K-PtCo/Al2O3via ball milling as an efficient catalyst for preferential oxidation of CO towards hydrogen purification

Abstract

Preferential oxidation of CO (PROX) is an effective process to cleanup CO in hydrogen for proton exchange membrane fuel cells (PEMFCs). Prevailing catalysts face challenges, such as a high outlet CO concentration, a narrow operation temperature window, and a poor stability. To tackle these challenges, in this study, a potassium-promoted PtCo/Al2O3 catalyst with low metal loading was fabricated using a ball milling process. The addition of appropriate amount of potassium was found to be compelling in strengthening the catalytic activity at 100–240 °C. With a GHSV of 40,000 ml g−1h−1 at 120–160 °C, the 1.5 K-0.5Pt1Co/Al2O3 (0.5 wt% Pt loading) can reduce CO from 1 % to less than 2 ppm while maintaining good stability for a long period. The addition of potassium to PtCo/Al2O3 enhanced the PROX activity by facilitating carboxyl dehydrogenation. The carboxyl pathway was found to be more facile on K2O/Pt3Co (111), resulting in the superior catalytic abilities of potassium-modified PtCo/Al2O3 catalysts.