ЕСТЕРИФІКАЦІЯ ДИСТИЛЯТУ ВІЛЬНИХ ЖИРНИХ КИСЛОТ Н-БУТИЛОВИМ СПИРТОМ

Butyl esters of free fatty acids are widely used in various industries, particularly for lubricants, biofuels, perfume, pharmaceutical manufacture, etc. The influence of reaction temperature, catalyst content, and reagent ratio on esterification reaction between n-butyl alcohol and free fatty acids contained in the distillate of sunflower oil deodorization was studied. Sulfuric acid was used as a catalyst. Optimal values of the catalyst concentration, reagent ratio, and reaction temperature were determined to achieve maximum conversion of free fatty acids. The reaction progress was monitored by accumulating the water layer in the water separator and titrating the reaction products with an alkali solution, followed by calculating their acid number and free fatty acid conversion. The influence of the catalyst concentration on the reaction intensity was investigated. It was shown that the optimal catalyst concentration in the reaction mixture is 2.3·10-3 mol·L-1, ensuring a free fatty acids conversion of 97.1%. Increasing the catalyst concentration to 2.0·10-2 mol·L-1 does not enhance the reaction rate and free fatty acids conversion, on the contrary, it slightly reduces their conversion. At a molar ratio of free fatty acids to: n-butyl alcohol of 1: 2 and at a catalyst concentration of 2.0·10-2 mol·L-1, a free fatty acids conversion of 94.9% was achieved. The effect of temperature on esterification was also examined. It was established that below a temperature of 100 °C, the reaction proceeds very slowly, with no visible water layer formation in the water separator. A free fatty acids conversion of over 90% is achieved at a temperature exceeding 105 °C. The temperature range of 105–125 °C corresponds to conversion varied between 91.6% and 96.9%. The optimal conditions for esterification of the free fatty acids distillate with n-butyl alcohol were determined as follows: a catalyst concentration of 2.3·10-3 mol·L-1, the molar ratio of free fatty acids to n-butanol of 1:2, and a reaction temperature of 115–125 °C, ensuring an free fatty acids conversion of over 95%.