150

0 CO • CH4

1.0 2.0, 3.0 4.0 Stoichiometric ratio Performance of Ru-base catalyst: Exit CO and CH4 concentrations vs. stoichiometric ratio

If a CO converter were installed downstream of the reformer to reduce the CO concentration below 7,000 ppm before entering the reactor, the target CO concentration of 10 ppm could well be realized at reactor exit.

The influence of differences in catalyst temperature was insignificant in the range covered (100 - 150°C).

(3-2) Effect of temperature on catalyst performance

The selective oxidation process involves exothermic reaction, which makes it important to ensure a uniform temperature distribution through the catalyst bed. For this reason a comparison was made between two alternative arrangements: (a) filling the reactor with catalyst only; (b) diluting the catalyst with inert (glass) beads to disperse the generated heat.

The results revealed the catalyst diluted with 6.3-fold volume of glass beads to have effectively served to spread the heat. In the present experimetal setup, a thermostat was used as heat source, but no means was provided for actively removing the generated heat. Hence, the catalyst temperature exceeded 250°C in the leading catalyst layer, which for this reason could only remove less than 90% of the CO.

A possible solution to the above difficulty may be the adoption of a heat exchanger type reactor to remove heat, in combination with catalyst dilution.

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