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![e Comparison of gravimetric density and volumetric density of several fuels depending on lower heating values [2].](profile/Ezgi-Dundar-Tekkaya/publication/300001386/figure/fig1/AS:645500231483392@1530910656606/e-Comparison-of-gravimetric-density-and-volumetric-density-of-several-fuels-depending-on.png)
e Comparison of gravimetric density and volumetric density of several fuels depending on lower heating values [2].
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![Fig. 2 e TEM image of MCM-41 [27].](profile/Ezgi-Dundar-Tekkaya/publication/300001386/figure/fig2/AS:645500231491584@1530910656638/e-TEM-image-of-MCM-41-27_Q320.jpg)
Decreasing supply of fossil fuels and concerns about environmental issues makes hydrogen a good alternative to fossil fuel sources as it is an environmentally friendly energy carrier. However, the storage of hydrogen is the main challenge to its effective use. For the utilization of hydrogen, the development of safe, effective and high capacity sto...
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Context 1
... limited resources of fossil fuels and the rising demand of energy is a matter of fact, which is also closely related to the environmental issues. Hence, green technologies have been developed to reduce the consumption of fossil fuels. Hydrogen that is an environmentally friendly energy carrier is one of the best alternatives to the fossil fuel sources for both stationary and mobile applications. For this reason although there is an increasing demand for hydrogen production, storage is the bottleneck against widespread use of hydrogen due to its low volumetric density. In order to meet the commercial needs, the Department of Energy (DOE) of the United States has tar- geted system level hydrogen storage capacity of 5.5 wt% (1.8 kWh/kg) and 0.040 kg/L (1.3 kWh/L) by the fiscal year 2020 which requires a much higher gravimetric capacity ( Fig. 1) of the material alone [1]. Reversibility, feasibility and safety are also matters of concern for the development of storage sys- tems. Hence, it is an attractive research topic to maintain the DOE targeted hydrogen uptake and develop new materials for this ...
Context 2
... against widespread use of hydrogen due to its low volumetric density. In order to meet the commercial needs, the Department of Energy (DOE) of the United States has tar- geted system level hydrogen storage capacity of 5.5 wt% (1.8 kWh/kg) and 0.040 kg/L (1.3 kWh/L) by the fiscal year 2020 which requires a much higher gravimetric capacity ( Fig. 1) of the material alone [1]. Reversibility, feasibility and safety are also matters of concern for the development of storage sys- tems. Hence, it is an attractive research topic to maintain the DOE targeted hydrogen uptake and develop new materials for this ...
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![Detailed physical characteristics of ammonia [34,35].](publication/342175152/figure/tbl1/AS:905624686690306@1592929159687/Detailed-physical-characteristics-of-ammonia-34-35_Q320.jpg)
Ammonia is considered to be a potential medium for hydrogen storage, facilitating CO2-free energy systems in the future. Its high volumetric hydrogen density, low storage pressure and stability for long-term storage are among the beneficial characteristics of ammonia for hydrogen storage. Furthermore, ammonia is also considered safe due to its high...
Citations
... compressed gas or cryogenic liquid, storage in solid form is one of the more suitable ways for the hydrogen fuel. This includes using the absorption on metal hydrides and complex hydrides [13,14], as well as various nanoporous materials [15,16] and in particular metal-organic frameworks (MOF) [17] or zeolites [18,19]. ...
Hydrogen storage by physisorption on carbon-based materials is limited by comparatively low adsorption energies. However, decoration of the carbon substrate with alkali, alkaline earth, or other metal atoms has been proposed as a means to enhance adsorption energies. The decoration affects also the stability of these materials since it makes them more stable and resilient in the repeated cycles of charge and discharge that would be required for a good material devoted to storage. We investigate hydrogen storage capacities of small polycyclic aromatic hydrocarbons (PAHs) cations grown in ultracold helium nanodroplets by analyzing the ion abundances and stabilities. The observations are assessed with quantum chemical calculations and atomistic simulations. It is experimentally shown that the addition of an alkali ion significantly enhances the hydrogen adsorption of the studied PAHs, up to 25% over the bare PAH in the experimental conditions studied here, and the simulations confirm this general trend except for some minor residual discrepancies in the special stabilities (magic numbers). Several approaches to study larger and different PAH compounds are also proposed, and for all cases it is found that alkali decoration increases energy stability by more than 100%.
