We prepared activated charcoal-supported Co-Mo carbide catalysts to investigate the effects of solution pH and initial Co/Mo molar ratio. In the absence of Co, no Mo adsorption was observed at pH above the pHzpc of AC, whereas the introduction of Co at pH > 6 resulted in the co-precipitation of Mo and Co and facilitated Mo adsorption. CO conversions for CO methanation at 400 °C and 30 bar achieved over samples prepared at pH 3 were initially high but decreased with increasing reaction time, whereas CO conversions were maintained at >90% with increasing reaction time for samples prepared at pH > 6. XPS analysis of these high-performance catalysts revealed that the predominant state of surface Mo was Mo0 rather than Mo4+ and Mo6+. Catalysts with maximum methanation activity, i.e., those with the highest surface Mo0 content, were obtained at pH 7 and an initial Co/Mo molar ratio of 1.0.
Bibliographical noteFunding Information:
We acknowledge financial support from the R&D Convergence Program (CAP-16-11-KAERI) funded by the NST (National Research Council of Science & Technology) of the Republic of Korea.
© 2019 Elsevier Ltd
- Activated charcoal
- Cobalt molybdenum carbide
- Initial Co/Mo molar ratio
- Wet impregnation
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Industrial and Manufacturing Engineering