Preparation and Characterization of Lta-Type Zeolite Framework Dispersed Ruthenium Nanoparticles and Their Catalytic Application in the Hydrolytic Dehydrogenation of Ammonia-Borane for Efficient Hydrogen Generation

Abstract

The safe and efficient hydrogen storage and production are major obstacles to use hydrogen as an energy carrier. Therefore, significant efforts have been focused on the development of new materials for the chemical hydrogen storage and production. Of particular importance, ammonia-borane (NH3BH3) is emerging as one of the most promising solid hydrogen carrier due to its high gravimetric hydrogen storage capacity (19.6 wt.%) and low molecular weight (30.8 g/mol). ammonia-borane can release hydrogen gas upon catalytic hydrolysis under mild conditions. Herein, the discovery of a new catalytic material, ruthenium nanoparticles stabilized by ZK-4 zeolite framework, for this important reaction has been reported. This new catalyst system was prepared by borohydride reduction of ruthenium(III)-exchanged ZK-4 zeolite in water at room temperature. The characterization of the resulting material by advanced analytical tools shows the formation of ZK-4 zeolite dispersed ruthenium nanoparticles (2.9 +/- 0.9 nm). The catalytic performance of the resulting supported ruthenium nanoparticles depending on activity, lifetime and reusability was demonstrated in the hydrolytic dehydrogenation of ammonia-borane. They were found to be highly active (initial TOF = 5410 h(-1)), long-lived (TTO = 36,700) and reusable catalyst (retaining of > 85% of initial activity in the 5th reuse) in this important catalytic reaction at room temperature under air. (C) 2012 Elsevier B.V. All rights reserved.