Improving temperature uniformity and performance of CO preferential oxidation for hydrogen-rich reformate with a heat pipe

• Heat pipes are applied to improve CO removal by cooling over-heated inlet side of packed-bed PROX reactors.
• Longitudinal temperature distributions in the reactor are measured for different test conditions.
• Without a heat pipe, the CO yields are unacceptable at low O2/CO ratios.
• An embedded heat pipe results in low CO yields and high CO conversions.
• This convenient method improves CO removal performance under suitable conditions.

Preferential oxidation (PROX) is an effective, but highly temperature-sensitive, method of CO removal for hydrogen-rich reformates. In a packed-bed catalytic reactor, oxidation is strongest at the inlet side and the local catalyst pellets become over-heated with poor heat conduction. As a result, the enhanced parasitic H2 oxidation consumes oxygen and suppresses CO conversion. This study applies a heat pipe to improve the temperature uniformity in a tubular one-stage packed-bed reactor by transporting heat downstream and thereby improve CO removal. In the experiments, the fuel mixture containing 2% of CO, 75% of H2, and 23% of CO2, further mixed with air at O2/CO = 0.75, 1.0 or 1.25, is supplied with stepwise increase of feeding rate under a fixed environmental temperature of 99 ± 1 °C. The proposed simple method is found to significantly improve temperature uniformity and CO removal for the present test conditions with O2/CO = 1.0 and 1.25.