Thesis (D.Eng.)--Chulalongkorn University, 2010

To study the development of calcium oxide based catalysts for transesterification of soybean oil with ethanol. The weak basic compounds (NH4OH) and the strong basic compounds (NaOH, KOH and Ca(OH)2) were used to load on CaO. All catalysts were characterized by XRD, BET, TEM, CO2-TPD and TGA to examine the characteristics and properties which could affect transesterification reaction. The results showed that Ca(OH)2 and NH4OH loaded CaO based catalysts, calcined Ca(OH)2 and CaO from limestone had potential to be used as heterogeneous catalysts for transesterification reaction. The CaO loaded with 3.7 wt% of Ca(OH)2 was found to exhibit the highest catalytic activity among all catalysts investigated. The maximum ethyl esters content achieved was 96.3 wt% after 10 hours of the reaction. The optimum conditions were 9:1 molar ratio of ethanol to oil and 13.8 (wt% by oil) of catalyst operated at 70℃ for 10 hours. The results also showed that the catalytic activity of catalysts depended upon the crystal structure and the agglomeration of catalysts. Reusability of the catalyst was investigated and it was found that the conversion of biodiesel maintained the same level after recycling of at least 3 times.