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Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves)

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A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Chemical and Molecular Sciences".

Deadline for manuscript submissions: closed (31 August 2021) | Viewed by 32308

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Special Issue Editors

Prof. Dr. Sibele Pergher

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Departamento de Química, Universidade Federal do Rio Grande do Norte, Natal, Caixa 1524, Brazil
Interests: chemistry and materials with emphasis on synthesis and characterization of inorganic solids; Synthesis catalysts; zeolites; clays; mesoporous materials; lamellar materials; adsorption; catalysis processes
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Prof. Dr. Katia Bernardo-Gusmão

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Instituto de Química, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 15003, Brazil
Interests: olefin epoxidation/oligomerization/polimerization catalysis; synthesis and catalyst application of hybrid materials obtained by the sol-gel method; zeolites and mesoporous materials synthesis and application as catalyst support

Special Issue Information

Dear Colleagues,

This Special Issue will be dedicated to Molecular Sieves concerning the annual Cycles of Lectures on Molecular Sieves held on 2013 to 2018 in Brazil (Natal, Campinas and Porto Alegre). These lectures addressed the synthesis, characterization, and application of molecular sieves materials such as zeolitic type materials, mesoporous materials (SBA-15, MCM-41, HMS, and similar), metal-organic framework structures (MOFs), porous carbons, and lamellar materials (pillared clays, HDL, and delaminated materials), and their applications in adsorption, catalysis, and separation process. This Special Issue will give a global vision of researchers from world-wide universities, research centers, and industry working on molecular sieves materials and sharing the latest results on their synthesis and characterization, giving rise a special interest in their applications in basic and industrial processes.

Prof. Dr. Sibele B. C. Pergher
Prof. Dr. Katia Bernardo-Gusmão
Guest Editors

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Keywords

molecular sieves materials
zeolites
pillared clays
mesoporous materials
MOFs
porous carbon
lamellar materials
catalysis
adsorption
separation

Published Papers (11 papers)

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Research

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15 pages, 2584 KiB

Open AccessArticle

A Multi-Nuclear MAS-NMR Study on the Structural Properties of Silicalite-1 Zeolite Synthesized Using N- and P-Based Organic Structure Directing Agents

by Joaquin Martinez-Ortigosa, Jorge Simancas, Jose A. Vidal-Moya, Fernando Rey, Susana Valencia and Teresa Blasco

Appl. Sci. 2021, 11(15), 6850; https://0-doi-org.brum.beds.ac.uk/10.3390/app11156850 - 26 Jul 2021

Viewed by 2206

Abstract

The nature of organic structure directing agents (OSDAs) is of paramount importance in the final properties of zeolites, particularly the framework and porosity. Recently, the use of P-containing OSDAs has been employed for new zeolites, but there is little discussion compared to their analogues N-OSDAs. The main objective of this work is the characterization of pure silica MFI zeolite (silicalite-1) prepared by the dual-template route with tetrapropylammonium (TPA), tetrapropylphosphonium (TPP) cations, and mixtures thereof aiming to understand by advanced NMR methods how the nature of the organic influences the physico-chemical properties of the zeolite. Silicalite-1 has been successfully synthesized using the dual-template procedure with TPA and TPP molecules. Both OSDAs are incorporated into the zeolite without any specific preference, differently to that observed before for the TEA/TEP system, and homogenously mixed inside of the zeolite voids. The presence of TPP leads to the incorporation of less F, raising the concentration of Q³-defective sites in the silicalite-1 zeolites. Detailed NMR results indicate that those structural defects are close to the –CH₃ group of the entrapped OSDAs in the zeolite and these defects consist of at least two silanol groups stabilizing the Si-O^- species, which is responsible for the charge balancing. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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11 pages, 2260 KiB

Open AccessArticle

Insight in the Crystallization Kinetics of AlPO₄-11 Molecular Sieve Using Di-Isopropylamine as Template

by Renilson O. Mapele, Antonio O. S. Silva, Marcelo J. B. Souza, Anne M. G. Pedrosa, Ana C. F. Coriolano, Glauber J. T. Fernandes, Valter J. Fernandes, Jr. and Antonio S. Araujo

