Formaldehyde Selectivity in Methanol Partial Oxidation on Silver: Effect of Reactive Oxygen Species, Surface Reconstruction, and Stability of Intermediates

Karatok, Mustafa
Şensoy, Mehmet Gökhan
Vovk, Evgeny I.
Toffoli, Hande
Toffoli, Daniele
Ozensoy, Emrah
Selective oxidation reactions on heterogeneous silver catalysts are essential for the mass production of numerous industrial commodity chemicals. However, the nature of active oxygen species in such reactions is still debated. To shed light on the role of different oxygen species, we studied the methanol oxidation reaction on Ag(111) single-crystal model catalyst surfaces containing two dissimilar types of oxygen (electrophilic, Oe and nucleophilic, On). X-ray photoelectron spectroscopy and low energy electron diffraction experiments suggested that the atomic structure of the Ag(111) surface remained mostly unchanged after accumulating low Oe coverage at 140 K. Temperature-programmed reaction spectroscopic investigation of low coverages of Oe on Ag(111) revealed that Oe was active for methanol oxidation on Ag(111) with a high selectivity toward formaldehyde (CH2O) production. High surface oxygen coverages, on the other hand, triggered a reconstruction of the Ag(111) surface, yielding Ag oxide domains, which catalyzes methanol total oxidation to CO2 and decreases the formaldehyde selectivity. This important finding indicates a trade-off between CH2O selectivity and methanol conversion, where 93% CH2O selectivity can be achieved for an oxygen surface coverage of θO = 0.08 ML (ML = monolayer) with moderate methanol conversion, while methanol conversion could be boosted by a factor of μ4 for θO = 0.26 ML with a suppression of CH2O selectivity to 50%. Infrared reflection absorption spectroscopy results and density functional theory calculations indicated that Ag oxide contains dissimilar adsorption sites for methoxy intermediates, which are also energetically less stable than that of the unreconstructed Ag(111). The current findings provide important molecular-level insights regarding the surface structure of the oxidized Ag(111) model catalyst directly governing the competition between different reaction pathways in methanol oxidation reaction, ultimately dictating the reactant conversion and product selectivity.
ACS Catalysis


Electrochemical and chemical oxidation of K(C2H5OCS2),[Ni(C2H5OCS2)(2)] and [N(C2H5)(4)][Ni(C2H5OCS2)(3)]
Dag, O; Önal, Ahmet Muhtar; Isci, H (1996-06-26)
Electrochemical and chemical oxidation of (Et-Xan(-)), [Ni(Et-Xan)(2)] and [Ni(Et-Xan)(3)](-) (Et-Xan(-) = C2H5OCS2- have been studied by Cyclic Voltammetry and in situ UV-Vis spectroscopy in acetonitrile at room temperature. Cyclic Voltammograms (CV) of Et-Xan(-) and Ni(Et-Xan)(2) display one (0.00 V) and two (0.35 and 0.80 V) irreversible oxidation peaks, respectively, referenced to Ag/Ag+(0.10 M) electrode. However, CV of Ni(Et-Xan)(3)(-) displays one reversible (-0.15 V) and two irreversible (0.35, 0.80...
Catalytic oxidation of nitrogen containing compounds for nitrogen determination
Karakaş, Gürkan (2019-02-15)
The high temperature catalytic oxidation (HTCO) performance of Al2O3 supported Pt, Cu, Cu-Ce and Fe catalysts were systematically studied with a perspective of selective oxidation of nitrogenous compounds to nitric oxide for quantitative determination of bound nitrogen. The catalyst samples were prepared via impregnation and characterized by XRD and BET. In addition, temperature programmed reaction experiments with acetonitrile and oxygen were conducted to evaluate the catalytic activity and selectivity tow...
Enantioselective michael addition of 1-nitropropane to nitroolefins with 2-aminodmap and quinine based bifunctional organocatalysts
Kanberoğlu, Esra; Tanyeli, Cihangir; Department of Chemistry (2015)
1,3-dinitro compounds are key materials in the synthesis of a variety of important fine chemicals. Moreover, they are reduced to 1,3-diamines which are starting materials of biologically active compounds, agrochemicals and pharmaceuticals. In this study, ((2S,3S)-1,3-dinitropentan-2-yl)benzene was synthesized via the Michael addition of 1-nitropropane to trans-β-nitrostyrene in the presence of chiral bifunctional 2-aminoDMAP and quinine based organocatalysts. In the first part of study, reaction conditions ...
Ethylene and acetaldehyde production by selective oxidation of ethanol using mesoporous V-MCM-41 catalysts
Gucbilmez, Yesim; Doğu, Timur; Balci, Suna (2006-05-10)
Vanadium-incorporated MCM-41 type catalytic materials, which were synthesized by a direct hydrothermal synthesis procedure, showed very high activity and high selectivity in the production of ethylene from ethanol in an oxidative process. Ethylene selectivity showed a significant increase with an increase in temperature over 300 degrees C, while relatively high acetaldehyde selectivities were observed at lower temperatures. An ethylene yield value of 0.66 obtained at 400 degrees C with an O-2/ethanol feed r...
Coordination polymerization of cyclic ethers by metal xanthates and carbamates
Taş, Hüseyin; Alyürük, Kemal; Department of Polymer Science and Technology (2003)
Zinc xanthates are active catalysts in stereoregular polymerization of propylene oxide and markedly more stable than that of known classical stereoregular catalysts. But steric control of zinc xanthates is weaker. To find more effective catalyst systems the isopropyl xanthates of Cu, Pb, Ni, Fe, Al and Sn are investigated and only copper (Cu(isoPr)Xt) and tin (Sn(isoPr)Xt) isopropyl xanthates were appeared to be active, but Cu(isoPr)Xt yielded only low molecular weight product. Therefore Sn(isoPr)Xt system ...
Citation Formats
M. Karatok, M. G. Şensoy, E. I. Vovk, H. Toffoli, D. Toffoli, and E. Ozensoy, “Formaldehyde Selectivity in Methanol Partial Oxidation on Silver: Effect of Reactive Oxygen Species, Surface Reconstruction, and Stability of Intermediates,” ACS Catalysis, pp. 6200–6209, 2021, Accessed: 00, 2021. [Online]. Available: