Study On The Biodiesel From Rice Bran Oil In Supercritical Methanol

Facing the challenges of energy shortage and environment pollution, all the world have began to seek new, green and substitutable biomass Energy to mitigate the consume of non-renewable energy. Then Biodiesel(BD) has come into more and more people's notice with its alternative and renewable characteristics. So developing Biodiesel industry is signality.Although conventional chemical technology using alkaline catalysts has been applied to the industrial production of biodiesel fuel, there are several drawbacks to this approach, difficulties in the recovery of products, environmental pollution caused by lye exclusion, strict requests for material and so on, and all of them reduce exorbitant cost. While Preparation of biodiesel using supercritical fluid techniques has been explored as the most promising process in recent years. Its the largest major merit is no catalyst needed in the reation, the contents of free fatty acid and water in oils, and attains higher conversion rate in much shorter time. Compared with other chemical methods, purification of products is much simpler and environmentally friendly. BD has a great development prospect, but high feedstock impediments its wider commercialization. In order to take the advantages of the supercritical transesterification reaction as well as decrease the cost of biodiesel, the production of biodiesel from rice bran oil (RBO) in supercritical methanol has been investigated in this experiment, which aimed at improving the use efficiency of RBO. This paper adopted response surface method to get the optimized condition.First to develop an accurate determination method of fatty acid methyl esters in biodiesel by GC dodecanoic acid methyl ester was used as internal standard. The optimum operating condition is oven temperature 220℃, injector and detector temperature 250℃, carrier gas N₂, injection volume 1μL , split flow rate 1:10. The method had a wide linear range, good reproducibility and high accuracy.Examined the transesterification of triavetin and methanol conducted in supercritical methanol in the absence of catalyst. The optimum reaction condition could be performed at the temperature of 295.9℃within 40.5 min with 25.1:1 molar ratio of methanol to oil.Then added sodium methoxide as catalyst in reaction system, and the optimum reaction condition was molar ratio of methanol to soybean oil of 31.2, reaction temperature of 275℃, reaction time of 31.4 min, and catalyst amount of 0.14 wt%, it was found that the yield of methyl esters had not observably increased because of the acid value of rice bran oil was high.