Appl. Sci. 2021, 11(14), 6544; https://0-doi-org.brum.beds.ac.uk/10.3390/app11146544 - 16 Jul 2021

Cited by 1 | Viewed by 1610

Abstract

The hydrothermal synthesis of aluminophosphate molecular sieve type AlPO₄-11 was processed from chemicals containing psueudobohemite, 85% phosphoric acid, water, and di-isopropylamine as templating agent. The crystallization of the samples was studied by taking samples in times from 2 to 74 h. The obtained white powder products were characterized by X-ray diffraction patterns (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG) and differential scanning calorimetry (DTG) data and pH measurement of the mother liquor. The pore volume, as determined from TG and DTG curves, was ca. 0.17 cm³g⁻¹. The percent relative crystallinity was determined by XRD and FT-IR methods. The crystallization kinetics evidenced that the hydrothermal synthesis of AlPO₄-11 exhibited in its initial phase a behavior of first order reaction with a specific velocity constant of ca. 0.25 h⁻¹, as determined from XRD and FT-IR data. The results obtained by both X-ray diffraction and infrared spectroscopy are comparable, and FT-IR is found to be a rapid method for estimating crystallinity and structure of aluminophosphate. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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17 pages, 4962 KiB

Open AccessArticle

Influence of Preparation Conditions on the Catalytic Performance of Mo/H-ZSM-5 for Methane Dehydroaromatization

by Maria Teresa Portilla, Francisco J. Llopis, Manuel Moliner and Cristina Martinez

Appl. Sci. 2021, 11(12), 5465; https://0-doi-org.brum.beds.ac.uk/10.3390/app11125465 - 12 Jun 2021

Cited by 4 | Viewed by 1846

Abstract

Methane, the main component of natural gas, is an interesting source of chemicals and clean liquid fuels, and a promising alternative raw material to oil. Among the possible direct routes for methane conversion, its aromatization under non-oxidative conditions has received increasing attention, despite the low conversions obtained due to thermodynamic limitations, because of its high selectivity to benzene. Mo/H-ZSM-5, the first bifunctional zeolite-catalyst proposed for this reaction, is still considered as one of the most adequate and has been widely studied. Although the mono- or bifunctional nature of the MDA mechanism is still under debate, it is generally accepted that the Mo species activate the C-H bond in methane, producing the intermediates. These will aromatize on the Brønsted acid sites of the zeolite, whose pore dimensions will provide the shape selectivity needed for converting methane into benzene. An additional role of the zeolite’s Brønsted acid sites is to promote the dispersion of the Mo oxide precursor. Here, we show the influence of the different preparation steps—metal incorporation, calcination and activation of the Mo/ZSM-5- on the metal dispersion and, therefore, on the activity and selectivity of the final catalyst. Metal dispersion is enhanced when the samples are calcined under dynamic conditions (DC) and activated in N₂, and the benefits are larger when the metal has been incorporated by solid state reaction (SSR), as observed by FESEM-BSE and H₂-TPR. This leads to catalysts with higher activity, increased aromatic selectivity and improved stability towards deactivation. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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11 pages, 3128 KiB

Open AccessArticle

Optimization of Parameters and Methodology for the Synthesis of LTA-Type Zeolite Using Light Coal Ash

by Thiago J. T. Cruz, Mariele I. S. Melo and Sibele Pergher

Appl. Sci. 2020, 10(20), 7332; https://0-doi-org.brum.beds.ac.uk/10.3390/app10207332 - 20 Oct 2020

