Sustainable membrane-based technologies can cut the energy requirements, operational and capital costs by up to 50% for energy intensive processes such as H2 capture from methane.
Although polymer membranes dominate the gas separation market, controlling permeability/selectivity at high pressures is challenging. Recently mixed matrix membranes (MMMs), where an inorganic material embedded into a polymer matrix, have attracted attention as they can combine the functionality of the porous material with polymer processability.
Metal–organic frameworks (MOFs) that are comprised of metal ions connected by organic linkers, are the most promising ones due to their diverse and flexible structure.
This PhD application will explore the development of MOF/polymer MMMs, by increasing selectivity to enable membrane based H2 purification.
Benefits
With a reduction in cost for membranes the appetite for gas separation could increase which could unlock hydrogen transition earlier.
Learnings
Outcomes
The final thesis for this PhD project is currently being drafted and is due in September 2026. Regular quarterly meetings are held with the PhD student for discussing project updates, challenges and guidance is provided. A critical review of the findings is undertaken and questions are raised with the student on the testing approach, research methodology and outcomes presented. Based on the latest updates from the project, the following findings were presented in the latest quarterly meeting:
Adsorption isotherms of H2, CH4, and CO2 were conducted on the synthesised MOFs.
The newly prepared polymer membrane (PEI Foam/Dense) exceeded both H2/CH4 and H2/CO2 upper bounds, indicating excellent performance as a H2 purification membrane.
Key Findings across the previous quarters over the annual year 2025-2026 are listed below:
ZIF-7 synthesis time has been dramatically reduced from 48 hours to as little as 10 minutes using microwave-assisted synthesis.
Dense ZIF-7/PEI mixed matrix membranes were successfully fabricated at high loadings (up to 50 wt%), showing improved hydrogen selectivity
Porous ("foam") PEI membranes exhibited exceptionally high gas permeabilities, though their selectivity is much lower than dense membranes and some results may be influenced by defects such as pinholes.
Demonstrated an increase in H2/CO2 selectivity from 3.0-4.3 with ZIF-7 incorporation.
A next step as part of the research is to understand why the PEI foam/dense surpasses the H2/CH4 upper bounds. Another interesting observation was around the adsorption isotherms for CO2 and CH4 where it was observed that ZIF-7-I is the most favorable phase for adsorption, exhibiting both high uptake at low pressures and the highest total adsorption capacity. Introducing ZIF-7-III progressively reduces adsorption, and pure ZIF-7-III shows very limited adsorption, indicating poorer pore accessibility or weaker interactions with the adsorbed species.
Lessons Learnt
Time management is a crucial learning for projects at low TRL such as this one. Due to unforeseen circumstances, orders for chemicals and equipment were significantly delayed which resulted in delays for the permeability apparatus. In response to this, project focus shifted towards optimising the MOF synthesis with the aid of microwave energy. This shifted focus resulted in an interesting discovery and highlighted the importance of managing time within the project.
