CO2 Conversion to CO in Synthesis Gas Production
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Solution Overview
Problem
Current processes for producing synthesis gas from heavy carbon-containing materials like coal, biomass, and petroleum residues are inefficient and incompatible with these feedstocks, limiting the production of high-quality liquid fuels and petrochemicals, and result in low carbon yield and excessive CO2 emission.
Innovation Solution
Implementing a process that includes a stage for separating CO2 from synthesis gas and converting it into CO using a hydrogen-rich gas with an H2/CO ratio greater than 3, in a separate reaction zone, enhancing the carbon yield by reversing the water gas shift reaction and integrating energy recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If partial oxidation process is used for heavy carbon-containing materials, then synthesis gas production is compatible with heavy feedstocks, but CO2 emissions are excessive and carbon yield is low
Solution Approach 1:
The patent applies this principle by capturing CO2 from the partial oxidation process and converting it back into CO through reverse water-gas shift reaction. The harmful CO2 emission is transformed into a useful resource (CO) that can be reused in Fischer-Tropsch synthesis, thereby converting a waste product into a valuable feedstock component.
Solution Approach 2:
The patent implements CO2 recovery and recycling. Instead of discarding CO2 as a waste product, the process separates and recovers CO2 from the synthesis gas stream, then converts it back to CO which is fed back into the synthesis process, creating a circular carbon flow that improves overall carbon efficiency.
2Quantity of substance
If steam reforming is used for light hydrocarbons, then high hydrogen yield is achieved, but the process is incompatible with heavy carbon-containing feedstocks
Solution Approach 1:
The patent creates a universal gasification system that can handle both light hydrocarbons and heavy carbon-containing materials. By combining partial oxidation (which handles heavy feedstocks) with reverse water-gas shift reaction (which enhances hydrogen production), the system achieves multi-functionality and broad feedstock compatibility while maintaining high hydrogen yields.
Solution Approach 2:
The patent changes the operational parameters by conducting the reverse water-gas shift reaction at high temperatures (above 700°C) and using specific catalysts. These parameter changes enable the process to achieve hydrogen enhancement levels that were previously only attainable through steam reforming, but now applicable to heavy feedstocks as well.
3Productivity
If CO2 is separated and converted via reverse water gas shift reaction, then carbon yield is enhanced, but process complexity increases
Solution Approach 1:
The patent merges the CO2 separation unit with the reverse water-gas shift reaction zone. By integrating these functions into a combined system where CO2 is separated and immediately converted in the same operational framework, the patent reduces the number of discrete units and simplifies the overall process flow while maintaining enhanced carbon yield.
Solution Approach 2:
The patent uses a catalyst as an intermediary substance that facilitates the reverse water-gas shift reaction. The catalyst enables the conversion of CO2 to CO at lower temperatures and with higher efficiency, thereby simplifying the reaction conditions and reducing the complexity of temperature control and reaction management.
4Productivity
If hydrogen-rich gas with H2/CO ratio >3 is used for CO2 conversion, then carbon yield increases, but energy consumption increases
Solution Approach 1:
The patent performs preliminary heating of the CO2-containing gas stream to high temperatures (above 700°C) before it enters the reverse water-gas shift reaction zone. This preliminary thermal preparation ensures that the subsequent hydrogenation reaction proceeds more efficiently with lower additional energy input, thereby reducing overall energy consumption while maintaining high carbon yield.
Solution Approach 2:
The patent replaces mechanical compression and high-pressure systems with a thermal-based approach. By using high-temperature treatment and catalytic conversion, the process achieves CO2 conversion without requiring complex high-pressure equipment, thereby reducing mechanical energy consumption and system complexity.
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 increases the carbon yield of liquid hydrocarbons produced and improves energy efficiency, allowing for the production of high-quality fuels while reducing CO2 emissions.
Implementation Method 1
converting it into CO using a hydrogen-rich gas with an H2/CO ratio greater than 3, in a separate reaction zone, enhancing the carbon yield by reversing the water gas shift reaction
Implementation Method 2
enhancing the carbon yield by reversing the water gas shift reaction... which is enhanced by high temperatures
Data Source
AI summary
Process for the production of liquid hydrocarbons from a feedstock that comprises at least one elementary feedstock from the group of biomass, coal, lignite, petroleum residues, methane, and natural gas, comprising: at least one stage a) for gasification of the feedstock by partial oxidation and/or steam reforming to produce a synthesis gas SG; a stage b) for separating CO2 from SG and a portion of the effluent of the subsequent stage c); the mixing of a portion of the CO2 that is separated with a gas of an H2/CO ratio of more than 3; a stage c) for partial conversion with hydrogen, thermal or thermocatalytic, of the CO2 that is present in said first mixture according to the reaction: CO2+H2→CO+H2O in a specific reaction zone that is separated from said gasification zone or zones; a stage d) for Fisher-Tropsch synthesis on a synthesis gas that comprises at least a portion of SG and at least a portion of the CO that is produced by the conversion of CO2 into hydrogen.