Alkene Epoxidation with Ethylbenzene Hydroperoxides Using Molybdenum Heterogeneous Catalysts

Abstract

Molybdenum-containing catalysts were prepared by anchoring Mo(VI) groups onto different aminofunctionalized silica surfaces and then tested in the epoxidation reaction of 1-octene with ethylbenzene hydroperoxide (EBHP) as an oxidant. Catalytic performance was found to depend on the chemical structure and nature of the functional group. EBHP conversion-time profiles exhibited an S-shaped behavior, suggesting that an induction period is required to develop the active site. Selectivity-conversion plots indicated that selectivities as high as 80% could be obtained at EBHP conversions of about 80% when the Mo complexes were immobilized on a silica substrate functionalized with a diamino-containing moiety. In contrast, surface functionalization with sCOOH was found to be detrimental, as acid groups catalyze EBHP decomposition. Experiments designed to determine possible leaching of molybdenum into the reaction medium during the tests indicated that the catalyst prepared on a triamine-containing substrate exhibited good stability with almost no change in performance after three consecutive runs. The high stability of the Mo(VI) complex in this catalyst was shown by UV-vis and photoelectron spectroscopic techniques.

Synthesis of Mo–Fe3O4@SiO2@P4VP core–shell–shell structured magnetic microspheres for alkene epoxidation reactions

“…The XPS peaks of Mo 3d 5/2 and Mo 3d 3/2 are 232.1 and 235.2 eV (Fig. 4b), which are often attributed to Mo(VI) species coordinated to nitrogen or oxygen groups [36]. The results confirm that Mo(VI) has been successfully immobilized onto the Fe 3 O 4 @SiO 2 @P4VP microspheres.…”

“…In addition, ethanol is an environmentally friendly and green solvent, not like other solvents (e.g., CH 3 CN, CCl 4 and CHCl 3 ). Even though tertbutylhydroperoxide [18] or ethylbenzenehydroperoxide [36] can also be used as oxidant for the production of epoxides, they suffer from the alcohol co-products (e.g., tert-butanol or 1-phenylethanol). However, H 2 O 2 gives water as the only by-product, as well as low cost and ready availability.…”

Mo(VI) Complexes Immobilized on SBA-15 as an Efficient Catalyst for 1-Octene Epoxidation

“…Figure 10 shows XPS spectra of both samples in the Mo3d (A) and O1s (B) energy regions. The Mo3d region shows well-resolved spectral lines at 231.3 and 234.4 eV, typical of the Mo3d5/2 and Mo3d3/2 spin orbit, respectively [29,30]. As observed, very similar Mo3d XPS spectra are obtained for fresh and used catalyst, indicating that molybdenum oxidation state and its coordination sphere remains unaltered during the epoxidation reaction.…”

Green Process Engineering as the Key to Future Processes

“…There has been a considerable amount of publications on polymer supported alkene epoxidation catalysts, such as Fe, Ni and Co [69], Ru [70], Ti [71], Mn [72], Mo [73] and Cu [74]. Additionally, polymer supported molybdenum catalysts have been reported to be effective for alkene epoxidation using alkyl hydroperoxide as the oxygen source [75][76][77][78][79][80][81][82][83].…”