Development of a compact hydrogen generator from sodium borohydride

Abstract

Chemical hydrides can be a simple and safe hydrogen vector for polymer fuel cells. In particular the catalytic hydrolysis of sodium borohydride (NaBH 4) is here envisaged to produce on-demand hydrogen to be supplied to a small solid polymer fuel cell in a portable energy generator. A compact hydrogen generator is designed around a tubular catalytic reactor, whose catalytic powder is held in place by magnetic field. The gas is generated by the exothermic hydrolysis reaction of an aqueous sodium borohydride solution in contact with no-noble catalyst particles inside the reactor. The reaction produces wet hydrogen and borate, which is soluble in water and not harmful to the environment. When hydrogen demand stops, the reactor is emptied and the hydrolysis reaction ceases. A generator was then tested showing a smooth operation and a reasonably good performance. Correct choice of operating conditions and start-up procedures are requested to have a hydrogen production adequate to the fuel cell needs.