Cu nanoparticles prepared by metal vapor synthesis (MVS) were immobilized on 3-aminopropyl-functionalized silica at room temperature. HRTEM analysis of the catalyst showed that the copper nanoparticles are present with mean diameters limited in the range 1.0-4.5 nm. TPR analysis was performed in order to study the oxidation state of the supported copper nanoparticles. The supported catalyst was used both in batch and in a packed-bed reactor for continuous-flow CuAAC reaction. The activation of the copper catalyst by reduction using phenyl hydrazine in continuous-flow conditions was demonstrated. Along with the high catalytic activity (productivity up to 1689 mol/mol), the catalyst can be used several times with negligible Cu leaching in the product (<9 ppm), less than allowed Cu contaminant in pharmaceuticals. The applicability of packed-bed flow reactor was showed by sequentially converting different substrates in their corresponding products using same column

There is a renewed interest in designing solid acid catalysts particularly due to the significance of Lewis acid catalyzed processes such as Friedel–Crafts acylation and alkylation and cellulose hydrolysis for the development of sustainable chemistry. This paper reports a new focus point on the properties of supported CuO on silica, a material that up to now has been considered only as the precursor of an effective hydrogenation catalyst. Thus, it deals with a re-interpretation of some of our results with supported copper oxide aimed to unveil the root of acidic activity exhibited by this material, e.g. in alcoholysis reactions. Several techniques were used to highlight the very high dispersion of the oxide phase on the support allowing us to ascribe the acidic behavior to coordinative unsaturation of the very small CuO particles. In turn this unsaturation makes the CuO particles prone to coordinate surrounding molecules present in the reaction mixture and to exchange them according to their nucleophilicity.

Copper–zirconia catalysts find many applications in different reactions owing to their unique surface properties and relatively easy manufacture. The so-called methanol economy, which includes the CO₂ and CO valorization and the hydrogen production, and the emerging (bio)alcohol upgrading via dehydrogenative coupling reaction, are two critical fields for a truly sustainable development in which copper–zirconia has a relevant role. In this review, we provide a systematic view on the factors most impacting the catalytic activity and try to clarify some of the discrepancies that can be found in the literature. We will show that contrarily to the large number of studies focusing on the zirconia crystallographic phase, in the last years, it has turned out that the degree of surface hydroxylation and the copper–zirconia interphase are in fact the two mostly determining factors to be controlled to achieve high catalytic performances.