Metal-containing zeolites exhibit remarkable catalytic activity for hydrogenation owing to the synergistic interactions between acid and metal sites. In the aqueous phase, the presence of water and, in particular, hydronium ions, complicate the adsorption of H₂ and organic substrates. It is shown how hydrated hydronium ions formed from zeolite Brønsted acid sites promote the rate of hydrogenation of phenol on Pt by modifying reaction pathways in the aqueous phase. Hydrogen is preferentially added to the ortho-C of phenol at low concentrations of hydronium ions, while at high concentrations of hydronium ions hydrogen adds to both ortho- and para-C of phenol with equal probability. A proton coupled electron transfer (PCET) pathway is hypothesized to occur at metal surfaces associated with large concentrations of hydrated hydronium ions and adsorbed H, establishing a (quasi-) equilibrium open circuit potential. In the presence of lower concentrations of hydrated hydronium ions, the reaction follows a Langmuir-Hinshelwood mechanism in which adsorbed H atoms add to co-adsorbed phenol. DFT calculations show a lower activation energy barrier for the PCET pathway in the presence of hydronium ions compared to the pathway following a Langmuir-Hinshelwood type mechanism.

由于酸和金属位点之间的协同相互作用，含金属沸石对加氢具有显着的催化活性。在水相中，水的存在，特别是水合氢离子，使 H ₂的吸附复杂化和有机底物。显示了由沸石布朗斯台德酸位点形成的水合水合氢离子如何通过改变水相中的反应途径来促进苯酚在 Pt 上的氢化速率。在水合氢离子浓度低时，氢优先添加到苯酚的邻位 C，而在水合氢离子浓度高时，氢以相等的概率添加到苯酚的邻位和对位 C。假设质子耦合电子转移 (PCET) 途径发生在与大浓度水合水合氢离子和吸附的 H 相关的金属表面，建立（准）平衡开路电位。在较低浓度的水合水合氢离子存在下，反应遵循 Langmuir-Hinshelwood 机制，其中吸附的 H 原子添加到共吸附的苯酚中。