... Heterogeneous catalysts offer a cleaner and more environmentally friendly production alternative than their counterpart in the homogeneous phase, in addition easier recovery and substitution of hazardous reagents. [3] This is why researchers have directed their interest to the development of catalytic pathways from heterogeneous catalysts. [4] Among the materials that can be used as supports, mesoporous materials as MCM-41 with large surface area (up to 1500 m 2 /g) and an ordered hexagonal arrangement of cylindrical pores [5] are preferred for transformation of big molecules and for adsorption processes. ...
... [4] Among the materials that can be used as supports, mesoporous materials as MCM-41 with large surface area (up to 1500 m 2 /g) and an ordered hexagonal arrangement of cylindrical pores [5] are preferred for transformation of big molecules and for adsorption processes. [3] Sn-MCM-41 is an active material for the production of nopol, [6] a conversion of 99.6 % and a selectivity to nopol of 98 % (0.5 mmol of β-pinene, 1 mmol of paraformaldehyde, 25 mg of Sn-MCM-41 with a content of 510 μmol Sn/g support , 1 mL of toluene, 90°C) [7] have been obtained. The rate law of this reaction was reported from data obtained in a batch reactor using a kinetics model based on the Langmuir-Hinshelwood approach with the surface reaction of reactants adsorbed on catalytic sites of the same nature as limiting step. ...
The kinetic study of the synthesis of nopol from β‐pinene and formaldehyde generated ex‐situ was carried out in a continuous flow process using Sn‐MCM‐41 wall‐coated microreactors of 1/8“ stainless steel tubes. The presence of Sn²⁺ and Sn⁴⁺ species was identified through XPS and TEM; the homogeneous distribution of tin on the support throughout the surface of the coating was verified by SEM analysis. Taylor flow regime and the kinetic control of the reaction were verified with hydrodynamic studies. A determination coefficient of 0.92 was obtained for the mathematical adjustment of the equation that described the reaction pathway obtained under the assumption of a dual‐site Langmuir‐Hinshelwood formalism with product desorption as the limiting step.
... Additionally, specific surface properties were imparted to OMS by various modification processes, i.e., grafting, co-condensation, or creating hybrid core-shell structures. The enormous application potential of the obtained materials in sorption [26][27][28][29][30][31][32], catalysis [33][34][35][36], delivery [37][38][39][40][41][42][43], separation [44], chromatography [45], energy conversion, and storage [46][47][48] In this work, the green approach in the SBA-15 synthesis is presented. The proposed new strategy is based on using aluminum phyllosilicate (bentonite) as an alternative silica source to commercial agents such as TEOS, TMOS (tetramethyl orthosilicate), or TBOS (tetrabutyl orthosilicate) [49][50][51]. ...
Citation: Zienkiewicz-Strzalka, M.; Pikus, S.; Skibinska, M.; Blachnio, M.; Derylo-Marczewska, A. The Structure of Ordered Mesoporous Materials Synthesized from Aluminum Phyllosilicate Clay (Bentonite). Molecules 2023, 28, 2561. Abstract: This paper reports the synthesis and structural analysis of mesoporous silica materials with the use of aluminum phyllosilicate clay (bentonite) as an alternative silica source. In the proposed synthesis, bentonite, as natural aluminosilicate, was used instead of commercially available and quite expensive tetraethyl orthosilicate (TEOS) silica source. The objective of the research study was to determine the effect of aluminum loading in the mesoporous silica body for ordering structure, porosity, and potential sorption capacity to thorium ions. The unique direction developed in this procedure is focused on preparing advanced materials from natural sources with their own desired functionality and general availability. The applied procedure based on the classic, one-step synthesis of SBA-15 silicates was modified by gradually increasing the bentonite amount with simultaneous reduction of the TEOS content. The structural and morphological characterization, as well as evaluation of the porous structure of the obtained materials, was performed using powder wide-angle X-ray diffraction (XRD), small-angle scattering (SAXS), transmission and scanning electron microscopy (TEM, SEM), low-temperature nitrogen adsorption-desorption methods and potentiometric titration. The new, cost-effective composites for the removal of Th(IV) ions are proposed. The synergistic effect of expanding the porous surface using bentonite as a silica precursor and the presence of thorium-binding groups (such as Al 2 O 3) is indicated.
