Oleylamine-Stabilized Copper(0) Nanoparticles: An Efficient and Low-Cost Catalyst for the Dehydrogenation of Dimethylamine Borane

Abstract

Copper(0) nanoparticles, in situ generated from the reduction of copper(II) 2-ethylhexanoate during the dehydrogenation of dimethylamine borane (DMAB) at 50.0±0.1 °C in toluene solution, are active catalysts in hydrogen generation from DMAB, but not very stable against agglomeration. Addition of 5.0 equivalents of oleylamine (OAm) was found to stabilize copper(0) nanoparticles noticeably, while maintaining high catalytic activity. Oleylamine-stabilized copper(0) nanoparticles could be isolated from the solution and characterized by XRD, TEM, UV/Vis, attenuated total reflectance (ATR)-FTIR, and 11B NMR spectroscopies. Our report also includes (i) comparative catalytic activities of copper(0) nanoparticles in the absence and presence of OAm depending on the initial [OAm]/[Cu] ratio, catalyst concentration, substrate concentration, and temperature, (ii) the catalytic lifetime of copper(0) nanoparticles in the absence and presence of OAm in the dehydrogenation of DMAB at 50.0±0.1 °C, (iii) testing the ease of isolation and reusability of copper(0) nanoparticles in the absence and presence of OAm in the dehydrogenation of DMAB, (iv) the results of quantitative kinetic poisoning experiments by using 1,10-phenanthroline, showing that copper(0) nanoparticles are kinetically competent catalysts in the dehydrogenation of DMAB. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim