Hybrid Adsorptive Membrane Reactor for Hydrogen Purification
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Solution Overview
Problem
Conventional steam reforming processes for hydrogen production, particularly for methane, face challenges such as high operating temperatures, low equilibrium conversions, and the presence of CO in the product gas, which requires additional processing steps to meet fuel cell specifications, especially for small-scale and mobile applications.
Innovation Solution
A hybrid adsorbent-membrane reactor (HAMR) system that combines a catalyst with a membrane and an adsorbent to selectively separate and purify hydrogen, allowing it to operate at milder conditions and reduce CO levels by adsorbing CO2, thereby enhancing product yield and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional steam reforming is used for hydrogen production, then hydrogen can be produced from methane, but high operating temperatures (exceeding 1000 K) and high pressures (up to 30 bar) are required, which are not convenient or economical for small-scale applications
Solution Approach 1:
The patent changes the operating parameters by introducing a membrane reactor system that enables steam reforming at lower temperatures (below 1000 K) and reduced pressures compared to conventional packed bed reactors. The membrane selectively removes hydrogen from the reaction zone, shifting the equilibrium and allowing milder operating conditions while maintaining productivity.
Solution Approach 2:
The patent extracts hydrogen from the reaction mixture in real-time using a selective membrane. By continuously removing hydrogen from the reaction zone, the system prevents the reverse reaction and shifts the equilibrium toward more hydrogen production, enabling the process to operate at lower temperatures and pressures than conventional systems.
2Productivity
If conventional steam reforming is used, then hydrogen production can be achieved, but equilibrium conversions remain relatively low, requiring additional processing steps to meet fuel cell specifications
Solution Approach 1:
The membrane reactor continuously extracts hydrogen from the reaction zone, maintaining a low hydrogen partial pressure that drives the reforming reaction forward. This in-situ separation achieves high equilibrium conversions and produces hydrogen stream that meets fuel cell specifications without requiring extensive downstream processing.
Solution Approach 2:
The patent merges the chemical reaction and separation functions into a single integrated membrane reactor system. The membrane simultaneously separates hydrogen from the reaction mixture and enables the reforming reaction to proceed to higher conversion, eliminating the need for separate purification units.
3Productivity
If conventional reformers operate at high temperatures to increase reaction rate, then hydrogen production efficiency improves, but CO levels in the product gas increase, requiring additional CO removal processing
Solution Approach 1:
The selective membrane extracts hydrogen from the reaction zone, creating a concentration gradient that drives the water-gas shift reaction to convert CO and H2O into CO2 and H2. This continuous hydrogen removal enables CO conversion at lower temperatures, reducing CO levels in the final product without sacrificing reaction rate.
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
The HAMR system achieves enhanced methane conversion, hydrogen yield, and product purity, reducing the need for complex downstream processing and enabling operation at lower temperatures, thus meeting the requirements for fuel cell applications.
Implementation Method 1
a membrane disposed in the chamber for selectively permitting the desired product and the by-product to pass through the membrane
Implementation Method 2
an adsorbent disposed in the chamber for adsorbing the by-product
Implementation Method 3
a catalyst disposed in the chamber for facilitating a water-gas-shift reaction of the reactants to produce at least one desired product and at least one by-product
Data Source
AI summary
A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.