Synthesis of biodiesel from waste oil by glycerol pre-esterification

The waste oil with high acid value was used as raw material, and compared the pre-esterification of methanol and glycerol. The results showed that methanol pre-esterification can reduce the acid value to below 4 mgKOH/g only by multiple chemical reactions. But glycerol can reduce the acid value to less than 2 mgKOH/g once without catalysis. Through orthogonal experiment, the optimal process was obtained: the mass ratio of glycerol pre esterified oil to methanol was 10:3, the amount of catalyst was 0.8 % of the mass of oil, the reaction temperature was 65 degrees C, the reaction time was 150 min, and the conversion rate was 96.7 %. The results of characteristic comparison and process analysis show that glycerin pre-esterification not only has fast reaction, good effect and better environmental protection, but also has the same quality as methanol pre-esterification, and it's easier to realize the continuous process of biodiesel synthesis from waste oil with high acid.

Automated summary

The study shows that glycerol in pre-esterification of waste oil can reduce the acid value to a lower level in one step, and the optimized process conditions obtained through orthogonal experiment can achieve high conversion rate and good environmental protection, making it easier to realize the continuous synthesis of biodiesel from waste oil with high acid.