Catalytic behavior of Mg–Al and Zn–Al mixed oxides in the transesterification of rapeseed oil: comparison of batch and fixed bed reactors

The activity and the selectivity of Mg–Al and Zn–Al mixed oxides were studied in the transesterification of rapeseed oil with methanol in both batch and fixed bed reactors. Mg–Al and Zn–Al mixed oxides were prepared by the calcination of Mg–Al and Zn–Al hydrotalcites with the Mg/Al and Zn/Al molar ratios 2. Zn–Al mixed oxide possessed higher ester yield than Mg–Al mixed oxide under the same reaction conditions in a batch reactor. In a fixed bed reactor, Zn–Al mixed oxides possessed high ester yield after 32 h time on stream (ca 88% at 115 °C).