Miniature NH3 cracker based on microfibrous entrapped Ni-CeO2/Al2O3 catalyst monolith for portable fuel cell power supplies

A miniature ammonia cracker, with an overall weight of ≈195 g and volume of ≈50 cm3, has been developed for portable fuel cell power supply. The cracker is composed of a SS-316L tube body, a heating rod and monolithic microfibrous CeO2-promoted Ni/Al2O3 catalysts incorporated within the annular housings between the heating rod and the inner wall of the tubular body. The catalyst monolith is obtained by placing CeO2 and Ni onto the microfibrous carrier consisting of 3.5 vol% 8 μm diameter nickel fibers and 38 vol% 100–200 μm Al2O3 particulates through stepwise incipient wetness impregnation method using cerium and nickel nitrate precursors. This cracker shows pleasing operability for high efficiency H2 production via ammonia cracking with low pressure drop. Roughly 158 W equivalents of H2 can be produced with ammonia conversion of >99.9% at 600 °C and 1100 standard cubic centimeter per minute (sccm) ammonia feed gas rate within this cracker through the entire 300 h test. Power density and energy density are estimated to be ≈3160 W/L and ≈2150 Wh/kg, respectively.