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Oxidation of Alcohols with Molecular Oxygen on Solid Catalysts

“…Silver-based catalysts are well established in the gas-phase oxidation of alcohols and diols ,,− but rarely used in the liquid phase. Recently, the quantitative transformation of benzyl alcohol to benzaldehyde in oxygen was achieved over a 0.6% Ag/pumice catalyst under mild conditions (348 K, 1 bar) .…”

Role of active components of an Ag/Al2O3/cordierite catalyst in selective reduction of NO by ethanol

“…The role of silver in the form of Ag + cations and Ag n d+ nanoclusters is to activate the organic reducing agent by means of its partial oxidation to obtain adsorbed intermediates with high reactivity (in the case of ethanol: enolate (CH 2 =CH-O -) and acetate ions) [3,14], i.e., silver is a redox site for activation of the reducing agent. We also know that partial oxidation of primary alcohols occurs on sufficiently large metallic silver particles (30-50 nm) coated with an oxide film (for example, commercial catalysts for oxidation of methanol to formaldehyde and oxidation of ethylene glycol to glyoxal) [15]. Consequently, silver can participate in formation of not only redox sites but also additional Lewis acid sites.…”

“…Formation of Lewis acid sites, including silver, can occur as a result of its reaction with oxygen in the gas phase or the aluminum oxide lattice [8]. Since oxygen chemisorbed on silver is a strong surface base, on the oxidized silver surface there is a conjugate Lewis acid-base pair: Ag d+ LAg d+ -O 2d- [15]. Summing up, we arrive at the conclusion that silver (in the form Ag + and Ag n d+ ) in the Ag/Al 2 O 3 /cordierite catalysts is responsible for its bifunctionality, forming both redox and additional Lewis acid sites.…”

Structural and Functional Designs of Catalysts for Reduction of Nitrogen (I), (II) Oxides

“…The higher activity of silver-alumina catalysts with 0.3-0.6 Ag wt.% in selective reduction of NO with C 2 and C 4 alcohols at oxygen excess can be attributed to the silver localization mainly in the state of Ag + cations and Ag n δ+ (n ≤ 8) clusters (Kyriienko et al 2013). During the catalytic reaction, oxygen chemisorption on silver clusters and nanoparticles leads to the formation of strong surface base (Voronova et al 2003), and thus, Lewis conjugate acid-base pair is present on the oxidized surface of silver. The possible scheme of alcohols activation on silver-containing acidic sites (Ag n δ+ ) can be as follows: donor-acceptor interaction of alcohol (as Lewis base) and silver [as Lewis acid; Figure 1(b)]; formation of enolic or aldehyde species by partial oxidation of the alcohol by oxygen chemisorbed on silver clusters.…”