Preparation and Characterization of Me₂O₃−CeO₂ (Me = B, Al, Ga, In) Mixed-Oxide Catalysts

Abstract

The present work is focused on the synthesis and characterization of ceria-based mixed oxides. Ceria was combined with the other oxides from group III, with the intention of improving the catalytic properties of thus obtained materials. (B 2 O 3 , Al 2 O 3 , Ga 2 O 3 , In 2 O 3 )-CeO 2 mixed oxides with a wide range of Me 2 O 3 contents have been prepared by a coprecipitation route. The obtained solid materials have been characterized in terms of their structural, textural, and surface properties, including the acid-base and red-ox features, by a variety of techniques (BET, XRD, Raman, SEM, TG, TPR-TPO). The acid-base properties were estimated by the adsorption of probe molecules (NH 3 and SO 2 ), investigated by the use of two techniques: microcalorimetry and XPS. The obtained materials exhibited satisfactory homogeneity; the highest surface areas were achieved for Al 2 O 3 -CeO 2 mixed oxides. Only the fluorite structure of CeO 2 was observed by XRD for all prepared mixed oxides, along with the presence of oxygen vacancies, which has been proven by Raman spectroscopy. Red-ox properties were investigated for In 2 O 3 -CeO 2 samples. The degree of reduction decreased with In 2 O 3 loading. Besides, the reduction-oxidation cycle, performed up to 830 °C, changed the morphology and structure of the samples irreversibly, leading to crystallization of In 2 O 3 . Among all investigated materials, only boria created significant acidity, whereas the basicity has been found to be dependent on the nature and amount of group III metal.

Textural, structural, and morphological characterizations and catalytic activity of nanosized CeO2–MOx (M=Mg2+, Al3+, Si4+) mixed oxides for CO oxidation

“…Auroux et al systematically studied the structure, texture, surface, and redox features of CeO 2 -M 2 O 3 (M = B, Al, Ga, In) mixed oxides prepared by coprecipitation and sol-gel method, respectively. Some general conclusions had been obtained that CeO 2 -Al 2 O 3 mixed oxides exhibited the highest surface area and the presence of oxygen vacancies could be identified by Raman spectra [11,12]. Based on these above-mentioned literatures, we could find that they present the similar consideration, namely the combination of ceria with the same valance metal oxide.…”

“…However, it was reported that pure ceria had poor thermal stability and low specific surface area. To improve the property of ceria, many works have been performed by introducing foreign oxide, such as TiO 2 [8], ZrO 2 [9], SiO 2 [10], M 2 O 3 (M: B, Al, Ga, In) [11,12], SnO 2 [13], MnO x [14], HfO 2 [15], Co 2 O 3 [16], CaO [17], and so on. These doped ceria-based mixed oxides would cause the changes of structural, electronic, reductive, and oxygen migration properties due to doped ions incorporating into the ceria lattice to generate defects or the formation of a new phase [18].…”

Size Controlled Preparation and Effect of Sintering Temperature on the Structural Properties of Nanocrystalline Ceria-Lanthana Solid Solution

“…In the present work, attempts were made for the size controlled preparation of cerialanthana solid solution (CLSS) assisted with cetyltrimethylammonium bromide (CTAB) and their physicochemical characterization. The adopted co-precipitation method facilitates the formation of nanoparticles with high surface area, homogenous distribution and good thermal stability [9,10].…”

A Novel Route Toward Fabrication of Twofold‐Shaped CeO2 Dendrites

“…[2,3] Because of these characteristics, ceria has been widely used as a promoter in the three-way catalysts for the elimination of toxic autoexhaust gases, [4][5][6] as oxygen sensors, [7,8] as solid electrolytes in the solid oxide fuel cells, which utilizes their oxygen storage capacity, [9][10][11] as absorbents for fluoride ion or arsenic-based compounds, and as substances to filter out ultraviolet rays. [12] Cerium oxide also has a high thermal stability, displays optical behavior, electrical conductivity, and diffusivity.…”

“…In the past few years, the synthesis of some novel CeO 2 structures, including nanorods, [15][16][17][18] nanowires, [19][20][21][22][23] nanotubes, [24,25] nanocubes, [26] microplates, [27] and other morphological structures [28][29][30][31][32][33][34][35][36] have been reported by chemical scientists. In this paper, twofold-shaped CeO 2 dendrites were successfully fabricated for the first time by thermal treatment of the cerium carbonate hydroxide precursor, which was synthesized by hydrothermal reaction of Ce(NH 4 as the cerium source is a novel route toward fabrication of CeO 2 particles; the traditional direct precipitation-decomposition route uses Ce 3+ as the cerium source. The influence of DEA on dendrite formation is discussed.…”