... H 2 is readily transportable and can be preserved in a variety of materials. The fundamental technique for fuel cells and other associated field development is H 2 storage [129]. ...
The transportation sector is one of the major consumers of fuel i.e., mostly relying on fossil-based fuels. With the rising energy demand and consumption of fossil fuels, the concentration of pollutants and greenhouse gases (GHGs) are increasing in the atmosphere. Hydrogen (H 2) is a well-known source of clean energy options and a better alternative to fossil fuels. It has the potential to become a promising fuel for renewable transportation by providing safe, efficient, stable, accessible, and customer-friendly energy. This is due to its many characteristics, such as energy density, high calorific value, affordability, and a wide variety of production methods. H 2 has the potential to completely replace the use of fossil fuel in internal combustion engines. The review highlights the recent advances in H 2 production, storage, and transportation. Apart from the conventional steam reforming technique i.e., producing around 85% of the world's grey H 2 , several clean techniques such as partial oxidation, plasma reforming, water electrolysis, pyrolysis, and photoelectrolysis are comprehensively discussed. Despite its many advantages, H 2 storage is a significant issue. Hence, the recent advances and challenges in H 2 storage i.e., physical, and material-based techniques have been deliberated. Further, the risks involved during the production , handling, and transportation of H 2 fuel is highlighted, and the latest trends in its safety recommendations have been suggested. Finally, the techno-economic feasibility challenges and its outlook has been discussed.
... Current Study replacement for diminishing fossil reserves [39][40][41][42][43][44]. ...
... Despite the significance of the DRM, there is scarce documentation available (at present) on its commercialization. Some sources attribute this to the high temperature requirement for the reaction especially [3,[39][40][41][42][43]; while many others argued that inevitable coke formation and product molar ratios are responsible [40,44,45]. No clear record appeared as a search result (in all fields) on "Prospects of methane dry reforming" in the WoS, particularly in comparison to only 5 for "valorization of dry methane reforming" while only 20 articles appeared for the combined search of "valorization" and "dry methane reforming" (as at March 17th, 2022). ...
Environmental pollution and energy depletion are among society's great concerns today. Simultaneous removal of the two most harmful greenhouse gases viz; CH 4 and CO 2 by dry reforming of methane (DRM) is a promising alternative. Production of hydrogen as a substitute fuel is an exciting and promising technology since it contributes to the decrease of environmentally hazardous emissions. Despite the numerous environmental incentives of the DRM process, it is still at an immature stage in the industry; its main problems are being highly endo-thermic, severe catalyst coking and subsequent deactivation among others. Hereunder, the bibliometric analysis of title search from 1970 to 2022 for keywords, countries, journals, inter-country coauthor networks and co-occurrence visualizations using the WoS database along with the R-studio were presented. Within 32 years (1990-2022), data were filtered from 1000 publications, 863 of which are research papers with an average citation of 6.182 per document, 34 review articles and 86 article proceedings with 1730 and 1338 total author keywords, respectively. It is justified that a research gap still exists as the DRM industrialization is only partly achieved. In the subsequent sections, highlights of the significance of commercializing the process is highly emphasized while effort is devoted to devising techniques to address related challenges undermining its commercialization. Possible solutions to problems that may hinder the commercialization of the process were discussed and how its commercialization will be of immense benefit in that profitable implementation could generate feed for the Fischer-Tropsch's energy process. To wind up, the article stated how the various factors can be put into practice for hydrogen production.
