The Research Of Fix-bed Catalyst On Biodiesel

Biodiesel is a kind of renewable biomass energy which is harmless to environment. The application of biodiesel can reduce the dependence on fossil energy, and can largely reduce the pollution to the atmospheric environment. The use of liquid base catalyst has many shortcomings such as high working strength, low working yield, high pollution and it is not fit for high acid value materials. The research on the fix-bed catalyst is very important for the development of biodiesel technology.In view of the development of biodiesel, firstly, the solid transesterification catalyst is studied; then the fix-bed transesterification catalyst and esterification catalyst are also studied on the basis. The three-neck bottles are used as batch reactors, and the Mg-Al hydrotalcite is used as the catalyst, the soybean oil as the raw material for biodiesel preparation, The molar ratio of methyl/oil, reaction time, reaction temperature, the amount of catalyst and other factors on the reaction yield, and the best reaction conditions are studied; Mg-Al hydrotalcite and alumina are used to synthesize the ester exchange fix-bed catalyst, and the molar ratio of methayl/oil, space velocity, reaction temperature, pressure and other factors on the reaction, and the life of catalyst for continuous biodiesel production are studied. The properties of biodiesel are analyzed to compared with 0# fossil diesel oil.The results show that in the batch reactor, the best reaction conditions for the production of biodiesel are molar ratio of methyl/oil 12:1, the reaction time of 5h, the reaction temperature 75℃, the amount of catalyst 4%; In the fix-bed reactor, the best reaction conditions are molar ratio of methyl/oil 21:1, space velocity of 0.5h-1, the reaction temperature 340℃, pressure of 2MPa. Mg-Al hydrotalcite has high catalytic activity in the ester exchange reaction, and is suitable for fix-bed. The properties of the biodiesel are similar to the ones of 0# fossil diesel oil. Alkali-catalyzed transesterification of the raw material requires the raw materials with low acid value of not more than 5mgKOH/g, otherwise the catalyst will be deactivated and saponificated and emulsification and other operational problems may occur. High acid value raw materials must be processed to reduce the acid value. In this paper, the fix-bed esterification method is used to reduce the acid value of raw materials. Alumina and zinc oxide are used to synthesize a fix-bed esterification catalyst and the molar ratio of methyl/oil, reaction temperature, space velocity and other influence factors are studied. The results show that the optimum conditions for the mass ratio of fusel oil 0.5, reaction temperature 250℃, low space velocity.