Solid Oxide Electrolysis for Tailored Synthesis Gas
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Solution Overview
Problem
Current methods for producing methanol and hydrocarbon products from H2 and CO2-rich synthesis gas are inefficient, requiring large reactors, expensive purification processes, and complex reverse water gas shift reactions, with no standard solution for Fischer-Tropsch synthesis.
Innovation Solution
A method involving separate electrolysis of water and CO2-rich streams using solid oxide electrolysis cells to produce a synthesis gas with a tailored CO/CO2 molar ratio of 0.2-0.6, reducing reactor size, hydrogen consumption, and eliminating the need for steam reforming and reverse water gas shift reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam reforming of hydrocarbon feedstock is used to produce synthesis gas, then H2 and CO2 are produced, but the process is inefficient and requires expensive purification and complex reverse water gas shift reactions
Solution Approach 1:
The patent segments the synthesis gas production process into separate electrolysis units: one for water electrolysis producing H2, and another for CO2 electrolysis producing CO. This segmentation eliminates the need for steam reforming and subsequent complex purification and reverse water gas shift reactions, directly producing a synthesis gas with optimized composition for methanol and hydrocarbon synthesis.
Solution Approach 2:
The patent replaces the thermal-chemical steam reforming process with electrochemical electrolysis processes. By using electricity to directly split water and CO2, the method substitutes the complex mechanical/thermal system (steam reforming converters, purification systems, shift converters) with a more direct electrochemical approach, reducing overall process complexity.
2Productivity
If a high CO2 to CO ratio in synthesis gas is used for methanol synthesis, then methanol production is achieved, but a larger conversion reactor and more expensive downstream purification are required
Solution Approach 1:
The patent changes the key parameter of synthesis gas composition by electrolyzing CO2 to produce CO directly, achieving a CO2 to CO ratio of 1:1 or lower. This parameter change optimizes the synthesis gas for methanol conversion, improving reaction efficiency and reducing the required reactor volume, as the electrolysis unit itself can serve as the conversion reactor.
Solution Approach 2:
The electrolysis unit performs multiple functions: it acts as both the CO2 conversion reactor and the synthesis gas production unit. This multi-functionality eliminates the need for separate, large-volume methanol conversion reactors and downstream purification systems, as the electrolysis process directly produces synthesis gas with optimal composition for methanol synthesis.
3Productivity
If reverse water gas shift reaction is used to convert CO2 to CO for Fischer-Tropsch synthesis, then CO is produced, but expensive and complex shift converters are required
Solution Approach 1:
The patent replaces the reverse water gas shift reaction system with direct CO2 electrolysis. Instead of using complex shift converters and water gas shift reactions, the method uses an electrolysis unit to directly convert CO2 to CO, providing a simpler and more cost-effective pathway for producing CO needed for Fischer-Tropsch synthesis of hydrocarbons.
Solution Approach 2:
The patent extracts the CO production function from the complex reverse water gas shift reaction system and implements it through direct CO2 electrolysis. This extraction simplifies the overall process by removing the need for shift converters and associated complex equipment, while still achieving the required CO production for hydrocarbon synthesis.
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 results in a more reactive synthesis gas, reducing reactor sizes, energy consumption, and carbon footprint, while simplifying the process and reducing capital expenses by eliminating the need for recycle compressors and purification systems.
Implementation Method 1
passing it through an electrolysis unit for producing a feed stream comprising CO and CO2
Implementation Method 2
The step of providing a carbon dioxide-rich stream and passing it through an electrolysis unit for producing a feed stream comprising CO and CO2 is conducted as a once-through operation in a solid oxide electrolysis cell unit i.e. SOEC-CO2
Implementation Method 3
providing a water feedstock and passing it through an electrolysis unit for producing a feed stream comprising H2
Implementation Method 4
converting said synthesis gas into methanol... 3 H2+CO2═CH3OH+H2O, CO+2 H2═CH3OH
Implementation Method 5
converting said synthesis gas into methanol... in a methanol synthesis reactor
Implementation Method 6
converting said synthesis gas into a hydrocarbon product... by Fischer-Tropsch synthesis (FT)
Implementation Method 7
converting said synthesis gas into a hydrocarbon product... through a Fischer-Tropsch (FT) synthesis unit
Data Source
AI summary
A method and system for producing a synthesis gas for use in the production of methanol, or a hydrocarbon product such as a synthetic fuel, comprising the steps of: providing a carbon dioxide-rich stream and passing it through an electrolysis unit for producing a feed stream comprising CO and CO2; providing a water feedstock and passing it through an electrolysis unit for producing a feed stream comprising H2; combining said feed stream comprising CO and CO2 and said feed stream comprising H2 into said synthesis gas; and converting said synthesis gas into said methanol or said hydrocarbon product.