Intensification of acid catalyzed synthesis of tricaprylin using ultrasound pretreatment

Abstract

Intensified synthesis of tricaprylin from caprylic acid and glycerol has been investigated based on novel approach of using ultrasound only in initial stages of the esterification under solvent free conditions. The effect of ultrasonic conditions such as time and power during the pretreatment as well as the reaction conditions such as substrate molar ratio, reaction time and catalyst loading during the conventional reaction on the yield of tricaprylin has been investigated. It was observed that the optimum pretreatment conditions were irradiation time of 60min with 240W supplied power and 60% duty cycle. The optimum reaction conditions were 4:1 molar ratio of caprylic acid to glycerol, catalyst loading as 1% and operating temperature of 170°C. Three different catalysts as sulphuric acid, hydrochloric acid and para-toluene sulphonic acid (PTSA) have been used to investigate the effect of type of catalyst and also the effect of the presence of adsorbent as silica gel was investigated. The obtained results confirmed that the activity of H2SO4 was higher as compared to HCL and PTSA. It was conclusively established that ultrasound pretreatment based approach greatly influenced the rate of reaction in comparison to the conventional approach and resulted in a green processing approach with maximum tricaprylin yield of 96.6% achieved in 9h of reaction time compared to 24h with conventional approach.