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

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 degrees 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 % H-2) with viscosities less than 1000 cP at 25 degrees 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.