The Research Of Aluminum-magnesium Oxide Supported Catalyst Made Biodiesel

Biodiesel is a sort of reproduceable energy which is green, environmental and safe. Biodiesel is one of the important meanings to solve the problems of energy shortage and environmental pollution. But, when currently alkaline bases were mainly used for catalyze the synthesis of biodiesel. Catalyzing the synthesis of biodiesel also bring problems of separation, recovery and Industrial wastewater. Therefore, it is necessary to look for a green, environmental, effective catalyst. Solid base catalyst has its merits. Therefore, it has a great significance in experiment and theory research of the highly active solid alkali catalyst biodiesel synthesis.In this paper, a series of Mg-Al oxide hydrotalcite precursor was made by using co-precipitation method, Mg-Al oxide carrier were made by high temperature roasting and loaded with different quality potassium carbonate by impregnation method to prepare catalysts. It was charactered by BET, CO2-TPD and XRD method. Made the soybean oil transesterification as a model to evaluate the activity of catalyst.The results of the study shows that the best preparation conditions for catalyst was magnesium aluminum ratio of1:1, the best crystallization time is10h, the best quality of loaded potassium carbonate was30%, and the optimal transesterification conditions were n(methanol):n(oil)=10:1, reaction time4h, reaction temperature60℃, and m(catalyst):m(oil)=0.015, the conversion rate of soybean oil was79.8%.In the best preparation conditions:BET characterizations showed that the specific surface area of Mg-Al-O carriers was282.6877m2/g, the total pore volume of pores was0.600239cm3/g, the average pore width was8.49331nm; CO2-TPD characterizations showed that the catalyst had appropriate intensity alkali activity centers when the quality of loaded potassium carbonate was30%, and had the best catalytic activity for soybean oil to biodiesel by transesterification; and XRD characterizations showed that potassium carbonate highly spread in the magnesium aluminum oxide carriers.