Novel hybrid membranes for post combustion CO₂ capture in power plant and industry – HyMemCOPI

Goal of the Project:
HyMemCOPI focuses on post-combustion CO₂ capture, takes the advantages of polymer membranes (flexibility, processability and low cost), and makes a breakthrough improvement in the membrane properties for CO₂ capture by integrating multifunctional nano-sized particles in the polymer matrix.

CO₂ selectivity over N2 of more than 100, and permeance of more than 1 m3/(m2/h/bar) through the hybrid membrane will be aimed. This performance will enable this post-combustion membrane technology to become the next-generation CO₂ capture technology.
Technical content:
The project aims to gain understanding of the transport phenomena in hybrid membrane materials, considering the effect of multifunctional nano-sized materials which will enable improved fabrication of low cost and high performance hybrid membranes for CO₂ capture. SINTEF will develop cost efficient synthesis of well-defined multifunctional nano-materials for the fabrication of the novel hybrid membranes. NTNU and SINTEF will together investigate the integration of the nano-materials into the polymer matrix and shape, manufacture and test the membranes.
Technical advantages:
The results from HyMemCOPI will provide an understanding of the CO₂ transport mechanism through the membrane and how the nano-sized particles affect the membrane properties. They will also take major steps toward a robust design and manufacturing of hybrid membranes. HyMemCOPI will keep the advantages of the polymer membranes (flexibility, processability and low cost) and make a groundbreaking improvement in flux and permeability by integrating hybrid nanosized particles (down to less than 10 nm) in the polymer.
R&D challenges:
Various scientific and technical bottlenecks can be identified that could hamper a breakthrough development of hybrid membranes:
•    Lack of fundamental understanding of the affinity between polymer and fillers, and unclear influence of the inorganic particle size and amount.
•    Lack of fundamental understanding on transport properties mechanisms, especially regarding the influence of the inorganic filler and the interphase at the insert surface.
•    Challenge in fabricating hybrid / MMMs as hollow fibre membranes, which results in defective layers with very low permeance
•    Chain immobilization, pore blocking effect and/or aggregation of the nanosized fillers

Hence, all the mentioned issues clearly illustrate the crucial gap existing in the knowledge supply chain from materials fundamentals to membrane application, and are aimed to be targeted in the HyMemCOPI project.
Results to date:
The project started officially on the 1st of July 2013, and the PhD position at the NTNU was announced with a deadline in August 2013, and the position was offered to Gabriel Guerrero Heredia. He started in the position on March 1st 2014. Since the start of the project, the aim has been to confirm the breakthrough results obtained in the FP7-EU project iCap (FP7-ENERGY-2009.5.1.1). In this project, very promising results were obtained with a combination of polyvinyl alcohol (PVA) and hybrid organic-inorganic particles (polyhedral oligomeric silsesquioxane, POSS) called FunzioNano. The iCap results show CO₂ permeance of 1 m3(STP)/(m2·h·bar) at CO₂/N2 selectivity >100.

With the aim to gain understanding of the transport phenomena in these hybrid membrane materials, membranes have been prepared with and without the addition of the FunzioNano® particles to a PVA selective layer. The thin PVA selective layer with a thickness layer in the range of 4-5 micron is supported by a PPO hollow fibre support. The membrane performance has been evaluated varying CO₂ feed content and pressure. Results obtained at atmospheric pressure show a CO₂/N2 separation factor of around 60 at a CO₂ permeance equal to 0.3 m3/(m2/h/bar). A decreasing CO₂ permeance is observed with increasing CO₂ content in the feed. Incorporation of FunzioNano® results in a large increase in CO₂ permeance, however, combined with a somewhat lower CO₂/N2 separation factor. During operation at elevated feed pressures, the permeance of the PPO-PVA/FunzioNano® membrane reaches a maximum permeance value (0.34 m3·m-2·h-1·bar-1 ) at 1.5 bar. A further increase in feed pressure reduces the permeance due to membrane compaction or saturation of the activated transport. The CO₂/N2 separation factor remains relatively stable over the pressures investigated.

In conclusion, the results show that there are discrepancies with the previously obtained results in iCap. In upcoming work we will therefore investigate in depth the various parameters and variables which may influence the preparation of membranes, containing the functionalized nanoparticles, which will enable improved membrane design and fabrication, and finally more efficient and robust membranes. Membrane synthesis – timing and drying are important parameters are key variables to obtain consistent results. Additionally, there is a lack of fundamental understanding on the transport mechanisms, especially regarding the influence of the inorganic filler and the interphase of filler - polymer. So far the project has resulted in three scientific conference contributions.