Study On Preparation Of Biodiesel Process By Solid Heterophony Acid Catalysts

Bio-diesel is currently the focus of social research, which has widespread use in clean energy. In different kinds of catalyst was applied in producing bio-diesel, solid acid catalyst not only could be separated from the reaction medium and avoid environmental pollution problems.,but also is more fixable catalytic some oil which has high acidity. So solid acid catalyst is a development promising catalyst. In this paper, for one thing, select the easy to get and cheaper as materials to prepare four solid acid catalysts, which was characterized by FT-IR、NH3-TPD、BET and XRD. For another thing, used KxH3-xPW12O40(x=0.5-3)、SO42-/TiO2、SO42-/7Al2O3 and SO42-/TiO2-Al2O3 as solid acid catalyst to synthesize bio-diesel with methanol and castor oil. The factors of preparation and transesterification reaction were investigated The main work of research and conclusions are as follows:(1) With a simple method, we prepared KxH3-xPW12O40(x=0.5-3) solid acid in different conditions, and characterized of it by XRD, IR, TPD and BET. The result shows that they are in accordance with Keggin structure of heterophony acid salt. Through characterization of K2.5H0.5PW12O40, we find it in phosphotungstic acid potassium series has larger specific surface area, microprint increased acid amount. The K2.5H0.5PW12O40 solid acid catalyst exhibited the highest activity for transesterifieation under the most optimized reaction factor:30:1 methanol/castor oil mole ratio,15% catalyst/mol oil, reacted at 160 ℃ for 4 hours, the water content was not more than 0.2% in the raw materials, the ester yield was up to 89.41%. The catalyst recycled at four times after simple disposed, the ester yield reached 85.80%.The liquid phase analysis map of bio-diesel, Ricinoleic acid methyl ester has high acidity in the biodiesel.(2) By the coprecipitation method in room temperature, firstly SO42-/TiO2、SO42-/Al2O3 and SO42-/TiO2-Al2O3 solid acid were prepared under different conditions, and secondly characterized of them by XRD and BET. The result shows that the specific surface area of SO42-/TiO2 solid acid reached 196.16m2/g in the calcinations temperature at 450"C and impregnation concentration at 0.75 mol/L, catalyzed transesterification to synthesize bio-diesel, the ester yield was 69.46%. Under the calcinations temperature at 600’C and impregnation concentration at 1.25mol/L, the specific surface area of SO42-/Al2O3 was 105.25m2/g. At the same time,it was used to synthesize bio-diesel, the ester yield was 52.99%. It was obviously that the catalytic activity of SO42-/TiO2 solid acid catalyst was higher than SO42-/Al2O3 solid acid catalyst. While prepared in the calcinations at 450℃ and impregnation concentration at 0.75 mol/L, Ti/Al mol ratio 2:1, the specific surface area of SO42-/TiO2-Al2O3 was up to 201.6m2/g, the crystalline phase of anatine was completely, and it exhibited the highest activity for transesterification under the most optimized reaction factor:24:1 methanol/castor oil mole ratio,10% catalyst/mol oil, reacted at 160℃ for 5 hours,the ester yield was reached 86.87%. The catalyst recycled at four times after simple disposed, the ester yield also reached 83.54%.