Preparation Of Solid Base Catalysts And Its Application In Synthesis Of Biodiesel Through Race Bran Oil

With the decrease of the storage of the fossil fuel and the deterioration of ecological environment, biodiesel has been paid increasing attention as one of the alternative fuels. But at present, the production of biodiesel exist disadvantages as follows. Firstly, the costs of the biodiesel are too high, among the total, raw material accouts up to 75%. Secondly, the method to synthesis biodiesel is mainly transesterification with homogeneous base as catalyst, although that is a kind of mature technology, there are many shortcomings including environmental pollution and saponification during the reaction, which results in difficulty in products separation.In view of the problems above mentioned, a new mothod to synthesis biodiesel was adopted by transesterification from rice bran oil with methanol catalyzed by solid base.(1) The content of main components in rice bran was determinated by use of Kjeldahl nitrogen determination and other methods. Acid value and saponification value of rice bran oil were determined too. The results showed that moisture is 11%, total sugar is 48%, protein 12%, lipid 13%, and ash content in rice bran is 10%. Acid value is 1.03mg KOH/g and saponification value is 196mgKOH/g. Average molar mass of rice bran oil is 859g/mol.(2) Two kinds of solid base catalyst were prepared by immersionγ-Al 2 O 3(powderyγ-Al 2 O 3and grainyγ-Al 2 O 3) as carrier in NaHCO3 solution and calcining respectively. The preparation conditions of solid base catalyst were also optimized. Base strength and alkaline dosage were determined by aniline indicator method. The solid base catalysts were characterized by IR. It indicated that the optimum NaHCO3 loading amount in the powdery catalyst is 30% while the grainy catalyst is 20%. Calcining temperature of catalysts both are 550℃. The alkaline dosage of base strength higher than 27 is above 4.5mmol/g. Reactive material NaAlO2 in both solid base catalysts was confirmed by infrared spectrum.(3) In this paper, single factor experiment and orthogonal experiment were used to investigate the effect of various factors on the ester-exchange reaction. The results indicate that the optimum conditions of the transesterification using powdery catalyst as catalyst were the catalyst amount about 3%, mole ratio of methanol to race bran oil about 10:1, reaction temperature about 60℃and reaction time about 100min. The optimum conditions of the transesterification using grainy catalyst as catalyst were the catalyst amount about 2.5%, mole ratio of methanol to race bran oil about 10:1, reaction temperature about 60℃and reaction time about 90min. The order of the influencing factors to the transesterification from rice bran oil with methyl alcohol catalyzed by both solide base catalysts was catalyst dosage>molar ratio of methyl alcohol to race bran oil>reaction temperature >reaction time. The yield of biodiesel reached 93.8% under the optimum condition. The GC-MS and IR results indicated that the product of biodiesel was fatty acid methyl ester.