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pp.253-258
Activated magnetite (Fe3O4-δ) was applied to reducing CO2 gas emissions to avoid greenhouse effects. Wet and dry methods were developed as a CO2 removal process. One of the typical dry methods is CO2 decomposition using activated magnetite (Fe3O4-δ). Generally, Fe3O4-δ is manufactured by reduction of Fe3O4 by H2 gas. This process has an explosion risk. Therefore, a non-explosive process to make Fe3O4-δ was studied using FeC2O4·2H2O and N2. FeSO4·7H2O and (NH4)2C2O4·H2O were used as starting materials. So, α-FeC2O4·2H2O was synthesized by precipitation method. During the calcination process, FeC2O4·2H2O was decomposed to Fe3O4, CO, and CO2. The specific surface area of the activated magnetite varied with the calcination temperature from 15.43 m2/g to 9.32 m2/g. The densities of FeC2O4·2H2O and Fe3O4 were 2.28 g/cm3 and 5.2 g/cm3, respectively. Also, the Fe3O4 was reduced to Fe3O4-δ by CO. From the TGA results in air of the specimen that was calcined at 450˚C for three hours in N2 atmosphere, the δ-value of Fe3O4-δ was estimated. The δ-value of Fe3O4-δ was 0.3170 when the sample was heat treated at 400˚C for 3 hours and 0.6583 when the sample was heat treated at 450˚C for 3 hours. Fe3O4-δ was oxidized to Fe3O4 when Fe3O4-δ was reacted with CO2 because CO2 is decomposed to C and O2.
