Defect engineered Co/NiO-MgO catalysts for efficient CO₂ methanation

Area of Science:

• Catalysis and Materials Science
• Sustainable Chemistry and Energy

Background:

• Carbon dioxide (CO2) methanation is crucial for climate change mitigation, renewable energy storage, and carbon recycling.
• Catalyst design and synthesis significantly impact CO2 methanation efficiency and selectivity.
• Nickel-based catalysts, particularly NiO-MgO, are promising but require optimization for enhanced performance.

Purpose of the Study:

• To investigate the influence of synthesis methods and cobalt incorporation on NiO-MgO catalysts for CO2 methanation.
• To correlate catalyst properties (defect density, reducibility, adsorption) with catalytic activity and selectivity.
• To identify the optimal catalyst formulation and synthesis route for efficient CO2 to methane conversion.

Main Methods:

• Synthesis of NiO-MgO catalysts with varying cobalt incorporation (ionic substitution, wet impregnation) and synthesis speeds.
• Comprehensive characterization using techniques to determine structural, morphological, and textural properties.
• Evaluation of catalytic performance via CO2 conversion and CH4 selectivity measurements at 400 °C, supported by in situ FTIR analysis.

Main Results:

• The Co/NiO-MgO catalyst prepared via ionic substitution using solution combustion (CNM_IC) exhibited the highest performance.
• CNM_IC achieved 72% CO2 conversion and 96% CH4 selectivity, attributed to high oxygen vacancy concentration and basic sites.
• The catalyst demonstrated excellent stability, maintaining high performance over 25 hours of continuous operation.

Conclusions:

• Cobalt incorporation and specific synthesis methods, like solution combustion with ionic substitution, significantly enhance CO2 methanation over NiO-MgO catalysts.
• Catalyst properties such as oxygen vacancies and basicity are key factors controlling activity and selectivity.
• The developed CNM_IC catalyst presents a stable and efficient solution for CO2 utilization and methane production.