Separation-Free High-Purity Hydrogen Production via the Mechanochemical Ammonia-Silicon Reaction under Mild...

Area of Science:

• Materials Science
• Chemical Engineering
• Renewable Energy

Background:

• Ammonia (NH3) is a promising hydrogen (H2) carrier due to its high hydrogen content and ease of liquefaction.
• Conventional ammonia cracking for H2 production requires high temperatures (400-600 °C) and costly gas separation.
• There is a need for energy-efficient and cost-effective methods for high-purity H2 generation from ammonia.

Purpose of the Study:

• To develop a novel mechanochemical process for producing high-purity hydrogen from ammonia under mild conditions.
• To investigate the feasibility of using silicon (Si) as a reactant in mechanochemical ammonia conversion.
• To explore the simultaneous production of valuable byproducts, such as silicon nitride (Si3N4), from waste materials.

Main Methods:

• A mechanochemical ammonia-silicon (MAS) reaction was developed utilizing dynamic mechanical actions (ball milling).
• The reaction conditions were optimized for mild temperature operation (50.0 °C).
• Experimental and theoretical analyses were employed to understand the reaction mechanism and the role of silicon nanoparticles.

Main Results:

• The MAS reaction achieved 100.0% ammonia conversion and 100.0% hydrogen purity without additional separation.
• A high hydrogen production rate of 102.5 mmol h⁻¹ was realized.
• The process successfully converted end-of-life silicon solar panels into high-value silicon nitride (Si3N4), demonstrating economic viability.

Conclusions:

• The mechanochemical ammonia-silicon reaction offers an efficient and cost-effective pathway for high-purity hydrogen production under mild conditions.
• The dynamic evolution of silicon nanoparticles is crucial for efficient hydrogen extraction from ammonia.
• This approach presents a sustainable method for hydrogen generation and valuable material recycling from solar waste.