequently chemically activated using activating agents like KOH in order to tailor the development of favorable porosity. However, the synergistic effect of hydrothermal carbonization (HTC) process conditions as well as KOH activating conditions on the development of surface morphology is required to be assessed with the application of such porous superactivated hydrochars in hydrogen storage application. In this study, highly porous superactivated hydrochars were fabricated from inexpensive and abundant loblolly pine. Loblolly pine was hydrothermally carbonized at 180 °C, 220 °C and 260 °C and the hydrochars were then activated at different experimental conditions of 700 °C, 800°C and 900 °C using solid KOH to loblolly pine hydrochar ratio of 2:1, 3:1 and 4:1 to produce superactivated hydrochars. Superactivated hydrochars as well as loblolly pine and its corresponding hydrochars underwent physicochemical analysis as well as surface morphology analysis by SEM and nitrogen adsorption isotherms at 77 K in order to investigate the effect on BET, pore volume, and pore size distribution due to various process conditions. The superactivated hydrochars were then analyzed to quantify total hydrogen storage capacity of these materials at 77 K and up to pressure of 55 bar. Porosity of superactivated hydrochars were as high as 3666 m²/g of BET specific surface area (SSA), total pore volume of 1.56 cm³/g and micropore volume of 1.32 cm³/g with the hydrogen storage capacity of 10.2 wt.% at 77 K and 55 bar. It was conclusive from principal component analysis that higher HTC temperature with moderate activation condition demonstrated favorability in developing porous superactivated hydrochars for hydrogen storage applications.