Special Issue "Molecular Sieves: Synthesis, Characterization and application (concerning to the Cycle of Lectures on Molecular Sieves)"

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

Deadline for manuscript submissions: 31 October 2019.

Special Issue Editors

Guest Editor
Prof. Dr. Sibele Pergher Website E-Mail
Departamento de Química, Universidade Federal do Rio Grande do Norte, Natal Caixa postal 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
Guest Editor
Prof. Dr. Katia Bernardo-Gusmão Website E-Mail
Instituto de Química, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil, Caixa Postal: 15003, CEP 91.501-970
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

Manuscript Submission Information

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Keywords

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

Published Papers (4 papers)

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Research

Open AccessFeature PaperArticle
Hybrid Ionic Liquid–Silica Xerogels Applied in CO2 Capture
Appl. Sci. 2019, 9(13), 2614; https://doi.org/10.3390/app9132614 - 28 Jun 2019
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 [...] Read more.
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
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Open AccessFeature PaperArticle
Conversion of Stearic Acid into Bio-Gasoline over Pd/ZSM-5 Catalysts with Enhanced Accessibility
Appl. Sci. 2019, 9(11), 2386; https://doi.org/10.3390/app9112386 - 11 Jun 2019
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 [...] Read more.
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
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Open AccessFeature PaperArticle
Separation of N–C5H12–C9H20 Paraffins Using Boehmite by Inverse Gas Chromatography
Appl. Sci. 2019, 9(9), 1810; https://doi.org/10.3390/app9091810 - 30 Apr 2019
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; [...] Read more.
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
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Open AccessArticle
NO-CH4-SCR Over Core-Shell MnH-Zeolite Composites
Appl. Sci. 2019, 9(9), 1773; https://doi.org/10.3390/app9091773 - 28 Apr 2019
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 [...] Read more.
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
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