High Temperature PBI Membrane Hydrogen Purification
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Solution Overview
Problem
High temperature PBI-based electrochemical hydrogen pumps face challenges in purifying hydrogen gas streams containing high concentrations of hydrogen sulfide impurities, as existing technologies are constrained by low temperature gas purity requirements.
Innovation Solution
A high temperature PBI-based electrochemical hydrogen pumping method that introduces hydrogen gas streams with up to 1,000 ppm of hydrogen sulfide into a hydrogen pumping cell, operating at 140° C. to 200° C. and 0 PSI to 300 PSI, using a membrane with catalysts on the anode and cathode surfaces, and adjusting relative humidity to inhibit catalyst poisoning, resulting in purified hydrogen with less than 10 ppm of impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If low temperature PEM systems are used for hydrogen purification, then the system can operate at lower temperatures, but the system becomes extremely sensitive to hydrogen sulfide impurities requiring stringent gas purity requirements
Solution Approach 1:
The patent changes the operating temperature parameter from low temperature (conventional PEM) to high temperature (120-200°C for PBI membranes). This parameter change fundamentally alters the system's tolerance to impurities, allowing it to process hydrogen streams with hydrogen sulfide concentrations up to 1,000 ppm without catalyst poisoning, thereby resolving the contradiction between operating temperature and impurity sensitivity
Solution Approach 2:
The patent employs phosphoric acid doped polybenzimidazole (PBI) composite membrane material instead of conventional perfluorosulfonic acid polymer membranes. This composite material combines the benefits of high temperature stability with improved impurity tolerance, enabling operation at elevated temperatures while maintaining membrane integrity and selectivity, thus resolving the contradiction between temperature operation and catalyst protection
2Object-affected harmful factors
If scrubbing technologies are used to remove hydrogen sulfide, then fuel impurities can be removed, but the process complexity and cost increase
Solution Approach 1:
The patent extracts the hydrogen sulfide impurity removal function directly from the electrochemical pump system by utilizing the high temperature PBI membrane's inherent tolerance to hydrogen sulfide. Instead of adding separate scrubbing units, the system leverages the membrane's properties to allow hydrogen sulfide passage while purifying hydrogen, thereby simplifying the overall process architecture and reducing device complexity
Solution Approach 2:
The high temperature PBI-based electrochemical pump serves multiple functions simultaneously: it acts as both a hydrogen purification device and a hydrogen sulfide tolerant system. The membrane performs selective hydrogen transport while tolerating hydrogen sulfide impurities, eliminating the need for separate scrubbing technologies and reducing overall system complexity
3Object-affected harmful factors
If high temperature PBI-based electrochemical hydrogen pumping is used, then tolerance to hydrogen sulfide improves, but the membrane requires stable operation at elevated temperatures
Solution Approach 1:
The patent uses phosphoric acid doped polybenzimidazole (PBI) composite membrane material that combines high temperature stability with hydrogen sulfide tolerance. The PBI polymer matrix provides structural integrity at elevated temperatures while the phosphoric acid doping enhances ionic conductivity and impurity tolerance, ensuring reliable operation under harsh conditions
Solution Approach 2:
The patent operates the PBI membrane at controlled high temperatures (120-200°C), optimizing the balance between hydrogen sulfide tolerance and membrane stability. This temperature parameter optimization ensures the membrane maintains its structural integrity and functional performance while achieving the desired impurity tolerance
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 method effectively purifies hydrogen gas streams with high hydrogen sulfide concentrations, demonstrating stable operation and high reliability, with hydrogen sulfide levels reduced below detection limits, and maintaining performance over extended periods.
Implementation Method 1
an electrochemical pump is designed to oxidize and reduce hydrogen at the anode and cathode, respectively in an electrolytic mode
Implementation Method 2
an electrochemical pump is designed to oxidize and reduce hydrogen at the anode and cathode, respectively in an electrolytic mode
Implementation Method 3
using a membrane with catalysts on the anode and cathode surfaces
Implementation Method 4
Phosphoric acid doped polybenzimidazoles (PBI) as membranes for high temperature polymer electrolyte membrane fuel cells
Implementation Method 5
an electrochemical pump is designed to oxidize and reduce hydrogen at the anode and cathode, respectively in an electrolytic mode
Data Source
AI summary
Methods for purifying a hydrogen gas stream are provided that can include: introducing the hydrogen gas stream into the hydrogen pumping cell, and collecting a purified hydrogen gas from the hydrogen pumping cell. The hydrogen gas stream can include hydrogen sulfide in an amount of about 10 ppm to about 1,000 ppm, and can have a relative humidity of about 0.1% or more at the operational temperature and pressure of the hydrogen pumping cell.