Influence of the ZrO2 Crystalline Phases on the Nature of Active Sites in PdCu/ZrO2 Catalysts for the Methanol Steam Reforming Reaction—An In Situ Spectroscopic Study

Abstract

In this work, the electronic properties of the metal sites in cubic and monoclinic ZrO2 supported Pd and PdCu catalysts have been investigated using CO as probe molecule in in-situ IR studies, and the surface composition of the outermost layers has been studied by APXPS (Ambient Pressure X-ray Photoemission Spectroscopy). The reaction products were followed by mass spectrometry, making it possible to relate the chemical properties of the catalysts under reaction conditions with their selectivity. Combining these techniques, it has been shown that the structure of the support (monoclinic or cubic ZrO2) affects the metal dispersion, mobility, and reorganization of metal sites under methanol steam reforming (MSR) conditions, influencing the oxidation state of surface metal species, with important consequences in the catalytic activity. Correlating the mass spectra of the reaction products with these spectroscopic studies, it was possible to conclude that electropositive metal species play an imperative role for high CO2 and H2 selectivity in the MSR reaction (less CO formation).

Lignosulfonate-Assisted In Situ Deposition of Palladium Nanoparticles on Carbon Nanotubes for the Electrocatalytic Sensing of Hydrazine

“…Notably, broad peaks were recorded at 2 theta around 40.1° and 46.5°. The positions correspond to the grid planes (111) and (200), respectively, and are correlated with the JCPDS card 05-0681 [75,76]. Furthermore, the peak shapes suggest that the immobilized palladium species have a noncrystalline, presumably amorphous structure.…”

A comparison of dry and wet condition CO oxidation activity of a supported silver catalyst at low temperature

“…S10b†). The XRD pattern of Ag/ZrO 2 suggested a monoclinic structure (2 θ = 28.1°, 31.4°, 34.2° and 50.2°) 80 and the peaks at 2 θ = 38.2°, 44.2°, 55.3°, 64.4° and 77.4° are assigned to the incorporation of Ag (ESI; Fig. S10c†).…”

Characterization of model and real catalysts by APXPS

“…In this work we investigated Pd-Cu bimetallic catalysts supported on zirconia for the methanol steam reforming (MSR) reaction to produce H2 [27]. Methanol is liquid at room temperature, what makes it easy to transport, and it is a well suited fuel for H2 production due to its high H/C ratio and because it does not have C-C bonds, which leads to a lower reforming temperature than for other alcohols .…”