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Molecular Aspects in Porous Silicas Related to Adsorption and Catalytic Processes

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Physical Chemistry and Chemical Physics".

Deadline for manuscript submissions: closed (31 October 2023) | Viewed by 12030

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Departamento de Química Inorgánica, Cristalografía y Mineralogía (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Campus de Teatinos, Universidad de Málaga, 29071 Málaga, Spain
Interests: heterogeneous catalysis; mesoporous solids synthesis; acid–base catalysis; biomass valorization by means of catalytic processes
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Special Issue Information

Dear Colleagues,

Both silica and silica-based materials have attracted the scientific community in recent decades. The main efforts have been focused on the incorporation and dispersion of metallic phases on its surface, the improvement of the acid, basic or redox properties, surface functionalization, the control of the morphology and pore diameter distribution, and the design of silica-based materials with higher mechanical and thermal stability. These new perspectives and approaches have been opened in many fields, including adsorption and catalysis.

This Special Issue focuses on recent advances in molecular aspects in porous silica-based materials related to adsorption and catalytic processes. This Special Issue is open to accept the submission of new manuscripts related to new synthetic approaches, one-pot or post-synthetic functionalization, surface characterization, structure–activity correlation or tailored mesoporous silica nanoparticles with a specific applications in adsorption and catalysis implying new synthetic approaches, one-pot or post-synthetic functionalization, surface characterization, structure–activity correlation, tailored mesoporous silica nanoparticles with a specific catalytic application of great environmental or industrial interest with medical, environmental or industrial purposes.

Dr. Ramón Moreno Tost
Dr. Juan Antonio Cecilia
Guest Editors

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Keywords

  • silica
  • porous silica
  • catalysis
  • adsorption
  • silica functionalization
  • hybrid materials
  • surface chracterization
  • metal incorporation

Published Papers (5 papers)

