Hydrogen Storage with Spectroscopic Identification of Chemisorption Sites in Cu-tdpat via Spillover from a Pt/activated Carbon Catalyst
Hydrogen spillover to the Cu-TDPAT (TDPAT = 2,4,6-tris(3,5-dicarboxylphe-nylamino)-1,3,5-triazine) metal-organic framework is probed with adsorption measurements, ex situ characterization techniques, and density functional theory (DFT) calculations. At 1 bar and 300 K, hydrogen chemisorption to Pt/AC/Cu-TDPAT exceeds that expected for physisorption by 8-fold, which is attributable to both catalyst insertion and the creation of structural defects. Hydrogenation of (a) the Cu-O-C bond of the Cu paddlewheel, (b) the sp2 N heterocycle, and (c) the secondary amine is demonstrated with ex situ spectroscopy. Exothermic (with respect to H2) hydrogenation at the Cu-O-C bond of the paddlewheel is substantiated by DFT. However, hydrogenated Cu-O-C is metastable, as evidence for dissociation is found at higher temperature (i.e., 473 K H2). DFT calculations demonstrate hydrogenation of the N groups may occur exothermically only for a charged ligand, suggestive that defects may contribute to hydrogen chemisorption. At high pressure, slow adsorption rates and material instability render the material unsuitable for practical hydrogen storage applications.
C. Y. Wang et al., "Hydrogen Storage with Spectroscopic Identification of Chemisorption Sites in Cu-tdpat via Spillover from a Pt/activated Carbon Catalyst," Journal of Physical Chemistry C, vol. 118, no. 46, pp. 26750-26763, American Chemical Society (ACS), Oct 2014.
The definitive version is available at https://doi.org/10.1021/jp507395p
Chemical and Biochemical Engineering
United States. Department of Energy.Office of Energy Efficiency and Renewable Energy
Keywords and Phrases
Adsorption; Catalysts; Chemisorption; Crystalline materials; Defects; Density functional theory; High pressure engineering; Hydrogen; Hydrogenation; Organometallics; Platinum; Adsorption measurement; Chemisorption sites; Hydrogen chemisorption; Hydrogen spill overs; Material instability; Metal organic framework; Spectroscopic identification; Structural defect; Hydrogen storage
International Standard Serial Number (ISSN)
Article - Journal
© 2014 American Chemical Society (ACS), All rights reserved.