US EPA

990699 

Journal Article 

Ammonia Vapor Removal by Cu(3)(BTC)(2) and Its Characterization by MAS NMR 

Peterson, GW; Wagner, GW; Balboa, A; Mahle, J; Sewell, T; Karwacki, CJ 

2009 

Yes 

Journal of Physical Chemistry C
ISSN: 1932-7447
EISSN: 1932-7455 

113 

31 

13906-13917 

English 

20161144 

10.1021/jp902736z 

Adsorption equilibria and NMR experiments were performed to study the adsorption and interactions of ammonia with metal-organic framework (MOF) HKUST-1, or Cu(3)(BTC)(2) (BTC = 1,3,5-benzenetricarboxylate). Ammonia capacities determined from chemical breakthrough measurements show significantly higher uptake capacities than from adsorption alone, suggesting a stronger interaction involving a potential reaction with the Cu(3)(BTC)(2) framework. Indeed, (1)H MAS NMR reveals that a major disruption of the relatively simple spectrum of Cu(3)(BTC)(2) occurs to generate a composite spectrum consistent with Cu(OH)(2) and (NH(4))(3)BTC species under humid conditions-the anticipated products of a copper(II) carboxylate reacted with limited ammonia. These species are not detected under dry conditions; however, reaction stoichiometry combined with XRD results suggests the partial formation of an indeterminate diammine copper (II) complex with some residual Cu(3)(BTC)(2) structure retained. Cu(II)-induced paramagnetic shifts exhibited by various species in (1)H and (13)C MAS NMR spectra are consistent with model compounds and previous literature. Although results show extensive ammonia capacity of Cu(3)(BTC)(2), much of the capacity is due to reaction with the structure itself, causing a permanent loss in porosity and structural integrity.