Gas-phase Dehydration of Glycerol Catalyzed by Platelet SBA-15 Supported W/Zr/Nb Mixed Oxides
Date Issued
2015
Date
2015
Author(s)
Yuan, Ding-Jier
Abstract
Solid acids have been found to be efficient catalysts for dehydration of glycerol to form acrolein. In this study, we chose mixed metal oxides to be the catalysts, because the acid strength is easy to control, they have good thermal stability, and they can be regenerated easily. In this study, mixed metal oxides containing Nb, W, and Zr were supported over various materials (SBA-15, Al2O3, and MgO) by impregnation method through super-critical-fluid treatment. The physico-chemical properties were characterized by several techniques, including NH3-TPD, XRD, and N2 sorption. The acidic support material (Al2O3) was found to give highest glycerol conversion and acrolein selectivity. However, the catalyst decayed rapidly. On the other hand, the catalysts prepared by one-step impregnation over platelet SBA-15 were found to be more efficient than others in maintaining the catalyst lifetime. Moreover, the catalyst with metal oxides entering the channels of SBA-15 (Nb11W30Zr59-SBA-15-p-H2O2), gave better catalytic activity than that just covered the outer surfaces (Nb11W30Zr59-SBA-15-t-H2O2). The most efficient catalyst could retain glycerol conversion of 69% and acrolein selectivity of 70% after 24 h time-on-stream.
Subjects
WO3
ZrO2
Nb2O5
SBA-15
super-critical-fluid
glycerol
acrolein
Type
thesis
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