Preparation, Structure and Thermolysis Characteristics of Ammonia Borane

Ammonia borane (NH3BH3, AB) is an excellent source of hydrogen(19.6 wt %) for fuel cell applications. In this paper, pure ammonia borane is successfully prepared by using amino complex for ammonia complex Ag(NH3)2Cl as new ammonia source, and sodium borohydride (NaBH4) as boron source. The composition and constitution of the products are measured by XRD and FT-IR. The thermolysis of ammonia borane is significant for its practical application. Boric acid plays a role in improving ammonia borane hydrogen performance. The effects of different mass ratio of boric acid and ammonia borane on dehydrogenation are tested by XRD, TG/DTA and TPD-MS. The results show that boric acid can decrease the first level dehydrogenation temperature of ammonia borane decrease to about 85°C (working temperature of PEMFC). What’s more, the onset temperature of AB’s thermolysis can decrease to about 60°C when the mass ratio of ammonia borane and boric acid is equal to 3:1. This makes ammonia borane be more suitable for the application in on-board hydrogen storage system.