(215g) Esterification of Carboxylic Acids Present in the BIO-OIL Produced By Thermal Cracking of Triacylglycerols
The production of alternative fuels from renewable sources has been object of several studies in recent years. A promising alternative is the conversion of biomass to biofuels by thermal cracking. Through this process, it is possible to obtain a liquid product called bio-oil, with physicochemical properties similar to the petroleum crude oil. However, bio-oil might contain a high amount of carboxylic acids that results on a high acid index ranging from 110 mg KOH/g of sample to 207 mg KOH/g of sample, whereas the maximum required by the current legislation (EN 14104) is 0.5 mg KOH/g of sample. In this work, the bio-oil was produced from commercial soybean oil at 525°C and a mass flow rate of 350 g/h. The objective of this study is to perform esterification reactions in order to reduce the acidity index of the bio-oil. These reactions present a methodology of easy operation, low cost and may reduce the bio-oil corrosivity. For this, alcoholic reagents, ethanol and methanol, were used for the esterification reactions. The influence of different temperatures, reaction times, catalysts and, stoichiometric ratios between the reagents on the reduction of the acid number and improvement of the bio-oil quality were evaluated. Good results were obtained with the esterification reaction using ethanol, sulfuric acid, bio-oil to ethanol ratio of 10:5, temperature of 60°C and reaction time of 90 minutes. The acid index of the bio-oil sample decreased from 111.33 mg KOH/g of sample to 34.64 mg KOH/g of sample, resulting in a reduction of approximately 70%.