Development of novel Ag/bauxite nanocomposite as a heterogeneous catalyst for biodiesel production

Highlights

A novel in situ synthesized bauxite/Ag nanocomposite was applied for tranesterification of sunflower oil.

Synthesized Ag nanocomposite was found as rice-shapes with average size of 50 nm.

The conversion of 94% was achieved under optimized reaction.

The synthesized catalyst was successfully reused and the yield of 71.79% was obtained at the end of 8th cycle.

Abstract

Ag/bauxite nanocomposites have been prepared using in situ reduction of aqueous AgNO3 solution in a bauxite matrix and investigated for the transesterification of sunflower oil with methanol in order to study their potential as heterogeneous catalysts. The prepared nanocopmosites were characterized by XRD, SEM, EDX, FT-IR, and TG- DTA. The Central Composite Design of the Response Surface Methodology was used to optimize the effect of reaction temperature, reaction time, catalyst loading and methanol to oil molar ratio on the yield of fatty acid methyl esters. The highest yield was obtained at 67 °C reaction temperature, 3 h reaction time, 0.3 wt.% catalyst loading and 9:1 methanol to oil molar ratio. Under the optimal conditions, the methyl ester content was 94% and the catalyst successfully reused for at least 7 cycles without significant deactivation.

Graphical abstract

Keywords

  • Bauxite;
  • Ag nanostructures;
  • Nanocomposite;
  • Transesterification;
  • Biodiesel

Abbreviations

  • BET, Brunauer–Emmett–Teller;
  • CCD, central composite design;
  • DTA, differential thermal analysis;
  • EDX, energy disperse X-ray spectroscopy;
  • FAME, fatty acid methyl esters;
  • FID, flame ionization detector;
  • FT-IR, fourier transform infrared spectroscopy;
  • RSM, response surface methodology;
  • SEM, scanning electron microscope;
  • TGA, thermogravimetric analysis;
  • XRD, X-ray diffraction

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