Bicarbonate Electrolyzer With Hydrogen Oxidation for CO2 Conversion
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Solution Overview
Problem
Existing electrolyzers are inefficient and costly for reducing carbon dioxide from bicarbonate solutions, requiring high electrical potentials and low current densities, and lack effective methods for capturing atmospheric carbon dioxide.
Innovation Solution
A method and apparatus for electrolyzing bicarbonate solutions at low applied potentials (up to 3V) with high current densities (500 mA cm−2) and CO2 utilization rates over 40%, using an electrolyzer with an ion exchange membrane and a cathode adapted for direct bicarbonate reduction, coupled with a hydrogen oxidation reaction at the anode to provide protons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electrolysis methods are used to reduce carbon dioxide from bicarbonate solutions, then carbon capture can be achieved, but high electrical potentials and low current densities are required resulting in inefficiency and high operational costs
Solution Approach 1:
The patent changes the chemical form of carbon dioxide from gaseous CO2 to bicarbonate ions in aqueous solution, enabling direct electrolytic reduction at lower potentials. This parameter change from gas phase to dissolved ion phase allows the reaction to proceed more efficiently with reduced energy input requirements
Solution Approach 2:
The patent introduces bicarbonate ions as an intermediary species that facilitates the carbon dioxide reduction reaction. Instead of directly reducing gaseous CO2, the system uses bicarbonate ions formed from CO2 capture, which serve as a more reactive intermediate that can be reduced at lower electrical potentials through direct electron transfer at the cathode
2Productivity
If conventional electrolysis methods are used, then carbon dioxide reduction can occur, but current densities are low resulting in slow reaction rates and high operational costs
Solution Approach 1:
The patent changes the physical state and chemical form of the carbon substrate from gaseous CO2 to dissolved bicarbonate ions, which increases the availability of reactant at the electrode surface. This parameter change enables higher current densities by improving mass transport and increasing the concentration of reducible species in the electrolyte solution
Solution Approach 2:
The patent replaces the conventional mechanical/gaseous CO2 supply system with an electrochemical system using bicarbonate ions. This substitution eliminates the need for complex gas handling and pressurization equipment, simplifying operation while enabling higher current densities through direct ionic conduction and electron transfer
3Reliability
If conventional electrolysis methods are used, then carbon dioxide can be reduced, but faradaic efficiency is low resulting in significant CO2 byproduct formation
Solution Approach 1:
The patent changes the reaction pathway by using bicarbonate ions instead of gaseous CO2, which alters the electrochemical mechanism. This parameter change leads to more selective reduction reactions with fewer side reactions, thereby improving faradaic efficiency and reducing unwanted CO2 byproduct formation
Solution Approach 2:
The patent uses bicarbonate ions as a selective intermediary that directs the reduction reaction toward desired products. The bicarbonate ion structure and chemistry provide a more controlled reaction pathway that enhances selectivity and minimizes competing reactions that would otherwise produce CO2 byproducts
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
Achieves efficient conversion of bicarbonate to useful products like carbon monoxide, formate, and ethylene with low CO2 byproduct, enhancing faradaic efficiency and reducing operational costs.
Implementation Method 1
The protons (H+) may be transported through an ion exchange membrane to the cathode
Implementation Method 2
Methods and apparatus for performing electrolytic conversion of bicarbonate in solution into useful products
Implementation Method 3
The method involves the direct reduction of bicarbonate at the cathode
Implementation Method 4
with an oxidation reaction at the anode. The oxidation reaction may provide a source of protons (H+) to the cathode
Data Source
AI summary
Methods and apparatuses for converting carbon dioxide to useful compounds are disclosed. The method involves reducing bicarbonate solution in an electrolyzer. Bicarbonate solution is supplied to the cathode. The direct reduction of bicarbonate at the cathode may be coupled with an oxidation reaction at the anode. The oxidation reaction may provide a source of protons (H+) to cathode for the reduction of bicarbonate. The oxidation reaction may be a hydrogen oxidation reaction (HOR). Hydrogen gas (H2) may be supplied to the anode. In some embodiments, a source of gas may be supplied to the bicarbonate solution to form a pressurized solution before supplying the solution to the cathode.