Preparation and Characterization of Nanocrystalline CeO₂

Abstract

For the purpose of developing a novel and effective nano-CeO2catalyst used in biomass gasification for tar removal, nanocrystalline CeO2particles were successfully prepared by the homogeneous precipitation method, and different approaches including TG, FT-IR, XRD and SEM were used to characterize the CeO2nano-particles and precursors in this study. The analysis results indicated that the synthesized precursor was hydrated cerium basic carbonates and its formula was identified as Ce2O(CO3)2•nH2O, and it can completely transform into nanocrystalline CeO2particles below 400 °C under the air atmosphere. The prepared CeO2nano-particles were found spherical in shape and well dispersed; they had high purity and a fine crystal phase of cubic syngony structure with a mean size of 13 nm.

Process Optimization and Preparation of Ferric Oxide Nanoparticles by Homogeneous Precipitation Method

“…The increases of n(urea)/n(nitric iron) will result in more ammonia released from the urea hydrolysis, which lead to the alkaline enhancement of solution PH to generate amounts of the precipitate, thus the precipitate is more completely and its yield also increases. At the same time, the increasing degree of supersaturation of solution can help the formation of small size particles according to the chemical reaction kinetics theory [6,7].In addition, the constitutive crystal component CO 2 generated by the hydrolysis of urea in the sealed container increase the solubility of CO 2 in solution, which is conducive to generate a more fine and uniform precipitate [8]. It is seen from figure 3 that the reactant ratio of n(urea)/n(nitric iron) reaches more than 5:1, the increase of sediment yield is not significant, Fe 3+ precipitation is almost completely.…”