Microwave-irradiated zinc chloride catalyzed glycerolysis of high free fatty acid vegetable oil

• Main Author: Dizon, Arniel Ching O.
• Format: text
• Published: Animo Repository 2015
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/4957
• Institution: De La Salle University

Biodiesel, a popular alternative to fossil-based diesel, can be produced from cheap and sustainable sources like waste cooking oil. However, waste cooking oil, with its inherent FFA content, requires a pre-treatment step to lower the FFA content, making it available for alkali-catalyzed transesterification. The catalytic glycerolysis of FFA can be a practical, alternative pre-treatment step for high-FFA feedstocks. This pre-treatment method is coupled with microwave irradiation in this study to provide possible improvements on current reaction parameters of zinc chloride catalyzed glycerolysis using conventional heating. This study investigated the effect of microwave irradiation, as well as the reaction parameters: reaction temperature (160-200°C), reaction time (30-150 min), glycerol-to-oil mass ratio (1-3), and catalyst amount (0-2 wt.% mixture), to the zinc chloride catalyzed glycerolysis reaction of high-FFA simulated waste cooking oil by determining the FFA conversion during glycerolysis. The glycerolysis reaction rate slows down as time progresses and as FFA is consumed, as observed in the effect of time with FFA conversion. The effect of temperature with FFA conversion is linear within the 40°C temperature range. The increase in temperature favors the increase in FFA conversion since glycerolysis is an endothermic reaction. Also, the increase in temperature increases reaction rate according to the Arrhenius equation. FFA conversion is affected by the amount of glycerol relative to oil. A smaller amount of glycerol is favored for better homogenization of the two phases. FFA conversion and reaction rates were found to be limited by the catalyst amount at low catalyst concentrations while at high catalyst amount above optimum, reaction rate is only limited by FFA concentration. Consequently, the optimum conditions for the microwave-irradiated catalytic glycerolysis are 200°C, 2 hours reaction time, 1:1 glycerol-to-oil mass ratio, and catalyst amount of 1.217 % wt. of mixture.