PETR 129 |
| There is tremendous interest currently in the development of single stage water-gas-shift (WGS), CO + H2O = CO2 + H2, conversion catalysts to generate hydrogen for fuel cells. Hydrophilic oxide supported Pt catalysts show promise for this. Such catalysts are bi-functional where Pt activates CO and the oxide activates H2O. Among the catalysts studied, Pt/TiO2 was, intrinsically the most active. However, it deactivated with time due to sintering of Pt particles assisted by oxygenate specie, (HCHO) formed during reaction. Addition of Re to the catalyst help overcome sintering and thus deactivation. This catalyst also shows enhanced activity. Kinetic and in situ spectroscopic studies indicate that, for Pt/TiO2, WGS reaction occurs via two routes, viz, (i) an associative formate route involving red-ox regeneration and (ii) the classical red-ox sequence. In the case of Pt-Re/TiO2 catalyst rhenium is present at least partly as ReOx, and provides an additional red-ox route for WGS reaction in which ReOx is reduced by CO generating CO2 and re-oxidized by H2O forming H2. Observations from kinetic (transient and steady state) experiments and in situ IR spectroscopic studies are used to understand the working of the catalyst and justify the mechanistic reaction sequences discussed above. The Pt-Re catalyst has high enough activity to meet the requirements (8.10-5 molH2 g-1cat s-1) of 50kW fuel cell car using 1kg catalyst. |
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2nd Symposium on Hydrogen from Renewable Sources and Refinery Applications
8:00 AM-11:25 AM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 209, Oral
Division of Petroleum Chemistry |