Sono-synthesis of biodiesel from soybean oil by KF/γ-Al2O3 as a nano-solid-base catalyst

Abstract

In this work, biodiesel has successfully prepared via ultrasonic method in a short time and low temperature by nano-solid-base catalyst (KF/γ-Al₂O₃). The catalyst was obtained by calcination of a mixture of KF and γ-Al₂O₃ m(KF)/m(γ-Al₂O₃) at 500 °C for 3 h. Nano-solid-base catalyst was characterized with scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), thermal gravimetry (TG) and the Hammett indicator methods. The TEM image depicted nanoparticles and uniform dispersion of active phase over alumina. The XRD analysis confirmed the formation of potassium aluminum fluoride (K₃AlF₆) and potassium oxide, active catalyst for transesterification. The transesterification of soybean oil with methanol was performed by using both low frequency ultrasonic reactor (20 kHz) and mechanical stirring in the presence of KF/γ-Al₂O₃. The influence of various parameters such as ultrasonic power, oil/methanol molar ratio, catalyst concentration, time, and temperature were studied on the biodiesel formation. The maximum yield (95%) was achieved by applying 45 W acoustic power, molar ratio of alcohol to oil at 12:1, catalyst concentration of 2.0 wt%, 40 min sonication, and temperature of 50 °C. The transesterification was performed in 360 min using mechanical stirring with 76% yield. The results confirm that ultrasound significantly accelerates the transesterification reaction in comparison with the mechanical stirring.

RETRACTED: Experimental design and kinetic study of ultrasonic assisted transesterification of waste cooking oil over sulfonated carbon catalyst derived from cyclodextrin

“…Some researcher has tried to study the biodiesel production from edibleoils and non-edible oils by using heterogeneous catalyst with an ultrasonic system [19]. Shahraki et al [20] reported that transesterification catalysis of soybean oil by KF/g-Al 2 O 3 achieved with sono-synthesis. Pukale et al [21] studied transesterification of waste cooking oil in the presence of heterogeneous solid catalyst and the results of optimum conditions such as catalyst concentration of 3 wt.% of K 3 PO 4 and reaction time of 90 min gave a highest biodiesel yield up to 92.0%.…”

Application of Microwave Irradiation for Preparation of a KOH/Calcium Aluminate Nanocatalyst and Biodiesel

“…The sharp band around 1385 cm −1 is assigned to the stretching vibration of Al–O–H groups due to hydrogen bonding with the Al 2 O 3 surface that was disappeared at the high calcination temperature . The peak was probably shifted to a higher wavenumber as a result of the formation of a new structure in the catalyst with the increase of the calcination temperature which can be assigned to the stretching vibration of Al–O–K groups in K 3 AlO 3 phases as well as the peaks at 1010 and 1470 cm −1 . Physically adsorbed water on the samples was observed at around 1636 and 3400 cm −1 .…”

“…Solid‐base catalysts usually contain a support such as alumina and zirconia , and one or more active phases such as a potassium component , . The supports are generally used to provide a more specific surface area and larger pores for active species, and active phases have the main role in converting the feedstock to biodiesel.…”

Ultrasonic Pretreatment Transesterification for Solid Basic‐Catalyzed Synthesis of Fatty Acid Methyl Esters

“…Ultrasonic assisted transesterification processes for biodiesel production can significantly shorten reaction time [10][11][12][13][14]. To be the best of our knowledge, the effect of ultrasound on the liquid-liquid heterogeneous reaction system could be divided into two aspects.…”