Materials Engineering and Scale-up of Fluid Phase Chemical Hydrogen Storage for Automotive Applications

Abstract

Among candidates for chemical hydrogen storage in proton exchange membrane (PEM) fuel cell automotive applications, ammonia borane (AB, NH3BH3) is considered to be one of the most promising materials due to its high hydrogen content of 14–16 wt % below 200 °C. Motivated by our previous study based on a model slurry of AB in silicone oil, optimized with an ultrasonic process, we proceeded to scale-up to liter size batches with solid loadings up to 50 wt % (ca. 8 wt % H2) with viscosities less than 1000 cP at 25 °C. The use of a non-ionic surfactant, Triton X-15, shows significant promise in controlling the level of foaming produced during the thermal dehydrogenation of the AB. Stable homogeneous slurry of high solid loading was shown as a viable hydrogen delivery source, based on the new and efficient processing techniques and the ability to adequately control the foaming.

Engineering Challenges of Solution and Slurry-Phase Chemical Hydrogen Storage Materials for Automotive Fuel Cell Applications

“…This report details our research findings related to chemical hydrogen storage not only in the narrow context related to ammonia borane and alane but also in the broader, more general context of chemical hydrogen storage materials. This manuscript complements the published works [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ] that put into perspective the challenges of hydrogen storage for automotive applications.…”

“…Ammonia borane slurries were prepared with silicone oil (CAS #: 63148−58−3) and Triton X−15 (anti-foaming surfactant, CAS #: 9036−19−5) ranging from 20–50 wt% solids loadings. Choi and Westman investigated preparation methods and optimized the AB slurry to reach up to 50 wt% solid loadings in the silicone oil by reducing particle size and selecting tip-sonication for mixing which was highly beneficial for obtaining well-dispersed slurries and acceptable flowability [ 8 , 9 ].…”