Electrochemical Reduction System with Hydrogen Removal
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Solution Overview
Problem
Current electrochemical CO2 reduction processes struggle to achieve ethylene concentrations above 10% due to problematic flow conditions and the dominance of the hydrogen evolution reaction, which reduces CO2 electrolyzer performance.
Innovation Solution
A system that recycles unreacted gases, including N2 or CO2, along with products, back into a gas reduction reactor, combined with a hydrogen removal device to eliminate H2 byproducts, allowing for higher gas conversion rates without decreasing gas flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the inlet flow rate of CO2 is reduced significantly to achieve ethylene concentrations above 10%, then ethylene concentration is improved, but the hydrogen evolution reaction dominates and CO2 reduction performance deteriorates
Solution Approach 1:
The patent extracts and removes hydrogen gas from the recycled gas stream using a hydrogen removal device (such as a palladium membrane or selective catalyst) before the gas is reintroduced to the reactor. This prevents hydrogen accumulation that would otherwise dominate the hydrogen evolution reaction and suppress CO2 reduction, allowing high ethylene concentrations to be achieved without sacrificing CO2 reduction performance
Solution Approach 2:
The patent introduces a hydrogen removal device as an intermediary component in the gas circulation loop. This device acts as a mediator that selectively removes hydrogen from the gas stream, enabling the system to maintain high ethylene concentrations while preventing the hydrogen evolution reaction from outcompeting CO2 reduction at the catalyst surface
2Productivity
If a recirculation system is implemented to increase gas conversion rates, then conversion efficiency is improved, but hydrogen byproduct accumulates and impedes further gas reduction
Solution Approach 1:
The patent extracts the harmful hydrogen byproduct from the recirculated gas stream using a selective hydrogen removal device positioned in the circulation loop. This allows the system to maintain high gas conversion rates through recirculation while continuously removing accumulated hydrogen that would otherwise inhibit further reduction reactions
Solution Approach 2:
The patent converts the harmful effect of hydrogen byproduct accumulation into a benefit by implementing a hydrogen removal device that selectively extracts hydrogen from the recirculated stream. The removed hydrogen can be purified and utilized as a valuable byproduct, while the hydrogen-depleted gas continues to undergo efficient reduction reactions in the recirculation system
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 ethylene concentrations of at least 10%, roughly 10 to 20 times higher than in single-pass systems, while preventing H2 from impeding gas reduction and allowing for the potential production of other chemicals like ammonia and hydrazine.
Implementation Method 1
a hydrogen removal device (e.g., an electrochemical hydrogen pump) is placed in series with a nitrogen reduction reactor or a carbon dioxide reduction reactor, which effectively removes most or all the H2 from the recycled gas stream
Implementation Method 2
Much progress has been made towards improving the efficiency of electrochemical CO2 reduction to ethylene, particularly by tuning the microenvironment of Cu catalysts
Data Source
AI summary
This disclosure provides systems, methods, and apparatus related to electrochemical reduction of gasses. In one aspect, a method includes flowing a gas through a reduction device. The gas is carbon dioxide (CO2) or nitrogen (N2). The reduction device reduces the gas and generates a product stream including the gas, hydrogen (H2), and a chemical. The product stream is flowed through a hydrogen removal device. The hydrogen removal device removes hydrogen from the product stream. The product stream with the hydrogen removed is flowed through the gas reduction device.