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The Microstructure of Copper Zinc Oxide Catalysts: Bridging the Materials Gap

“…The non-linearity frequently observed in correlations of copper surface area and catalytic activity in methanol chemistry, is a strong evidence for the existence of additional bulk or surface structural parameters that govern the activity of copper nanoparticles. 5,6,7 The superior interface between the Cu particles and the ZnO support in the homogeneous microstructure of the more active Cu/ZnO catalysts, can be correlated to the previously reported increased degree of strain in the Cu particles in the highly active Cu/ZnO catalysts as determined by averaging bulk structural techniques (XRD, NMR). 18 Thus, the higher degree of disorder in the Cu nanoparticles, which corresponds to an increased deviation from the "ideal" structure of bulk copper metal, results from an increased interface area between Cu and ZnO and is indicative of a more active copper catalysts.…”

“…4 Conversely, copper nanoparticles have recently been shown to exhibit surfaces with different catalytic activities and, in addition to the surface area, bulk structural parameters like microstrain in the copper particles were identified to correlate with the catalytic activity of Cu/ZnO catalysts in methanol synthesis and methanol steam reforming. 5,6,7 Microscopic evidence of the nature of the "real" structure of the most active copper catalysts remains scarce. 8,9,10 High-resolution transmission electron microscopy (TEM) and in situ TEM studies have been performed on copper particles supported on ZnO with a copper concentration of less than 10 %.…”

Steam reforming of methanol over copper-containing catalysts: Influence of support material on microkinetics

“…Irreversible alloy formation of the active copper species with support material and thermal sintering of small Cu particles and thereby the reduction of the active surface area are two of the possible reasons [35,36]. E.g.…”

Single step combustion synthesized Cu/Ce0.8Zr0.2O2for methanol steam reforming: structural insights fromin situXPS and HRTEM studies

“…But with the progress of reaction, the methanol conversion exhibited by the former catalyst decreases below that of the latter and is associated with a larger amount of CO formation. The deactivation of catalyst is mainly associated with the thermal sintering of the small copper nanoparticles leading to a decrease of the active SA [30][31][32] and or the reduction of oxidized copper to its metallic form. 3 The phase analyses as well as structural studies have already proved that metallic copper is present in both the aged samples, the size of Cu particles being larger in the higher Cu-loaded sample Cu15CZ80.…”