Near Ambient Condition Ammonia Synthesis and In-Situ CO₂ Co-Reduction to Urea from Nitrate

Area of Science:

• Catalysis
• Green Chemistry
• Inorganic Chemistry

Background:

• Nitrate (NO3-) is a prevalent water pollutant and a potential nitrogen source.
• Efficient conversion of nitrate to valuable chemicals like ammonia (NH3) and urea is highly desirable.
• Current methods for nitrate reduction often require harsh conditions or expensive catalysts.

Purpose of the Study:

• To develop a novel method for simultaneous nitrate to ammonia conversion and CO2 to urea synthesis.
• To investigate the efficacy of thermally activated hydrogen peroxide (H2O2) for these transformations.
• To confirm the products and reaction pathways using advanced analytical techniques.

Main Methods:

• Utilizing thermally activated hydrogen peroxide (H2O2) at approximately 100 °C.
• Performing in-situ cascade reactions for simultaneous nitrate reduction and CO2 co-reduction.
• Employing absorption spectroscopy, 1H nuclear magnetic resonance (NMR), 15N isotopic labeling, and high-resolution mass spectrometry (HR-MS) for product verification.

Main Results:

• Achieved up to ~100 mM ammonia (NH3) synthesis from nitrate (NO3-).
• Demonstrated in-situ cascade CO2 co-reduction to urea (up to ~1.36 mM).
• Confirmed NH3 and urea formation through rigorous spectroscopic and isotopic analyses.

Conclusions:

• Thermally activated H2O2 provides an efficient pathway for nitrate to ammonia conversion and CO2 to urea synthesis under mild conditions.
• This dual-functionality offers a sustainable approach for nitrogen management and chemical production.
• The method shows promise for practical applications in environmental remediation and chemical synthesis.