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Keywords = carbon molecular sieve

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28 pages, 4148 KiB  
Article
Energy Potential of Zea mays Grown in Cadmium-Contaminated Soil
by Agata Borowik, Jadwiga Wyszkowska, Magdalena Zaborowska and Jan Kucharski
Energies 2025, 18(9), 2402; https://doi.org/10.3390/en18092402 - 7 May 2025
Viewed by 445
Abstract
Cadmium is a non-essential element for proper plant growth and development and is highly toxic to humans and animals, in part because it inters with calcium-dependent processes in living organisms. For this reason, a study was conducted to assess the potential for producing [...] Read more.
Cadmium is a non-essential element for proper plant growth and development and is highly toxic to humans and animals, in part because it inters with calcium-dependent processes in living organisms. For this reason, a study was conducted to assess the potential for producing maize (Zea mays) biomass in cadmium-contaminated soil for energy purposes. The energy potential of Zea mays was evaluated by determining the heat of combustion (Q), heating value (Hv), and the amount of energy produced from the biomass. Starch, compost, fermented bark, humic acids, molecular sieve, zeolite, sepiolite, expanded clay, and calcium carbonate were assessed as substances supporting biomass production from Zea mays. The accumulation and redistribution of cadmium in the plant were also investigated. The study was conducted in a vegetation hall as part of a pot experiment. Zea mays was grown in uncontaminated soil and in soil contaminated with 15 mg Cd2+ kg−1. A strong toxic effect of cadmium on the cultivated plants was observed, causing a 62% reduction in the biomass of aerial parts and 61% in the roots. However, it did not alter the heat of combustion and heating value of the aerial part biomass, which were 18.55 and 14.98 MJ kg−1 d.m., respectively. Of the nine substances tested to support biomass production, only four (molecular sieve, compost, HumiAgra, and expanded clay) increased the yield of Zea mays grown in cadmium-contaminated soil. The molecular sieve increased aerial part biomass production by 74%, compost by 67%, expanded clay by 19%, and HumiAgra by 15%, but none of these substances completely eliminated the toxic effects of cadmium on the plant. At the same time, the bioaccumulation factor (BAF) of cadmium was higher in the roots (0.21–0.23) than in the aerial parts (0.04–0.03), with the roots showing greater bioaccumulation. Full article
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15 pages, 4108 KiB  
Article
Improved CO2/CH4 Separation in Carbon Molecular Sieve Membranes via Copolymerization of Long-Chain Flexible Structures
by Yingxiu Wu, Haiyan Guo, Bingyu Zhao, Yuxiu Yu, Yaodong Liu and Shouchun Zhang
Membranes 2025, 15(5), 128; https://doi.org/10.3390/membranes15050128 - 27 Apr 2025
Cited by 1 | Viewed by 937
Abstract
Carbon molecular sieve (CMS) membranes demonstrate considerable advantages and significant potential in the separation of CO2 and CH4. Nevertheless, current research predominantly emphasizes the enhancement of CMS membranes through the incorporation of rigid structures and chain spatial stacking. The role [...] Read more.
