Nicholaus Prasetya’s research while affiliated with University of Luxembourg and other places

Hydrogen has emerged as one of the cleanest energy vectors that can support the transition into a green economy and thus can facilitate the transition to a carbon-neutral environment. Common hydrogen production methods include coal gasification, steam reforming, methane pyrolysis, and water electrolysis. All the hydrogen production methods produce a mixture of H2 and other products such as CO2, N2 and CH4 depending on the method. To separate hydrogen from the other molecules, common methods like cryogenic distillation and pressure swing adsorption have been used widely. In addition to these methods, membranes can be used which offer energy efficiency compared to the previously mentioned methods. The widely used membranes for H2 separation are metallic membranes such as palladium-based membranes. Despite their high separation performance, they are not cost-effective. Another type of membrane that can address cost-efficiency, energy consumption, and performance limitations, is the polymeric membrane. Moreover, polymeric membranes are also solution-processable and thus bringing another advantage from a fabrication point of view. However, polymeric membranes usually suffer from a permeability-selectivity trade-off. Therefore, there is a need to improve the hydrogen separation performance of polymeric membranes, and one effective strategy is forming mixed matrix membranes (MMM). MMM is a composite membrane comprised of at least two components: polymers and fillers. The presence of the fillers in this type of membrane is important to improve the separation performance of the polymeric membranes. This review then aims to provide an overview of MMM used for hydrogen separation starting from their fabrication strategies until thorough discussions and assessments of different fillers. Moreover, this article also comprehensively evaluates the performance of the MMM by assessing their improvement on the separation performance and scrutinizing the impact of the filler's physical properties on the MMM performance. Lastly, the outlook for the field is also given to direct the future research in this field.

With the pressing concern of the climate change, hydrogen will undoubtedly play an essential role in the future to accelerate the way out from fossil fuel‐based economy. In this case, the role of membrane‐based separation cannot be neglected since, compared with other conventional process, membrane‐based process is more effective and consumes less energy. Regarding this, metal‐based membranes, particularly palladium, are usually employed for hydrogen separation because of its high selectivity. However, with the advancement of various microporous materials, the status quo of the metal‐based membranes could be challenged since, compared with the metal‐based membranes, they could offer better hydrogen separation performance and could also be cheaper to be produced. In this article, the advancement of membranes fabricated from five main microporous materials, namely silica‐based membranes, zeolite membranes, carbon‐based membranes, metal organic frameworks/covalent organic frameworks (MOF/COF) membranes and microporous polymeric membranes, for hydrogen separation from light gases are extensively discussed. Their performances are then summarized to give further insights regarding the pathway that should be taken to direct the research direction in the future.

With the pressing concern of the climate change, hydrogen will undoubtedly play an essential role in the future to accelerate the way out from fossil fuel-based economy. In this case, the role of membrane-based separation cannot be neglected since, compared with other conventional process, membrane-based process is more effective and consumes less energy. Regarding this, metal-based membranes, particularly palladium, are usually employed for hydrogen separation because of its high selectivity. However, with the advancement of various microporous materials, they could challenge the status quo of the metal-based membranes since they could offer both high hydrogen permeability and selectivity while also relatively cheaper to be produced. In this article, the advancement of five main microporous material membranes, namely silica-based membranes, zeolite membranes, carbon-based membranes, metal organic frameworks/covalent organic frameworks (MOF/COF) membranes and microporous polymeric membranes are extensively discussed. Their performances for hydrogen separation are then summarized to give further insights regarding the pathway that should be taken to direct the research direction in the future.

