| Biodiesel produced by the transesterification of natural oils with methanol, ethanol or other short-chain alcohols is an environmental benefits, biodegradable and nontoxic fuel. With a traditional homogeneous acid or base catalyst, the transesterification product is difficult to be separated and the waste water from washing catalyst may pollute environmental. Using a solid base catalyst can obtain pure product and avoid the problem of catalyst deposition.As the same time, the problem of long reaction time with solid acid catalyst is overcame.(1) A series of Zr1Lax catalysts with La/Zr molar ratio of 1,2,3,5, and 10 were prepared by co-precipitation method. X-ray diffraction patterns of the catalysts revealed that some new substance was created. The strength and amount of basic sites on the catalyst surface was measured by temperature-programmed desorption of carbon dioxide (CO2-TPD). CO2-TPD profiles showed that the density and amount of basic sites on the surface of the catalyst changed with the different mole ratio of La:Zr. The catalytic activity of the catalyst was associated with the alkalescence on the surface of the catalyst.The effect of the different mole ratio of La:Zr, methanol to oil molar ratio, catalyst amount and the reaction time on the transesterification process of rapeseed oil with methanol was investigated. A highest FAME yield of 96.3% was achieved on the Zr1La10 catalyst calcined at 700℃at a reaction time of 5 h.(2) Mesoporous 0.1M/ZrO2 (M=Li, Na, K, Mg, Ca) solid base catalysts were successfully synthesized by using a sol-gel method. The catalytic activities of the catalysts were tested via transesterification reactions of soybean oil with methanol. Both 0.1Mg/ZrO2 and 0.1Ca/ZrO2 catalysts showed no catalytic activity in this reaction, while Li, K modified ZrO2 catalysts achieved high yield of biodiesel production. Besides, under the optimum reaction conditions, a FAME yield of as high as 98.2% was achieved on 0.1Li/ZrO2 catalyst calcined at 650℃.
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