Abstract
Vanadium modified mesocellular silica foams (MCF) materials (V content ca. 3 and 5 wt%) prepared by the impregnation method show mainly isolated or low-polymeric VOx species, which was confirmed by means of Raman spectroscopy and DR UV–Vis. Textural measurements, and also XRD and TEM results indicate that the characteristic mesocellular structural features of MCFs are preserved after vanadium incorporation. The MCF-supported vanadia catalysts exhibit much higher propene conversion and propene oxide productivity when compared to vanadium modified mesoporous silicas of 2D structure, demonstrating that apart from the presence of highly dispersed isolated vanadium species, internal molecular transport within three-dimensional ultra large pores of MCF materials also plays an important role in gas-phase propene epoxidation.Graphical
Highlights
Propene oxide (PO), applied for polyurethane synthesis and for the production of many other consumer goods, belongs to the most important organic intermediates the demand for which is continually increasing [1, 2]
FT-IR spectra recorded for bare mesocellular silica foams (MCF) and vanadium modified MCF support indicate that vanadium species interact with the hydroxyl groups characterized with an IR band at 3735 cm−1, which are considered as non-acidic
The presented study has demonstrated that MCF material with its unique textural structure is an attractive support applicable for the fabrication of promising V/MCF catalysts that are highly active in propene epoxidation
Summary
Propene oxide (PO), applied for polyurethane synthesis and for the production of many other consumer goods, belongs to the most important organic intermediates the demand for which is continually increasing [1, 2]. These processes are complex, expensive and not environmentally friendly. The search for a method of direct propene epoxidation in a gas phase is one of the most desirable and challenging goals of PO production. Molecular oxygen would be the most desirable oxidant for propene epoxidation because of its availability and low price. Direct propene with oxygen oxidation brings about a mainly unselective process. Silica supported ruthenium-copper based catalyst modified with alkaline ions indicated relatively high PO yields when oxygen was used for propene oxidation [3]. Utilization of hydrogen peroxide synthesised in situ from a hydrogen and oxygen mixture as an oxidant has been commercialized [4]
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