Carbon molecular sieve (CMS) membranes demonstrate considerable advantages and significant potential in the separation of CO2 and CH4. Nevertheless, current research predominantly emphasizes the enhancement of CMS membranes through the incorporation of rigid structures and chain spatial stacking. The role of flexible structures in this context remains inadequately understood. To address this gap, we introduced long-chain polydimethylsiloxane (PDMS) and copolymerized it to synthesize polyimide that combines rigid and flexible frameworks. This approach enabled us to investigate the impact of flexible structures on the structure and properties of carbon membranes by varying the PDMS content. The findings indicated that flexible PDMS significantly influenced the thermal decomposition behavior of polyimide and facilitated in situ silicon doping within the carbon membranes, thereby modifying the pore characteristics of the carbon film. Specifically, with a 10% addition of PDMS, the CO2 permeability of the CMS membrane reached 9556 Barrer, representing an enhancement of 103.9% and surpassing the 2019 upper bound for CO2/CH4 separation. Furthermore, the effect of pyrolysis temperature was also examined. Ultimately, this study offers a novel perspective on regulating the structural and performance characteristics of carbon membranes through the integration of long-chain flexible structures. Full article
(This article belongs to the Topic Membrane Separation Technology Research)
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16 pages, 3415 KiB  
Article
Catalytic Properties of ZnZrOx Obtained via Metal–Organic Framework Precursors for CO2 Hydrogenation to Prepare Light Olefins
by Rundong Cai, Heping Zheng, Hong Liang, Xiankun Chen and Jianhua Tang
Metals 2025, 15(4), 380; https://doi.org/10.3390/met15040380 - 28 Mar 2025
Viewed by 1623
Abstract
The conversion of CO2 into light olefins over bifunctional catalysts is a promising route for producing high-value-added products. This approach not only mitigates excessive CO2 emissions but also reduces the chemical industry’s reliance on fossil fuels. Among bifunctional catalysts, ZnZrOx [...] Read more.
The conversion of CO2 into light olefins over bifunctional catalysts is a promising route for producing high-value-added products. This approach not only mitigates excessive CO2 emissions but also reduces the chemical industry’s reliance on fossil fuels. Among bifunctional catalysts, ZnZrOx is widely used due to its favorable oxide composition. In this work, ZnZrOx solid solution was synthesized by calcining an MOF precursor, resulting in a large specific surface area and a small particle size. Characterization studies revealed that ZnZrOx prepared via MOF calcination exhibited an enhanced CO2 activation and H2 dissociation capacity compared to that synthesized using the co-precipitation method. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) showed that CO2 adsorption on ZnZrOx led to the formation of carbonate species, while HCOO* and CH3O* intermediates were generated upon exposure to the reaction gas. When ZnZrOx was combined with SAPO-34 molecular sieves under reaction conditions of 380 °C, 3 MPa, and 6000 mL·g_cat−1·h−1, the CO2 conversion reached 34.37%, with a light olefin yield of 15.13%, demonstrating a superior catalytic performance compared to that of the co-precipitation method. Full article
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19 pages, 2724 KiB  
Article
Carbon Molecular Sieve Membranes from Acenaphthenequinone–Biphenyl Polymer; Synthesis, Characterization, and Effect on Gas Separation and Transport Properties
by Jesús Ortiz-Espinoza, Olivia Hernández-Cruz, Mikhail Zolotukhin, F. Alberto Ruiz-Treviño, María Isabel Loría-Bastarrachea and Manuel Aguilar-Vega
Polymers 2025, 17(4), 541; https://doi.org/10.3390/polym17040541 - 19 Feb 2025
Viewed by 812
Abstract
A rigid, high temperature-resistant aromatic polymer, poly(1,1′-biphenyl)-6,8a-dihydroacenaphthylene-1(2H)-one (BDA) comprising acenaphthenequinone and biphenyl was successfully synthesized by superacid catalyzed polymerization. BDA has a high decomposition temperature (Td = 520 °C) that renders it a viable candidate for carbon molecular sieve membranes (CMSM) formation. [...] Read more.
