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Catalysts, Vol. 8, Pages 667: Alkali-Free Zn–Al Layered Double Hydroxide Catalysts for Triglyceride Transesterification

Research paper by Nazrizawati A. Tajuddin, Jinesh C. Manayil, Mark A. Isaacs, Christopher M.A. Parlett, Adam F. Lee, Karen Wilson

Indexed on: 23 Dec '18Published on: 18 Dec '18Published in: Catalysts



Abstract

Zn–Al layered double hydroxides (LDHs) of general formula [Zn2+(1−x)Al3+x(OH)2]x+(CO32−)x/2·yH2O are promising solid base catalysts for the transesterification of lipids to biofuels. However, conventional synthetic routes employ alkali hydroxide/carbonate precipitants which may contaminate the final LDH catalyst and biofuel. The use of (NH3)2CO3 and NH3OH as precipitants affords alkali-free Zn–Al-LDHs spanning a wide composition range. The hydrothermal reconstruction of calcined Zn–Al-LDHs offers superior solid basicity and catalytic activity for the transesterification of C4–C18 triglycerides with methanol, compared with cold liquid phase or vapour phase reconstruction. Hydrothermally activated Zn3.3–Al-LDH was stable towards leaching during transesterification.