Estimation of activation enthalpies and entropiesNO oxidation rates r were measured in units of ቂ ேை ௦ ೌ ቃ on silica, SIL-1, SIL-1D, BEA and CHA at NO conversions below 20%. Under the conditions investigated NO is the limited reactant and oxygen is present in excess by at least a factor of 100. Plug-flow hydrodynamic formalisms were used to correct for small changes in reactant concentrations along the bed and to report rates at inlet conditions.Rates were then reported on volumetric basis in order to allow for a direct comparison with reaction rates in the unconstrained volumewhere the ‫݁ݒ݅ݐܿܽ‬ ‫݁݉ݑ݈ݒ‬ is the void space in the solid where the reaction can occur normalized by the mass of the catalyst.The ‫݁ݒ݅ݐܿܽ‬ ‫݁݉ݑ݈ݒ‬ for SIL-1, SIL-1D, BEA, CHA was calculated using the microporous volume (reported in Table 1). On silica we estimate the active volume from its surface area (446 m 2 g -1 ) and the molecular diameter of N 2 O 4 (0.58 nm) giving a total of 0.262 cm 3 g -1 . For the homogeneous reaction, instead, ‫ݎ‬ ௩ was calculated considering as active volume the volume of the empty cell

Mechanistic aspects involved in the formation of N2 and of N2O during the reduction of gas-phase NO and of NO x stored over a model PtBa/Al2O3 NSR catalyst are investigated using unlabeled ammonia and labeled NO. The reduction of the stored NO x species (labeled nitrites and nitrates) with NH3 leads to the selective formation of N2 as a major product and of small amounts of nitrous oxide. Based on the nitrogen isotopic distribution, it appears that N2 formation occurs primarily through the statistical coupling of N-atoms formed by dissociation of NO x - and NH3-related surface intermediates, although an SCR-pathway (involving the coupling of NH3- and NO-derived ad-species) is also likely to occur. It appears as well that the formation of nitrous oxide involves either the coupling of two adsorbed NO molecules or the recombination of an adsorbed NO molecule with an adsorbed NH x fragment.

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The presence of the weakly-associated encounter complex in the model frustrated Lewis pair solution (FLP): tris(tert-butyl)phosphine (P(Bu)) and tris(pentafluorophenyl)borane (BCF) in benzene, was confirmed via PB correlation analysis from neutron scattering data. On average, ca. 5% of dissolved FLP components were in the associated state. NMR spectra of the FLP in benzene gave no evidence of such association, in agreement with earlier reports and the transient nature of the encounter complex. In contrast, the corresponding FLP solution in the ionic liquid, 1-decyl-3-methylimidazolium bistriflamide, [Cmim][NTf], generated NMR signals that can be attributed to formation of encounter complexes involving over 20% of the dissolved species. The low diffusivity characteristics of ionic liquids is suggested to enhance high populations of encounter complex. The FLP in the ionic liquid solution retained its ability to split hydrogen.