Cited by 6 | Viewed by 2163

Abstract

The synthesis of zeolites using waste as a source of Si and Al is well known, and light coal ash has been studied to minimize the problems of waste management and mitigate environmental effects. The residue used in this work was supplied by Coal Workers Assistance Society (SATC) Criciúma–SC/Brazil, and had 24.09% Al₂O₃ and 54.25% SiO₂ in its chemical composition. Synthesis studies using this residue with the objective of obtaining LTA zeolites were carried out by hydrothermal means, alkaline fusion, and the combination of the two methods, varying parameters such as crystallization time, Na/T ratio, OH/ratio, ultrasound exposure, gel agitation temperature, and the alkaline melting temperature of the residue. The results were characterized by X-ray diffraction (XRD) techniques and scanning electron microscopy (SEM-FEG). It was possible to obtain 70% crystalline zeolite type LTA for the first time at mild conditions with temperatures below 200 °C by alkaline fusion with smaller amounts of NaOH and short times (2 h). Thus, suitable parameters were determined for future scaling. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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14 pages, 4678 KiB

Open AccessArticle

Zeolite-Supported Ni Catalysts for CO₂ Methanation: Effect of Zeolite Structure and Si/Al Ratio

by Javier Francisco da Costa-Serra, Cristina Cerdá-Moreno and Antonio Chica

Appl. Sci. 2020, 10(15), 5131; https://0-doi-org.brum.beds.ac.uk/10.3390/app10155131 - 26 Jul 2020

Cited by 16 | Viewed by 3151

Abstract

The urgent need to reduce CO₂ emissions requires the development of efficient catalysts for the conversion of CO₂ into chemicals and fuels. In this study, a series of nickel catalysts supported on ITQ-2 and ZSM-5 zeolites have been prepared, characterized and tested in the hydrogenation reaction of CO₂ towards methane. Specifically, two ITQ-2 and two ZSM 5 zeolites with different aluminum content have been studied. For both types, the higher Si/Al ratio of the material, the more active the catalyst due probably to its higher hydrophobicity. The largest difference was found for the ITQ-2 samples, being the CO₂ conversion for the sample with a greater Si/Al ratio 50 points higher at 350 °C. Comparing both zeolite structures, while similar catalytic results were obtained with the samples with lower Si/Al ratio, a distinctly higher activity was found for the ITQ-2 zeolite without aluminum, pure silica. Therefore, this result suggests that the presence of aluminum is of particular relevance. Among the studied materials, the catalyst supported on the delaminated ITQ-2 zeolite without Al was the most active catalyst. Its higher activity was mainly attributed to the smaller crystallite size of nickel supported on the large external surface area presented by this zeolite. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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16 pages, 2429 KiB

Open AccessArticle

Tunable Effect of the Calcination of the Silanol Groups of KIT-6 and SBA-15 Mesoporous Materials

by Adriano M. Basso, Bruna P. Nicola, Katia Bernardo-Gusmão and Sibele B. C. Pergher

Appl. Sci. 2020, 10(3), 970; https://doi.org/10.3390/app10030970 - 02 Feb 2020

Cited by 20 | Viewed by 4294

Abstract

The calcination process is a crucial step during SBA-15 and KIT-6 synthesis. It is used to completely remove the organic template and condense silanol groups, and it allows the determination of the textural and physical properties of these materials, depending on the adopted conditions. Moreover, calcination influences the number of silanols available on the surface of the material. The concentration of silanols is important if these materials were synthesized for use in adsorption or functionalization. To understand and optimize the silanol groups of SBA-15 and KIT-6, in this study, the temperature and time calcination parameters were varied. The experiments were performed at 300, 400, and 500 °C for 300, 400, and 500 min. The results show that the ideal temperature to preserve the silanol groups is 300 °C, but to optimize the textural properties, it is better to calcine these molecular sieves at 400 °C. A calcination for 10 h did not give better results than a calcination for 5 h, demonstrating that the former duration is excessive for use. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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11 pages, 1634 KiB

Open AccessFeature PaperArticle

Hybrid Ionic Liquid–Silica Xerogels Applied in CO₂ Capture

by Aline S. Aquino, Michele O. Vieira, Ana Sofia D. Ferreira, Eurico J. Cabrita, Sandra Einloft and Michèle O. de Souza

Appl. Sci. 2019, 9(13), 2614; https://0-doi-org.brum.beds.ac.uk/10.3390/app9132614 - 28 Jun 2019

