Thermal stability of nano Ce_1−xTi_xO₂ material system for X < 0.2

Abstract

Ceria (CeO2) is a technologically promising compound due to a remarkable set of properties. However, the use of ceria also has drawbacks, the most pronounced of which is the material's poor thermal stability. This property limits the use of ceria‐based materials at elevated temperatures, in many technological applications. To overcome this, the addition of TiO2 is proposed. Such addition essentially creates a new material system, namely Ce1−xTixO2. In this work, an array of techniques were employed to determine the thermal stability of this new compound range (X < 0.2). Results show that when nano‐sized, TiO2 is fully soluble in CeO2 in this range. After heat treatment, however, the material coarsens and the solubility limit decreases to less than 2 at.%. as the compound undergoes significant changes. These include solute segregation and phase separation. Finally, the factors that affect compound stability are discussed.

Surface properties of Ca, Ti‐doped CeO2 and their influence on the reverse water‐gas shift reaction

“…At elevated temperatures, both CeO 2 and the dispersed metal can sinter, giving rise to a loss of surface area and therefore a decrease in catalytic performance 9 . The incorporation of metal ions into the CeO 2 lattice (often forming a solid solution) has been suggested, since doping can aid to both slow down the sintering process and modulate adsorption processes during catalytic reactions 11‐17 …”

“…29 In this work, we have produced solid solutions, Ti-doped and Ca,Ti co-doped ceria, all of which have been shown to be stable up to 700°C. 11 The effect of doping on the interactions of CO 2 and water vapor with the materials' surface was investigated, followed by an analysis of their performance as a catalysts for the RWGS reaction. Through these steps, the effect of doping on the materials' surface and gas-surface interaction is better understood.…”

“…9 The incorporation of metal ions into the CeO 2 lattice (often forming a solid solution) has been suggested, since doping can aid to both slow down the sintering process and modulate adsorption processes during catalytic reactions. [11][12][13][14][15][16][17] The nature of interaction of water molecules with the surface of pure ceria has been investigated, utilizing both experimental methods 18-20 and computational modeling. [21][22][23] Similar works have also studied the interactions of carbon dioxide (CO 2 ) with ceria.…”