Tham khảo tài liệu 'biodiesel feedstocks and processing technologies part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Transesterification in Supercritical Conditions 259 2003 Kusdiana Saka 2004a and the reactivity of supercritical alcohols were all reported Warabi et al. 2004 . In 2004 the first supercritical transesterification of sunflower oil with ethanol and supercritical carbon dioxide in the presence of a lipase enzyme were investigated in a batch reactor Madras et al. 2004 . However during 2001 - 2005 the maximum alkyl ester contents were generally observed at nearly the same reaction conditions as that reported earlier by the Japanese pioneers Kusdiana Saka 2001 Saka Kusdiana 2001 . In 2005 carbon dioxide and propane were introduced as co-solvents to obtain milder operating parameters for the supercritical transesterification with methanol Cao et al. 2005 Han et al. 2005 . Then the two-step supercritical process Minami Saka 2006 was demonstrated to reduce those operating parameters. In the following years various catalysts were employed to assist the supercritical transesterification to achieve the maximum alkyl esters content but at milder operating conditions Demirbas 2007 Wang et al. 2008 Wang et al. 2007 Wang Yang 2007 Yin et al. 2008b . The continuous production of biodiesel in supercritical methanol was reported in 2006 Bunyakiat et al. 2006 Minami Saka 2006 and 2007 He et al. 2007b . Therefore the research focus on the reduction of the elevated operating conditions and continuous process has been ongoing since 2005. In 2007 the gradual heating technique was introduced to limit or prevent thermal cracking of the unsaturated fatty acids and so prevent the reduction in the final methyl esters content obtained He et al. 2007b . At the same time the effect of using co-solvents to reduce the viscosity of vegetable oils was successfully investigated Sawangkeaw et al. 2007 . Supercritical transesterification in ethanol was studied in a continuous reactor in 2008 Vieitez et al. 2008 . In 2009 carbon dioxide was applied to supercritical transesterification with ethanol to .
