Adsorption and Reaction of Acetaldehyde on Shape-Controlled CeO₂ Nanocrystals: Elucidation of Structure–Function Relationships

Abstract

CeO 2 cubes with {100} facets, octahedra with {111} facets, and wires with highly defective structures were utilized to probe the structure-dependent reactivity of acetaldehyde. Using temperature-programmed desorption (TPD), temperature-programmed surface reactions (TPSR), and in situ infrared spectroscopy, it was determined that acetaldehyde desorbs unreacted or undergoes reduction, coupling, or C−C bond scission reactions, depending on the surface structure of CeO 2 . Room-temperature FTIR indicates that acetaldehyde binds primarily as η 1 -acetaldehyde on the octahedra, in a variety of conformations on the cubes, including coupling products and acetate and enolate species, and primarily as coupling products on the wires. The percent consumption of acetaldehyde ranks in the following order: wires > cubes > octahedra. All the nanoshapes produce the coupling product crotonaldehyde; however, the selectivity to produce ethanol ranks in the following order: wires ≈ cubes ≫ octahedra. The selectivity and other differences can be attributed to the variation in the basicity of the surfaces, defects densities, coordination numbers of surface atoms, and the reducibility of the nanoshapes.

Effect of nanostructured support on the WGSR activity of Pt/CeO2 catalysts

“…Furthermore, addition of dopants into the ceria have been demonstrated to modify the Pt-support interaction and consequently the resulting WGSR activity, having a direct effect on the reaction mechanism [15,16]. We have recently demonstrated that the oxygen storage capacity and low temperature reducibility of the ceria can be tuned by varying its morphology at the nano-scale by selectively exposing different crystal planes [17], leading to further studies by other groups [18,19]. In this paper, we demonstrate the relationship between the surface chemical and physical properties of nanostructured ceria and the resulting platinum-support interaction, reducibility of ceria and consequently, WGSR activity, providing relevant insights for future catalyst design in this field.…”

Nanoshaped CuO/CeO2 Materials: Effect of the Exposed Ceria Surfaces on Catalytic Activity in N2O Decomposition Reaction

“…[8][9][10][11] This manifests itself through different selectivity or improved activity, which enables the catalyst to be operated at lower temperatures. Numerous theoretical [12][13][14] and experimental [8][9][10][11][15][16][17][18][19][20][21] investigations have revealed that nanoshaped CeO 2 (nanocubes and nanorods) with well-defined {100} and {110} reactive planes show higher catalytic activity than conventional and thermodynamically more stable polyhedral CeO 2 nanoparticles. This is likely connected to lower activation energy for oxygen vacancy formation over {110} and {100} planes, compared to {111}.…”

Effects of Morphology of Cerium Oxide Catalysts for Reverse Water Gas Shift Reaction

“…CO oxidation [23][24][25], NO reduction [26] and WGS reaction [27]. Ceria nanorods exhibited superior activity in oxidation of CO, 1,2-dichloroethane, ethyl-acetate and ethanol [19,[28][29][30], methanol conversion in presence of CO 2 [31], methanol [32] and acetaldehyde decomposition [33] compared to ceria cubes and octahedra. Moreover, shuttleshaped particles composed of closely packed ceria nanorods displayed higher activity for CO oxidation compared to ceria nanorods [34], which has been attributed to enhanced porosity, surface area and oxygen deficiency of these nanoshapes compared to ceria rods.…”