(748g) Structural Integrity of Biomass-Derived Materials for Hydrogen Storage at High Pressure and Cryogenic Temperature

With the global transition towards a sustainable hydrogen (H₂) economy, the potential of H₂ is explored due to its competent aspect of being renewable and of zero-emission. However, the main challenge of its application is storing in solid-state material which often requires high pressure (around 700 bar) and low temperature (around -196 °C). Therefore, the use of H₂ energy is still struggling to thrive. Along with the adsorption parameters (e.g., high microporous surface area, large pore volume, etc.), the adsorption sites and the interaction between adsorption sites with H₂ are vital in storing H₂.

Moreover, it has been recently observed that the presence of oxygen functional groups also plays an important role in uptake H₂. However, to the best of authors’ knowledge, no study has been done on the stability of storage materials as they are experienced with low temperature and high pressure. Thus, the objective of this study was to investigate the structural stability of the H₂ storage materials. Henceforth, a set of biomass-derived superactivated hydrochars were prepared from cellulose acetate by hydrothermal carbonization at 220 and 260 °C followed by KOH activation at 700 °C for 1 h. The volumetric H₂ storage experiments were carried out in High-Pressure Volumetric Analyzer (HPVA) at 100 bar and -196 °C. A total of 9 consecutive cycles of operation were conducted for each superactivated hydrochar. The BET surface area, pore volume, pore size, and volumetric H₂ uptake of the material were determined after each cycle. Additionally, surface morphology of the superactivated hydrochars were evaluated by Scanning Electron Microscope (SEM) analyzer. Analyses showed that the superactivated hydrochars underwent only a 4.5% decrease in the specific surface area and around 1.7% decrease in pore volume after 9 cycles of consecutive H₂ adsorption and desorption, signifying high stability of the material for cyclic H₂ storage.