Gas-phase Dehydration of Glycerol Catalyzed by SBA-15 Supported W/Zr Mixed Oxides
Date Issued
2012
Date
2012
Author(s)
Lin, Chun-Wei
Abstract
Tungstated zirconia has been found to be efficient catalysts in many acid-catalyzed reactions. The gas-phase dehydration of glycerol to acrolein is of great economical value. Mesoporous SBA-15 has great potential as catalyst support due to its ordered pore structure, high surface area and good hydrothermal stability. In the present study, mesoporous SBA-15 was used as the support for preparing supported tungstated zirconia (WZ) catalysts in order to increase the surface area and the dispersion of metal oxides. The catalysts prepared through pre-impregnation and subsequent supercritical treatment were found to retain ordered porous structure and well-dispersed W/Zr catalytic sites based on the results of XRD, N2 physisorption and EM photos. Factors of catalyst preparation such as the pre-impregnation solvents, supporting sequences of active phases, and morphology differences of silica supports in influencing the catalytic performances were examined.
The gas-phase dehydration of glycerol in the presence of water was investigated using fixed-bed reactor, and product analysis was performed by gas chromatography. From the catalytic results, all samples facilitated the same acrolein selectivity around 80%, with hydroxyacetone as the major by-product. The combination of platelet SBA-15 as support and MeOH/H2O (1:1 v:v) as pre-impregnation solvent gave catalysts having higher glycerol conversion. Moreover, the catalytic activities were retained after several cycles. The optimal calcination temperature for preparing the catalysts of the lowest deactivation rate was at 775 oC.
Subjects
WO3/ZrO2
Solid acid
Acrolein
Glycerol
Type
thesis
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