Catalysts for the WGS reaction are commercially available and their performance is well understood for application to natural gas-derived syngases where the CO concentrations are in the range 5-10%. However, in the case of coal-derived syngases where CO concentration is relatively high (in the range of 40-60%), a considerably higher degree of shifting is required. This study therefore investigated the performance of a commercially available catalyst in the environment that it might encounter when applied to coal-derived syngases. In particular it seeks to define the performance of a high temperature catalyst in atmospheres that have high concentrations of H2 or CO2 as might be encountered in a packed-bed membrane reactor application.
The tests were performed using syngas compositions that are consistent with those that might be encountered in both a dry-feed, Shell-type gasifier and a slurry-feed GE-type gasifier. A comprehensive set of experiments was then performed at 450oC to measure the kinetic parameters for the catalyst. It was found that the rate of CO conversion (in mol/g catalyst/s) at a reaction temperature of 450°C could be accurately described by the following power law rate model:

where R´= 8.3144 J/mol/K

The above rate expression demonstrate the impact that the reverse WGS reaction can have on overall CO conversion rate due to the presence of CO2, and to a lesser extent H2 in the syngas. Even at the front-end of the reactor the reverse WGS reaction can be significant.