Biodiesel production from refined sunflower vegetable oil over KOH/ZSM5 catalysts

Highlights

KOH/ZSM5 catalysts were prepared by wet impregnation.

K2O-ZSM5 interaction beneficial to inhibit “K” leaching.

Methyl ester yield higher than 95%.

35KOH/ZSM5 catalyst stable for several runs.

Transesterification reaction mostly at the outer surface of the solid.

Abstract

ZSM5 zeolite was impregnated with different KOH loadings (15 wt.%, 25 wt.% and 35 wt.%) to prepare a series of KOH/ZSM5 catalysts. The catalysts were calcined at 500 °C for 3 h and then characterized by N2 adsorption–desorption and X-ray diffraction (XRD) techniques. The catalysts were tested in the transesterification reaction in a batch reactor at 60 °C and under atmospheric pressure. It was found that KOH/ZSM5 with 35 wt.% loading showed the best catalytic performance. The best reaction conditions in the presence of KOH/ZSM5 (35 wt.%) were determined while modifying the catalyst to oil ratio and the reaction time. The highest methyl ester yield (>95%) was obtained for a reaction time of 24 h, a catalyst to oil ratio of 18 wt.%, and a methanol to oil molar ratio of 12:1. The properties of produced biodiesel complied with the ASTM specifications. The catalytic stability test showed that 35KOH/ZSM5 was stable for 3 consecutive runs. Characterization of the spent catalyst indicated that a slight deactivation might be due to the leaching of potassium oxides active sites.

Keywords

  • Biodiesel;
  • Transesterification;
  • KOH;
  • ZSM5;
  • Reusability

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