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Research

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17 pages, 4821 KiB  
Article
Distinctive Electric Properties of Group 14 Oxides: SiO2, SiO, and SnO2
by Antonio Nuno Guerreiro, Ilidio B. Costa, Antonio B. Vale and Maria Helena Braga
Int. J. Mol. Sci. 2023, 24(21), 15985; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms242115985 - 05 Nov 2023
Viewed by 1920
Abstract
The oxides of group 14 have been widely used in numerous applications in glass, ceramics, optics, pharmaceuticals, and food industries and semiconductors, photovoltaics, thermoelectrics, sensors, and energy storage, namely, batteries. Herein, we simulate and experimentally determine by scanning kelvin probe (SKP) the work [...] Read more.
The oxides of group 14 have been widely used in numerous applications in glass, ceramics, optics, pharmaceuticals, and food industries and semiconductors, photovoltaics, thermoelectrics, sensors, and energy storage, namely, batteries. Herein, we simulate and experimentally determine by scanning kelvin probe (SKP) the work functions of three oxides, SiO2, SiO, and SnO2, which were found to be very similar. Electrical properties such as electronic band structure, electron localization function, and carrier mobility were also simulated for the three crystalline oxides, amorphous SiO, and surfaces. The most exciting results were obtained for SiO and seem to show Poole–Frankel emissions or trap-assisted tunneling and propagation of surface plasmon polariton (SPP) with nucleation of solitons on the surface of the Aluminum. These phenomena and proposed models may also describe other oxide-metal heterojunctions and plasmonic and metamaterials devices. The SiO2 was demonstrated to be a stable insulator interacting less with the metals composing the cell than SnO2 and much less than SiO, configuring a typical Cu/SiO2/Al cell potential well. Its surface charge carrier mobility is small, as expected for an insulator. The highest charge carrier mobility at the lowest conduction band energy is the SnO2’s and the most symmetrical the SiO’s with a similar number of electron holes at the conduction and valence bands, respectively. The SnO2 shows it may perform as an n-type semiconductor. Full article
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16 pages, 5112 KiB  
Article
Microwave-Assisted Synthesis of Zeolite A from Metakaolinite for CO2 Adsorption
by Marilia R. Oliveira, Juan A. Cecilia, Daniel Ballesteros-Plata, Isabel Barroso-Martín, Pedro Núñez, Antonia Infantes-Molina and Enrique Rodríguez-Castellón
Int. J. Mol. Sci. 2023, 24(18), 14040; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms241814040 - 13 Sep 2023
Cited by 2 | Viewed by 906
Abstract
The global demand for energy and industrial growth has generated an exponential use of fossil fuels in recent years. It is well known that carbon dioxide (CO2) is mainly produced, but not only from fuels, which has a negative impact on [...] Read more.
The global demand for energy and industrial growth has generated an exponential use of fossil fuels in recent years. It is well known that carbon dioxide (CO2) is mainly produced, but not only from fuels, which has a negative impact on the environment, such as the increasing emission of greenhouse gases. Thus, thinking about reducing this problem, this study analyzes microwave irradiation as an alternative to conventional heating to optimize zeolite A synthesis conditions for CO2 capture. Synthesis reaction parameters such as different temperatures (60–150 °C) and different time durations (1–6 h) were evaluated. The CO2 adsorption capacity was evaluated by CO2 adsorption–desorption isotherms at 25 °C and atmospheric pressure. The results showed that the synthesis of zeolite A by microwave irradiation was successfully obtained from natural kaolinite (via metakaolinization), reducing both temperature and time. Adsorption isotherms show that the most promising adsorbent for CO2 capture is a zeolite synthesized at 100 °C for 4 h, which reached an adsorption capacity of 2.2 mmol/g. Full article
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20 pages, 8543 KiB  
Article
New Approaches for Pb(II) Removal from Aqueous Media Using Nanopowder Sodium Titanosilicate: Kinetics Study and Thermodynamic Behavior
by Ionela Carazeanu Popovici, Simona Dobrinaș, Alina Soceanu, Viorica Popescu, Gabriel Prodan and Ichinur Omer
Int. J. Mol. Sci. 2023, 24(18), 13789; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms241813789 - 07 Sep 2023
Viewed by 682
Abstract
Microporous sodium titanosilicate, Na2TiSiO5, has been successfully prepared using the sol–gel method. The structural and morphological characterization of synthesized product has been made via thermal analyses (TG-DTG), X-ray diffraction (XRD), and electron microscopy (SEM and TEM). Adsorption properties of [...] Read more.
Microporous sodium titanosilicate, Na2TiSiO5, has been successfully prepared using the sol–gel method. The structural and morphological characterization of synthesized product has been made via thermal analyses (TG-DTG), X-ray diffraction (XRD), and electron microscopy (SEM and TEM). Adsorption properties of the synthesized Na2TiSiO5 nanopowder for Pb(II) removal of aqueous media was investigated in different experimental conditions such as the contact time, the initial metal concentration, the pH, and the temperature. The Pb(II) adsorption on Na2TiSiO5 was discussed according to the kinetics and thermodynamics models. The adsorption kinetics of Pb(II) have been better described by the PS-order kinetic model which has the highest fitting correlation coefficients (R2: 0.996–0.999) out of all the other models. The adsorption results have been successfully fitted with the Langmuir and Redlich–Paterson models (R2: 0.9936–0.9996). The calculated thermodynamic parameters indicate that the Pb(II) adsorption is an endothermic process, with increased entropy, having a spontaneous reaction. The results have revealed a maximum adsorption capacity of 155.71 mg/g at 298 K and a very high adsorption rate at the beginning, more than 85% of the total amount of Pb(II) being removed within the first 120 min, depending on the initial concentration. Full article
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16 pages, 4375 KiB  
Article
Correlations between H2 Permeation and Physical/Mechanical Properties in Ethylene Propylene Diene Monomer Polymers Blended with Carbon Black and Silica Fillers
by Jae K. Jung, Ji H. Lee, Sang K. Jeon, Nae H. Tak, Nak K. Chung, Un B. Baek, Si H. Lee, Chang H. Lee, Myung C. Choi, Hyun M. Kang, Jong W. Bae and Won J. Moon
Int. J. Mol. Sci. 2023, 24(3), 2865; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms24032865 - 02 Feb 2023
Cited by 3 | Viewed by 1599
Abstract
H2 permeation in peroxide-crosslinked EPDM blended with carbon black (CB) and silica fillers was studied at pressures ranging from 1.2 MPa to 90 MPa via the volumetric analysis technique. H2 uptake in the CB-filled EPDM revealed dual-sorption behaviors via Henry’s law [...] Read more.
H2 permeation in peroxide-crosslinked EPDM blended with carbon black (CB) and silica fillers was studied at pressures ranging from 1.2 MPa to 90 MPa via the volumetric analysis technique. H2 uptake in the CB-filled EPDM revealed dual-sorption behaviors via Henry’s law and the Langmuir model, which were attributed to H2 absorption by the polymer chains and H2 adsorption at the filler interfaces, respectively. Additionally, single-sorption mechanisms were observed for neat EPDM and silica-blended EPDM according to Henry’s law, indicating H2 absorption by the polymer chain. The linear decreases in the diffusivity with filler content for the silica-blended EPDMs were attributed to increases in the diffusion paths caused by the filler. Exponential decreases in the diffusivity with increasing filler content and in the permeation with the physical/mechanical properties for CB-filled EPDMs were caused by decreases in the fractional free volume due to increased densities for the EPDM composites. Moreover, good filler-dependent correlations between permeability and density, hardness, and tensile strength were demonstrated for EPDMs used as sealing materials for O-rings. From the resulting equation, we predicted the permeation value without further measurements. Thus, we can select EPDM candidates satisfying the permeation guidelines used in hydrogen infrastructure for the future hydrogen economy. Full article
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Review

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16 pages, 3721 KiB  
Review
A Review of the CFD Modeling of Hydrogen Production in Catalytic Steam Reforming Reactors
by Nayef Ghasem
Int. J. Mol. Sci. 2022, 23(24), 16064; https://0-doi-org.brum.beds.ac.uk/10.3390/ijms232416064 - 16 Dec 2022
Cited by 2 | Viewed by 6257
Abstract
Global demand for alternative renewable energy sources is increasing due to the consumption of fossil fuels and the increase in greenhouse gas emissions. Hydrogen (H2) from biomass gasification is a green energy segment among the alternative options, as it is environmentally [...] Read more.
Global demand for alternative renewable energy sources is increasing due to the consumption of fossil fuels and the increase in greenhouse gas emissions. Hydrogen (H2) from biomass gasification is a green energy segment among the alternative options, as it is environmentally friendly, renewable, and sustainable. Accordingly, researchers focus on conducting experiments and modeling the reforming reactions in conventional and membrane reactors. The construction of computational fluid dynamics (CFD) models is an essential tool used by researchers to study the performance of reforming and membrane reactors for hydrogen production and the effect of operating parameters on the methane stream, improving processes for reforming untreated biogas in a catalyst-fixed bed and membrane reactors. This review article aims to provide a good CFD model overview of recent progress in catalyzing hydrogen production through various reactors, sustainable steam reforming systems, and carbon dioxide utilization. This article discusses some of the issues, challenges, and conceivable arrangements to aid the efficient generation of hydrogen from steam reforming catalytic reactions and membrane reactors of bioproducts and fossil fuels. Full article
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