Probing Surface Properties and Reaction Intermediates During Heterogeneous Catalytic Oxidation of Acetaldehyde

Abstract

The influence of Cu on various metal oxide supports was investigated for the catalytic oxidation of acetaldehyde (ACA). The activity of the catalysts towards ACA conversion and the CO2 yield decrease in the order: Cu/CeO2>Cu/TiO2≈Cu/ZrO2> Cu/Al2O3>Cu/SiO2. Spontaneous adsorptive conversion of ACA to surface carboxylates, such as bridging and bidentate acetates, was detected over the basic supports CeO2, TiO2, and ZrO2. Detailed temperature‐programmed studies found the high activity of Cu/CeO2 to stem mainly from the intrinsically high activity of the CeO2 support. In contrast, similar studies on Cu/TiO2 demonstrated the activity improvements imparted by Cu were predominantly additive. Despite the difference in origin of ACA oxidation activity over Cu/CeO2 and Cu/TiO2, the overall concerted effects of basicity‐induced carboxylate formation and availability of surface oxygen were thought to be overriding factors crucial in the overall catalytic reactivity.

Difference in the deactivation of Au catalysts during ethanol transformation when supported on ZnO and on TiO2

“…The presence of acetate species can be deduced by the 1456 and 1513 bands, due to -COOsymmetric and antisymmetric stretching, respectively. 52 Spectral characteristic features of acetaldehyde at 1691 cm À1 n(C]O) was also found in the used catalysts. Characteristic bands of the condensation product crotonaldehyde appeared at 1658 and 1634 cm À1 .…”

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

“…A higher basicity has been reported to correlate to a more ionic surface, which would be able to donate electron density from surface O to the α-carbon of acetaldehyde, therefore oxidizing the acetaldehyde and leading to acetate groups. 12 The cubes displayed bands associated with acetate groups (and the octahedra, to a lesser extent) in the TP-DRIFTS. However, the wires produce a large amount of acetone in the TPD, compared to the small amounts observed on the cubes and none on the octahedra.…”

“…10 Previously, experiments have shown that CeO 2 is an active catalyst to promote the coupling of acetaldehyde, an oxygenate species, to form several products including crotonaldehyde, crotyl alcohol, butane, butadiene, and acetone. 11,12 Oxygenates have garnered much attention as fuel additives, as components obtained from the processing of biomass, and as an intermediate for value-added products. 13 However, the conversion of oxygenates upon catalysis is not well-understood.…”

Visible‐Light‐Induced Selective Photocatalytic Oxidation of Benzylamine into Imine over Supported Ag/AgI Photocatalysts

“…This finding indicates that the photocatalytic active component may not be a semiconductor mechanism. For a semiconductor photocatalyst, photons with energy larger than the bandgap (the light with shorter wavelength) could cause reactions on it 17–19. Given that AgI has a bandgap of 2.8 eV, the irradiation with λ >443 nm cannot initiate the photocatalysis reaction.…”