Methanatlon

Figure 6. An Arrhenius plot of the rate of methanatlon over a clean and sulfided Ru(OOOl) catalyst. Sulfur coverages (6g s) are expressed as fractional monolayers.

Figure 7. Relative methanatlon rate as a function of sulfur coverage on a Ru(OOOl) catalyst. Reaction temperature 550K.

Methanatlon Studies. Because the most effective way to determine the existence of true bimetallic clusters having mixed metal surface sites Is to use a demanding catalytic reaction as a surface probe, the rate of the CO methanatlon reaction was studied over each series of supported bimetallic clusters. Turnover frequencies for methane formation are shown In Fig. 2. Pt, Ir and Rh are all poor CO methanatlon catalysts In comparison with Ru which Is, of course, an excellent methanatlon catalyst. Pt and Ir are completely inactive for methanatlon In the 493-498K temperature range, while Rh shows only moderate activity. 

All of the supported bimetallic catalysts studied show a sharp drop in methanatlon activity when the Ru/M ratio falls below four. 

Surface and bulk characterization were carried out using electron spectroscopy for chemical analysis (ESCA or XPS) and x-ray diffraction (XRB). The results will be discussed In relation to methanatlon activity. 

Binary Alloys. The reported methanatlon activity ( ) of the oxidized alloys, expressed as the amount of CO consumed/gs. Is plotted In Figure 3B as a function of their nickel content. The activity of... 

Comparison of the surface analysis and methanatlon activity of (Nl Th ) alloys (Figure 6) shows that there Is some Interdependence betweeK the surface concentration of Nl and activity high Nl surface concentration generally results In greater methanatlon activity. 

Figure 7. Methanatlon rate as a function of temperature obtained from Pt black compared to TiOo x modified Pt black. Ea 25 1 kcal mole-1 for Pt, Ea = 20. 1 kcal mole"1 for Ti02 ...

CnH2n+2 4 IIH2O —> WCO + (2W +1)H2 C0 + 3H2 CH4 + H20 C0 + H20 C02+H2 The result is a mixture of methane, carbon monoxide, carbon dioxide, and trace amounts of ethane and other hydrocarbons. With partial carbon dioxide removal it is possible to produce town gas with medium calorific value containing about 30% CH4, 30% H2, and 2% CO. The process can be used to produce SNG. In this case there ate multiple methanatlon stages and complete removal of CO2 to give a product containing about 98.5% CH4,0.9% H2, and 0.1% CO. 

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