... Hydrogen can be physically stored as a gas or a liquid [69]. Physical storage means storing it in its molecular form. ...
The unbridled use of fossil fuels is a serious problem that has become increasingly evident over the years. As such fuels contribute considerably to environmental pollution, there is a need to find new, sustainable sources of energy with low emissions of greenhouse gases. Climate change poses a substantial challenge for the scientific community. Thus, the use of renewable energy through technologies that offer maximum efficiency with minimal pollution and carbon emissions has become a major goal. Technology related to the use of hydrogen as a fuel is one of the most promising solutions for future systems of clean energy. The aim of the present review was to provide an overview of elements related to the potential use of hydrogen as an alternative energy source, considering its specific chemical and physical characteristics as well as prospects for an increase in the participation of hydrogen fuel in the world energy matrix.
... Hydrogen can be physically stored as a gas or a liquid [69]. Physical storage means storing it in its molecular form. ...
Citation: Farias, C.B.B.; Barreiros, R.C.S.; da Silva, M.F.; Casazza, A.A.; Converti, A.; Sarubbo, L.A. Use of Hydrogen as Fuel: A Trend of the 21st Century. Energies 2022, 15, 311.
... One of the major challenges in integrating fuel cells into the energy system is the overcoming the inconveniences of hydrogen storage as highly compressed gas in large and thick tanks or the cost of cryogenic liquid hydrogen, especially for portable and on-board uses. Other approaches for hydrogen storage such as its absorption in high surface carbon-based materials such as nanotubes, nanorods, graphite and activated carbon [3,4], and other non-carbon materials such as mesoporous silica (MCM-41) [5], high entropy alloys [6,7], metallic organic frameworks (MOFs) [8][9][10] have emerged, but the main drawback is that their gravimetric hydrogen capacity is lower than 1% at ambient temperature and high pressure up to 100 bar, which is far below the respective gravimetric and volumetric performance target of 4.5 wt% and 30 g/L and the ultimate target of 6.5 wt% and 50 g/L at 233-358 K and 5-12 bars set by the US Department of Energy (DoE) for usable hydrogen storage capacity of on-board or mobile storage systems for the year 2020. Some of the MOFs achieve gravimetric hydrogen capacity on par to or even better than the DoE's target at much higher pressures and at cryogenic temperature (77 K) but as the temperature is increased, to as high as 160 K, the capacity sharply drops. ...
Methylcyclohexane (MCH), one of the liquid organic hydrogen carriers (LOHCs), offers a convenient way to store, transport, and supply hydrogen. Some features of MCH such as its liquid state at ambient temperature and pressure, large hydrogen storage capacity, its well-known catalytic endothermic dehydrogenation reaction and ease at which its dehydrogenated counterpart (toluene) can be hydrogenated back to MCH and make it one of the serious contenders for the development of hydrogen storage and transportation system of the future. In addition to advances on catalysts for MCH dehydrogenation and inorganic membrane for selective and efficient separation of hydrogen, there are increasing research interests on catalytic membrane reactors (CMR) that combine a catalyst and hydrogen separation membrane together in a compact system for improved efficiency because of the shift of the equilibrium dehydrogenation reaction forwarded by the continuous removal of hydrogen from the reaction mixture. Development of efficient CMRs can serve as an important step toward commercially viable hydrogen production systems. The recently demonstrated commercial MCH-TOL based hydrogen storage plant, international transportation network and compact hydrogen producing plants by Chiyoda and some other companies serves as initial successful steps toward the development of full-fledged operation of manufacturing, transportation and storage of zero carbon emission hydrogen in the future. There have been initiatives by industries in the development of compact on-board dehydrogenation plants to fuel hydrogen-powered locomotives. This review mainly focuses on recent advances in different technical aspects of catalytic dehydrogenation of MCH and some significant achievements in the commercial development of MCH-TOL based hydrogen storage, transportation and supply systems, along with the challenges and future prospects.
