Metal-oxygen bond, strength and

VIII. A Generic Description of the Relationship between Metal-Oxygen Bond Strength and Selectivity... 

Tethwisch, D.G. and Dumesic, J.A. (1986) Effect of metal-oxygen bond strength on properties of oxides. 1. Infrared spectroscopy of adsorbed carbon monoxide and carbon dioxide, Langmuir, 2, 73. 

The application of 170 NMR spectroscopy to obtain structural information about polyoxoanions, mainly in nonaqueous solution, had been examined and discussed in detail (99). A very useful finding was that chemical shifts are determined largely by metal-oxygen bond strengths. An inverse correlation exists between the 170 shift and the shortest bond length to a given metal. In aqueous solution the existence of [Mo7024]6 could be confirmed by the use of 170 and "Mo NMR spectroscopy (100-104). Evidence for the existence of the three... 

Selectivity and Metal-Oxygen Bond Strength. The metal-oxygen bond strength could be measured as the differential heats of reoxidation of the reduced... 

If these data are accepted as relevant, at least for the reduction process one of Sachtler and de Boer s conclusions (i.e., that activity should decrease with increasing metal oxygen bond strength) appears confirmed. 

The crystal face dependence and the activity of the various group 8-10 metals can be understood in terms of the metal-oxygen bond strength. On an active metal both O2 and H2 are dissociatively adsorbed, oxides are not formed under reaction conditions, and the heat of adsorption for Oacisis relatively low. 

Zhang electronegativity, and metal-oxygen bond strengths for the cations included in this study. 

Procedure (B) was performed based on 5 different redox metal oxides which had proven to be catalytically active towards propene formation as a result of procedure A and 3 additional metal oxides of strong metal oxygen bond strength i. e., MgO of basic nature, B2O3 of acidic nature and LajOs on which dissociative oxygen adsorption takes place. 

Sachtler and de Boer (136), following up ideas developed by Schenck and by Balandin regarding the importance of metal-oxygen bond strength for selective catalysis, measured the reduction rates of catalysts with hydrogen, and compared these to activities and selectivities in the oxidation of propylene to acrolein, using as a test mixture CjHg/Og/Ar = 1/2/5 at about 500°. Some results are collected in Table XIII. There... 

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