Insights into Adsorption of NH₃ on HKUST-1 Metal–Organic Framework: A Multitechnique Approach

Abstract

We report a careful characterization of the interaction of NH3 with the Cu(II) sites of the [Cu2C4O8] paddle-wheel cornerstone of the HKUST-1 metallorganic framework, also known as Cu3(BTC)2. The general picture emerging from combining XRPD, EXAFS, XANES, mid- and far-IR, DRUV–vis, and EPR techniques is that the presence of traces of water has relevant consequences on the effect of ammonia on the MOF framework. NH3 adsorption on the dry system results in a strong chemisorption on Cu(II) sites that distorts the framework, keeping the crystallinity of the material. Perturbation observed upon NH3 adsorption is analogous to that observed for H2O, but noticeably enhanced. When the adsorption of ammonia occurs in humid conditions, a time-dependent, much deeper modification of the system is observed by all of the considered techniques. On a methodological ground, it is worth noticing that we used the optimization of XANES spectra to validate the bond distance obtained by EXAFS.

H2S interaction with HKUST-1 and ZIF-8 MOFs: A multitechnique study

“…[13e15]. Moreover, HKUST-1 has been well studied for other gases like ammonia [16]. The interaction of small molecules with the coordinatively unsatured metal centres of the HKUST-1 by means of density functional theory have been studied for CO, CO 2 , OCS, SO 2 , NO, NO 2 , N 2 O, NH 3 , PH 3 and other small molecules [17].…”

Ammonia Adsorption and Co-adsorption with Water in HKUST-1: Spectroscopic Evidence for Cooperative Interactions

“…[13][14][15] However, the degradation associated with the presence of moisture renders HKUST-1 unsuitable for practical applications. [13][14][15][16][17] Therefore, probing co-adsorption of gases in MOFs with open metal center such as HKUST-1 is important. Previous work characterizing water and ammonia exposure of HKUST-1 were performed ex-situ after exposure to high concentrations of water and ammonia.…”

MoS2 supported on P25 titania: A model system for the activation of a HDS catalyst

“…037-1492, with r MoAS = 2.366 Å and r MoAMo = 3.161 Å) has been used as geometrical input for the fits. The higher shells paths and the multiple-scattering paths of bulk MoS 2 have been optimized according to the isotropic expansion approximation[55,56] using as unique parameters a and r 2 that have been optimized as follows: a = +0.006 ± 0.001 and r 2 = 0.0042 ± 0.0006 Å 2 .…”