A rigid, high temperature-resistant aromatic polymer, poly(1,1′-biphenyl)-6,8a-dihydroacenaphthylene-1(2H)-one (BDA) comprising acenaphthenequinone and biphenyl was successfully synthesized by superacid catalyzed polymerization. BDA has a high decomposition temperature (Td = 520 °C) that renders it a viable candidate for carbon molecular sieve membranes (CMSM) formation. BDA precursor pyrolysis at 600 °C (BDA-P600) leads to a carbon turbostratic structure formation with graphene-like amorphous strands in a matrix with micropores and ultramicropores, resulting in a carbon structure with higher diffusion and higher selectivity than dense BDA. When the BDA pyrolysis temperature is raised to 700 °C (BDA-P700), the average stacking number of carbon layers N increases, along with an increase in the crystallite thickness stacking Lc, and layer plane size La, leading to a more compact structure. Pure gas permeability coefficients P are between 3 and 5 times larger for BDA-P600 compared to the BDA precursors. On the other hand, there is a P decrease between 10 and 50% for O2 and CO2 between CMSM BDA-P600 and BDA-P700, while the large kinetic diameter gases N2 and CH4 show a large decrease in permeability of 44 and 67%, respectively. It was found that the BDA-P700 WAXD results show the emergence of a new peak at 2θ = 43.6° (2.1 Å), which effectively hinders the diffusion of gases such O2, N2, and CH4. This behavior has been attributed to the formation of new micropores that become increasingly compact at higher pyrolysis temperatures. As a result, the CMSM derived from BDA precursors pyrolyzed at 700 °C (BDA-P700) show exceptional O2/N2 gas separation performance, significantly surpassing baseline trade-off limits. Full article
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9 pages, 1196 KiB  
Article
A Rapid and Green Method for the Preparation of Solketal Carbonate from Glycerol
by Sanjib Kumar Karmee, Sreedhar Gundekari, Louis C. Muller and Ajinkya Hable
Reactions 2025, 6(1), 15; https://doi.org/10.3390/reactions6010015 - 13 Feb 2025
Viewed by 1147
Abstract
Glycerol is a biogenic waste that is generated in both the biodiesel and oleo-chemical industries. The value addition of surplus glycerol is of utmost importance for making these industries economically profitable. In line with this, glycerol is converted into glycerol carbonate, a potential [...] Read more.
Glycerol is a biogenic waste that is generated in both the biodiesel and oleo-chemical industries. The value addition of surplus glycerol is of utmost importance for making these industries economically profitable. In line with this, glycerol is converted into glycerol carbonate, a potential candidate for the industrial production of polymers and biobased non-isocyanate polyurethanes. In addition, glycerol can also be converted into solketal, which is the protected form of glycerol with a primary hydroxyl functional group. In this contribution, we developed a microwave-assisted solvent and catalyst-free method for converting solketal into solketal carbonate. Under conventional heating conditions, the reaction of solketal with dimethyl carbonate resulted in 70% solketal carbonate in 48 h. However, under microwave heating, 90% solketal carbonate was obtained in just 30 min. From the perspective of sustainability and green chemistry, biomass-derived heterogeneous catalysts are gaining importance. Therefore, in this project, several green catalysts, such as molecular sieves (MS, 4Å), Hβ-Zeolite, Montmorillonite K-10 clay, activated carbon from groundnut shell (Arachis hypogaea), biochar prepared from the pyrolysis of sawdust, and silica gel, were successfully used for the carbonyl transfer reaction. The obtained solketal carbonate was thoroughly characterized by 1H NMR, 13C NMR, IR, and MS. The method presented here is facile, clean, and environmentally benign, as it eliminates the use of complicated procedures, toxic solvents, and toxic catalysts. Full article
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13 pages, 1934 KiB  
Article
Ceria-Catalysed Production of Dimethyl Carbonate from Methanol and CO2: Effect of Using a Dehydrating Agent Combined with a Solid Cocatalyst
by Dichao Shi, Svetlana Heyte, Mickaël Capron and Sébastien Paul
Molecules 2024, 29(23), 5663; https://doi.org/10.3390/molecules29235663 - 29 Nov 2024
Viewed by 928
Abstract
The direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol over ceria-based catalysts, in the presence of a dehydrating agent shifting the thermodynamical equilibrium of the reaction, has received significant interest recently. In this work, several dehydrating agents, such as molecular [...] Read more.
The direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol over ceria-based catalysts, in the presence of a dehydrating agent shifting the thermodynamical equilibrium of the reaction, has received significant interest recently. In this work, several dehydrating agents, such as molecular sieves, 2,2-dimethoxypropane (DMP), dimethoxymethane (DMM) and 1,1,1-trimethoxymethane (TMM), are combined with commercial ceria to compare their influence on the DMC yield obtained under the same set of operating conditions. TMM is found to be the most efficient; however, its conversion is not complete even after 48 h of reaction. Therefore, it is proposed for the very first time, to the best of our knowledge, to add a second solid cocatalyst in the reaction medium to accelerate the TMM hydration reaction without degrading the DMC already formed. Basic oxides and acidic zeolites with different Si/Al ratios are employed to accelerate the hydration of TMM, so as to improve the DMC yield. 13X was identified as the best option to play this role. Finally, three different commercial cerias are tested in the presence of TMM and molecular sieve 13X as the second catalyst. The most efficient combination of ceria, TMM, and molecular sieve 13X is ultimately tested in a 250 mL autoclave to start to scale up the process. A very high DMC production of 199.5 mmol DMC/gcat. is obtained. Full article
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15 pages, 5385 KiB  
Article
The Synergistic Effect of Pore Architect and Reducibility in Ceria-Promoted Ni Molecular Sieve for Methane Dry Reforming
by Norah Alwadai, Abdulaziz A. M. Abahussain, Vijay Kumar Shrivastava, Salma A. Al-Zahrani, Anis H. Fakeeha, Naif Alarifi, Mohammed O. Bayazed, Khaled M. Banabdwin, Rawesh Kumar and Ahmed Al-Fatesh
Catalysts 2024, 14(12), 852; https://doi.org/10.3390/catal14120852 - 24 Nov 2024
Cited by 2 | Viewed by 1147
Abstract
Methane and carbon dioxide, the primary contributors to global warming, are now at critical levels, threatening the extinction of numerous organisms on our planet. In this regard, dry reforming of methane reactions have gained considerable attention because of the conversion capacity of CH [...] Read more.
Methane and carbon dioxide, the primary contributors to global warming, are now at critical levels, threatening the extinction of numerous organisms on our planet. In this regard, dry reforming of methane reactions have gained considerable attention because of the conversion capacity of CH4 and CO2 into synthetic/energy-important syngas (H2 and CO). Herein, a molecular sieve (CBV3024E; SiO2/Al2O3 = 30) with ZSM-8-type pore architect, is utilized as the support for the active site of Ni and Ce promoters. Catalysts are characterized by surface area and porosity, X-ray diffraction study, Raman and infrared spectroscopy, thermogravimetry analysis, and temperature-programmed reduction/desorption techniques. A total of 2 wt.% ceria is added over 5Ni/CBV3024E to induce the optimum connectivity of aluminum in the silicate framework. NiO residing in these porous cages are mostly under “prominent interaction with support” which is reduced easily into metallic Ni as the active sites for DRM reactions. The active sites over 5Ni2Ce/CBV3024E remain stable during the DRM reaction and achieve ~58% H2 yield after 300 min TOS at 42,000 mL/(gcat.h) GHSV and ~70% H2 yield after 20 h at 26,000 mL/(gcat.h) GHSV. The high activity after a longer time stream justifies using CBV3024E molecular sieves as the support and ceria as the promoter for Ni-based catalyst towards the DRM reaction. Full article
(This article belongs to the Special Issue Advances in Catalytic Dry Reforming of Methane)
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23 pages, 13110 KiB  
Article
Boron Removal in Aqueous Solutions Using Adsorption with Sugarcane Bagasse Biochar and Ammonia Nanobubbles
by Lianying Liao, Hao Chen, Chunlin He, Gjergj Dodbiba and Toyohisa Fujita
Materials 2024, 17(19), 4895; https://doi.org/10.3390/ma17194895 - 6 Oct 2024
Cited by 5 | Viewed by 1792
Abstract
Boron is a naturally occurring trace chemical element. High concentrations of boron in nature can adversely affect biological systems and cause severe pollution to the ecological environment. We examined a method to effectively remove boron ions from water systems using sugarcane bagasse biochar [...] Read more.
