Ruthenium(0) Nanoparticles Supported on Multiwalled Carbon Nanotube As Highly Active Catalyst for Hydrogen Generation from Ammonia-Borane

摘要

Ruthenium(0) nanoparticles supported on multiwalled carbon nanotubes (Ru(0)@MWCNT) were in situ formed during the hydrolysis of ammonia—borane (AB) and could be isolated from the reaction solution by nitration and characterized by ICP-OES, XRD, TEM, SEM, EDX, and XPS techniques. The results reveal that ruthenium(0) nanoparticles of size in the range 1.4—3.0 nm are well-dispersed on multiwalled carbon nanotubes. They were found to be highly active catalyst in hydrogen generation from the hydrolysis of AB with a turnover frequency value of 329 min~(-1). The reusability experiments show that Ru(0)(SMVVCNTs are isolable and redispersible in aqueous solution; when redispersed they are still active catalyst in the hydrolysis of AB exhibiting a release of 3.0 equivalents of H2 per mole of NH3BH3 and preserving 41% of the initial catalytic activity even after the fourth run of hydrolysis. The lifetime of Ru(0)@MWCNTs was measured as 26400 turnovers over 29 h in the hydrolysis of AB at 25.0 ±0.1 °C before deactivation. The work reported here also includes the kinetic studies depending on the temperature to determine the activation energy of the reaction (E_a = 33 ± 2 kj/mol) and the effect of catalyst concentration on the rate of the catalytic hydrolysis of AB, respectively.