B-N Polymer Embedded Iron(0) Nanoparticles as Highly Active and Long Lived Catalyst in the Dehydrogenation of Ammonia Borane


Duman S., Metin O., ÖZKAR S.

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, vol.13, no.7, pp.4954-4961, 2013 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 13 Issue: 7
  • Publication Date: 2013
  • Doi Number: 10.1166/jnn.2013.7604
  • Title of Journal : JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
  • Page Numbers: pp.4954-4961
  • Keywords: Iron Nanoparticles, Heterogeneous Catalyst, Dehydrogenation, Ammonia Borane, Chemical Hydrogen Storage, AMINE-BORANE, COMPLEX, EFFICIENT, DECOMPOSITION, REGENERATION, ADDUCTS, SYSTEM, FE

Abstract

B-N polymer embedded iron(0) nanoparticles (NPs) were in-situ generated from the reduction of iron(III) acetylacetonate during the dehydrogenation of ammonia borane (AB) in THF solution at 40.0 +/- 0.5 degrees C. The iron(0) NPs could be isolated as powder from the reaction solution by centrifugation and characterized by UV-Vis, TEM, and XRD. They are redispersible in polar solvent such as THF and yet highly active catalysts in the dehydrogenation of AB providing a TOF value of 202 h(-1) at 40.0 +/- 0.5 degrees C. The catalytic activity of iron(0) NPs compare well with those of the known homogenous and heterogeneous precious metal catalysts reported so far. They are also long-life catalysts in the dehydrogenation of AB providing 1410 turnovers over 18 h at 40.0 +/- 0.5 degrees C. The poisoning experiments using carbon disulfide show that the dehydrogenation of AB catalyzed by iron(0) NPs is a heterogeneous catalysis. The catalytic dehydrogenation of AB in the presence of iron(0) NPs was followed by measuring the volume of hydrogen generated and by B-11-NMR spectroscopy. Our report also includes the results of a detailed kinetic study on the catalytic dehydrogenation of AB depending on the catalyst concentration, substrate concentration, and temperature. The dehydrogenation of AB produces sparingly soluble B-N polymers which provide just enough stability to the iron(0) NPs. The co-precipitation of some iron(0) NPs with the sparingly soluble polymers causes a slight decrease in the catalytic activity toward the end of dehydrogenation. However, iron(0) NPs embedded in B-N polymers appear to be an efficient catalyst in hydrogen generation from ammonia borane at moderate temperature.