Hydrophobic Promoter‐Enhanced Tandem Catalysis for Alkene Epoxidation With H 2 and O 2
Defu Yin, Jiamin Yuan, Dong Lin, Zhihua Zhang, Wei Fang, Zhiqiang Liu, Chaohe Yang, Xuezhi Duan, Anmin Zheng, De Chen, Xinggui Zhou, Liang Wang, Xiang FengABSTRACT
The efficiency of tandem catalysis is fundamentally limited by the transport of transient intermediates. In the direct epoxidation of alkenes with H 2 and O 2 , in situ generated H 2 O 2 rapidly decomposes during diffusion, rendering most Ti active sites kinetically inaccessible and imposing a long‐standing performance ceiling. Here, we overcome this limitation by engineering hydrophobic transport channels via physical integration of a hydrophobic polymer with bifunctional Au/TS‐1 catalysts. This microenvironment accelerates H 2 O 2 migration away from hydroxyl‐rich surfaces toward remote Ti sites while suppressing nonproductive decomposition. Molecular dynamics simulation studies show that the diffusion of H 2 O 2 on hydrophobic surfaces is significantly higher than on hydrophilic surfaces, as reflected experimentally by a 25% increase in tandem H 2 O 2 efficiency. Moreover, the hydrophobic channels promote rapid desorption of epoxide products, suppressing ring‐opening reactions and carbonaceous accumulation, resulting in a stable ∼90% epoxide selectivity over 200 h. This strategy exhibits broad generality across Au–Ti bifunctional catalysts for alkene epoxidation using in situ generated H 2 O 2 , with an outstanding H 2 utilization efficiency of 73.5% achieved over the Au/TS‐1‐B catalyst under the identical standard reaction conditions employed throughout this work. This work establishes diffusion control of metastable surface species as a principle for breaking intrinsic transport–decomposition trade‐offs in tandem catalysis.