Cited by 15 | Viewed by 3057

Abstract

The imidazolium-based ionic liquids (ILs) are solvents known for selectively solubilizing CO₂ from a gas CH₄/CO₂ mixture, hence we have produced new hybrid adsorbents by immobilizing two ILs on xerogel silica to obtain a solid–gas system that benefits the ILs’ properties and can be industrially applied in CO₂ capture. In this work, the ILs (MeO)₃Sipmim.Cl and (MeO)₃Sipmim.Tf₂N were used at different loadings via the sol–gel process employing a based 1-methyl-3-(3-trimethoxysylilpropyl) imidazolium IL associated to the anion Cl⁻ or Tf₂N⁻ as a reactant in the synthesis of silica xerogel. The CO₂ adsorption measurements were conducted through pressure and temperature gravimetric analysis (PTGA) using a microbalance. SEM microscopies images have shown that there is an IL limit concentration that can be immobilized (ca. 20%) and that the xerogel particles have a spherical shape with an average size of 20 µm. The adsorbent with 20% IL (MeO)₃Sipmim.Cl, SILCLX20, shows greater capacity to absorb CO₂, reaching a value of 0.35 g CO₂ / g adsorbent at 0.1 MPa (298 K). Surprisingly, the result for xerogel with IL (MeO)₃Sipmim.Tf₂N shows poor performance, with only 0.05 g CO₂ / g absorbed, even having a hydrophobic character which would benefit their interaction with CO₂. However, this hydrophobicity could interfere negatively in the xerogel synthesis process. The immobilization of ionic liquids in silica xerogel is an advantageous technique that reduces costs in the use of ILs as they can be used in smaller quantities and can be recycled after CO₂ desorption. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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17 pages, 3975 KiB

Open AccessFeature PaperArticle

Conversion of Stearic Acid into Bio-Gasoline over Pd/ZSM-5 Catalysts with Enhanced Accessibility

by Marta Arroyo, Laura Briones, José María Escola and David P. Serrano

Appl. Sci. 2019, 9(11), 2386; https://0-doi-org.brum.beds.ac.uk/10.3390/app9112386 - 11 Jun 2019

Cited by 5 | Viewed by 3449

Abstract

Palladium supported on nanocrystalline ZSM-5 (n-ZSM-5, Si/Al = 32) and hierarchical ZSM-5 (h-ZSM-5) with different acidity (Si/Al = 33, 51, 122) were tested in the liquid-phase conversion of stearic acid under nitrogen atmosphere (6 bar). The incorporation of Pd into ZSM-5 zeolite increased significantly the share of gasoline in the reaction products due to the promotion by this metal of both decarboxylation and hydrogen transfer reactions. Likewise, the Pd nanoparticles dispersed over the zeolitic support favored the conversion of light olefins formed by end-chain cracking reactions into gasoline-range hydrocarbons according to an oligomerization/cyclization/aromatization pathway. Additionally, Pd/h-ZSM-5 gave rise to higher conversion and selectivity towards gasoline than Pd/n-ZSM-5, due mainly to the enhanced accessibility and improved Pd dispersion achieved when using the hierarchical zeolite. The decrease in the Si/Al atomic ratio in Pd/h-ZSM-5 samples resulted in a rise in the stearic acid conversion, although it was lower than expected. This finding denotes that, for supports with high acid sites concentration, the Pd availability became the limiting factor as the metal was loaded in similar amounts in all catalysts. Finally, the increase of the reaction temperature with the Pd/h-ZSM-5 (122) catalyst augmented both stearic acid conversion and gasoline selectivity, since it enhanced the conversion of the light olefins, formed as primary cracking products, into liquid hydrocarbons. Therefore, it can be concluded that Pd supported on hierarchical ZSM-5 zeolite is a convenient catalyst for obtaining bio-gasoline from oleaginous feedstock. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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13 pages, 2921 KiB

Open AccessFeature PaperArticle

Separation of N–C₅H₁₂–C₉H₂₀ Paraffins Using Boehmite by Inverse Gas Chromatography

by José L. Contreras-Larios, Antonia Infantes-Molina, Luís A. Negrete-Melo, Juan M. Labadie-Suárez, Hernani T. Yee-Madeira, Miguel A. Autie-Pérez and Enrique Rodríguez-Castellón

