Otimização da produção de biodiesel através da reação de transesterificação do óleo de mamona utilizando um catalisador básico homogêneo.

Abstract

This dissertation aimed to optimize the transesterification reaction for biodiesel production using castor oil and a basic homogeneous catalyst. To the reaction was analyzed for catalyst production (sodium hydroxide + methanol methoxide potassium + water) and by reducing the castor oil, acid value. Adsorption was applied to remove the water formed in the process, because water deactivates the catalyst and shifts the equilibrium towards the hydrolysis reaction, forming soap. The thermodynamic and kinetic study of liquid phase adsorption of methanol-water mixtures was carried out using zeolite 3A as adsorbent. An experimental design was carried out for the reaction for catalyst production. The variables concentration of KOH and adsorbent concentration in the reaction were investigated. The concentration of KOH was the most statistically significant response on the amount of methoxide formed during the production of the catalyst (within a 90% level of confidence). To the amount of water present in the reaction, just the interaction between the concentration of KOH and the adsorbent concentration, both in the linear term, were statistically significant. Tests for catalyst production in a porous bed were carried out. The studied factors were average grain size (3,1 mm; 3,68 mm and 4,38 mm) and uptake flow rate (2 and to 6 mL/min). The best condition were the smallest diameter of the particle and the highest uptake flow rate, because there was a reduction of resistance to mass transfer at the particle sorbent. The transesterification reaction were carried out in different conditions to evaluate the effect of the acidity of the castor oil and the effect of the removal of water by adsorption during the production of the catalyst. The castor oil presented an acidity of 4 mgKOH/g which can be considered high to be used in the transesterification reaction. To reduce the acidity, a neutralization step of oil using the co-product of the reaction (glycerin). The neutralization step with glycerin was able to reduce the acidity to 0,48 mgKOH / g. It was observed that the conversion into methyl esters was as high as 93,79 % for biodiesel prepared from the transesterification reaction of the castor oil neutralized with the catalyst produced using the adsorption process. It was observed that the use of adsorption of water in producing catalyst presented an improvement by 12% in the conversion of oil into methyl esters.