Synthesis of biodiesel from sunflower oil over potassium loaded alumina as heterogeneous catalyst: The effect of process parameters

Abstract

Heterogeneous catalysis is in recent focus of research for biodiesel production from vegetable oils because of advantages such as easy separation and reuse of catalysts, although homogeneous catalysis is most commonly used method. The aim of this study was preparation of γ-Al 2 O 3 supported by modified sol-gel procedure, synthesis of the KI/Al 2 O 3 catalyst and testing its activity in the transesterification of sunflower oil with methanol. Influences of different process parameters on conversion of sunflower oil to methyl esters were examined. The gained results implicate that the potassium iodide incorporation into/ /onto the structure of γ-Al 2 O 3 significantly influences textural and structural properties of the catalyst. Additionally, the catalyst basic strength is increased and all together those properties are positively affecting the activity of the catalyst in the reaction of transesterification of sunflower oil with methanol. The impregnation of alumina with potassium iodide resulted in the additional formation of basic catalytically active sites. The surface properties of the catalyst have an essential impact on its catalytic performance. Under relatively mild process conditions and relatively short reaction time, the usage of the KI/Al 2 O 3 catalyst resulted in very high conversion to fatty acids methyl esters (i.e., 99.99%).

The significance of textural and structural properties of potassium loaded y-alumina catalyst on the final catalytic efficiency in the transesterification of sunflower oil

“…Loading of potassium iodide on alumina can lead to a high activity of the catalyst in the transesterification reaction, as it was shown by recent studies [22][23][24]. Marinkovic et al [24] have found that the catalysts prepared by loading 37 wt.% of KI onto Al 2 O 3 and calcinated at 1043 K for 3h resulted in the highest conversions of 99.99% to fatty acids methyl-esters under relatively mild conditions [24].…”

“…The KI/Al 2 O 3 catalysts were prepared by incipient wetimpregnation of γ-Al 2 O 3 with desired amounts of potas-sium iodide aqueous solutions to the nominal amount of KI 37 wt.%. This procedure was conducted for 2 h. After that, the catalysts were dried at 120 °C for 3 h, and then the catalysts were activated by heating at 770 °C with the temperature rate of 10 °C/min for 3 h [24].…”

“…Pore volume was calculated from the volume adsorbed at the relative pressure of 0.99 by using the desorption branch of isotherms, by Barrett-Joyner-Halenda (BJH) method. The results concerning textural properties of the catalysts were obtained by using a Micromeritics ASAP 2010 instrument [24].…”

“…X-Ray diffraction (XRD) measurements were conducted on Philips AMD 1011 X-ray diffractometer with a radiation source Cu K_(λ = 0.154 nm) at 40 kV and 50 mA. Data were collected over the 2θ range 10 -80 °C with the step size of 0.017° at a scanning speed of 5° min −1 [24].…”

“…Scanning electron microscope SEM JOEL 101 with an accelerating voltage of 20 kV was used to obtain SEM micrograms of the catalysts samples [24].…”