Ultra-rapid formation of mixed H2/DIOX/THF hydrate under low driving force: Important insight for hydrate-based hydrogen storage

Abstract

Hydrate was considered to be the next generation hydrogen storage material, and hydrate-based hydrogen storage (HBHS) would play an important role in future hydrogen economy, but sluggish hydrate formation kinetics presents huge technological challenge for its application. Herein, a nano promoter of -SO3−@PSNS was prepared by soap-free emulsion polymerization, and a dual kinetic promoter system (L-methionine/-SO3−@PSNS) was applied to enhance the formation kinetics of mixed H2/DIOX hydrate. At a moderate condition (12 MPa and 274.15 K), hydration efficiency under a driving force of 2.1 MPa is significantly enhanced by the synergy of the dual kinetic promoters, hydrate induction time reduces from 443.2 ± 209.73 min to 24.7 ± 17.16 min, while hydrate growth rate increases by 43.75%, and hydrogen storage capacity is up to 0.473 ± 0.041 wt% that increases by 62.8%. At a more moderate condition (10 MPa and 274.15 K) with an extremely low driving force of 0.1 MPa, enhanced hydrate formation was obtained in a composite promotion system of the dual kinetic promoters and dual thermodynamic promoters (THF/DIOX), which also performs exceptionally in term of recycling. The presence of a small amount (0.35 mol%) of THF reduces the induction time by 93.5%, and hydrate growth rate increases by 130.18%, while satisfactory hydrogen storage capacity (0.346 ± 0.017 g/g) is still remained in mixed H2/DIOX/THF hydrate, the structure of which was confirmed by Raman spectrum. This work presents an effect approach on enhancing the formation kinetics of H2-contained hydrate under low driving force, and this finding provides important insight for HBHS.