Reverse Water-Gas Shift Process for CO Production
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Solution Overview
Problem
Existing methods for the reverse water-gas shift reaction, such as those disclosed in WO2019175476A1 and WO2020114899A1, are inefficient in converting carbon dioxide and hydrogen to carbon monoxide, often requiring excessive hydrogen combustion to maintain heat balance and lacking optimal catalyst usage.
Innovation Solution
A process involving a sub-stoichiometric oxygen combustion of a carbon dioxide and hydrogen gas mixture in a reverse water-gas shift vessel, followed by passage through a catalyst bed, cooling, and carbon dioxide removal to produce a carbon monoxide gas stream, with excess hydrogen and recycled carbon dioxide used to maintain reaction efficiency and desired H2:CO ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If hydrogen is combusted in excess to maintain heat balance in the reverse water-gas shift reaction, then the reaction temperature is maintained, but hydrogen consumption increases and conversion efficiency decreases
Solution Approach 1:
The patent changes the chemical parameters of the system by introducing a sub-stoichiometric amount of oxygen (0.2-0.5 times the stoichiometric amount) to enable partial combustion. This parameter change allows the reaction to proceed with lower hydrogen consumption while maintaining sufficient heat generation for the reverse water-gas shift reaction, directly resolving the contradiction between temperature maintenance and hydrogen consumption
Solution Approach 2:
Oxygen serves as an intermediary substance that mediates the heat generation process. Instead of relying solely on hydrogen combustion, oxygen acts as a mediator that enables partial oxidation reactions, providing an alternative pathway for heat generation that reduces direct hydrogen consumption while maintaining reaction temperature
2Productivity
If a catalyst is used in the reverse water-gas shift reaction, then conversion efficiency improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by using a specifically designed catalyst composition ( nickel-oxide-based catalyst with particular properties) at the reaction zone where conversion is needed. This localized application of optimized catalyst material achieves high conversion efficiency without requiring complex catalyst systems throughout the entire device, resolving the contradiction between productivity and device complexity
3Loss of substance
If sub-stoichiometric oxygen is used for combustion, then hydrogen consumption is reduced, but complete combustion is not achieved
Solution Approach 1:
The patent converts the potentially harmful incomplete combustion into a beneficial process by controlling the oxygen amount to be sub-stoichiometric (0.2-0.5 times stoichiometric). This controlled incomplete combustion actually benefits the process by reducing hydrogen consumption while the reverse water-gas shift reaction compensates for any unreacted hydrogen, turning what would normally be a deficiency into an advantage
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 process enhances the conversion efficiency of carbon dioxide to carbon monoxide, reduces hydrogen consumption, and optimizes the H2:CO ratio for downstream processes like Fischer-Tropsch synthesis, while utilizing renewable energy sources for oxygen and hydrogen production.
Implementation Method 1
combusting it with a sub-stoichiometric amount of an oxygen gas stream to form a combusted gas mixture
Implementation Method 2
passing the combusted gas mixture though a bed of reverse water-gas shift catalyst disposed within the reverse water-gas shift vessel
Implementation Method 3
cooling the crude product gas mixture to below the dew point and recovering a condensate
Data Source
AI summary
A process for producing a gas stream comprising carbon monoxide comprising the steps of (a) feeding a gas mixture comprising carbon dioxide and hydrogen to a burner and combusting it with a sub-stoichiometric amount of an oxygen gas stream to form a combusted gas mixture comprising carbon monoxide, carbon dioxide, hydrogen and steam, (b) passing the combusted gas mixture through a bed of reverse water-gas shift catalyst to form a crude product gas mixture containing carbon monoxide, steam, hydrogen and carbon dioxide, (c) cooling the crude product gas mixture to below the dew point and recovering a condensate to form a dewatered product gas, (d) removing carbon dioxide from the dewatered product gas in a carbon dioxide removal unit to form the gas stream comprising carbon monoxide, and (e) combining carbon dioxide recovered by the carbon dioxide removal unit with the gas mixture comprising hydrogen and carbon dioxide.