Rapeseed oil transesterification by heterogeneous catalysis
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- Peterson, G.R. & Scarrah, W.P. J Am Oil Chem Soc (1984) 61: 1593. doi:10.1007/BF02541639
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Methyl fatty esters derived from vegetable oils are a promising fuel for direct injection diesel engines. This study’s purpose was to identify a heterogeneous catalyst to selectively produce methyl fatty esters from low erucic rapeseed oil. Most experiments were at atmospheric pressure and approximately the corresponding boiling point temperature of the mixture, 60–63 C. However, the catalytic activity of an anion exchange resin was tested at 200 C and 68 atm (1000 psig) and at 91 C and 9.2 atm (135 psig). All samples were analyzed by thin layer chromatography with samples from the elevated temperature and pressure experiments also analyzed by mass spectroscopy. The most promising catalyst examined was CaO·MgO. The activities of the catalysts CaO and ZnO appear to be enhanced with the addition of MgO, therefore the transesterification reaction mechanism may be, in this instance, bifunctional. The anion exchange resin catalyst at 200 C and 68 atm generated substantial amounts of both methyl fatty esters and straight-chain hydrocarbons, even though these reactions did not go to completion. At 91 C and 9.2 atm the cracking also occurred but at a substantially reduced rate, and no transesterification was noted.