Electrochemical Nitrogen Reduction with Ylide Proton Carriers
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Solution Overview
Problem
Existing electrochemical nitrogen reduction reactions (NRR) for ammonia synthesis face challenges such as low faradaic efficiency and NH3 yield rates due to competition from the hydrogen evolution reaction (HER), and the inefficiency of alcohol-based proton carriers, which are uneconomically consumed and lead to insoluble by-products that increase cell resistance.
Innovation Solution
A method using a cationic proton carrier, such as an alkyl phosphonium cation, capable of reversible deprotonation to form a neutral phosphonium ylide proton acceptor, in a non-aqueous electrolyte, facilitates continuous electrochemical dinitrogen reduction to ammonia, minimizing anionic species and enhancing reaction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alcohol-based proton carriers are used in electrochemical nitrogen reduction, then protons can be supplied for ammonia synthesis, but the proton carriers are uneconomically consumed and lead to insoluble by-products that increase cell resistance
Solution Approach 1:
The patent changes the chemical nature of the proton carrier from neutral alcohol molecules to cationic species (such as phosphonium or sulfonium cations). This parameter change allows the proton carriers to remain soluble and active throughout the reaction process, preventing the formation of insoluble by-products that would increase cell resistance. The cationic nature enables continuous operation without significant carrier consumption.
Solution Approach 2:
The patent employs a composite electrolyte system containing cationic proton carriers, their corresponding neutral ylide forms, and appropriate anions. This composite approach creates a balanced system where the cationic proton carriers can be regenerated from their ylide forms, reducing net consumption and maintaining low cell resistance throughout the ammonia synthesis process.
2Quantity of substance
If alcohol-based proton carriers are used in electrochemical nitrogen reduction, then protons can be supplied for ammonia synthesis, but insoluble by-products form that increase cell resistance
Solution Approach 1:
The patent changes the chemical nature of the proton carrier from neutral alcohol molecules to cationic species (such as phosphonium or sulfonium cations). This parameter change allows the proton carriers to remain soluble and active throughout the reaction process, preventing the formation of insoluble by-products that would increase cell resistance. The cationic nature enables continuous operation without significant carrier consumption.
3Productivity
If conventional electrochemical nitrogen reduction is used, then ammonia can be produced, but faradaic efficiency is low due to competition from hydrogen evolution reaction
Solution Approach 1:
The patent changes the proton delivery mechanism by using cationic proton carriers that can directly transfer protons to the nitrogen reduction reaction site. This parameter change in proton transfer kinetics enhances the selectivity for ammonia production over hydrogen evolution, improving faradaic efficiency while maintaining productive ammonia synthesis rates.
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 achieves higher faradaic efficiencies and improved cell stability by avoiding anionic degradation pathways, with lower initial cell resistance and increased reaction rates, enabling efficient ammonia production.
Implementation Method 1
the electrolyte comprises a cationic proton carrier capable of reversible deprotonation to form an ylide proton acceptor
Implementation Method 2
introducing protons to the electrolyte by anodic oxidation of a hydrogen-containing species
Implementation Method 3
cathodically reducing the dinitrogen in the presence of certain metals to produce ammonia
Implementation Method 4
continuous electrochemical dinitrogen reduction to produce ammonia
Data Source
AI summary
The invention provides a method of continuous electrochemical dinitrogen reduction to produce ammonia, the method comprising: supplying dinitrogen to an electrochemical cell comprising an electrolyte in contact with at least a cathode; introducing protons to the electrolyte by anodic oxidation of a hydrogen-containing species; and cathodically reducing the dinitrogen in the presence of a metal selected from lithium, magnesium, calcium, strontium, barium, zinc, aluminium and vanadium to produce ammonia, wherein the electrolyte comprises a cationic proton carrier capable of reversible deprotonation to form a neutral proton acceptor, wherein the neutral proton acceptor is an ylide.