Impact of Precipitants on the Structure and Properties of Fe-Co-Ce Composite Catalysts

Abstract

Fe-Co-Ce composite catalysts were prepared by coprecipitation method using CO(NH 2 ) 2 , NaOH, NH 4 HCO 3 , and NH 3 ·H 2 O as precipitant agents. The effects of the precipitant agents on the physicochemical properties of the Fe-Co-Ce based catalysts were investigated by SEM, TEM, BET, TG-DTA, and XRD. It was found that the precipitant agents remarkably influenced the morphology and particle size of the catalysts and affected the COD removal efficiency, decolorization rate, and pH of methyl orange for catalytic wet air oxidation (CWAO). The specific surface area of the Fe-Co-Ce composite catalysts successively decreased in the order of NH 3 ·H 2 O, NH 4 HCO 3 , NaOH, and CO(NH 2 ) 2 , which correlated to an increasing particle size that increased for each catalyst. For the CWAO of a methyl orange aqueous solutions, the effects of precipitant agents NH 3 ·H 2 O and NaOH were superior to those of CO(NH 2 ) 2 and NH 4 HCO 3 . The catalyst prepared using NH 3 ·H 2 O as the precipitant agent was mostly composed of Fe 2 O 3 , CoO, and CeO 2 . The COD removal efficiency of methyl orange aqueous solution for NH 3 ·H 2 O reached 92.9% in the catalytic wet air oxidation. Such a catalytic property was maintained for six runs.