Restructuring Co-CoO_x Interface with Titration Rate in Co/Nb-CeO₂ Catalysts for Higher Water-Gas Shift Performance

Area of Science:

• Catalysis
• Materials Science
• Chemical Engineering

Background:

• Hydrogen production via the water-gas shift reaction (WGS) is crucial for various industrial applications.
• Cobalt-modified ceria (CeO2) catalysts show promise for WGS, but their performance is sensitive to preparation methods.

Purpose of the Study:

• To investigate the effect of precipitant addition rate during coprecipitation on the synthesis of Co/Nb-CeO2 catalysts.
• To evaluate the performance of these catalysts for hydrogen generation through the WGS reaction.

Main Methods:

• Synthesis of Co/Nb-CeO2 catalysts using coprecipitation with varying precipitant addition rates (1, 5, 15, 25 mL/min).
• Characterization using techniques such as X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and Raman spectroscopy.
• Evaluation of catalytic activity and stability for the WGS reaction at a high gas hourly space velocity (315,282 h⁻¹).

Main Results:

• Catalyst prepared at 5 mL/min (5-Co/Nb-CeO2) exhibited well-dispersed small cobalt particles (3-8 nm) with strong Co-CeO2 interaction.
• This optimal catalyst demonstrated a high turnover frequency of 9.8 s⁻¹ and achieved thermodynamic equilibrium conversion.
• The 5-Co/Nb-CeO2 catalyst showed stable performance for 168 hours, attributed to stable CO-Coδ+ intermediate formation.

Conclusions:

• The precipitant addition rate significantly influences cobalt particle size, dispersion, and interaction with CeO2, impacting WGS performance.
• The 5-Co/Nb-CeO2 catalyst is highly effective for hydrogen generation from synthesis gas, offering a stable and efficient solution.
• The study highlights the importance of controlled synthesis for developing advanced catalysts for WGS.