CO removal for hydrogen purification via Water Gas Shift and COPROX reactions with monolithic catalysts

A combination of Water Gas Shift (WGS) and CO preferential oxidation (COPROX) reactions is considered a promising approach for CO removal in an H-2 feed employed for PEM fuel cells. Honeycomb monolithic catalysts were studied for this purpose, firstly coated with Ce or Ce-Pr, then with Cu or Cu-Ni, (mass gained similar to 35%). Computational Fluid Dynamics simulation showed that outer channels (close to reactor wall) presented a slightly lower flow in comparison with flow in inner ones. The Pr content in WGS monoliths modulated the activity-selectivity ratio showing an optimal value for 15 at.% in case of Ni-containing samples due to a significant selectivity improvement towards WGS (hindering methanation). A Cu/ceria monolithic sample was tested as COPROX catalyst. The CO conversion presented a maximum value with the increase of the operation temperature. Besides, a larger contact time (achieved by modifying monolith length) also enhanced the undesired H-2 oxidation reaction as same as a larger O-2/CO ratio. As a consequence, a temperature window around to 130 degrees C, a contact time close to 0.1 g.s/cm(3), and a O-2/CO = 1 M ratio was determined as the most adequate parameters set.

Automated summary

The combination of Water Gas Shift (WGS) and CO preferential oxidation (COPROX) reactions is considered effective for CO removal in H-2 feed for PEM fuel cells. Monolithic catalysts coated with Ce or Ce-Pr and Cu or Cu-Ni showed promising results with a 35% mass increase. Adjusting the Pr content in WGS monoliths and using Cu/ceria monolithic samples for COPROX resulted in optimal activity-selectivity ratios. Operating at around 130 degrees C with a contact time of 0.1 g.s/cm^3 and an O-2/CO = 1 M ratio was found to be the most suitable parameters set.