Comparing the practical hydrogen storage capacity of porous adsorbents: Activated carbon and metal-organic framework

Abstract

For the transition to a society powered by hydrogen energy, it is important to ensure the safe delivery of enough hydrogen. One promising method for storing and transporting hydrogen is sorbent-based cryo-adsorption. To assess the effectiveness of this physisorption-based method, hydrogen storage performance can be evaluated in various ways, including (gravimetric and volumetric) excess, absolute, total uptake, and useable capacity. However, previous literature mostly reported one or two of these indicators sporadically, which made it challenging to analyze the practical and comprehensive hydrogen storage capacity. Herein, we evaluate the most practical activated porous carbons and Metal-organic framework (MOF) as hydrogen storage materials using all relevant indicators. Specifically, the optimized useable capacity is defined as the H2 amount per the mass of adsorbent that can be released from the maximum tank pressure to the back pressure at optimized working temperature. This is considered the most practical measure of a tank system's capabilities. Thus, the maximum useable capacity can be determined based on temperature, so it is important to identify the ideal temperature conditions. It is noteworthy that our result revealed opposing the previous stereotypes which claimed that practical hydrogen storage is favored by lower temperatures.