Fischer-Tropsch Hydrocarbon Synthesis with CO2-to-CO Recycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing processes for synthesizing hydrocarbons from synthesis gas are inefficient and result in high carbon dioxide emissions, requiring carbon capture and storage, and do not effectively utilize renewable energy sources.
Innovation Solution
A process that integrates a Fischer-Tropsch synthesis with a reverse water-gas shift unit, utilizing the water by-product from Fischer-Tropsch synthesis in an electrolysis unit to produce oxygen and hydrogen, which are then used to enhance the synthesis gas generation and shift reaction, while using renewable energy for electrolysis to reduce carbon intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hydrocarbon synthesis processes are used from synthesis gas, then hydrocarbons can be produced, but carbon dioxide emissions are significant and process efficiency is low
Solution Approach 1:
The patent combines Fischer-Tropsch synthesis with water electrolysis and reverse water-gas shift reactions in an integrated system. The electrolysis unit uses renewable electricity to split water into hydrogen and oxygen, with hydrogen fed to the reverse water-gas shift unit to convert CO2 to CO, which then feeds the Fischer-Tropsch synthesis. This merging of units creates a closed-loop system that converts CO2 emissions into useful hydrocarbon products, simultaneously improving productivity and reducing harmful emissions.
Solution Approach 2:
The invention converts the harmful CO2 by-product of synthesis gas production into a valuable resource. The CO2 stream from the synthesis gas unit is fed to the reverse water-gas shift unit where it reacts with hydrogen to produce CO, the essential feedstock for Fischer-Tropsch synthesis. This transforms the harmful CO2 emission into a beneficial building block for hydrocarbon production, eliminating the need for carbon capture while maintaining or improving hydrocarbon yield.
2Object-generated harmful factors
If carbon capture and storage steps are added to reduce emissions, then carbon dioxide emissions are reduced, but process complexity and cost increase
Solution Approach 1:
Instead of capturing and storing CO2 as waste, the invention converts it into a valuable feedstock through the reverse water-gas shift reaction. The CO2 from synthesis gas production is transformed into CO, which then serves as the carbon source for Fischer-Tropsch hydrocarbon synthesis. This approach eliminates the need for separate carbon capture and storage infrastructure, reducing process complexity while effectively managing CO2 emissions by incorporating them into the product stream.
Solution Approach 2:
The system is self-sufficient in terms of hydrogen supply. The water electrolysis unit generates hydrogen that is immediately consumed by the reverse water-gas shift unit to convert CO2 to CO. This internal hydrogen production and consumption cycle eliminates the need for external hydrogen sources or complex carbon management infrastructure, allowing the system to manage its own emissions while maintaining simplicity.
3Quantity of substance
If water electrolysis is integrated to provide hydrogen for reverse water-gas shift, then hydrogen availability increases and CO2 is converted to CO, but energy consumption increases
Solution Approach 1:
The invention changes the energy source parameter from conventional fossil-based electricity to renewable electricity sources. The water electrolysis unit is powered by renewable energy, which not only provides the necessary energy for hydrogen production but also fundamentally changes the carbon intensity of the process. This parameter change enables the system to consume energy while simultaneously reducing net carbon emissions, as the renewable electricity does not produce CO2 during generation.
Solution Approach 2:
The integrated system operates continuously with water electrolysis providing steady hydrogen supply to the reverse water-gas shift unit, which continuously converts CO2 to CO for Fischer-Tropsch synthesis. This continuous operation maximizes the utilization of renewable energy input and maintains steady-state production, improving overall energy efficiency compared to batch processes or systems with intermittent operation.
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 increases hydrocarbon product yield, reduces carbon dioxide emissions to negative levels, and eliminates the need for carbon capture and storage, while maximizing liquid fuel production from various feedstocks.
Implementation Method 1
at least a portion of the FT water stream is fed to an electrolysis unit to provide an oxygen stream, which is fed to the synthesis gas generation unit, and a hydrogen stream
Implementation Method 2
at least a portion of the carbon dioxide stream recovered from the carbon dioxide removal unit and a portion of the hydrogen stream produced by the electrolysis unit are fed to a reverse water-gas shift unit to produce a carbon monoxide stream
Data Source
AI summary
A process for synthesising hydrocarbons is described comprising the steps of (a) making a synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide from a feedstock in a synthesis gas generation unit, (b) removing carbon dioxide to produce a carbon dioxide stream and purified synthesis gas comprising hydrogen and carbon monoxide for synthesis in a Fischer-Tropsch hydrocarbon synthesis unit wherein (i) at least a portion of the FT water stream is fed to an electrolysis unit to provide an oxygen stream, which is fed to the synthesis gas generation unit. Carbon dioxide stream recovered from the carbon dioxide removal unit and a portion of the hydrogen stream produced by the electrolysis unit are fed to a reverse water-gas shift unit to produce a carbon monoxide stream, with carbon monoxide stream from the reverse water-gas shift unit is fed to the Fischer-Tropsch hydrocarbon synthesis unit.