Transesterification of triglycerides in high and low quality oil feeds over an HT2 hydrotalcite catalyst

Theoretical Study of the Transesterification of Triglycerides to Biodiesel Fuel under Various Conditions

“…The triglyceride is converted stepwise to a diglyceride, a monoglyceride and finally, to glycerol by removal of an alkyl in each step, as shown in Fig. 2, where R 1 , R 2 and R 3 represent long chain alkyl groups (Boocock et al, 1998;Jin F. et al, 2007;Demirbas, 2008;Barakos et al, 2008). Accordingly, we expect that systematic theoretical estimations of transesterification reaction activation energies are essential to clarify the transesterification pathways and the complex acid or base-catalyzed transesterification mechanism.…”

First Generation Biodiesel

“…However, the transesterification catalyzed with Mg-Al HT catalysts prepared by coprecipitaion, the best ester conversions from soybean oil and triglycerides were below 80% (Barakos et al, 2008;Cantrell et al, 2005;Xie et al, 2006a). But, if the transesterification reaction occurs under high temperature and pressure, the uncalcined hydrotalcite could show higher activity (Barakos et al, 2008). Calcining hydrotalcite materials at high temperature, the interlayer water is lost first, followed by dehydroxylation and decomposition of interlayer carbonate to CO 2 , which generate an interactive, high surface (ranging from 150 to 300 m 2 /g) area and well-dispersed mixed oxides that completely destroyed the layered structure (Corma et al, 2005;Mckenzie et al, 1992).…”

“…In the biodiesel synthesis process, the Mg/Al molar ratio of hydrotalcites is usually set from 2 to 4, with the ratio 3 being chosen as the best in terms of basic activity by many authors (Cantrell et al, 2005;Fishel & Davis, 1994;Xie et al, 2006a;Zeng et al, 2008). However, the transesterification catalyzed with Mg-Al HT catalysts prepared by coprecipitaion, the best ester conversions from soybean oil and triglycerides were below 80% (Barakos et al, 2008;Cantrell et al, 2005;Xie et al, 2006a). But, if the transesterification reaction occurs under high temperature and pressure, the uncalcined hydrotalcite could show higher activity (Barakos et al, 2008).…”

Catalysing Sustainable Fuel and Chemical Synthesis

“…anions between layers to balance the overall charge [120], and are conventionally synthesised via co-precipitation from their nitrates using alkalis as both pH regulators and a carbonate source. Mg-Al hydrotalcites have been applied for TAG transesterification of poor and high quality oil feeds [121] such as refined and acidic cottonseed oil (9.5 wt% FFA), and animal fat feed (45 wt% water), delivering 99 % conversion within 3 h at 200°C. It is important to note that many catalytic studies employing hydrotalcites for transesterification are suspect due to their use of Na or K hydroxide/carbonate solutions to precipitate the hydrotalcite phase.…”