Preparation Of Biodiesel With Rice Bran Oil

The key procedure for the biodiesel (methyl ester) processing in industry concludes two stages of esterification and the ester exchange. The main problems existing in the present reseach are the acid value is too high in the esterification stage, the conversion rate of ester exchange is low, and there is a needing of purification for products of high-purity methyl ester.Therefore, the study was conducted in this paper to resove the above problems. The main contents and results are listed in the followings:(1)When strong sulfuric acid was used as catalyst in the esterification stage, four primary factors were studied to investigate their affects on acid value in the esterification working procedure. Single-factor experimental design and the orthogonal-test design were used to conduct the experiments. Concentration of methyl alcohol in weight showed as the most important factor, followed by the amount of catalyst, reaction temprature and reaction time, affecting the acid value. The optimal reaction conditions of esterification were obtained as methyl alcohol quality score of 30%, concentration of catalyst in weight 3%, reaction temperature of 70℃and reaction time of 2.5h. Under the optimal conditions, the acid value was reduced to 2.2, which met the requirement of subsequent procedure.(2) In the procedure of interesterification, NaOH was used as the catalyst to analyze the effect of four primary factors affecting the rate of interesterification. By using single-factor experimental design and orthogonal test, four factors showed greatly influence on the rate of interesterification in the turn of concentration of methyl alcohol in weight, reaction time, reaction temperature and the amount of catalyst. The optimal reaction conditions of interesterification was obtained as concentration of methyl alcohol in weight 30%, concentration of catalyst in weight 1.5%, reaction temperatures 70℃, and reaction time 2.0h. Under such optimal conditions, the rate of interesterification was obtained as 95%.(3)The optimal reaction conditions for additional esterification were obtained as: concentration of catalyst (w/w) 4%, reaction temperature 65℃and reaction time 3.0h. Under this optimal reaction conditions, the rate of ester exchange reached to 98.7%.(4)In the part of molecular distillation part, technical parameters for evaporation in the first-level film was-0.097MPa, 100℃, and flux input of 300g/h. Parameters for molecular evaporation in the fist-level scrabng film were temperature in the input of 160℃, temperature in the outlet of 150℃, vacuum of 20Pa and the flux input of 298.56g/h.