Metal Oxides in Heterogeneous Oxidation Catalysis: State of the Art and Challenges for a More Sustainable World

Abstract

This Review presents current knowledge, recent results, and challenges for the future in heterogeneous oxidation catalysis in liquid and gaseous phases on solid metal oxide catalysts. Metal oxides that are used as catalysts and their main structures and properties are summarized, as well as their catalytic properties in selective and total oxidation reactions, which were studied intensively, experimentally and theoretically, by Professor Jerzy Haber during his scientific life. Some emphasis is placed on the classical and unusual catalyst activation procedures for improving catalytic properties for better efficiency. For a more sustainable world, several examples are given of the oxidation of biomass derivatives to synthesize valuable chemicals and of other applications of metal oxides, such as depollution, photocatalysis, hydrogen production and fuel‐cell components. The importance of metal oxide catalysis in environmental and green chemistry and sustainability is discussed, and challenges for the future are considered.

“Traditional” Sol-Gel Chemistry as a Powerful Tool for the Preparation of Supported Metal and Metal Oxide Catalysts

“…The preparation of mixed-oxide catalysts and supported metal oxide catalysts commonly involves aqueous-phase methods (ion-exchange, impregnation and deposition–precipitation), which predominate at the industrial scale for environmental and economic reasons [58]. The great interest in the production of new materials with unique properties by sol-gel routes coincides with the growing recognition that the conventional methods of materials processing have inherent limitations in homogeneity due to difficulty in controlling the agglomeration of the active phase, yielding weak binding between active phase and the carrier.…”

Optimized Conditions for the Palladium‐Catalyzed Hydrogenolysis of Benzyl and Naphthylmethyl Ethers: Preventing Saturation of Aromatic Protecting Groups

“…One of the most common methods for deprotection of benzyl groups is metal‐catalyzed hydrogenolysis. Palladium is often preferred over ruthenium or platinum due to its lower propensity to cause the saturation of aromatics . Thus, the mild nature of palladium‐catalyzed hydrogenolysis has led to its popularity in global deprotections of, e.g., peptides and oligosaccharides, even allowing for the presence of biologically interesting functionalization of hydroxyl groups such as acetates ( Cryptococcus neoformans ) and cyclic phosphates ( Vibrio cholerae ) .…”

Influence of the Fuel/Oxidant Ratio on the Elaboration of Binary Oxide Catalyst by a Microwave-Assisted Solution Combustion Method

“…In this category, the active phase can consist of a single metal oxide or a combination of metal oxides. Metal oxide catalysts are applied in a wide range of catalytic reactions, including selective reduction reactions, selective oxidation reactions and total oxidation reactions [1][2][3]. Transition metal oxides are very interesting in heterogeneous catalysis, due to their improved and tunable acid-base and redox properties [4][5][6][7].…”