... Storage of excess renewable energy carriers in natural and engineered environments is critical to meeting our energy needs on demand. In this context, there is an emerging interest in exploring subsurface environments (Pfeiffer and Bauer, 2015;Berta et al., 2018;Shi et al., 2020) and engineered materials (Yun et al., 2002;Düren et al., 2004;Dündar-Tekkaya and Yürüm, 2016) to store clean energy carriers such as biomethane and hydrogen. Further, safe and permanent storage of CO 2 in geologic formations at the gigaton scale is essential if renewable and non-renewable carbon-bearing fuels continue to be used (Bachu et al., 2007;Aydin et al., 2010;Michael et al., 2010;Jiang, 2011;Zhang and Bachu, 2011). ...
Advancing a portfolio of technologies that range from the storage of excess renewable natural gas for distributed use to the capture and storage of CO2 in geological formation is essential for meeting our energy needs while responding to challenges associated with climate change. Delineating the surface interactions and the organization of these gases in nanoporous environments is a less explored but highly relevant approach to develop novel materials for gas storage or for predicting the fate of stored gases in subsurface environments. To this end, the molecular scale interactions underlying the organization and transport behavior of CO2 and CH4 molecules in silica nanopores need to be investigated. To probe the influence of hydrophobic surfaces, a series of classical molecular dynamics (MD) simulations are performed to investigate the structure and dynamics of CO2 and CH4 confined in OH-terminated and CH3-terminated silica pores with diameters of 2, 4, 6, 8, and 10 nm at 298 K and 10 MPa. Higher adsorption extents of CO2 compared to CH4 are noted on OH-terminated and CH3-terminated pores. The adsorbed extents increase with the pore diameter. Further, the interfacial CO2 and CH4 molecules reside closer to the surface of OH-terminated pores compared to on the surface of CH3-terminated pores. The lower adsorption extents of CH4 on OH-terminated and CH3-terminated pores result in higher diffusion coefficients compared to CO2 molecules. The diffusivities of both gases in OH-terminated and CH3-terminated pores increase systematically with the pore diameter. The higher adsorption extents of CO2 on OH-terminated and CH3-terminated pores are driven by the higher van der Waals and electrostatic interactions with the pore surfaces while CH4 adsorption is mainly due to van der Waals interactions with the pore walls. These findings provide the interfacial chemical basis underlying the organization and transport behavior of pressurized CO2 and CH4 gases in confinement.
... MCM-41 is a mesoporous material with high surface area and a regular hexagonal array of large cylindrical pores that can be used as catalyst, catalyst support or as adsorbent. Some MCM-41 applications are encapsulation of metals, the adsorption of biomolecules for drug delivery, storage of hydrogen and hydrocarbons, and reactions of epoxidation and esterification, among others (Ref [6][7][8][9]. ...
A method for washcoating of MCM-41 onto the internal surface of a stainless steel tubular microreactor was developed. The suspension was prepared with polyvinyl alcohol, milled MCM-41, colloidal silica, water, and acetic acid, with mass percentage of x1, x2, x3, x4 and x5, respectively. The effect of the slurry composition on the characteristics of the coating (adhesion, thickness and loading) was identified by a statistical mixture design; values of x1, x2, x3 and x4 were varied and x5 was fixed in 1.0 wt.%. The thickness and homogeneity of the coating in the microreactor were evaluated by SEM, while loading and adhesion were gravimetrically estimated. In the cases, a good adherence layer was found. The statistical methodology of mixture D-Optimal type showed that the component of the suspension with the highest effect on the coating properties was PVA. Thickness (22 ± 5 µm) and loading (2.59 mg/cm2) of the coating were optimized with the criteria of a minimum thickness with a maximum possible loading due to the need to find the right combination to increase microreactor efficiency in applications such as catalysis. The optimal composition of the suspension obtained by statistical analysis was PVA (1.9 wt.%), MCM-41 (15.2 wt.%), colloidal silica (5.0 wt.%) and water (76.9 wt.%).
