2.3. In-situ titrations
Titration experiments with NO (10 wt.% NO, balance N2,
Matheson, Research Purity) and H2O (deionized, 18.3 MΩ)
were conducted at 423 K under constant reaction conditions: 14.5 kPa
N2O, 1.5 kPa CH4, t = 2 h. For NO
titration experiments, NO was fed over MIL-100(Fe) prior to the
introduction of CH4 and N2O due to the
significant time it takes for NO to break through the MOF bed in
comparison to the reactants (Section S2.6, SI). Under titrant co-feeds,
inert carrier gas (He, Matheson, Ultra High Purity) concentrations were
reduced to maintain constant reactant partial pressures. Total
quantities of NO and H2O adsorbed by MIL-100 were
estimated through breakthrough curves measured using an online mass
spectrometer (MKS Cirrus 2) at the outlet of the bed. Molar flow rates
were calibrated with respect to those of argon (internal standard) under
the assumption that no argon was adsorbed by the sample.