Selective oxidation of primary carbon-hydrogen bonds with oxygen is of crucial importance for the sustainable exploitation of available feedstocks. To date, heterogeneous catalysts have either shown low activity and/or selectivity or have required activated oxygen donors. We report here that supported gold-palladium (Au-Pd) nanoparticles on carbon or TiO(2) are active for the oxidation of the primary carbon-hydrogen bonds in toluene and related molecules, giving high selectivities to benzyl benzoate under mild solvent-free conditions. Differences between the catalytic activity of the Au-Pd nanoparticles on carbon and TiO(2) supports are rationalized in terms of the particle/support wetting behavior and the availability of exposed corner/edge sites.

Iron copper zeolite (Fe‐Cu‐ZSM‐5) with aqueous hydrogen peroxide is active for the selective oxidation of methane to methanol. Iron is involved in the activation of the carbon–hydrogen bond, while copper allows methanol to form as the major product. The catalyst is stable, re‐usable and activates methane giving >90 % methanol selectivity and 10 % conversion in a closed catalytic cycle (see scheme).

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Au–Pt alloy nanoparticles deposited on Mg(OH)2 (see STEM‐HAADF image) show high activity in the selective oxidation of polyols using molecular oxygen as oxidant at mild and base‐free conditions.

The development of a catalytic, one-step route for the oxidation of methane to methanol remains one of the greatest challenges within catalysis. Of particular importance is the need to develop an efficient route that proceeds under mild reaction conditions so as to avoid deeper oxidation and the economic limitations of the currently practiced syngas route. Recently, it was demonstrated that a copper-and ironcontaining zeolite is an efficient catalyst for such a one-step process. The catalyst in question (Cu−Fe−ZSM-5) is capable of selectively transforming methane to methanol in an aqueous medium with hydrogen peroxide as the terminal oxidant. Nevertheless, despite its high activity and unparalleled methanol selectivity, the origin of its activity and the precise nature of its active species are not yet fully understood. Through a combination of catalytic and spectroscopic studies, we hereby demonstrate that extraframework Fe species are the active component of the catalyst for methane oxidation, although the speciation of these sites from synthesis to catalysis significantly alters the observed activity and selectivity. The analogies and differences between this system and other iron-containing zeolite-catalyzed processes, such as N 2 O-mediated benzene hydroxylation, are also considered.

We report a convenient excess anion modification and post-reduction step to the impregnation method which permits the reproducible preparation of supported bimetallic AuPd nanoparticles having a tight particle size distribution comparable to that found for sol-immobilization materials but without the complication of ligands adsorbed on the particle surface. The advantageous features of the modified impregnation materials compared to those made by conventional impregnation include a smaller average particle size, an optimized random alloy composition, and improved compositional uniformity from particle-to-particle resulting in higher activity and stability compared to the catalysts prepared using both conventional impregnation and sol immobilization methods. Detailed STEM combined with EDX analyses of individual particles have revealed that an increase in anion concentration increases the gold content of individual particles in the resultant catalyst, thus providing a method to control/tune the composition of the nanoalloy particles. The improved activity and stability characteristics of these new catalysts are demonstrated using (i) the direct synthesis of hydrogen peroxide and (ii) the solvent-free aerobic oxidation of benzyl alcohol as case studies.

The partial oxidation of methane to methanol presents one of the most challenging targets in catalysis. Although this is the focus of much research, until recently, approaches had proceeded at low catalytic rates (<10 h(-1)), not resulted in a closed catalytic cycle, or were unable to produce methanol with a reasonable selectivity. Recent research has demonstrated, however, that a system composed of an iron- and copper-containing zeolite is able to catalytically convert methane to methanol with turnover frequencies (TOFs) of over 14,000 h(-1) by using H(2)O(2) as terminal oxidant. However, the precise roles of the catalyst and the full mechanistic cycle remain unclear. We hereby report a systematic study of the kinetic parameters and mechanistic features of the process, and present a reaction network consisting of the activation of methane, the formation of an activated hydroperoxy species, and the by-production of hydroxyl radicals. The catalytic system in question results in a low-energy methane activation route, and allows selective C(1)-oxidation to proceed under intrinsically mild reaction conditions.

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