Membrane Reactor for In Situ Water Removal in Fischer-Tropsch Synthesis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In synthesis gas conversion reactions, such as Fischer-Tropsch reactions, the presence of water vapor reduces reaction kinetics and catalyst life due to high partial pressures, and the hydrogen to carbon monoxide ratio affects product distribution, leading to inefficiencies and undesirable byproducts.
Innovation Solution
A membrane-based system for in situ water removal and controlled hydrogen addition along the reactor length, using a water permselective membrane and a hydrogen-containing sweep gas to maintain a stable H2/CO ratio, enhancing reaction efficiency and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water is removed in situ using a membrane, then water partial pressure is reduced and reaction kinetics improve, but device complexity increases
Solution Approach 1:
The patent combines the reaction zone and separation zone into a single integrated reactor system. The membrane is positioned within the reactor such that water produced in the Fischer-Tropsch reaction is removed in situ through the membrane without requiring a separate dehydration unit. This merging of reaction and separation functions resolves the contradiction by achieving high CO conversion rates through effective water removal while avoiding the need for complex external water removal equipment.
Solution Approach 2:
The membrane serves multiple functions simultaneously: it acts as a selective barrier for water removal, provides structural support for the catalyst, and enables in situ dehydration while maintaining reaction conditions. This multi-functionality allows the system to achieve improved reaction kinetics through water removal without adding separate dedicated components for each function, thereby resolving the contradiction between productivity improvement and device complexity.
2Manufacturing precision
If hydrogen is added along the reactor length to maintain H2/CO ratio, then product distribution improves, but device complexity increases
Solution Approach 1:
The patent combines hydrogen addition with the water removal membrane system. Hydrogen is introduced through the same membrane structure that removes water, creating a dual-function membrane system that simultaneously controls water partial pressure and maintains H2/CO ratio. This merging of hydrogen addition and water removal functions into a single integrated system resolves the contradiction by achieving precise product distribution control without requiring separate hydrogen addition equipment.
3Device complexity
If conventional fixed bed reactors are used, then device complexity is low, but CO conversion rate is limited due to water accumulation
Solution Approach 1:
The patent extracts water from the reaction zone through a selective membrane that allows water vapor to pass through while retaining other reaction products and reactants. This extraction of water during the reaction process prevents water accumulation that would otherwise inhibit the Fischer-Tropsch reaction, thereby achieving high CO conversion rates while maintaining a relatively simple fixed bed reactor structure without complex external dehydration equipment.
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 CO conversion rates, reduces reactor size and catalyst volume, and minimizes tail gas recycle, leading to improved hydrocarbon product yields and reduced reactor length, while maintaining a stable H2/CO ratio and reducing undesirable byproduct formation.
Implementation Method 1
The water is removed from the reaction products through a membrane in communication with the reaction zone, said membrane having a retentate side facing the reaction zone and a permeate side opposite the retentate side
Implementation Method 2
A sweep gas containing hydrogen is caused to flow across the permeate side of the membrane at a hydrogen partial pressure sufficient to cause hydrogen to pass from the permeate side to the reaction zone
Data Source
AI summary
A synthesis gas conversion process for carrying out the process is disclosed. A hydrogen-containing sweep gas is caused to flow across a water permselective membrane adjacent a synthesis gas conversion reaction zone in which synthesis gas is contacted with a catalyst and converted to effluent including water. Water is removed from the reaction zone through the membrane. The sweep gas has sufficient hydrogen partial pressure to cause hydrogen to pass through the membrane into the reaction zone.