Aqueous Formate-Bicarbonate Hydrogen Storage with CO2-Activated Catalysis
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Solution Overview
Problem
Existing hydrogen storage systems face challenges in efficiently producing hydrogen gas free of COx by-products and achieving high catalyst activity in hydrogen carbonate hydrogenation, with the effect of CO2 on reaction rates being unpredictable and catalyst performance varying significantly across different conditions.
Innovation Solution
A process involving the hydrogenation of hydrogen carbonate in an aqueous reaction system with carbon dioxide present in the gas space, using a catalyst with the general formula [Ir(cod)(NHC)Pa]+nPb, where Ir is iridium, cod is 1,5-cyclooctadiene, NHC is an N-heterocyclic carbene, and Pa and Pb are 1,3,5-triaza-7-phosphadamantane or sulfonated triphenylphosphine, at elevated temperatures and pressures, to enhance catalyst activity and produce formate reversibly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CO2 is present in the gas space during hydrogenation of hydrogen carbonate, then catalyst activity increases up to six times, but the reaction system becomes more complex with multiple gases to manage
Solution Approach 1:
The invention merges the hydrogenation and decomposition reactions into a single integrated reaction system that operates reversibly. The same catalyst performs both hydrogenation of hydrogen carbonate to form formate, and decomposition of formate to release hydrogen, eliminating the need for separate systems and reducing overall complexity despite the enhanced functionality.
Solution Approach 2:
The iridium-based catalyst exhibits multi-functionality by catalyzing both the hydrogenation of hydrogen carbonate and the decomposition of formate. This universal catalyst performs multiple roles in the reversible hydrogen storage cycle, simplifying the system architecture while achieving high productivity through CO2 presence.
2Reliability
If a reversible reaction cycle is implemented for hydrogen storage, then hydrogen can be stored and released efficiently, but the process requires precise control of multiple parameters (temperature, pressure, pH)
Solution Approach 1:
The reversible reaction system incorporates inherent feedback mechanisms where the presence of CO2 in the gas phase automatically influences the equilibrium between hydrogen carbonate and formate. The system self-regulates through the carbonate-bicarbonate buffer system, which maintains pH stability and reduces the need for external control interventions.
Solution Approach 2:
The invention utilizes controlled parameter changes to drive the reversible reaction cycle. By adjusting temperature and pressure conditions, the system can shift between hydrogen storage (hydrogenation) and hydrogen release (decomposition) modes. The CO2 pressure serves as a key parameter that enhances catalyst activity while being easily controllable.
3Object-generated harmful factors
If formate decomposition is used to produce hydrogen, then hydrogen gas free of COx by-products is achieved, but the process requires specific catalyst conditions and pH control
Solution Approach 1:
The invention converts the typically harmful CO2 into a beneficial component that enhances catalyst activity. By maintaining CO2 in the gas phase during hydrogenation, the system achieves up to six-fold increase in catalyst activity. The CO2 that might be considered a by-product or contaminant becomes an essential element for optimizing the hydrogen storage process and eliminating COx emissions during formate decomposition.
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
The catalyst activity is up to six times higher than in systems without CO2, achieving efficient hydrogen gas production free of COx by-products and enabling a reversible hydrogen storage system suitable for fuel cells.
Implementation Method 1
contacting the hydrogen carbonate, hydrogen and catalyst with each other while carbon dioxide is present in the gas space. In this phase of the process, formate is produced
Implementation Method 2
the formate and the catalyst come into contact, so that hydrogen gas and hydrogen carbonate free of COx by-products are produced as the product of the reaction
Implementation Method 3
the reactants and reaction products are formed in a reversible reaction cycle using the reaction system according to the invention, and this reaction cycle is repeated in the required number of times
Data Source
AI summary
The subject of the invention is a process for the hydrogenation of hydrogen carbonate in an aqueous reaction system, where the process ensures that the hydrogen carbonate, hydrogen and catalyst come into contact with each other while carbon dioxide is present in the gas space. In this phase of the process, formate is produced. The subject of the invention is also a process for the catalytic decomposition of formate in an aqueous reaction system and the hydrogenation of hydrogen carbonate produced in the same reaction system according to the invention, where the reactants and the reaction products are formed in a reversible reaction cycle using the reaction system according to the invention, and this reaction cycle is repeated in the required number of times. In the mentioned formate mg decomposition process, the formate and the catalyst come into contact, so that hydrogen gas and hydrogen carbonate free of COX by-products are produced as the product of the reaction. Further subject of the invention is a hydrogen storage system based on the method according to the invention, preferably a hydrogen accumulator. Further subject of the invention is a hydrogen storage system according to the invention, preferably the use of a hydrogen accumulator for the storage of hydrogen required for the operation of a fuel cell (or other equipment requiring H2) and, where appropriate, for its release in as needed.