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CLIMIT-Forskning, utvikling og demo av CO2-håndtering

Nanocomposite Facilitated Transport Membranes for H2 purification

Alternative title: Nanokompositt baserte fasiliterttransportmembraner for H2 produksjon

Awarded: NOK 9.2 mill.

The FaT H2 project (Nanocomposite Facilitated Transport Membranes for H2 purification) aims to develop efficient and low-cost separation technology for hydrogen purification from various production processes. Hydrogen is widely recognized as the most promising non-carbon-based fuel for energy production in the future society. Currently, hydrogen is mainly obtained through steam reforming of hydrocarbons coming from fossil fuels (e.g., natural gas, coal) and biological sources (e.g., dark-fermentation of biomass) with subsequent H2 purification by pressure swing adsorption (PSA). The absence of CO2 and other by-products upon hydrogen combustion or usage in fuel cells makes it an environmental-friendly energy source, giving the possibility to reduce the anthropogenic impact on the environment, thus alleviating climate change. Compared to traditional separation methods, membrane separation is an emerging environmentally friendly technology that offers advantages, including a smaller footprint, lower capital and operating costs, and less energy consumption. Membrane technology for CO2/H2 separation, especially when using CO2-selective membranes to keep H2 on the high-pressure retentate side, has been considered more energy-efficient for further H2 transport and utilization. The proposed technology is based on CO2-selective membranes. FaT H2 project focuses on developing nanocomposite facilitated transport membranes using polymers containing CO2-philic carriers with surface-modified graphene oxide (GO) and its derivatives as 2D nano-fillers for enhanced CO2 transport. The project has been carried out as four work packages (WPs), including membrane material selection/characterization (WP1), fabrication of graphene-based nanocomposite membranes (WP 2), evaluation of membrane separation performance (WP3), and process analysis and cost estimation (WP 4). Nanocomposite-facilitated transport membranes with 2D nanofillers (e.g., GO or grafted-GO) have been synthesized, characterized, and evaluated. The membrane fabrication has been optimized with compatible porous supports and coating procedures, with different types and contents of mobile carriers and membrane thicknesses. In order to make the membranes CO2-selective in CO2/H2 separation, polyvinyl amine (PVAm) and polyallylamine (PAA) were selected as a polymeric matrix with covalently attached amino groups as CO2 carriers, and optimized GO as well as CO2-philic, grafted GO has been used as 2D nanofillers. The facilitated transport effect of amino groups in PVAm and PAA enhances CO2 transport, while the GO-based 2D nanosheets show barrier effects to compensate for the high H2 diffusivity. The GO-modified surface with higher CO2 affinity also brings in additional CO2 sorption sites. Three types of CO2-philic additives as mobile carriers have also been identified to improve CO2 permeation. The effects of elevated temperature (separation at about 25 -110 °C) and impurities (e.g., H2S, CO) have been investigated. Membranes with CO2/H2 selectivity of up to 22 with CO2 permeability 61.6 Barrer were reported; the separation performances are far above the Robeson upper bound, outperforming most reported membranes under the same separation conditions. The techno-economic analysis and benchmarking to integrate the synthesized membranes in specific H2 production processes have been performed using the data from lab testing. Two-stage and three-stage membrane systems have been evaluated for comparison. In the case of bio-hydrogen purification, the two-stage process using the developed membranes is found economically feasible and able to produce high purity H2 (99.5 vol.%) as fuel, which also simultaneously captures CO2 (CO2 loss < 1%) with high CO2 purity (>90 vol.%). The minimum specific cost of H2 purification is 0.235 $/Nm3 under optimal operating temperature. A third stage can be introduced to further increase the CO2 purity to make CO2 a side product, enabling negative carbon emission. Other findings during the research include: 1. Introducing even a small amount of GO or grafted GO (e.g., 0.5% PVA-GO) into facilitated transport membranes significantly improves the CO2/H2 selectivity. 2. The CO2/H2 separation performance of the membranes is thickness dependent. Increasing membrane thickness benefits CO2/H2 selectivity and CO2 transport, showing a typical facilitated transport effect. 3. The membranes have also been evaluated for their CO2/N2 and CO2/Helium separation performances (used as indicators for membrane material screening and optimization), presenting high separation performances. 4. The membranes can be fabricated into both flat sheet and hollow fiber modules.

