Optimization of MOFs-induced strategy for preparing anatase-free hierarchical TS-1 towards 1-hexene epoxidation: TPAOH dosage regulation, silanization and stabilizing acidic sites

CeOx‐induced oxygen vacancy‐enhanced Pt‐based titanium silicalite‐1 catalysts for selective conversion of levulinic acid

“…As shown in Figure 4B, the absorption peaks around wavenumbers of 1,450 cm −1 and 1,607 cm −1 can be attributed to the adsorption of pyridine molecules on the Lewis acid centers, and the weak absorption peaks around wavenumbers of 1,540 cm −1 , 1,597 cm −1 , and 1,639 cm −1 can be attributed to the adsorption of pyridine ions on the Brønsted acid centers. The peaks observed at 1493 cm −1 and 1,577 cm −1 wavenumber can be assigned to the adsorption of both pyridine ions and pyridine molecules on the Brønsted‐Lewis acid sites 40,41 . The Lewis acid centers possessed by the material are derived from the tetra‐coordinated skeletal titanium, and the formation of the Brønsted acid centers is related to hydroxyl defects on the defective zeolite 41 .…”

“…The peaks observed at 1493 cm À1 and 1,577 cm À1 wavenumber can be assigned to the adsorption of both pyridine ions and pyridine molecules on the Brønsted-Lewis acid sites. 40,41 The Lewis acid centers possessed by the material are derived from the tetra-coordinated skeletal titanium, and the formation of the Brønsted acid centers is related to hydroxyl defects on the defective zeolite. 41 Different types of acid sites play distinct and crucial roles in the lactonization of the intermediate 4-HVA.…”

“…40,41 The Lewis acid centers possessed by the material are derived from the tetra-coordinated skeletal titanium, and the formation of the Brønsted acid centers is related to hydroxyl defects on the defective zeolite. 41 Different types of acid sites play distinct and crucial roles in the lactonization of the intermediate 4-HVA. 4-HVA is first initiated by Lewis acid sites, and then efficiently converted to GVL under the coordination of a modest quantity of Brønsted acid sites.…”

Preparation of hierarchical TS-1 molecular sieve membrane catalyst and its catalytic performance for chloropropylene epoxidation

“…When the content of TPAOH was reduced, it led to a signi cant decrease in the backbone titanium species, which was because with a lower amount of TPAOH, the pH value of the system was lower, leading to a lower content of the silica source. The lower pH resulted in the inability of the silicon source to be fully hydrolyzed, leading to more trimeric or cyclic multimeric silicon species and fewer monomeric or dimeric silicon species in the system, which was not conducive to the introduction of titanium atoms [31]. After further increasing the TPAOH content to n(TPAOH)/n(TEOS) = 0.30, the content of the framework titanium species decreased slightly, which was likely because the pH of the system was too high at this time.…”

In Situ Tailoring the Crystalline Defects of Titanium Silicalite-1 (TS-1) to Improve the 1-Butene Epoxidation Performance

“…TS-1 is an important zeotype material for the isomorphous substitution of framework silicon with titanium. , The oxidants, including hydrogen peroxide and organic hydrogen peroxide, can efficiently be activated by the four-coordinated framework titanium, and alkenes, − ketones, − aromatics, − and alkanes − can selectively be oxidized under ambient conditions. Nowadays, TS-1 has been applied in the industrial process of propylene epoxidation to propylene oxide, − cyclohexanone ammoxidation to cyclohexanone oxime, − and phenol hydroxylation to dihydroxyl benzene. − In the epoxidation of alkenes, numerous studies on the influences of solvent and titanium environments were reported, and excellent catalytic performance has been achieved now, especially for propylene epoxidation.…”