One-pot Hydrothermal Synthesis of Mesoporous V-SBA-16 with a Function of the pH of the Initial Gel and its Improved Catalytic Performance for Benzene Hydroxylation

Abstract

V-SBA-16 catalysts with uniform cubic mesoporous structure were prepared by direct hydrothermal method as a function of the pH of the initial gel and characterized by ICP, XRD, TEM, N 2 adsorption-desorption, DRUV-vis and Raman spectra. The pH of the initial gel in synthesis of V-SBA-16 show important effects on the maintenance of well ordered mesoporous structure, introduced vanadium content and the incorporation of vanadium into the network of SBA-16 type mesoporous material. The initial gel system with a pH value of 2.0 was found to be a suitable for incorporation of vanadium and retaining the mesostructure of SBA-16. The catalytic activities of V-SBA-16 catalysts were evaluated for the hydroxylation of benzene using molecular O 2 as the oxidant. The highest phenol yield of 30.4% with a selectivity of 90% and turnover number of 105 were obtained over the VS-2.0 (1.67) sample prepared at the initial gel system with pH value of 2.0, which is attributed to its high V content and uniform framework V species that highly dispersed on the well ordered SBA-16 type mesoporous materials.

Facile Synthesis of Vanadium Oxide/Reduced Graphene Oxide Composite Catalysts for Enhanced Hydroxylation of Benzene to Phenol

“…The maximum absorption band shows an obvious red shift to 405 nm, which can be associated with the presence of H x V 2 O 5 crystallites. Moreover, the absorption band of VG-N-A400 further shifts to higher wavelength and the maximum absorption signal begin from about 485 nm, which can be assigned to the formation of bulk V 2 O 5 species [23,47].…”

One-pot synthesis of vanadium-containing silica SBA-3 materials and their catalytic activity for propene oxidation

“…Similar decrease of surface area and pore volume for high V loading samples (above 3 wt%) was also observed by other authors for vanadium containing SBA-15 materials. 17,18 The average pore diameters of vanadosilicate SBA-3 synthesized at low pH (<1) of both series are higher than these of their silica counterparts synthesized at the same pH. The pore size for both series increases with the pH applied during synthesis up to value 2.2 and then declines along with further pH increase.…”

“…Their high performance has been attributed to the wide dispersion of highly reducible vanadium-isolated species with tetrahedral coordination. [17][18][19][20][21][22] On the other hand, it was shown that all silica mesoporous materials modied with vanadium are active catalyst in propene epoxidation with N 2 O as an oxidant. The best results were obtained with catalysts prepared by impregnation of silica SBA-3 with vanadium ions.…”

Liquid phase hydroxylation of benzene to phenol over vanadyl acetylacetonate supported on amine functionalized SBA-15

“…Various supported vanadium catalysts, such as V/SiO 2 [10], VxOy@C [11], V-AlPO 5 [12] VOx/SBA-15 [13], VOx/TiO 2 [14], V-SBA-16 [15] and VO 2 -defects/ MWCNT [16] have been developed. The dispersed vanadium species would be easily released from the supports in acetic acid aqueous solution that is the most commonly used solvent for this reaction [17], and as a result, the catalysts exhibited poor catalytic stability [18].…”