Preparation and Characterization of CaO Nanoparticles/NaX Zeolite Catalysts for the Transesterification of Sunflower Oil

TLDR

Biodiesel is produced by transesterification of oil triglycerides with methanol or ethanol, using either homogeneous or heterogeneous catalysts. This study reports the transesterification of sunflower oil with methanol to produce biodiesel using CaO nanoparticles supported on NaX zeolite as catalyst. The authors varied CaO nanoparticle loading (5–25 wt %) on NaX zeolite, carried out reflux transesterification at 6 h with a 6:1 methanol:oil ratio, and characterized the catalyst by XRD, SEM, and XPS. Methyl ester content was highly influenced by basicity; the 16 wt % CaO catalyst yielded 93.5 % methyl esters and met European EN‑14214 specifications for viscosity, flash point, and acid value.

Abstract

Biodiesel is produced by the transesterification of oil triglycerides with methanol or ethanol, in the presence of a homogeneous or heterogeneous catalyst. This study aims to report the results of the transesterification of sunflower oil with methanol to produce biodiesel using CaO nanoparticles supported on NaX zeolite as catalyst. The effect of the CaO nanoparticles concentration on the NaX zeolite surface was studied in the range of 5−25 wt %. The transesterification reaction was carried out at reflux temperature of methanol, atmospheric pressure, a reaction time of 6 h, and with a 6:1 molar ratio of methanol to sunflower oil. Catalyst characterization was carried out by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. It was concluded that methyl esters content is highly influenced by basicity and that the best catalyst was the one holding 16 wt % CaO nanoparticles. The produced biodiesel was 93.5% methyl esters and was found to fulfill the specifications of European Norm UNE-EN 14214 regarding viscosity, flash point, and acid value.