Boron is a naturally occurring trace chemical element. High concentrations of boron in nature can adversely affect biological systems and cause severe pollution to the ecological environment. We examined a method to effectively remove boron ions from water systems using sugarcane bagasse biochar from agricultural waste with NH3 nanobubbles (10% NH3 and 90% N2). We studied the effects of the boron solution concentration, pH, and adsorption time on the adsorption of boron by the modified biochar. At the same time, the possibility of using magnesium chloride and NH3 nanobubbles to enhance the adsorption capacity of the biochar was explored. The carbonization temperature of sugarcane bagasse was investigated using thermogravimetric analysis. It was characterized using XRD, SEM, and BET analysis. The boron adsorption results showed that, under alkaline conditions above pH 9, the adsorption capacity of the positively charged modified biochar was improved under the double-layer effect of magnesium ions and NH3 nanobubbles, because the boron existed in the form of negatively charged borate B(OH)4 anion groups. Moreover, cations on the NH3 nanobubble could adsorb the boron. When the NH3 nanobubbles with boron and the modified biochar with boron could coagulate each other, the boron was removed to a significant extent. Extended DLVO theory was adopted to model the interaction between the NH3 nanobubble and modified biochar. The boron adsorption capacity was 36 mg/g at room temperature according to a Langmuir adsorption isotherm. The adsorbed boron was investigated using FT-IR and XPS analysis. The ammonia could be removed using zeolite molecular sieves and heating. Boron in an aqueous solution can be removed via adsorption with modified biochar with NH3 nanobubbles and MgCl2 addition. Full article
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15 pages, 3081 KiB  
Article
Direct Synthesis of Dimethyl Carbonate from Methanol and CO2 over ZrO2 Catalysts Combined with a Dehydrating Agent and a Cocatalyst
by Dichao Shi, Svetlana Heyte, Mickaël Capron and Sébastien Paul
Catalysts 2024, 14(10), 657; https://doi.org/10.3390/catal14100657 - 24 Sep 2024
Cited by 2 | Viewed by 1948
Abstract
Zirconia nanocrystals as catalysts for the direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide have received significant interest recently. In this paper, three zirconia-based catalysts presenting different monoclinic and tetragonal phase contents are prepared and characterized by X-ray diffraction (XRD), [...] Read more.
Zirconia nanocrystals as catalysts for the direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide have received significant interest recently. In this paper, three zirconia-based catalysts presenting different monoclinic and tetragonal phase contents are prepared and characterized by X-ray diffraction (XRD), N2 adsorption–desorption, transmission electron microscopy (TEM), and temperature-programmed desorption of NH3 and CO2 (NH3-TPD and CO2-TPD). The catalytic performances of these solids are evaluated in terms of DMC production. This production is low when using the bare zirconias, but it is significantly increased in the presence of 1,1,1-trimethoxymethane (TMM) playing the role of a dehydrating agent, which shifts the thermodynamic equilibrium. Moreover, the production of DMC is further improved by adding a second solid catalyst (cocatalyst), the molecular sieve 13X, to accelerate the hydration of TMM. Hence, the molecular sieve 13X plays a dual role by trapping water molecules formed by the reaction of DMC synthesis and providing strong acidic sites catalyzing TMM hydrolysis. To the best of our knowledge, the combination of two solid catalysts in the reaction medium to accelerate the water elimination to obtain higher DMC production from CO2 and methanol has never been reported. Full article
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11 pages, 4147 KiB  
Article
Introducing Molecular Sieve into Activated Carbon to Achieve High-Effective Adsorption for Ethylene Oxide
by Feng Liu, Lingyan Qin, Pingwei Ye, Bo Yang, Qiong Wu, Li Li, Yuwei Dai, Chuan Zhou and Sumin Li
Nanomaterials 2024, 14(18), 1482; https://doi.org/10.3390/nano14181482 - 12 Sep 2024
Cited by 1 | Viewed by 2003
Abstract
Presently, ethylene oxide (EtO) is posing a significant threat to both human health and the environment due to occasional or deliberate emissions. However, few works so far have focused on this issue. It is urgent to explore novel and effective technology to protect [...] Read more.
