A Titanium Silicalite‐1 (TS‐1) Catalyst with Abundant Active Ti‐VI Species for Efficient Conversion of Ethylene to Glycol
Huali Tan, Yi Zuo, Gudan Li, Bosong Zhang, Lina Li, Lingling Guo, Jianrong Zeng, Fei Song, Hong Yang, Xinwen Guo
Abstract
Abstract One‐pot synthesis of glycol from ethylene and H 2 O 2 is simple and environmentally friendly, making it a potential alternative for glycol production. The key to the success of this is to have a bifunctional catalyst with both oxidative activity for ethylene epoxidation and acidic centers for the hydration of ethylene oxide. Typically, the incorporation of trivalent metal ions into titanium silicalite‐1 (TS‐1) framework can provide the two types of active centers, but this often results in decreased oxidative activity. Here, we propose a dual‐chemical post‐treatment regime to introduce acid centers in TS‐1 while simultaneously improving oxidative activity. The combined tetrapropylammonium hydroxide (TPAOH) + (NH 4 ) 2 CO 3 post‐treatment not only produces abundant Ti(OSi) 2 (OH) 4 (Ti‐VI) species from Ti(OSi) 4 , but also creates internal cavities within TS‐1. Ti‐VI possesses both high oxidative activity and acidic sites. The presence of internal cavities enhances the diffusion on the catalyst as well as increases the accessibility of Ti‐VI species. Consequently, when applied as a catalyst, the combined‐treated TS‐1 demonstrates an outstanding catalytic performance, achieving 98.6 % conversion of H 2 O 2 and 99.8 % selectivity of EG, which is ≈2 times of the conventional TS‐1. This study also unveils the formation mechanism of Ti‐VI during the post‐treatment.