Influence of Solution and Thermal Treatments on Porous Silica-Alumina Particles for Hydrolytic Dehydrogenation of Ammonia Borane

This study investigated the influence of solution and thermal treatments of porous silica-alumina particles on their activity in the hydrolytic dehydrogenation of ammonia borane. Most of the residual sodium in the sample after preparation of the silica-alumina precursors was removed by treatment with aqueous hydrochloric acid. The treated sample exhibited high hydrogen evolution from the aqueous ammonia borane solution, probably because of an increase in the number of protonic acid sites on the surface of the porous particles due to the solution treatment. The soaking time during the calcination process to obtain porous silica-alumina particles also influenced their activity in the dehydrogenation reaction, and the activity increased with increasing soaking time. The sample calcined at 673 K for 9 h, followed by treatment with aqueous hydrochloric acid, exhibited the highest dehydrogenation activity.