Presently, ethylene oxide (EtO) is posing a significant threat to both human health and the environment due to occasional or deliberate emissions. However, few works so far have focused on this issue. It is urgent to explore novel and effective technology to protect against the threat of EtO. Herein, a series of AC/ZSM-5 composites were prepared to improve the adsorption performance for EtO, evaluated by dynamic breakthrough experiments. Particularly, the AC/ZSM-20% composite demonstrated a more excellent adsorption capacity of 81.9 mg/g at 25 °C and 50% RH than that of pristine AC and ZSM-5 with 32.5 and 52.3 mg/g, respectively. Moreover, the adsorption capacity of the AC/ZSM-20% composite remained constant even after five adsorption-desorption cycles. The adsorption mechanism of EtO on the composite is further revealed by density functional theory (DFT) calculations. Full article
(This article belongs to the Section Nanocomposite Materials)
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11 pages, 2075 KiB  
Article
Progress in Research on Coalbed Methane Purification Technology against the Background of Carbon Peak and Carbon Neutrality
by Lu Xiao, Houlin Liu, Xuanping Gong and Cheng Cheng
Processes 2024, 12(8), 1561; https://doi.org/10.3390/pr12081561 - 25 Jul 2024
Cited by 1 | Viewed by 1441
Abstract
Coalbed methane is released externally due to coal mining activities. Given its low concentration, which renders utilization challenging, China annually vents approximately 285 billion cubic meters of coalbed methane into the atmosphere, leading to significant energy waste and greenhouse gas emissions. To enhance [...] Read more.
Coalbed methane is released externally due to coal mining activities. Given its low concentration, which renders utilization challenging, China annually vents approximately 285 billion cubic meters of coalbed methane into the atmosphere, leading to significant energy waste and greenhouse gas emissions. To enhance the utilization rate of coalbed methane, mitigate these emissions, and promote a “green and low-carbon” energy supply, this article investigates pressure swing adsorption technology for purifying coalbed methane and analyzes the advantages, disadvantages, and application scopes of three processes: separation based on equilibrium effects, kinetic effects, and steric hindrance effects. The research findings reveal that equilibrium effect-based adsorption is particularly advantageous for purifying low-concentration coalbed methane, effectively capturing methane (CH4). Conversely, when dealing with medium- to high-concentration coalbed methane, methods leveraging kinetic effects prove more favorable. Within the context of equilibrium effects, activated carbon serves as a suitable adsorbent; however, achieving high-purity products entails substantial energy consumption. The methane saturation adsorption capacity of novel activated carbons has reached 2.57 mol/kg. Kinetic effect-based adsorbents, primarily carbon molecular sieves and zeolite molecular sieves, are characterized by lower energy demands. Currently, coal-based molecular sieves have achieved a CH4/N2 equilibrium separation factor of 4.21, and the amount of raw coal required to produce one ton of carbon molecular sieve has decreased to 2.63 tons. In light of the rapid advancement of intensive coal mining operations and the swift implementation of smart mine construction, there is an urgent need to intensify research on large-scale purification technologies for low-concentration coalbed methane. This will provide the technical foundation necessary for achieving “near-zero emission” of mine gas and facilitate the achievement of the goals of carbon peak and carbon neutrality. Full article
(This article belongs to the Special Issue New Research on Oil and Gas Equipment and Technology)
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15 pages, 1935 KiB  
Article
Carbon Molecular Sieve Membrane Reactors for Ammonia Cracking
by Valentina Cechetto, Gaetano Anello, Arash Rahimalimamaghani and Fausto Gallucci
Processes 2024, 12(6), 1168; https://doi.org/10.3390/pr12061168 - 6 Jun 2024
Cited by 7 | Viewed by 2757
Abstract
The utilization of ammonia for hydrogen storage relies on the implementation of efficient decomposition techniques, and the membrane reactor, which allows simultaneous ammonia decomposition and hydrogen recovery, can be regarded as a promising technology. While Pd-based membranes show the highest performance for hydrogen [...] Read more.
