Novel molecular catalyst candidates for H2 evolution from hydrogen storage materials

Wojciech I. Dzik 1Wojciech Grochala 1,2

1. Warsaw University, Faculty of Chemistry, Pasteura 1, Warszawa 02-093, Poland
2. Interdyscyplinarne Centrum Modelowania Matematycznego i Komputerowego (ICM), Żwirki i Wigury 93, Warszawa 02-089, Poland

Abstract

Thermal stability in a strongly reducing environment of Ni(II) and Cu(II) sulphate complexes with cyclam (1,4,8,11-tetraazacyclotetradecane), or its N-methylated derivatives, was examined using TGA and DSC techniques. Samples were prepared by mechanochemical doping of NaH or LiAlH4 with ca. 2-4 mol % (20-30 wt. %) of a complex. Samples of NaH doped with Ni(II) complexes decompose in two steps. The I-st step corresponds to one-electron reduction of Ni(II) with an evolution of small amounts of hydrogen. During the II-nd step a progressive degradation of the organic ligand takes place. Cyclam complex of CuSO4 - very stable thermodynamically - is very resistant to reduction by NaH (slow degradation is only above 120 oC), while its addition to LiAlH4 results in a decrease of the temperature of the first step of alanate's decomposition (by ca. 30 oC). These results suggest that a range of catalysts for H2 evolution from hydrides might now be expanded, and include cations of electropositive metals (provided the presence of strongly chelating ligands). Complexes studied here form molecular crystals which are much easier to disperse (at a molecular level) wihin a hydrogen storage material, as compared with commonly used extended solid catalysts (TiO2, SiO2, FeCl3). This allows to reduce time for the high-energy milling from days to less than a minute, and to make use of every single metal center as a catalytically active species. The drawback of molecular catalysts is in their large molecular mass; this decreases the active hydrogen content of a H2 storage material.

I thank for financial support of my participation in E-MRS Fall 2006 from a Nationwide Polish Catalytic Network "Nanomaterials as Catalysts for New, Environmentally Friendly Processes" (WD).

Legal notice
  • Legal notice:

    Copyright (c) Pielaszek Research, all rights reserved.
    The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
    In every case, proper references including Author(s) name(s) and URL of this webpage: http://science24.com/paper/7663 must be provided.

 

Related papers
  1. Phonon Dispersion Analysis as an Indispensable Tool for Correct Predictions of Solid State Polymorphism
  2. Application of Fourier Transform mid- and far-IR spectroscopy for studies of oxo– derivatives of Ag(II)
  3. Studies of H2 uptake by aluminum carbide (Al4C3) using volumetric absorption and elemental combustion analyses and FT-IR
  4. AgF2 as a 2D scaffold of the organic-inorganic hybrid materials with tailored magnetic properties? Probing reactivity of silver(II) fluoride towards a variety of inorganic and organic salts.
  5. Childish Benzene Games. What Else Can We Learn in Silico?
  6. Modelling electronic structure of unusual metallic fluorides of Ag(II)
  7. Superconductivity and the grand periodic table of the chemical elements

Presentation: Poster at E-MRS Fall Meeting 2006, Symposium B, by Wojciech I. Dzik
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-12 11:27
Revised:   2009-06-07 00:44
Google
 
Web science24.com
© 1998-2021 pielaszek research, all rights reserved Powered by the Conference Engine