Highly purified hydrogen production from ammonia for PEM fuel cell

Liquid ammonia is an attractive hydrogen carrier because of high storage capacity. According to ISO14687-2, an acceptable ammonia concentration in hydrogen for polymer electrolyte membrane (PEM) fuel cell vehicles is 0.1 ppm. When ammonia is used as the hydrogen carrier, about 1000 ppm of ammonia included in gas generated by ammonia decomposition at 773-823 K and 0.1 MPa has to be reduced to less than 0.1 ppm. Although several types of ammonia absorption materials are investigated as ammonia remover, the target value cannot be achieved by static adsorption methods. However, we have succeeded in that the ammonia concentration is reduced down to 0.01-0.02 ppm by using Li-exchange X-type zeolite (Li-X) as the absorbent and dynamic adsorption methods. Furthermore, Li-X is simply recycled by heating at 673 K. Therefore, Li-X is a durable and recyclable ammonia removal material for the highly purified hydrogen production from ammonia for PEM fuel cells.