Alkali-free zn–al layered double hydroxide catalysts for triglyceride transesterification

• Published in: Catalysts
• Main Author: Tajuddin N.A.; Manayil J.C.; Isaacs M.A.; Parlett C.M.A.; Lee A.F.; Wilson K.
• Format: Article
• Language: English
• Published: MDPI 2018
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062421592&doi=10.3390%2fcatal8120667&partnerID=40&md5=9f28c517c32c180547fb74cd88e189d1

Zn–Al layered double hydroxides (LDHs) of general formula Al3+ x(OH)2]x+(CO3Zn–Al2−)x/2·yH2O are promising solid base catalysts for the transesterification of lipids to biofuels. However, conventional synthetic routes employ alkali ydroxide/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. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.