Fe-doped TiO2 nanocrystals as highly efficient catalysts for heterogeneous catalytic transesterification of coconut oil

Abstract

Background

The impact of Fe doped TiO₂ nanocatalyst on the heterogeneous catalytic transesterification reaction of coconut oil into biodiesel has been investigated.

Methods

The nanocatalyst was prepared by sol-gel method using titanium isopropoxide as TiO₂ precursor and Fe(NO₃)₃ as iron (Fe) source. Several conditions of Fe-TiO₂ were synthesized, each with Fe concentration of 0.5 %, 1 %, and 1.5 %, and calcined at 500 °C. The nanocatalyst's physical and chemical characteristics including phase crystallinity and morphology were examined.

Significant findings

We found that the biodiesel conversion efficiency increases with the increasing of Fe content in the Fe-TiO₂ nanocatalyst and optimum at the Fe concentration of 1.5 % (w/w). The optimal Fe-TiO₂ nanocatalyst could yield biodiesel output as high as 30.8 %, under at a relatively low temperature of 60 °C. Furthermore, the presence of the nanocatalyst effectively reduced the free fatty acid content in the biodiesel product by 1.43 %. Moreover, the acidity of the produced biodiesel was exceptionally low, at 0.02 %, primarily attributed to lauric acid. These exceptional performances are believed to be attributed to the enhanced surface chemistry properties of the Fe-TiO₂ nanocatalyst. The Fe-TiO₂ system is expected to find extensive application in the cost-effective production of biodiesel.