We have studied ambient trapping of ammonia in metal organic frameworks functionalized with acidic species. Here we present detailed characterization of ammonia uptake in HKUST-1 (Cu3(BTC)2, BTC = 1,3,5-benzenetricarboxylate) containing between one and two molecules of H2SO4 per unit cell. The presence of sulfuric acid in the pores is demonstrated by Fourier Infra-Red Spectroscopy (FTIR) and the integrity of the structure is confirmed with X-Ray Diffraction (XRD). Total ammonia adsorption is improved by a factor of three compared to untreated HKUST-1. The uptake of ammonia was investigated by Inelastic Neutron Scattering (INS). Comparison of measured INS spectra to DFT simulations establishes the binding sites as the hydroxyl groups on the sulfuric acid. The adsorption of ammonia at the OH site leads to elongation of O-H-N bond rather than a full transfer of H+ to ammonia molecule, suggesting a reversible adsorption.

Ammonia adsorption in acid-modified HKUST-1

254th National Meeting (2017)

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