New knowledge and competence on CO2-selective membranes for CO2/H2 separation, especially with regard to the understanding of facilitated transport mechanism integrated with the involved effects of 2D nanosheets in the membranes and the fabrication of thin nanocomposite membranes with controlled thicknesses, were generated during the FaT H2 project. The project results enabled significant advances in membrane technology for CO2/H2 separation applications. Feasibility studies based on the separation performances of the developed membranes proved that using the CO2-selective membrane for H2 purification is more energy-efficient and economically beneficial than the H2-selective solution. The project outcome has drawn industrial attention to developing the technology, which may lead to new job opportunities. The knowledge generated has also contributed to building international knowledge in the field of membrane separation technology as well as methods for H2 purification and CO2 removal. The project team has published 7 academic articles in high-impact scientific journals (Journal of Membrane Science, Chemical Engineering Journal, Applied Materials Today, etc.), and another four manuscripts are in preparation. We have also disseminated the project results at international conferences, seminars, meetings, and public events (EuroMembrane, Carbon Capture Science and Technology, The Research Night, etc.). Published papers cover topics on membrane material optimization, the effects of 2D nanosheets, mobile carriers, membrane fabrication, separation performances, and techno-economic studies. The discoveries and knowledge built through the project have derived new project concepts and applications on graphene-based nanocomposite materials and the use of facilitated transport membranes for CO2/H2 separation, including the MOGLiS, 3S Battery, and BioH2Fuel project. The MOGLiS project (MOF@rGO-based cathodes for Li-S Batteries) funded by the M-ERA.NET call (2021-2023), and the 3S Battery project (Super selective separators for battery applications, a proposal submitted) are based on GO-based nanocomposite materials in battery applications, while the BioH2Fuels project (bio-hydrogen for fuels an EU project proposal) is to use CO2-selective membranes to remove CO2 directly from bio-reactors to enhance bio-hydrogen separation. From the competence-building and education perspective, one Ph.D. student and four master’s students, as well as three researchers, have received their academic training through carrying out research activities in the project.

The project entitled "Nanocomposite Facilitated Transport Membranes for H2 purification" (FaT H2) aims at developing an efficient separation technology to produce hydrogen as fuel using CO2-selective nanocomposite membranes. This project will focus on (1) the synthesis of facilitated transport membrane using nanocomposite material based on graphene derivatives, (2) the investigation of the transport properties, including the effects of impurities such as SO2, H2S, CO, and (3) the process design and techno-economic analysis of the proposed new membranes for specific H2 production process. The addition of graphene-based nanofiller to the facilitated transport membrane is expected to improve the membrane morphology at the nano-level, increasing the membrane stability and separation performance. Compared to H2-selective membranes, the use of CO2-selective membranes leads to several benefits. In the case of syngas, the high pressure of the produced hydrogen can be maintained, enhancing the fuel energy value, while in the case of biological production, CO2 will be removed by membrane from the head of the reactor, enhancing its production performance. The project will be performed within the membrane research lab at NTNU. SINTEF Industry will be project partner. A high-level international cooperation with reputable research institutes in the US (The Ohio State University, OSU) and UK (The University of Edinburgh) will also add great value to the research and education. Industry producers and end users of the developed technology, represented by Graphene-XT ASA (Italy) and CondAlign (Norway), will participate in the scientific steering meetings to provide industry perspectives. One Phd, one researcher, and several master students will receive their scientific training through the project.

Publications from Cristin

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CLIMIT-Forskning, utvikling og demo av CO2-håndtering