Commercial Hydrated Lime as a Cost-Effective Solid Base for the Transesterification of Wasted Soybean Oil with Methanol for Biodiesel Production

Abstract

The transesterification of used soybean oil with methanol was carried out over hydrated lime (HL), Ca(OH)2, and its decomposition products in the 200–500 °C range. The catalysts were characterized by X-ray powder diffraction (XRD), thermogravimetric analysis, and scanning electron microscopy. The XRD powder patterns demonstrated that the pristine sample consisted of a mixture of calcium hydroxide and calcite. It was noticed that the coexistence of CaO, Ca(OH)2, and CaCO3 remained up to 400 °C. At 500 °C, Ca(OH)2 is transformed into CaO so that this and CaCO3 are the only remaining phases. In the transesterification reaction, the influence of calcination temperature, reaction time, catalyst amount, methanol:oil ratio, and reaction temperature was studied. Full conversion of the raw materials into biodiesel (BD) was obtained with the fresh HL. In order to determine any change in the solid, it was recovered after 10, 30, and 60 min of reaction and analyzed by XRD analysis. Only Ca(OH)2, CaCO3, and traces of monohydrocalcite were detected. From the results it was demonstrated that the active phase for biodiesel production was calcium hydroxide. Furthermore, the catalyst was used up to three times without deactivation. A simple, economic, and environmentally friendly way to obtain biodiesel was developed considering (a) used soybean oil, considered waste, was employed as raw material, (b) hydrated lime is cheap and readily available, and (c) full conversion of the raw materials into BD was achieved with the as-received HL.

Evaluation of Hydrocalumite-Like Compounds as Catalyst Precursors in the Photodegradation of 2,4-Dichlorophenoxyacetic Acid

“…It is worth mentioning that the spherical particles were more obvious in the HC1 and HC2 samples. We noticed that sintering was identified in all samples giving rise to an Ostwald ripening effect which involves the growth of larger particles at the expense of smaller ones [56]. However, sintering was more evident in the HC3 sample where the spherical particles were practically absent and larger particles obtaining was noticed.…”

“…Finally, the last two observed thermal events identified in the 624-1000 ∘ C range were attributed to the total dehydroxylation and anion decomposition. Only one common decomposition peak was identified in all samples (∼737-754 ∘ C) which was attributed to calcite decomposition [56].…”

Possibility of Using Commercial Hydrated Lime as a Catalyst for Rapeseed Oil Methanolysis

“…This is confirmed by the results of sunflower oil methanolysis [55], where 1 wt% Ca(OH) 2 , after 120 min resulted in biodiesel yield <10%, while yield above 90% was obtained with 5 wt% of catalyst loading. Methanolysis of used soybean oil showed that the increase in conversion rate was proportional to the dose of hydrated lime [27]. In the study of methanolysis of refined sunflower oil [26], it was concluded that the applied concentration of Ca(OH) 2 (equivalent to 0.2% NaOH) was low, but even at higher catalyst concentrations (equivalent to 1% NaOH), oil conversions remained modest (<70% after 24 h), which was explained in term of low specific surface area of the catalyst (0.9 m 2 /g).…”

“…Calcium oxide (CaO) has been used as a catalyst in a large number of published studies of heterogeneous basecatalyzed transesterification [22], due to its high catalytic activity under mild reaction conditions, wide availability and low cost [23,24]. Compared to CaO, there are significantly fewer published studies on the use of calcium hydroxide, Ca(OH) 2 , for methanolysis of vegetable oils, and their findings are contradictory in terms of the achieved yield of methyl esters [25][26][27][28].…”

Mogućnost primjene hidratiziranog vapna kao katalizatora u procesu metanolize suncokretova ulja

“…17 U posljednje vrijeme pojedini autori su u svojim radovima potvrdili mogućnost uporabe hidratiziranog vapna kao efikasnog katalizatora metanolize sojina ulja uz konstataciju da nije potrebna nikakva dodatna aktivacija katalizatora. 18 Osnovni cilj u okviru ovog rada bilo je istraživanje mogućnosti primjene hidratiziranog vapna, komercijalnog produkta koji se primjenjuje u građevinarstvu, kao katalizatora u procesu metanolize suncokretova ulja i njegov utjecaj na prinos metilnih estera suncokretova ulja (MESU), tj. biodizela.…”