Ultrasound‐assisted transesterification of refined and crude palm oils using heterogeneous palm oil mill fly ash supported calcium oxide catalyst

Abstract

Ultrasound-assisted transesterification of refined palm oil (RPO) and crude palm oil (CPO) to produce biodiesel using a palm oil mill fly ash supported calcium oxide (CaO) catalyst is studied in this work. The reaction time is significantly reduced from a maximum of 360 min under conventional mixing to just 30 min with the use of ultrasound. Under ultrasonic cavitation, the required catalyst loading and methanol to oil molar ratio to produce comparable yields and fatty acid methyl esters (FAME) conversions as conventional mixing are lower. For RPO, the ultrasound-assisted transesterification conditions of 60% ultrasonic amplitude, 30 min reaction time, 4 wt.% catalyst loading, and 9:1 methanol to oil molar ratio result in maximum biodiesel yield and FAME conversion of 85.23% and 97.02%, respectively. As for CPO, maximum biodiesel yield of 73.23% and FAME conversion of 97.04% are obtained under the same conditions with the exception of a methanol to oil molar ratio of 12:1. Key physicochemical properties of the produced biodiesels are found to be within the limits set by EN 14214 and ASTM D 6751. Catalyst reusability tests indicate that the catalyst can be used up to three consecutive cycles after regeneration using methanol washing followed by recalcination at 850°C for 2 h.

Reaction conditions of ultrasound-assisted production of biodiesel: A review

“…Short production cycle, low production costs, the esterification rate and low environmental pollution; industrial difficulty. [22,39,66,67] Ultrasound-assisted production of biodiesel Z. Zhao et al free enzymatic transesterification of Macauba (Acrocomia aculeata) coconut oil by using a commercial immobilized lipase (Novozym 435).…”

“…Song produced biodiesel by using a two‐step enzymatic method of energy microalgae; the method yielded 80.1% biodiesel from microalgae oil by using methanol to oil molar ratio of 4:1, solution pH of 6, and speed of 180 rpm at 35 °C for 10 h. Ultrasound is an auxiliary tool introduced in chemical reactions and synthesis methods to promote the synthesis of biodiesel . Ho et al studied ultrasound‐assisted transesterification of refined palm oil (RPO) and crude palm oil (CPO) to produce biodiesel by using palm oil mill fly ash‐supported calcium oxide as catalyst. For RPO, the maximum biodiesel yield and fatty acid methyl ester (FAME) conversion rates of 85.23% and 97.02% were obtained through ultrasound‐assisted transesterification with 60% ultrasonic amplitude, 30 min reaction time, 4 wt.% catalyst loading, and 9:1 methanol to oil molar ratio.…”

“…Ultrasonic‐assisted method exhibits many advantages, such as short production cycle, low production costs, high yield, and low environmental pollution. Large‐scale industrialization is also very difficult in ultrasonic‐assisted method .…”

“…In recent years, a new kind of technology, namely, ultrasonic technology, has been widely used in aviation, aerospace, transportation, energy, geological exploration, medicine, and chemical industries; this technology is characterized by short wavelength, high frequency, and strong penetrating force [38]. With the rapid development of ultrasonic technology, ultrasonic chemical reaction has also been widely used to generate biomass energy [39]. The present review provides a detailed investigation on the influence of various operating parameters as well as sound evidence for industrial ultrasonic-assisted production of biodiesel.…”

Biodiesel Production from Waste Frying Oil by Ultrasound‐Assisted Transesterification

“…Finally, the conversion diminished at 90 min (81 %). Ho et al [25] found that, after 40 min, the conversion decreased in the ultrasound-assisted transesterification of palm oil. This finding suggests that the ultrasound irradiation enhances the reaction rate compared with the conventional reaction.…”