Confined water accelerated alkene epoxidation inside channels of Ti‐beta zeolite

Abstract Comprehensive mechanistic explorations and profound understandings of the interactions between water molecules and active intermediates harbors tremendous significance in the field of zeolite catalysis. Herein, we envision a strategy to accelerate alkene epoxidation reactions (e.g., 1‐pentene, 1‐hexene, cyclohexene, cyclooctene) with preformed H 2 O 2 inside confined channels of Ti‐beta by water molecules. Combined with in situ UV–vis, kinetic experiments, and DFT calculations, it is found that keen control of water molecules could effectively enhance H 2 O 2 adsorption and stabilize crucial oxygen intermediates (Ti‐OOH) by hydrogen bonding interactions. As a result, the yields of corresponding epoxides increased up to 20.5%. However, excessive water clusters construct a dense and robust hydrogen‐bond network, blocking the activation of reactants and further epoxidation over Ti sites. This finding not only sheds new light on the mechanism of water‐accelerated reaction, but also opens up new opportunities to enhance the efficiency of industrial epoxidation reactions involving H 2 O 2 .