Water is obviously a reactant and/or product in the ubiquitous hydration/dehydration reactions of biomass-derived molecules catalyzed by solid acids and bases. Consequently, water is necessarily a component of solvent systems when such reactions are conducted in the liquid phase. The presence and mobility of water can affect reaction rates (e.g., in the case of proton transfer via a proton shuttling mechanism). It also affects local concentrations by controlling partitioning between the bulk fluid and the solid-liquid interface, via its role in solvating solutes as well as the active sites in the solid phase. The ability to probe such interactions with high surface sensitivity has recently become possible using ambient temperature Overhauser Nuclear Dynamic Polarization NMR (ODNP-NMR) spectroscopy, in which tethered nitroxide radicals transfer polarization from an unpaired electron spin to the protons of near-surface water molecules. A series of silica-based catalysts were prepared with ordered mesopores and different surface hydroxyl densities, pore dimensions, and surface organic-inorganic compositions. The effect of catalyst structure and surface chemistry on the partitioning and mobility of adsorbed water was probed using ODNP-NMR.

Role of surface and solvent composition in the behavior of adsorbed water in porous and nonporous solid catalysts

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.