Hydrogen generation by means of the combustion of aluminum powder/sodium borohydride in steam

Hydrogen generation by means of the combustion of aluminum powder with sodium borohydride (NaBH4) addition in steam was studied by a pipe furnace at different temperatures. The ignition temperature and the maximum combustion temperature were obtained by an S-type thermocouple. Ignition delay times and combustion efficiencies were measured. The results show that aluminum powder is not ignited at 450 °C, but aluminum powder with NaBH4 addition is ignited under the same condition. The addition of NaBH4 significantly decreases the ignition delay time of aluminum powder. Moreover, the ignition delay times of aluminum powder without or with NaBH4 addition can decrease with increasing the temperature. Combustion products were analyzed by scanning electron microscopy, X-ray diffraction and a portable hydrogen analyzer. The results indicate that NaBH4 displays a key influence on hydrogen generation. Especially, for aluminum powder with 7 wt% NaBH4 addition, the obtained maximum volume concentration of hydrogen is about 21,000 ppm at 650 °C.