Tailoring the molecular environment around catalytically active sites allows for the enhancement of catalytic reactivity through a hitherto unexplored pathway. In zeolites, the presence of water creates an ionic environment via the formation of hydrated hydronium ions and the negatively charged framework aluminum tetrahedra. The high density of cation-anion pairs determined by the aluminum concentration of a zeolite induces a high local ionic strength that increases the excess chemical potential of sorbed and uncharged organic reactants. Charged transition states (carbocations for example) are stabilized, which reduces the energy barrier and leads to higher reaction rates. Using the intramolecular dehydration of cyclohexanol on H-MFI zeolites in water, we quantitatively show an enhancement of the reaction rate by the presence of high ionic strength as well as show potential limitations of this strategy.

调整催化活性位点周围的分子环境允许通过迄今为止尚未探索的途径增强催化反应性。在沸石中，水的存在通过形成水合水合氢离子和带负电的骨架铝四面体来创造离子环境。由沸石的铝浓度决定的高密度阳离子-阴离子对会引起高局部离子强度，从而增加吸附的和不带电的有机反应物的过量化学势。带电过渡态（例如碳正离子）得到稳定，这降低了能垒并导致更高的反应速率。利用环己醇在水中的H-MFI沸石分子内脱水，