Lithium Metal Nitrogen Removal Process
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Solution Overview
Problem
Current methods for removing nitrogen from natural gas are inefficient, costly, and often require large centralized facilities, with existing chemical treatments facing issues such as low efficiency, hazardous materials, and high energy consumption.
Innovation Solution
A process involving non-electrochemical and electrochemical reactions using lithium metal to produce lithium nitride from natural gas, followed by electrolytic regeneration of lithium metal, utilizing a lithium ion conductive membrane and non-aqueous solvents to efficiently remove nitrogen and other impurities at lower voltages and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fractional distillation or adsorption methods are used to remove nitrogen from natural gas, then nitrogen removal is achieved, but the major component methane is removed instead of the minor component nitrogen, increasing cost and inefficiency
Solution Approach 1:
The patent extracts nitrogen from natural gas by reacting it with lithium metal to form lithium nitride, which is then electrolyzed to regenerate lithium metal and release nitrogen gas. This targeted extraction of nitrogen without affecting methane resolves the contradiction by removing only the unwanted impurity while preserving the valuable methane component.
Solution Approach 2:
Lithium metal serves as an intermediary substance that facilitates nitrogen removal. It reacts with nitrogen to form lithium nitride, which can then be electrolyzed to regenerate the lithium metal and release pure nitrogen gas. This intermediary approach enables selective nitrogen removal without methane loss.
2Manufacturing precision
If existing chemical treatment methods are used, then nitrogen removal is achieved, but the processes are too complex and prohibitively expensive at modest scale
Solution Approach 1:
The patent segments the nitrogen removal process into two simple stages: (1) chemical reaction of nitrogen with lithium metal to form lithium nitride, and (2) electrolysis of lithium nitride to regenerate lithium metal and release nitrogen gas. This segmentation into discrete, simple steps reduces overall process complexity compared to complex fractional distillation or multi-stage adsorption systems.
Solution Approach 2:
The patent changes the chemical parameters by using lithium metal to transform nitrogen from a gaseous impurity into lithium nitride compound, then uses electrolysis to reverse the reaction. This parameter change approach simplifies the process by converting a difficult separation problem into a controlled chemical transformation and reversal.
3Manufacturing precision
If centralized facilities are used for nitrogen removal, then nitrogen can be removed effectively, but scale down economics are poor and the facilities are not adaptable to smaller operations
Solution Approach 1:
The patent employs a self-service approach where the lithium metal is regenerated in-situ through electrolysis of lithium nitride. The lithium metal produced during electrolysis can be reused in the chemical reaction step, creating a self-sustaining cycle that eliminates the need for external lithium supply and simplifies scaling to smaller operations.
Solution Approach 2:
The patent creates a universal process that can operate at various scales using the same basic chemistry. The lithium metal/Lithium nitride electrochemical system can be implemented in compact configurations for small operations or expanded for larger applications, providing scale adaptability through modular design of the reaction and electrolysis chambers.
4Ease of manufacture
If lithium amalgam is used instead of lithium metal, then the process can be implemented, but lithium amalgam contains hazardous mercury and is less efficient
Solution Approach 1:
The patent uses pure lithium metal instead of lithium amalgam, eliminating hazardous mercury entirely. The lithium metal is consumed in the reaction with nitrogen to form lithium nitride, then regenerated through electrolysis. This disposable/regenérable lithium metal approach avoids the permanent mercury contamination issue of lithium amalgam while maintaining process efficiency.
Solution Approach 2:
The patent changes the material parameter from lithium amalgam (containing mercury) to pure lithium metal. This parameter change eliminates the hazardous component while improving efficiency, as lithium metal has higher reactivity with nitrogen than lithium amalgam, enabling more effective nitrogen removal without mercury contamination.
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 method allows for efficient, cost-effective, and scalable removal of nitrogen and other impurities from natural gas, with the ability to operate at lower temperatures and voltages, enabling continuous regeneration of lithium metal and removal of nitrogen and other gases.
Implementation Method 1
The overall process for the removal of nitrogen from natural gas includes both non-electrochemical and electrochemical reactions. The non-electrochemical reactions involve reacting lithium metal with substantially dried natural gas to produce lithium nitride.
Implementation Method 2
The present invention further provides an electrolytic process of regenerating the lithium metal from the resulting lithium nitride, and optionally produced reduced species such as lithium polysulfide, lithium carbonate, lithium hydroxide, etc.
Data Source
AI summary
A method for removing nitrogen from natural gas includes contacting substantially dry natural gas that contains unwanted nitrogen with lithium metal. The nitrogen reacts with lithium to form lithium nitride, which is recovered for further processing, and pipeline quality natural gas. The natural gas may optionally contain other chemical species that may be reduced by lithium, such as carbon dioxide, hydrogen sulfide, and small amounts of water. These lithium reducible species may be removed from the natural gas concurrently with the removal of nitrogen. The lithium nitride is subjected to an electrochemical process to regenerate lithium metal. In an alternative embodiment, lithium nitride is reacted with sulfur to form lithium sulfide and nitrogen. The lithium sulfide is subjected to an electrochemical process to regenerate lithium metal and sulfur. The electrochemical processes are advantageously performed in an electrolytic cell containing a lithium ion selective membrane separator.