Hydrolysis Rate Improvement in Hydrogen Generation System Fueled by Powdery Sodium Borohydride for Fuel-Cell Vehicle

Abstract

Sodium borohydride (NaBH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) is attractive as a fuel for fuel-cell electric vehicles (FCEVs) and fuel-cell hybrid electric vehicles because of its high energy density. We proposed and constructed a high-density hydrogen generation system that generates a large amount of hydrogen by hydrolysis of powdery NaBH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> . However, our ability to conduct long driving tests was restricted by the low hydrogen generation rate at the start of the proposed system, particularly under low temperature. To overcome this problem, we added a citric acid solution catalyst at the start, thereby increasing the rate of hydrogen generation by a factor of 25 compared with the case of using a conventional nickel catalyst. In addition, we confirmed that using such a rapid hydrogen generation system had little effect on the power generation characteristics of a 100-W fuel cell, and we succeeded in conducting our driving tests of a FCEV fueled by powdery NaBH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> .