Optimization Models Type Box-Behnken in the Obtaining of Biodiesel from Waste Frying Oil using a Large-acidity Carbonaceous Catalyst.

The trans-esterification and esterification of waste vegetable oil mainly under sub-critical temperature of methanol in the presence of sulfonated char were achieved. The carbonaceous materials were analyzed by means of various physical and chemical techniques such as Raman spectroscopy, X-ray diffractometry, temperature programmed desorption and X-ray photoelectrons spectroscopy. The carbon-based large-acidity catalyst showed good chemical and thermal properties and a high performance in the production of methyl esters from waste vegetable oil, which was easily separated from the liquid mixture. A temperature of 210°C, reaction time of 20 min and a catalyst amount of 0.03 g were the optimal experimental conditions for the trans-esterification of the vegetable oil with methanol giving a conversion to triglycerides of 96.5% according to the response surface methodology. The design of experiments type Box-Behnken was successfully applied to study effects of the parameters in the production of biodiesel and it presented optimal conditions for maximum performance with values near to those experimentally found. The catalyst was recovered from the final mixture by filtration and reused without regeneration showing a catalytic activity stable up to 4 or more reaction cycles. [ABSTRACT FROM AUTHOR]