Hydrogen storage capacity enhancement of MIL-53(Cr) by Pd loaded activated carbon doping

White-box methodologies for achieving robust correlations in hydrogen storage with metal-organic frameworks

Hydrogen is recognized as a clean energy replacement for non-renewable fossil fuels, and the utilization of metal-organic frameworks (MOFs) for hydrogen storage has gained considerable interest in recent years. In this study, hydrogen storage in MOFs was estimated using white-box methods, namely group method of data handling (GMDH), genetic programming (GP), and gene expression programming (GEP), which are robust soft-computing methods known for generating innovative correlations. To this end, temperature, pressure, pore volume, and surface area were implemented as input parameters for constructing these robust correlations. After that, the superiority of the established correlations was demonstrated through multiple statistical and graphical error assessment. The results indicated, the GMDH model demonstrates the highest accuracy with root mean square error (RMSE), and mean absolute error (MAE) values of 0.410 and 0.307, respectively. However, the GEP model's accuracy was comparable to that of the GMDH model. In addition, sensitivity assessment showed that the pore volume and the pressure exhibit the strongest linear and non-linear relationships, respectively, with the H2 storage in MOFs. This was demonstrated by a Pearson correlation coefficient of 0.5 and a Spearman correlation coefficient of 0.56, respectively. Furthermore, temperature had a minimal negative impact on the H2 storage in MOFs according to Pearson, Spearman, and Kendall coefficients. Finally, to confirm the findings of the GMDH model, the leverage approach was applied, demonstrating that 96% of the data falls within the acceptable region, confirming the statistical reliability of the developed models.

Advancements in Solid-State Hydrogen Storage: A Review on the Glass Microspheres

Glass microspheres, with their unique internal structure and chemical stability, offer a promising solution for the challenges of hydrogen storage and transmission, potentially advancing the utility of hydrogen as a safe and efficient energy source. In this review, we systematically evaluate various treatment and modification strategies, including fusion, sol-gel, and chemical vapor deposition (CVD), and compare the performance of different types of glass microspheres. Our synthesis of current research findings reveals that specific low-cost and environmentally friendly modification techniques can significantly enhance the hydrogen storage efficiency of glass microspheres, with some methods increasing storage capacity by up to 32% under certain conditions. Through a detailed life-cycle and cost-benefit assessment, our study highlights the economic and sustainability advantages of using modified glass microspheres. For example, selected alternative materials used in lightweight vehicles have been shown to reduce density by approximately 10% while reducing costs. This review not only underscores the contributions of modified glass microspheres to overcoming the limitations of current hydrogen storage technologies but also provides a systematic framework for improving their performance in hydrogen storage applications. Our research suggests that modified glass microspheres could help to make hydrogen energy more commercially viable and environmentally friendly.

Recent Developments in Materials for Physical Hydrogen Storage: A Review

The depletion of reliable energy sources and the environmental and climatic repercussions of polluting energy sources have become global challenges. Hence, many countries have adopted various renewable energy sources including hydrogen. Hydrogen is a future energy carrier in the global energy system and has the potential to produce zero carbon emissions. For the non-fossil energy sources, hydrogen and electricity are considered the dominant energy carriers for providing end-user services, because they can satisfy most of the consumer requirements. Hence, the development of both hydrogen production and storage is necessary to meet the standards of a "hydrogen economy". The physical and chemical absorption of hydrogen in solid storage materials is a promising hydrogen storage method because of the high storage and transportation performance. In this paper, physical hydrogen storage materials such as hollow spheres, carbon-based materials, zeolites, and metal-organic frameworks are reviewed. We summarize and discuss the properties, hydrogen storage densities at different temperatures and pressures, and the fabrication and modification methods of these materials. The challenges associated with these physical hydrogen storage materials are also discussed.

Performance of Mixed Matrix Membranes Containing Porous Two-Dimensional (2D) and Three-Dimensional (3D) Fillers for CO₂ Separation: A Review

Application of conventional polymeric membranes in CO₂ separation processes are limited by the existing trade-off between permeability and selectivity represented by the renowned upper bound. Addition of porous nanofillers in polymeric membranes is a promising approach to transcend the upper bound, owing to their superior separation capabilities. Porous nanofillers entice increased attention over nonporous counterparts due to their inherent CO₂ uptake capacities and secondary transport pathways when added to polymer matrices. Infinite possibilities of tuning the porous architecture of these nanofillers also facilitate simultaneous enhancement of permeability, selectivity and stability features of the membrane conveniently heading in the direction towards industrial realization. This review focuses on presenting a complete synopsis of inherent capacities of several porous nanofillers, like metal organic frameworks (MOFs), Zeolites, and porous organic frameworks (POFs) and the effects on their addition to polymeric membranes. Gas permeation performances of select hybrids with these three-dimensional (3D) fillers and porous nanosheets have been summarized and discussed with respect to each type. Consequently, the benefits and shortcomings of each class of materials have been outlined and future research directions concerning the hybrids with 3D fillers have been suggested.