Over the past twenty years, metal-organic frameworks (MOFs) have emerged as extensively developed porous class of materials and are increasingly recognized as promising candidates for membrane-based CO2 separation. This potential primarily stems from the ability to deliberately customize their structure and functionalities to enhance interactions with guest molecules. In this study, we explore the use of MOF-525, a porphyrin-based MOF, as a nanofiller in a mixed matrix membrane (MMM) composed of 6FDA-DAM (6FDA: 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride; DAM: 2,4,6-trimethyl-1,3-diaminobenzene) polymer for CO2/N2 and CO2/CH4 separations. This particular MOF is chosen because of the possibility to metalate its porphyrin ring to tailor the interaction between the CO2 molecule and the MOF framework. As a result, the CO2/N2 and CO2/CH4 separation performance of the MMM loaded with metalated MOF-525 can be significantly improved without the necessity to use a very high nanoparticle loading. When compared to the bare polymeric membrane and 2 wt% non-metalated MOF-525 MMM, around 20% improvement in the membrane permeability and selectivity can be observed for the 2 wt% metalated MOF-525 MMM. Further analysis on the gas transport property of the MMM showed that the improvement mainly results from the enhanced CO2 solubility in the MMMs and improved interaction between the metalated MOF-525 and the CO2 molecule. However, it is also found that 2 and 5 wt% are the optimum loading value, above which the interfacial defects between the MOF nanoparticles and the polymers caused by the particle agglomeration starts to appear and thus deteriorating the membrane performance. This is also confirmed through the molecular simulations where some overestimations from the Maxwell model on the membrane permeability is observed particularly at high particle loading, indicating the agglomeration and the build-up of non-selective voids. Despite this, we have successfully shown in this study the high efficacy and efficiency of using metalated porphyrin MOFs for CO2 separation in a MMM since only relatively low particle loading (around 2 wt%) is required to improve the membrane performance.

Maintaining optimal relative humidity is paramount for human comfort. Therefore, the utilization of quartz crystal microbalance (QCM) as a humidity sensor platform holds significant promise due to its cost-effectiveness and high sensitivity. This study explores the efficacy of three free-base Zr porphyrin metal-organic frameworks (MOFs) - namely MOF-525, MOF-545, and NU-902 - as sensitive materials for QCM-based humidity sensors. Our extended experimental findings reveal that these materials exhibit notable sensitivity, particularly within relative humidity ranges of 40% to 100%. However, we observe potential irreversible adsorption sites within the MOF-545 framework, hindering its ability to revert to its initial state after prolonged exposure. In light of this observation, we conduct periodic cycling experiments at relative humidity levels of 40-70% to evaluate the measurement repeatability and feasibility of these sensors for indoor applications. Interestingly, the periodic cycling study demonstrates that MOF-545 shows promising repeatability, positioning it as a strong contender for indoor humidity sensing. In contrast, MOF-525 may necessitate extended desorption time, and NU-902 displays diminished sensitivity at low relative humidity levels. Nevertheless, a preliminary treatment of the MOF-545 QCM sensor may be necessary to address irreversible adsorption sites and uphold measurement repeatability, as only reversible adsorption sites are currently accessible. This study underscores the potential of MOF-based QCM sensors for effective humidity monitoring in indoor environments, thus facilitating improved comfort and environmental control.

Metal-organic frameworks (MOFs) have gained substantial attention as promising materials for gas separation membranes due to their exceptional porosity, tailorability, and functionalizability. In this study, we present a novel approach to further enhance the properties of porous polymer membranes emerging from MOFs through crosslinking of the organic linker molecules and subsequent metal-atom removal. To ensure reproducibility of the multi-step synthesis process and high quality of the resulting polymeric membranes, we automated the process and followed a machine learning optimization approach. The high-quality MOF-thin films (SURMOFs) were prepared in a layer-by-layer fashion directly on gold-coated porous alumina substrates. This direct synthesis proved crucial to preserve the structural integrity of the membranes and thus avoiding defect formation caused by a substrate-transfer process, which is usually required when advanced materials are used to fabricate a membrane. The initial SURMOF membrane exhibits moderate gas separation performance, once crosslinked, its gas selectivity could be significantly enhanced although with the compromise of lower gas permeance. Interestingly, once we removed the metal centers and thereby converted the SURMOF into a purely organic polymeric membrane, the membrane gas permeance could be restored almost to its initial condition while preserving the enhanced selectivities. In particular, the resulting polymeric membrane outperforms most commercially available polymer membranes for H2 /CO2 gas separation. This research outlines a promising approach to employ MOFs as template in the generation of advanced polymer membranes for various gas and liquid phase separation applications.