Biodiesel: o ônus e o bônus de produzir combustível

Abstract

IBiodiesel: the charge and the bond of the fuel producing RESUMO A dependência do petróleo e a poluição gerada pelo óleo diesel são as grandes desvantagens do uso deste combustível, o que vem estimulando a busca por fontes energéticas alternativas. Biodiesel é o combustível derivado de óleos vegetais ou de gordura animal

Cracking and hydrocracking of triglycerides for renewable liquid fuels: alternative processes to transesterification

“…As already mentioned in various Brazilian reviews [1][2][3][4][5][6][7] about the preparation of liquid fuels from triglycerides (or by-products from their refining or use), Brazilian interest in this area started in the 1970s, when the PROALCOOL program was initiated. In parallel to the need to obtain a liquid fuel (ethanol) for light vehicles, a need for liquid fuel for diesel engine vehicles rapidly appeared.…”

“…5,6 In fact, they used not only soybean oil, but also babassu oil, Jatropha curcas oil, as well as model stearic and oleic fatty acids. Commercial catalysts, some of them obtained from PETROBRAS/CENPES (Centro de Pesquisas e Desenvolvimento Leopoldo Américo Miguez de Mello da PETROBRAS), such as γ-alumina, silica, Ni-W/mordenite, Y and NH 4 Y zeolites, and catalysts prepared in the laboratory, such as transition alumina, niobium oxide, titanium oxide, either pure or modified by impregnation with metals (Ni/alumina, W/alumina) or with acidity promoters such as TiO 2 /SO 4 Tables 3, 4 and 5 show selected results of these data. 5,6,18 The presence of phosphoric acid, either supported on activated carbon or on silica, leads to liquid products with low residual acidity, implying a quasi total disappearance of the fatty acids which are formed in the absence of such active catalysts.…”

“…Some of the preceding authors also studied other catalysts in the thermocatalytic decomposition of oleic acid, more precisely alumina based catalysts, either pure or modified with H 3 PO 4 . 34 Experimental conditions were the same as above, in the case of reaction with niobium based catalysts.…”

“…As in the case of niobium based catalysts, the impregnation of the alumina with phosphoric acid favored deoxygenation reactions. The best results were obtained with an alumina support prepared in the laboratory and impregnated with 12 wt.% H 3 PO 4 . In this case, the acidity of the liquid products was found to be in the range of 0.2-0.4 mmol g -1 and the conversion of oleic acid reached values higher than 95%.…”

“…Various analyses of the biofuel transformations, focusing mainly on biodiesel, have been written in recent years by Brazilian scientists. [1][2][3][4][5][6][7] Although biodiesel is well accepted, there is a need to perform important purification of both the final biodiesel and the major reaction by-product of the transesterification: glycerol. These purification steps may have an important environmental impact.…”