Highly Active Catalyst for Preferential Oxidation of CO in H2-Rich Gas Mixture

Authors

  • Musaed S. Al-Ghamdi Research & Development Center, Saudi Arabian Oil Company (Saudi Aramco), Dhahran 31311, Saudi Arabia
  • Shakeel Ahmed Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia

Keywords:

Preferential oxidation, Composite catalyst, Hydrogen spillover, TPR

Abstract

Abstract: Preferential oxidation is one of the most effective methods for CO clean-up from the reformate stream prior to its introduction in the PEM fuel cell. In this work, Cu-Ce/γ-Al2O3 as a base catalyst promoted with Pt and Rh was prepared for the low temperature selective oxidation of CO in hydrogen rich syn gas mixture. Seven catalysts with atomic ratio of 100: 20: 3: 1 for Cu: Ce2O3: Pt: Rh were prepared with Cu loading in the range of 0.5 to 6%. Also, four catalysts were prepared to investigate the role of Pt and Rh in the catalyst activity. The effects of stoichiometric ratio of O2/CO and water vapor on the selective oxidation of CO as a function of temperature were investigated. The prepared catalysts were characterized by using gas sorption analyzer and temperature programmed reduction (TPR). Slight decrease in surface area and pore volume was observed with increasing metal loadings. The TPR results indicate shift towards higher temperature when Pt and Rh were added to Cu–Ce/γ-Al2O3 catalyst. Moreover, TPR result showed that there is a correlation between reduction temperature and the activity and selectivity of the catalyst. The loading of Cu, Ce, Pt, Rh metals for maximum activity and selectivity were 2.0, 0.657, 0.183, 0.0324 wt % respectively, which decreased CO concentration in the product to 4 ppm (99.96%). A synergistic effect of addition of Pt or/and Rh was observed to enhancement the activity and selectivity of the base catalyst (Cu-Ce/γ-Al2O3). The CO conversion was increased from 24.7 to 96.77% with addition of 0.183 wt% Pt to the base catalyst, while the addition of 0.0324 wt% Rh increased the CO conversion to 44.1%. Addition of 10 vol% of water vapor to the feed resulted in higher conversion at lower temperature. The CO conversion was increased whereas the temperature of maximum conversion was decreased by 20 ºC.

Published

2018-03-30

Issue

Section

Articles