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Porous Materials: Active Phases or Supports in Heterogeneous Catalysis

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A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Catalytic Materials".

Deadline for manuscript submissions: closed (15 May 2023) | Viewed by 18046

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Special Issue Editors

Dr. Angela Martins

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Guest Editor

Department of Chemical Engineering, Instituto Superior de Engenharia de Lisboa, 1950-007 Lisboa, Portugal
Interests: heterogeneous catalysis; zeolites; hierarchical zeolites; bifunctional catalysts; carbon materials; porous silicas
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Ana Paula Carvalho

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Guest Editor

Centro de Química Estrutural, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
Interests: synthesis and modification of porous solids, namely, zeolite structures and carbon materials from biomass through conventional and innovative approaches; characterization of materials through different techniques (e.g., physical adsorption of gases, adsorption of bases followed by infrared, X-ray diffraction, electron microscopies); study of the catalytic properties of zeolite materials in refining, petrochemistry, and fine chemistry such as Friedel–Crafts acylation reactions; application of carbon materials as adsorbents for the removal of pharmaceuticals from water (fundamental and applied studies); application of carbon materials for energy production and storage; carbon materials as catalysts or catalyst supports

Special Issue Information

Dear Colleagues,

Porous materials have attracted a large amount of interest due to their wide range of application in molecular separation, adsorption, and especially as catalysts or catalyst supports. A large set of porous materials such as zeolites and zeotypes, such as SAPOs, ALPOs, among others, metal organic frameworks (MOFs), carbon materials, and mesoporous silicas have in common the presence of a large surface area and pore volume. The micropores can act as microreactors, where the native active sites or introduced species, such as metals, promote the occurrence of catalytic reactions. On the other hand, the larger pores are ideal locations for the anchoring of bulky species such as enzymes or organometallic catalysts, preventing leaching and transforming homogeneous to environmentally friendly and reusable heterogeneous catalysts.

The aim of this Special Issue is to open the discussion concerning the synthesis, modification, and functionalization of porous materials, aiming to prepare innovative and effective catalysts or catalyst supports for heterogeneous catalytic reactions.

Prof. Dr. Angela Martins
Prof. Dr. Ana Paula Carvalho
Guest Editors

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Keywords

Porous materials
Heterogeneous catalysts
Hierarchical materials
Bifunctional catalysts
Catalysts supports
Zeolites
Zeotypes
Carbon materials
MOFs
Mesoporous silicas

Published Papers (7 papers)

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Research

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13 pages, 2139 KiB

Open AccessArticle

MCM-41-Type Mesoporous Silicas Modified with Alumina in the Role of Catalysts for Methanol to Dimethyl Ether Dehydration

by Natalia Szczepanik, Andrzej Kowalczyk, Zofia Piwowarska and Lucjan Chmielarz

Catalysts 2022, 12(11), 1324; https://doi.org/10.3390/catal12111324 - 27 Oct 2022

Cited by 2 | Viewed by 1351

Abstract

MCM-41-type mesoporous silicas were modified with alumina by the impregnation, co-condensation, and template ion-exchange (TIE) methods. The obtained materials were characterized with respect to their chemical composition (ICP-OES), textural parameters (low-temperature N₂ sorption), structure (XRD), and surface acidity (NH₃-TPD) and tested as catalysts of methanol to dimethyl ether (DME) dehydration in a flow microreactor system. The catalytic performance of the studied materials was analyzed with respect to their porous structure, as well as their density and the strength of their acid sites. It was shown that the performance of the studied catalysts depends on the contribution of the surface exposed aluminum species, as well as their aggregation. For the most active catalyst, the study of its catalytic stability under rection conditions was performed. It was shown that the catalyst can be effectively regenerated by the incineration of carbon deposits under air flow at 550 °C for 1 h. Full article

(This article belongs to the Special Issue Porous Materials: Active Phases or Supports in Heterogeneous Catalysis)

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13 pages, 1794 KiB

Open AccessFeature PaperArticle

Influence of Surface Chemistry of Carbon Nanofibers on the Hydrodechlorination of Chloroform to Olefins

by Sichen Liu, Víctor Frutos, María Ariadna Álvarez-Montero, Luisa María Gómez-Sainero, Juan José Rodriguez and Maria Martin-Martinez

Catalysts 2022, 12(10), 1084; https://doi.org/10.3390/catal12101084 - 21 Sep 2022

