Solid Electrolyte Membrane for Distributed Ammonia Synthesis
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Solution Overview
Problem
The Haber-Bosch process for ammonia production is inefficient at small scales due to high temperature-induced thermodynamic decomposition and catalyst poisoning, requiring large plants and high capital costs, while existing electrochemical methods suffer from low ammonia flux and high costs.
Innovation Solution
A solid electrolyte membrane is formed in situ within an electrochemical stack using a reactant metal and gas, such as lithium nitride, to facilitate nitride ion transport, enabling efficient ammonia synthesis at intermediate temperatures and reducing capital costs by eliminating moving parts and catalyst poisoning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Haber-Bosch process is used for ammonia production, then large-scale production is achieved, but capital costs and maintenance costs increase due to large plant requirements and moving parts
Solution Approach 1:
The patent replaces the mechanical compression system of Haber-Bosch with an electrochemical system using solid electrolyte membranes. The electrochemical cell uses electric current to drive nitrogen and hydrogen through the membrane to produce ammonia, eliminating the need for mechanical compressors and high-pressure equipment, thereby reducing device complexity and maintenance requirements while maintaining production capability
Solution Approach 2:
The patent changes the operating parameters from high temperature (380-520°C) and high pressure (120-220 bar) in Haber-Bosch to lower temperature and pressure conditions using electrochemical methods. This parameter change enables smaller scale production without requiring the large plant infrastructure and high capital investment associated with traditional Haber-Bosch processes
2Productivity
If high temperature conditions are used in Haber-Bosch process, then nitrogen and hydrogen reaction is accelerated, but ammonia thermodynamic decomposition increases reducing conversion rate
Solution Approach 1:
The patent changes the temperature parameter from high temperature (380-520°C) to lower temperature operation using electrochemical methods. The electrochemical cell operates at temperatures that prevent ammonia decomposition while still enabling the nitrogen reduction reaction, thereby improving ammonia conversion rate by eliminating the thermodynamic decomposition issue inherent in high-temperature thermal processes
3Productivity
If ruthenium catalyst is used for nitrogen reduction, then catalytic activity is improved, but catalyst poisoning from hydrogen prevents commercial use
Solution Approach 1:
The patent introduces a solid electrolyte membrane as an intermediary between the nitrogen feed side and the catalyst. The membrane selectively transports nitrogen species to the catalyst surface while blocking hydrogen, thereby protecting the ruthenium catalyst from poisoning by hydrogen while still enabling high nitrogen reduction activity
Solution Approach 2:
The patent replaces the traditional catalyst-based hydrogen management approach with an electrochemical membrane-based separation system. The solid electrolyte membrane uses electrochemical potential to selectively transport nitrogen species, eliminating the need for the catalyst to simultaneously perform both nitrogen activation and hydrogen rejection functions
4Device complexity
If electrochemical methods are used for ammonia synthesis, then capital costs are reduced and small scale production is enabled, but ammonia flux is low resulting in high operational costs
Solution Approach 1:
The patent uses composite solid electrolyte membranes combining multiple functional materials to achieve both high nitrogen permeability and high ammonia flux. The composite structure integrates ion-conducting phases with catalytically active phases, enabling the membrane to simultaneously transport nitrogen species efficiently and facilitate their reduction to ammonia at high rates, thereby resolving the flux limitation of earlier electrochemical methods
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 enhances ammonia conversion efficiency, reduces capital costs, and allows for distributed ammonia generation from flared gas or renewables, achieving comparable performance to Haber-Bosch processes with lower operational expenses.
Implementation Method 1
introducing a reactant gas into the precursor stack, wherein the reactant gas reacts with the reactant metal to form a solid electrolyte membrane in situ
Implementation Method 2
The solid electrolyte membrane comprises a nitride and can transport nitride ions
Data Source
AI summary
An electrochemical stack includes a solid electrolyte membrane as one of the components of a membrane electrode assembly. The membrane may have been formed during stack assembly via an in situ reaction.