Productions of ethyl esters (biodesel) from the transesterification core residual oil / Produção de esteres etilicos (biodiesel) a partir da transesterização basica de oleo residual

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Biodiesel (alkyl esters) is a clean burning fuel derived from a renewable lipid feedstock such as vegetable oil or animal fat. It is biodegradable, non-inflammable, nontoxic and produce much lesser COx, sulfur dioxide and unburned hydrocarbons than petroleum-based diesel. Nowadays, due to the price of virgin oil such as soybean and canola oils, the use of low-cost feedstock such as waste frying oils in a base-catalyzed process should help make biodiesel competitive in price with petroleum diesel, beyond being a suitable way to reuse waste materials. Waste frying oil ethanolysis was studied using sodium hydroxide and potassium hydroxide as catalysts. The waste oil was collected in restaurant boxes. The waste oil showed free fatty acids content up to 3.8% and typical problems related to this condition as soap formation and phase separation interference were observed. Then, experimental designs were carried out in specific conditions to solve such problems. The properties of waste oil studied were acid value, water content, fatty acids composition, iodine value, kinematic viscosity and density. At first, a fractional factorial experimental design was chosen to analyze the most significant factors (temperature, ethanol to oil molar ratio, type and amount of catalyst and time) on the conversion oil to biodiesel. The use of sodium hydroxide as catalyst resulted in a dense and homogeneous phase after ethanol distillation, then potassium hydroxide was chosen to the subsequent experimental designs. The temperature of 30ºC was found more suitable as well. Moreover, curvature was detected in the fractional factorial experimental designs studied and star points were included in the following ones. Afterwards, central composite designs were carried out with the most significant factors obtained in previous designs not only looking for the higher conversion rate but also good ester yield. The reaction was optimized using 1.3% KOH, 30°C, ethanol to oil molar ratio of 8:1 and 50 minutes of stirring. The surface response methodology was used to study the best conditions related to each design. At last, a computer-aided tool of this system was used to model the kinetic of biodiesel production in order to calculate kinetic parameters such as reaction rate constants and the activation energy.

ASSUNTO(S)

kinetic biodisel waste oil cinetica quimica flying oil biodiesel oleos e gorduras planejamento experimental

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