Viewed by 1366

Abstract

Functionalized carbon nanofibers (CNF) are fascinating materials to be used as supports in Pd-based catalysts for the treatment of waste chloroform (TCM) to produce light olefins through the catalytic hydrodechlorination (HDC). The CNF were functionalized by HNO₃, HCl, and urea. Compared to the Pd supported on un-treated CNF, all the catalysts using functionalized CNF as support showed lower turnover frequency values with higher stability, owing to their smaller Pd nanoparticles (NPs). These smaller Pd NPs are formed due to the stronger metal–support interactions promoted by the higher concentration of surface groups on the functionalized catalysts. Since the smaller Pd NPs could hinder the hydrogenation of olefins to paraffins, the selectivity to olefins increased on the functionalized catalysts. Moreover, the N-doped CNF was successfully formed on the catalyst functionalized by urea. Since the nitrogen functional groups (pyridinic N and pyrrolic N) could provide much stronger metal–support interactions compared to the oxygen functional groups on the other catalysts, the catalyst functionalized by urea showed the smallest Pd NPs among the four catalysts, leading to the highest selectivity to light olefins. Full article

(This article belongs to the Special Issue Porous Materials: Active Phases or Supports in Heterogeneous Catalysis)

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13 pages, 2764 KiB

Open AccessFeature PaperArticle

Exploring the Effect of Hierarchical Porosity in BEA Zeolite in Friedel-Crafts Acylation of Furan and Benzofuran

by Nelson Nunes, Ana P. Carvalho, Ruben Elvas-Leitão, Filomena Martins, Auguste Fernandes, João Rocha and Angela Martins

Catalysts 2022, 12(9), 1064; https://doi.org/10.3390/catal12091064 - 17 Sep 2022

Cited by 4 | Viewed by 1493

Abstract

Hierarchical BEA zeolite was prepared through desilication or desilication followed by acid treatment. The catalytic performance of BEA zeolite samples was evaluated using Friedel-Crafts acylations with two substrates of different molecular sizes, furan (5.7 Å) and benzofuran (6.9 Å), in the presence of acetic anhydride as acylating agent. The application of the simplified Langmuir-Hinshelwood kinetic model showed that the size of the substrate leads to different catalytic activities, with improved rate constant and turnover frequency (TOF) solely in the presence of benzofuran for both desilicated and further acid treated samples. The mesopores developed during the zeolite treatments have an important role as transportation channels by reducing diffusion limitations. The application of Quantitative Structure–Property Relationships (QSPR) allowed the finding of the most relevant properties of the zeolite and substrate with impact on the catalytic parameters. Full article

(This article belongs to the Special Issue Porous Materials: Active Phases or Supports in Heterogeneous Catalysis)

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12 pages, 1013 KiB

Open AccessArticle

Activity and Stability of Pd Bimetallic Catalysts for Catalytic Nitrate Reduction

by Ines Sanchis, Juan Jose Rodriguez, Angel F. Mohedano and Elena Diaz

Catalysts 2022, 12(7), 729; https://doi.org/10.3390/catal12070729 - 30 Jun 2022

Cited by 3 | Viewed by 1639

Abstract

In this work, we study the effect of modifying the metal loading (0.5–1.5 wt.% Pd and 0.1–1 wt.% Sn or In), the impregnation order of noble or promoter metal (Pd–Sn or Sn–Pd), and the type of promoter metal (Sn or In) during the preparation process for a Pd bimetallic catalyst, supported on γ-alumina, used in the catalytic reduction of nitrate. The deposition of the noble metal over the promoter metal, especially with Pd:Sn ratios (wt.) of 1:10 and 1:2, favored the hydrogen spillover rate and increased the H concentration on the catalyst surface, enhancing NH₄⁺ production. On the other hand, Pd–In catalysts showed higher activity than the Sn catalysts, as well as higher NH₄⁺ selectivity. The stability of the Pd–Sn/Al₂O₃ (1.5–1 wt.%) catalyst was evaluated in long-term experiments for the treatment of synthetic water (100 mg L⁻¹ NO₃⁻) and three different commercial drinking waters. This Pd–Sn/Al₂O₃ catalyst achieved a stable nitrate conversion for a duration of 50 h in the synthetic water treatment. However, the catalyst showed a significant activity loss in the presence of other ions (different to NO₃⁻) in the reaction medium, increasing slightly the selectivity to NH₄⁺. Full article

(This article belongs to the Special Issue Porous Materials: Active Phases or Supports in Heterogeneous Catalysis)

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17 pages, 3600 KiB

Open AccessArticle

Fenton-Type Bimetallic Catalysts for Degradation of Dyes in Aqueous Solutions

by Bebiana L. C. Santos, Pier Parpot, Olívia S. G. P. Soares, Manuel F. R. Pereira, Elisabetta Rombi, António M. Fonseca and Isabel Correia Neves

