Computational approach to study hydrogen storage in clathrate hydrates

Abstract

This work presents collectively, analyzes and compares the results from previous Monte Carlo studies performed towards the evaluation of the hydrogen-storage capacity of clathrate hydrates. Clathrate hydrates can be regarded as a special type of nanoporous material that consists of hydrogen-bonded water molecules that form cavities where gas molecules can be entrapped. Three different hydrates structures (sI, sII, and sH) are examined where hydrogen is either the single guest component or a second substance (promoter) coexists. The storage of hydrogen in hydrates can be simulated as a process of gas adsorption in a solid material and, consequently, the Grand Canonical Monte Carlo approach seems to be the most appropriate approach. These simulations are themselves consistent and, most importantly, they are in good agreement with the available experimental data. This fact illustrates the efficiency of the specific computational approach in the study of hydrates. The comparison between the three hydrate types shows that sH hydrates can store larger amounts of hydrogen than sI or sII hydrates. In particular, the maximum hydrogen content achieved is 3.6 wt% with pure hydrogen, and 1.4 wt% with the use of a promoter (at 274 K and 500 MPa).