In this research, a novel green mechanochemical dry gel conversion method (MDGC) is reported to obtain submicron-sized Ti-rich MWW zeolite. First, titanium and silica sources were milled under milder conditions in a planetary ball mill to construct the uniform SiO 2 -TiO 2 composite powders with higher Ti contents. Subsequently, submicron-sized Ti-rich MWW zeolite powder was prepared via dry gel conversion (DGC) route using the obtained composite under mixed steam environment consisting of water and piperidine. The physicochemical properties of the SiO 2 -TiO 2 composites before and after calcination and corresponding Ti-MWW-MDGC were investigated by XRD, UV–Vis, FT-IR, SEM, XRF, and N 2 absorption-desorption. Moreover, Ti-MWW (30)-MDGC exhibited a superior catalytic activity during epoxidation with H 2 O 2 compared with the traditional DGC method, and the conversion of 1-hexene increased from 4.2% to 26.3%. The MDGC method is a promising approach for the green production of various zeolites with higher heteroatom contents, such as TS-1, Ti-Beta and Sn-MWW, etc.
Ze Zong,Xuliang Deng,Dong Lin,Yang Xu,Qiuming He,Zhe Ma,De Chen,Chaohe Yang,Xiang Feng
Titanosilicate with H 2 O 2 stands out as a highly consequential oxidized catalytic system, prized for its user-friendly operation, mild conditions, and eco-friendly attributes. However, a synthesis strategy for large surface area titanosilicalites approaching the theoretical lowest Si/Ti ratio without extra-framework Ti species remains an ongoing challenge. In this study, we successfully synthesized single-crystalline Ti-rich nanosized aggregated TS-1 by shielding effect with a Si/Ti polymer. This polymer demonstrated effectiveness in restraining TiO 2 species by regulating the proximity of Si/Ti species in Ti-Diol-Si polymers. The polymer not only facilitated the synthesis of single-crystalline Ti-rich TS-1 but also exploited the chain length of PEG, functioning as a shielding cage by hydrogen bonds, to synthesize nanosized aggregated TS-1 (TS-1-PEG400). This TS-1-PEG400 exhibited superior conversion (~60%), selectivity (~90%), and stability in 1-hexene epoxidation. This study not only establishes a synthesis pathway for Ti-rich TS-1 but also holds the potential to enhance related industrial oxidation reactions involving titanosilicates and H 2 O 2 .
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