CO₂ Methanation: Nickel-Alumina Catalyst Prepared by Solid-State Combustion.

Area of Science:

• Green Chemistry
• Catalysis
• Materials Science

Background:

• Solvent-free synthesis methods are crucial for sustainable catalyst development.
• Carbon dioxide (CO2) methanation is a key process for converting greenhouse gases into valuable chemicals.
• Traditional catalyst synthesis often involves solvents, posing environmental and disposal challenges.

Purpose of the Study:

• To develop a solvent-free method for synthesizing a nickel-alumina catalyst for CO2 methanation.
• To investigate the structural and chemical properties of the synthesized catalyst.
• To evaluate the catalytic activity and performance in low-temperature CO2 methanation.

Main Methods:

• Solid-state combustion synthesis using hexakis-(imidazole) nickel (II) nitrate complex.
• Characterization using X-ray Powder Diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Hydrogen temperature-programmed reduction (H2-TPR).
• Evaluation of catalytic activity in a reaction mixture containing 4 vol% CO2.

Main Results:

• The synthesized nickel-alumina catalyst featured easily reducible nickel oxide localized on the alumina surface.
• Low-temperature activation of the catalyst was achieved.
• The catalyst exhibited higher activity in low-temperature CO2 methanation compared to an industrial catalyst (NIAP-07-01).
• The industrial catalyst contained significantly more hard-to-reduce nickel-aluminum spinel.

Conclusions:

• The proposed solvent-free solid-state combustion method simplifies catalyst preparation.
• The developed nickel-alumina catalyst offers enhanced low-temperature activity for CO2 methanation.
• This approach aligns with green chemistry principles by eliminating solvent use and disposal issues.