Hydrogen storage capacity of tetrahydrofuran and tetra-n-butylammonium bromide hydrates at favorable thermodynamic conditions

Abstract

An exploratory investigation was conducted to evaluate the feasibility of employing binary hydrates as a medium for H2 storage. Two reagents, tetrahydrofuran, (THF) and tetra-n-butylammonium bromide (TBAB), which had been reported previously to have potential to form binary hydrates with H2 at favorable conditions (i.e., low pressures and high temperatures), were investigated. A scale-up facility was employed to quantify the hydrogen storage capacity of THF binary hydrate. Gas chromatograph (GC) and pressure drop analyses indicated that the weight percentages of H2 in hydrate were less than 0.1%. This is well below the current USDOE target of 5.5 wt. % for transportation applications. To summarize, the major conclusions of this investigation are: H2 can be stored in binary hydrates at relatively modest pressures and temperatures which are probably feasible for transportation applications. The storage capacity of H2 in binary hydrate formed from aqueous solutions of THF over a concentration range extending from 2.78 to 8.34 mol % and at temperatures above 263 K and pressures below 11 MPa was < 0.1 wt. %. Under-saturated solutions of THF appeared to have the highest H2 storage capacity.