Appl. Sci. 2019, 9(9), 1810; https://0-doi-org.brum.beds.ac.uk/10.3390/app9091810 - 30 Apr 2019

Cited by 4 | Viewed by 2554

Abstract

The separation of a mixture of C5–C9 n-paraffins was achieved by Inverse Gas Chromatography (IGC) by using boehmite; AlO(OH), in a packed column with short exposure times and temperatures; from 45 °C to 52 °C. The boehmite was characterized by XRD; ATG; SEM; IR spectroscopy and N₂ adsorption. The material exhibited a low crystalline boehmite (AlOOH) structure and presented high hydration (pseudoboehmite). The reverse gas chromatography measurements showed that the elution temperatures of the C5–C9 n-paraffins were low compared with those obtained for other adsorbents. The differential heat of adsorption values ensures the satisfactory separation of the components in the C5–C9 mixture under suitable chromatographic conditions. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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12 pages, 1267 KiB

Open AccessArticle

NO-CH₄-SCR Over Core-Shell MnH-Zeolite Composites

by Yixiao Li, Quanhua Wang, Ding Wang and Xiaoliang Yan

Appl. Sci. 2019, 9(9), 1773; https://0-doi-org.brum.beds.ac.uk/10.3390/app9091773 - 28 Apr 2019

Cited by 5 | Viewed by 2622

Abstract

Selective catalytic reduction of NO with methane (NO-CH₄-SCR) in the presence of excess oxygen was investigated over the synthesized MnH-ZZs-n zeolite composite catalysts with FAU (as core) and BEA (as shell) topologies. XRD, SEM, and NH₃-TPD technologies were employed to characterize the catalysts. It is found that the topological structure of the zeolite affected the catalytic properties and H₂O/SO₂ tolerances considerably. MnH-ZZs-n catalysts exhibited much higher NO-CH₄-SCR activity than the physical mixture catalysts with comparable relative mass content of Y and Beta zeolites, particularly the ratio of Y and Beta at the range of 0.2–0.5 than the MnH-Beta catalysts with single topology. NH₃-TPD results showed that one new type of strong acidic sites formed in H-ZZs-n and remained in MnH-ZZs-n resulted from the interaction between the Lewis and Brönsted acid sites under a particular environment. The special zeolite-zeolite structure with ion-exchanged Mn ions in the core-shell zeolite composite catalysts contributed to the novel NO-CH₄-SCR properties. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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Review

Jump to: Research

13 pages, 3583 KiB

Open AccessReview

Zeolite Synthesis Using Imidazolium Cations as Organic Structure-Directing Agents

by Paloma Vinaches and Sibele Pergher

Appl. Sci. 2020, 10(1), 303; https://0-doi-org.brum.beds.ac.uk/10.3390/app10010303 - 31 Dec 2019

Cited by 7 | Viewed by 3750

Abstract

Imidazolium-derivative cations are very interesting molecules used as organic structure-directing agents (OSDAs) for zeolite synthesis, widening the possibilities of new materials and applications in this research area. In this review, the studies performed at LABPEMOL using this kind of compound are presented after a quick overview on imidazolium derivatives. The first zeolite synthesis results that started this research study were obtained with 1-butyl-3-methylimidazolium chloride. Then, the design of new OSDAs based on the imidazolium cation, such as 1,2,3-triethylimidazolium, 2-ethyl-1,3-dimethylimidazolium and 1,2,3-triethyl-4-methylimidazolium, is reported. Afterwards, the structure-direction effect caused by the introduction of heteroatoms with already-published imidazolium derivatives (for example, the Al³⁺ insertion into zeolite frameworks with two different OSDAs and the silicoaluminophosphate (SAPO) synthesis using 2-ethyl-1,3,4 trimethylimidazolium cations) is discussed. Finally, we also present a quick overview of some achievements of other laboratories. Full article

(This article belongs to the Special Issue Molecular Sieves: Synthesis, Characterization and Application (Concerning to the 6th Cycle of Lectures on Molecular Sieves))

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