Editorial: Special Issue on “Advances on Catalysts Based on Copper”

Copper-based catalysts are very active in a wide range of different reactions, such as methanol synthesis, steam reforming/WGS, hydrogenation/dehydrogenation/transfer hydrogenation, oxidation, dehydrogenative coupling, acid-base reactions, etc. These catalytic processes are, more and more, being applied to the transformation of renewable resources or platform molecules, such as lignocellulosic biomass, bioalcohols, HMF, furfural and vegetable oils. Therefore, copper catalysts are expected to play an important role in the transition towards a sustainable economy. Environmental remediation is another field in which copper-based catalysts are extremely promising. The Special Issue on “Advances on Catalysts Based on Copper” aims to cover the most recent progress and advances in the field of copper-based heterogeneous catalysts, with a special eye on biomass valorization for the production of high-added value molecules and sustainable energy production.

Bukhtiyarova et al. [1] studied Cu-Al mixed oxides in the flow hydrogenation of 5-acetoxymethylfurfural into 5-(acetoxymethyl)-2-furanmethanol, focusing on the effect of synthesis conditions, such as pH, temperature, aging time and precipitation rate, on Cu-Al layered double hydroxides. Under optimized reaction conditions, the 2 h Cu-Al catalyst, which was prepared at a constant temperature of 70 °C, a pH of 9 and an aging time of 2 h, provided a 98% yield of 5-(acetoxymethyl)-2-furanmethanol.

Liu et al. [2] investigated the degradation of methyl orange in the process of catalytic wet hydrogen peroxide oxidation by using Cu₂O particles deposited on an Al₂O₃ coating via an electrochemical method. The catalyst could reach a methyl orange degradation rate of 92% when the electrochemical deposition time was 30 min, with a catalyst dosage of 8 g and a temperature of 25 °C for 120 min. The catalytic system was also reused nine times with a final degradation rate of 75%, showing high stability.

Marelli et al. [3] adopted a simple and reproducible approach for the synthesis of a Cu-based heterogeneous catalyst on hierarchically meso-/macroporous silica monoliths, obtaining very small size-controlled CuO nanoparticles (mean diameter 2.9 nm) highly and homogeneously dispersed in the silica matrix. The catalyst was studied in the styrene oxide ring-opening reaction under continuous flow-through, reaching high conversion (97%) and selectivity (≥99%).

Singh et al. [4] reported on state-of-the-art copper-based metal–organic frameworks (MOFs) as emerging catalysts for click chemistry. Click chemistry is a robust and versatile strategy to synthesize large complex compounds from relatively smaller moieties; thus, the design of novel and effective Cu(I)-based MOF catalysts is of high importance.

Kótai at al. [5] reviewed the use of copper manganese oxide spinels as catalysts in a wide range of industrially important processes. These materials show different phase relations, metal ion valence/site distribution and chemical properties that can be exploited to obtain active materials for the oxidation of carbon monoxide, nitrogen oxide and hydrogen sulfide and the oxidative removal of organic solvents such as benzene, toluene and xylene from the air.

We would like to thank all the authors for their interesting contributions, the reviewers for their precious remarks and the Editorial Office for their constant support of this Special Issue.