REACTION KINETICS MECHANISMS AND CATALYSIS, vol.136, no.1, pp.85-106, 2023 (SCI-Expanded)
Biodiesel synthesis by using model waste sunflower oil and methanol was performed in presence of zirconium sulfate (ZS) heterogeneous catalyst. The effects of reaction parameters such as methanol/oil molar ratio, catalyst dosage, temperature and time were examined. The most appropriate conditions were found to be 9/1 molar ratio, 3 wt% catalyst dosage, at 115 degrees C of temperature for 4 h of time with a fatty acid methyl ester yield of 88%. Reusability of the catalyst was examined with X-ray diffraction of unused and used catalyst. Besides, reaction kinetics of simultaneous esterification and transesterification were investigated. The concentration terms of triglyceride and methanol were determined as driving force and adsorption groups. According to suggested Eley-Rideal mechanism adsorbed methanol reacted with triglyceride during the surface reaction step which was supposed to be rate limiting step for overall reaction. The constants of k, K-M and K-G were calculated as 5.84 x 10(-3) L g(cat)(-1) min(-1), 1.28 L mol(-1) and 2 x 10(-3) L mol(-1).