Electrolysis Apparatus for Low-Temperature Ammonia Generation
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Solution Overview
Problem
Current electrolysis methods for ammonia production face challenges such as high temperatures, high pressures, low conversion rates, and electrode degradation due to hydride formation, necessitating a more efficient and low-temperature process that minimizes electrolyte and electrode losses.
Innovation Solution
An electrolysis apparatus and method involving a cathode, anode, electrolyte, current source, nitrogen supply, and hydrogen halides (HCl, HBr, or HI) for forming nitride ions and metal ions, with optimized conditions for purging the electrolyte to produce ammonia at temperatures below 500°C, using metals like Li, Mg, Ca, Sr, Ba, Zn, or Al, and enabling reversible operation to regenerate the anode and minimize losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the Haber-Bosch process is used for ammonia production, then high ammonia output is achieved, but high temperatures and high pressures are required
Solution Approach 1:
The patent replaces the mechanical compression and high-temperature heating systems of the Haber-Bosch process with an electrochemical system. Electricity is used to drive the electrolysis of water to produce hydrogen, and electrochemical cells convert nitrogen and hydrogen into ammonia at ambient or near-ambient conditions, eliminating the need for high-pressure compressors and high-temperature reactors
Solution Approach 2:
The patent fundamentally changes the operating parameters from the extreme conditions of Haber-Bosch (450-550°C, 250-350 bar) to mild electrochemical conditions (ambient or near-ambient temperature and pressure). The process uses electrochemical potential to drive the nitrogen reduction reaction, allowing ammonia synthesis under dramatically different and more favorable thermodynamic conditions
2Productivity
If the Haber-Bosch process is used for ammonia production, then high ammonia output is achieved, but low conversion rate in a single pass occurs
Solution Approach 1:
The patent replaces the equilibrium-limited thermal process of Haber-Bosch with an electrochemical process that is not constrained by thermodynamic equilibrium in the same way. The electrochemical cells can achieve higher single-pass conversion rates by using electrical energy to drive the reaction forward, reducing the need for repeated compression and reheating cycles
Solution Approach 2:
The patent uses electrochemical cells to pre-react nitrogen and hydrogen into ammonia at high efficiency before any subsequent processing. The electrochemical step achieves substantial conversion in a single pass, eliminating the need for the repeated decompression, re-heating, and re-compression cycles required by the equilibrium-limited Haber-Bosch process
3Temperature
If gas diffusion electrodes are used for electrolytic ammonia production, then ammonia can be produced at lower temperatures, but electrode degradation due to hydride formation occurs
Solution Approach 1:
The patent introduces an intermediary substance (molten salt electrolyte containing alkali metal ions) that mediates between the hydrogen evolution reaction and the ammonia synthesis. The electrolyte serves as a medium that facilitates ion transport and reaction without requiring direct contact between hydrogen and the electrode material, thereby preventing hydride formation and electrode degradation
Solution Approach 2:
The patent changes the physical state and composition of the electrolyte medium from aqueous or solid-state systems to a molten salt system. This parameter change allows the process to operate at lower temperatures while using an electrolyte composition that is chemically inert toward hydrogen, preventing the hydride formation that degrades conventional gas diffusion electrodes
4Productivity
If conventional electrolysis methods are used, then ammonia production is achieved, but high electrolyte and electrode losses occur
Solution Approach 1:
The patent uses the molten salt electrolyte as an intermediary that enables the ammonia synthesis reaction without being consumed in the process. The electrolyte composition is designed to be chemically stable and inert toward both the electrodes and the reactants, minimizing degradation and loss of electrolyte and electrode materials over time
Solution Approach 2:
The patent designs the electrochemical cell system to be self-regenerating and self-sustaining. The electrolyte composition is maintained automatically through the reaction process itself, and the electrodes are protected from degradation by the chemically inert molten salt medium, reducing the need for frequent replacement or maintenance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient, low-temperature ammonia production with improved system efficiency and reduced electrode degradation, achieving high Faradic efficiency and current density while utilizing renewable energy sources.
Implementation Method 1
forming nitride ions from nitrogen at a cathode
Implementation Method 2
forming metal ions from a metal at an anode
Implementation Method 3
dissolving the nitride ions and metal ions in an electrolyte
Implementation Method 4
purging the electrolyte comprising the dissolved nitride ions and metal ions with HCl and/or HBr and/or HI
Data Source
AI summary
An electrolysis apparatus for producing ammonia, the apparatus comprising: a cathode; an anode; an electrolyte; a current source; a supply for nitrogen; and a supply for an acid, wherein the acid comprises at least one acid selected from the group consisting of: HCl, HBr, and HI.