The utilization of ammonia for hydrogen storage relies on the implementation of efficient decomposition techniques, and the membrane reactor, which allows simultaneous ammonia decomposition and hydrogen recovery, can be regarded as a promising technology. While Pd-based membranes show the highest performance for hydrogen separation, their applicability for NH3-sensitive applications, such as proton exchange membrane (PEM) fuel cells, demands relatively thick, and therefore expensive, membranes to meet the purity targets for hydrogen. To address this challenge, this study proposes a solution involving the utilization of a downstream hydrogen purification unit to remove residual ammonia, thereby enabling the use of less selective, therefore more cost-effective, membranes. Specifically, a carbon molecular sieve membrane was prepared on a tubular porous alumina support and tested for ammonia decomposition in a membrane reaction setup. Operating at 5 bar and temperatures ranging from 450 to 500 °C, NH3 conversion rates exceeding 90% were achieved, with conversion approaching thermodynamic equilibrium at temperatures above 475 °C. Simultaneously, the carbon membrane facilitated the recovery of hydrogen from ammonia, yielding recoveries of 8.2–9.8%. While the hydrogen produced at the permeate side of the reactor failed to meet the purity requirements for PEM fuel cell applications, the implementation of a downstream hydrogen purification unit comprising a fixed bed of zeolite 13X enabled the production of fuel cell-grade hydrogen. Despite performance far from being comparable with the ones achieved in the literature with Pd-based membranes, this study underscores the viability of carbon membranes for fuel cell-grade hydrogen production, showcasing their competitiveness in the field. Full article
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33 pages, 16903 KiB  
Article
Multi-Faceted Analysis of Phase-Change Composite Intended for Autonomous Buildings
by Michał Musiał and Lech Lichołai
Materials 2024, 17(11), 2604; https://doi.org/10.3390/ma17112604 - 28 May 2024
Cited by 1 | Viewed by 1130
Abstract
This paper presents the long-term, holistic results of research into an innovative heat accumulator based on an organic phase-change material in the form of a mixture of aliphatic alkanes, molecular silica sieves, carbon recyclate and epoxy and cement matrices. The research included chemical [...] Read more.
This paper presents the long-term, holistic results of research into an innovative heat accumulator based on an organic phase-change material in the form of a mixture of aliphatic alkanes, molecular silica sieves, carbon recyclate and epoxy and cement matrices. The research included chemical testing of vacuum soaking of molecular silica sieves with a liquid phase-change material. The results proved an improvement in the heat storage efficiency of the heat accumulators due to the addition of carbon recyclate by 28%, while increasing the heat storage time by 134 min, and a reduction in PCM leakage due to the use of molecular silica sieves. In addition to its cognitive scientific value, another research objective of the work achieved was to obtain response functions in the form of approximating polynomials. They provide a useful, validated and verified tool to predict the physical and chemical characteristics of heat accumulators with different contents of individual components. As part of the ongoing research, technical problems related to leak-proofing assurance and matrix selection for organic phase-change materials were also solved. The solution presented is in line with the issues of efficient use of renewable energy, low-carbon and energy-efficient circular economy. Full article
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20 pages, 5292 KiB  
Article
One-Step Production of Highly Selective Ethylbenzene and Propylbenzene from Benzene and Carbon Dioxide via Coupling Reaction
by Tianyun Wang, Yingjie Guan, Haidan Wu, Zhaojie Su, Jianguo Zhuang, Siyan Yan, Xuedong Zhu and Fan Yang
Catalysts 2024, 14(5), 288; https://doi.org/10.3390/catal14050288 - 24 Apr 2024
Viewed by 2034
Abstract
Utilizing carbon dioxide as a carbon source for the synthesis of olefins and aromatics has emerged as one of the most practical methods for CO2 reduction. In this study, an improved selectivity of 85% for targeting products (ethylbenzene and propylbenzene) is achieved [...] Read more.
