Hydrophobicity Manipulation of Titanium Silicalite-1 with Enhanced Catalytic Performance via Liquid-Mediated Defect Healing Treatment
Boqing Li, Kenta Iyoki, Piyapatch Techasarintr, S.P. Elangovan, Raquel Simancas, Tatsuya Okubo, Toshiyuki Yokoi, Toru Wakihara
Abstract
As a high-performance catalyst in the industry, titanium silicalite-1 (TS-1) has received extensive attention from researchers for decades. Using aqueous hydrogen peroxide as an oxidant, TS-1 exhibits high activity and selectivity for various oxidation reactions. However, the existence of silanol defects compromises its catalytic activity and leads to byproduct formation. In this research, we report a successful elimination of silanol defects and significant improvements in the catalytic activity of TS-1 via defect healing treatment. As confirmed by Fourier transform infrared spectroscopy (FT-IR), solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR), and water vapor adsorption isotherms, defect healing-treated samples are free of silanol defects with significantly improved hydrophobicity. To evaluate the catalytic performance, epoxidation of 1-hexene with H 2 O 2 was carried out. All defect healing-treated samples exhibit highly enhanced catalytic performance. The conversions of 1-hexene are increased by up to 70% compared to the corresponding pristine samples. After defect healing treatment, the turnover frequency is as high as 159 h –1 .