Delamination of Ti-MWW and High Efficiency in Epoxidation of Alkenes with Various Molecular Sizes

Abstract

A new titanosilicate, named Del-Ti-MWW, has been prepared by delaminating the lamellar precursor of Ti-MWW, which is postsynthesized from highly deboronated MWW zeolite with the assistance of cyclic amine. The amount of organic base used for supporting surfactant in swelling the layered structure should be controlled carefully to delaminate efficiently without the collapse of the structure. Ultrasound treatment is demonstrated to delaminate the swollen material more completely. Del-Ti-MWW materials have a large surface area, which mitigates effectively the steric restrictions imposed by conventional microporous titanosilicates to bulky molecules. Del-Ti-MWW, maintaining the fundamental structure of MWW zeolite and tetrahedral Ti species in the framework position, proves to be superior to TS-1, Ti-Beta, three-dimensional Ti-MWW and even mesoporous Ti-MCM-41 in the epoxidation of a wide range of bulky alkenes with hydrogen peroxide.

Novel surfactant-free route to delaminated all-silica and titanosilicate zeolites derived from a layered borosilicate MWW precursor

“…within 12-MR). 33 (002) reflections, decrease significantly after calcination of ERB-1P at 550°C in pattern (ii) in Fig. 2.…”

Layered zeolitic materials: an approach to designing versatile functional solids

“…The success of the delamination process was completely confirmed from TEM images which showed crystalline materials conformed by fewer sheets than 3D Ti-MWW, being even possible to appreciate single MWW sheets ( Figure 19). 101 This method could be an alternative to incorporate active tetrahedral titanium into the framework of MWW layers, avoiding postgrafting steps to covalently incorporate, in the external surface, active titanium complexes such as titanocene. 102,103,104 However, there is an alternative to this method to produce Ti-ITQ-2 starting from Ti-ITQ-1.…”

Layered Materials with Catalytic Applications: Pillared and Delaminated Zeolites from MWW Precursors

“…In fact, delaminated Ti-MWW zeolites were prepared with elevated surface area, higher than 1000 m 2 g −1 . The success of the delamination process was completely confirmed from TEM images which showed crystalline materials conformed by fewer sheets than 3D Ti-MWW, being even possible to appreciate single MWW sheets ( Figure 22) [34]. This method could be a serious alternative to incorporate active titanium into the framework of delaminated MWW materials directly during the synthesis process, avoiding postgrafting steps to covalently anchor, onto the external surface of MWW zeolitic layers, active titanium complexes such as titanocene, which partially blocked the free porous volume (Figure 23) [35].…”

“…These cooperative properties are evident when bulky molecules take part during the catalytic process, being possible to use both MCM-36 and ITQ-2 derivative materials as efficient catalysts to carry out also Fine Chemistry processes to obtain high value products with application in pharmaceutical, perfumes and fragrances, cosmetic, or food [137]. Inside this research field, delaminated materials obtained by grafting of titanocene was used as an excellent catalyst for epoxidation of olefins, yielding high conversions and selectivity to the desired epoxides [14] such as occurs with the Ti-ITQ-2 zeolites which contained tetrahedrally coordinated titanium after deboronation processes [34]. Related with this topic, comparative study of silane oxidations, olefin epoxidations, and thianthrene 5-oxide sulfoxidations, using the catalysts Ti-β and grafted Ti-ITQ-2 with H 2 O 2 and t-BuOOH as oxidants, was carried out.…”