Utilizing carbon dioxide as a carbon source for the synthesis of olefins and aromatics has emerged as one of the most practical methods for CO2 reduction. In this study, an improved selectivity of 85% for targeting products (ethylbenzene and propylbenzene) is achieved with a benzene conversion of 16.8% by coupling the hydrogenation of carbon dioxide to olefins over the bifunctional catalyst “Oxide-Zeolite” (OX-ZEO) and the alkylation of benzene with olefins over ZSM-5. In addition to investigating the influence of SAPO-34 and ZSM-5 zeolite acidity on product distribution, catalyst deactivation due to coke formation is addressed by modifying both molecular sieves to be hierarchical to extend the catalyst lifespan. Even after 100 h of operation at 400 °C, the catalysts maintained over 80% selectivity towards the target products, with benzene conversion over 14.2%. Furthermore, the pathway of propylbenzene formation is demonstrated through simple experimental design, revealing that the surface Brønsted acid sites of SAPO-34 serve as its primary formation sites. This provides a novel perspective for further investigation of the reaction network. Full article
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18 pages, 3870 KiB  
Article
Carbon–Carbon Composite Membranes Derived from Small-Molecule-Compatibilized Immiscible PBI/6FDA-DAM-DABA Polymer Blends
by Chamaal Karunaweera, Nimanka P. Panapitiya, Samitha Panangala, Edson V. Perez, Inga H. Musselman, Kenneth J. Balkus and John P. Ferraris
Separations 2024, 11(4), 108; https://doi.org/10.3390/separations11040108 - 1 Apr 2024
Cited by 1 | Viewed by 2067
Abstract
The use of immiscible polymer blends in gas separations is limited due to uncontrollable phase separation. In contrast, compatibilized immiscible polymer blends can be used as precursors with controlled morphologies that allow for a unique pore architecture. Herein, an immiscible polymer blend (1:1) [...] Read more.
The use of immiscible polymer blends in gas separations is limited due to uncontrollable phase separation. In contrast, compatibilized immiscible polymer blends can be used as precursors with controlled morphologies that allow for a unique pore architecture. Herein, an immiscible polymer blend (1:1) comprising polybenzimidazole (PBI) and the copolyimide 6FDA-DAM:DABA [3:2], derived from reacting 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 2,4,6-trimethyl-1,3-phenylenediamine (DAM) and 3,5-diaminobenzoic acid (DABA), were combined with durene diamine as a compatibilizer. The compatibilizer helped reduce the 6FDD domain sizes from 5.6 µm down to 0.77 µm and induced a more even 6FDA distribution and the formation of continuous thin-selective PBI layers. The carbon–carbon composite membranes derived from the compatibilized immiscible polymer blends showed a 3-fold increase in both H2 permeability and H2/CO2 selectivity compared to the membranes derived from non-compatibilized polymer blends. The H2 permeability of the compatibilized immiscible polymer blends increased from 3.6 to 27 Barrer, and their H2/CO2 selectivity increased from 7.2 to 20. The graphitic domain size of the carbon–carbon composite membranes derived from the polymer blends also increased from 6.3 nm for the non-compatibilized blend to 10.0 nm for the compatibilized blend. Full article
(This article belongs to the Section Materials in Separation Science)
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