Preparation Of Methyl Esters From Vegetable Oil Through Transesterification

In this research, methyl esters were obtained through transesterification of vegetable oil with methanol.Two transesterification systems were studied: nucleophilic transesterification by homogeneous catalyst and supercritical transesterification.(1)Study on the preparation of methyl esters from soybean oil and methanol through nucleophilic transesterification by homogeneous catalyst, using K alkali as a catalyst.The study revealed that the factors of influence were amount of catalyst > methanol / oil molar ratio > reaction temperature > reaction time. The data obtained for the different critical indicated that the optimal conditions for the transesterification are the amount of KOH catalyst 1.0% of raw materiel, methanol to oil molar ratio 6:1,reaction temperature 60℃and time 45 min.The 96.0% transesterification rate has been obtained under the optimal conditions. It has been proved that fatty acid triglyceride were transformed to methyl esters through analyzing the chemical compositions by GC and IR.The methyl esters being made by us is correspond to 0# diesel in capability index.We also studied the factors of influence ,such as amount of fatty acid,saponification number,iodine number,phospholipid(p meter),water content and the properties of industrial methanol. (2)The nucleophilic transesterification process by homogeneous catalyst was applied to cottonseed oil,corn oil and palm oil. The study revealed that experimental methods can be used to all kinds of vegetable oil.Compared the physical characteristics index and component analysis of the four vegetable oils and their methyl esters,it has been proven that the fatty acid composition of vegetable oils and their methyl esters are identical. The low-temperature fluidity of methyl esters was greatly influenced by the content and distribution of saturated fatty acid methyl esters.(3)The transesterification reactions between methanol at supercritical condition with cottonseed oil and soybean oil were studied. The study revealed that the effect of chemical composition of raw material are negligible. The experimental method can be used in the preparation of methyl esters from all kinds of vegetable oil. The methyl esters being made by us did correspond to diesel according to the capability index.(4)The recovery and refining technology of glycerol from the by-product of transesterification of rapeseed oil with methanol was researched. The by-product was neutralized to pH= 5.0.The bottom layer was atmospheric distillated,then was vacuum distillated at 15mmHg.The distillate was collected between 158℃and 165℃.The total yield of glycerol was up to 83.7% and the glycerol purity in the end-product was 98.6%.