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Zeolite confined rhodium(0) nanoclusters as highly active, reusable, and long-lived catalyst in the methanolysis of ammonia-borane

Caliskan, Salim
Zahmakiran, Mehmet
Özkar, Saim
Addressed herein is the preparation, characterization and the catalytic use of zeolite confined rhodium(0) nanoclusters in the methanolysis of ammonia-borane. Rhodium(0) nanoclusters; could be generated in zeolite-Y by a two-step procedure: (i) incorporation of rhodium(Ill) cations into the zeolite-Y by ion-exchange and (ii) reduction of rhodium(Ill) ions within the zeolite cages by sodium borohydride in aqueous solution, followed by filtration and dehydration by heating to 550 degrees C under 10(-4) Torr. Zeolite confined rhodium(0) nanoclusters are stable enough to be isolated as solid materials and characterized by ICP-OES, XRD. SEM, EDX, HR-TEM, XPS and N-2 adsorption-desorption technique. The zeolite confined rhodium(0) nanoclusters are isolable, bottleable, redispersible and reusable as an active catalyst in the methanolysis of ammonia-borane even at low temperatures. They provide exceptional catalytic activity with an average value of TOF = 380 h(-1) and unprecedented lifetime with 74,300 turnovers in the methanolysis of ammonia-borane at 25 +/- 0.1 degrees C. The work reported here also includes the full experimental details of the collection of a wealth of previously unavailable kinetic data to determine the rate law, and activation parameters (E-a, Delta H-not equal and Delta S-not equal) for the catalytic methanolysis of ammonia-borane.