Catalysts 2021, 11(1), 32; https://doi.org/10.3390/catal11010032 - 30 Dec 2020

Cited by 8 | Viewed by 2235

Abstract

Dye compounds are becoming a problematic class of pollutants for the environment, so it is important to develop stable catalysts for their elimination. First, several studies were performed with different Y zeolites (NaY, (NH₄)Y and USY) in order to select the best support for the preparation of the bimetallic catalysts. In particular, NaY zeolite was used as the support for Fe, Cu and Mn metals to prepare mono and bimetallic Fenton-type catalysts by the ion exchange method. The catalysts were characterized by several techniques, such as chemical analysis, nitrogen physisorption, X-ray diffraction (XRD), scanning electron microscopy (SEM) and cyclic voltammetry studies. Characterization results revealed that the metals were successfully ion-exchanged within the NaY zeolite. The prepared catalysts were tested for the aqueous-phase degradation of dye compounds (Procion yellow (PY) and Tartrazine (Tar)) at atmospheric pressure and different temperatures, using H₂O₂ as the oxidant. All the investigated samples were found to be active in degrading the dyes through the Fenton-type process; however, the oxidation rate was found to be higher in the presence of the bimetallic catalysts. CuFe-NaY displays the best mineralization rate for PY oxidation while MnFe-NaY shows the highest activity for Tar degradation. This work may provide further insight into the design of Fenton-type bimetallic catalysts with improved catalytic properties for environmental remediation. Full article

(This article belongs to the Special Issue Porous Materials: Active Phases or Supports in Heterogeneous Catalysis)

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15 pages, 3070 KiB

Open AccessArticle

Vapor-Phase Furfural Decarbonylation over a High-Performance Catalyst of 1%Pt/SBA-15

by Qiang Yuan, Jifeng Pang, Wenguang Yu and Mingyuan Zheng

Catalysts 2020, 10(11), 1304; https://doi.org/10.3390/catal10111304 - 12 Nov 2020

Cited by 6 | Viewed by 2395

Abstract

A high-performance Pt catalyst supported on SBA-15 was developed for furfural decarbonylation. Compared to Pt catalysts loaded on microporous DeAl-Hbeta zeolite and hierarchical micro-mesoporous MFI nanosheet (NS) materials, the 1%Pt/SBA-15 catalyst afforded notably higher activity, furan selectivity and stability owing to the negligible acid sites and proper mesopores on the SBA-15 support. Among a set of 1%Pt/SBA-15 catalysts bearing Pt nanoparticles (NPs) with sizes of 2.4–4.3 nm, the catalyst with 3.7 nm Pt NPs afforded the highest furan selectivity. Over the optimal catalyst, 88.6% furan selectivity and ca. 90% furfural conversion were obtained at 573 K and a high weight hourly space velocity (WHSV) of 16.5 h⁻¹. Moreover, the reaction temperatures at 440–573 K and the ratios of H₂ to furfural at 0.79–9.44 did not affect the reaction selectivity notably, showing that the reaction over 1%Pt/SBA-15 can be conducted over a wide range of conditions. The catalyst was stable under the harsh reaction conditions and lasted for 90 h without significant deactivation, demonstrating the superior property of SBA-15 as a catalyst support for furfural decarbonylation. Full article

(This article belongs to the Special Issue Porous Materials: Active Phases or Supports in Heterogeneous Catalysis)

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Review

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52 pages, 11057 KiB

Open AccessFeature PaperReview

by Angela Martins, Nelson Nunes, Ana P. Carvalho and Luísa M. D. R. S. Martins

Catalysts 2022, 12(2), 154; https://doi.org/10.3390/catal12020154 - 26 Jan 2022

Cited by 20 | Viewed by 6280

Abstract

Catalytic oxidation is a key technology for the conversion of petroleum-based feedstocks into useful chemicals (e.g., adipic acid, caprolactam, glycols, acrylates, and vinyl acetate) since this chemical transformation is always involved in synthesis processes. Millions of tons of these compounds are annually produced worldwide and find applications in all areas of chemical industries, ranging from pharmaceutical to large-scale commodities. The traditional industrial methods to produce large amounts of those compounds involve over-stoichiometric quantities of toxic inorganic reactants and homogeneous catalysts that operate at high temperature, originating large amounts of effluents, often leading to expensive downstream processes, along with nonrecovery of valuable catalysts that are loss within the reactant effluent. Due to the increasingly stringent environmental legislation nowadays, there is considerable pressure to replace these antiquate technologies, focusing on heterogeneous catalysts that can operate under mild reactions conditions, easily recovered, and reused. Parallelly, recent advances in the synthesis and characterization of metal complexes and metal clusters on support surfaces have brought new insights to catalysis and highlight ways to systematic catalysts design. This review aims to provide a comprehensive bibliographic examination over the last 10 years on the development of heterogeneous catalysts, i.e., organometallic complexes or metal clusters immobilized in distinct inorganic supports such as zeolites, hierarchical zeolites, silicas, and clays. The methodologies used to prepare and/or modify the supports are critically reviewed, as well as the methods used for the immobilization of the active species. The applications of the heterogenized catalysts are presented, and some case-studies are discussed in detail. Full article

(This article belongs to the Special Issue Porous Materials: Active Phases or Supports in Heterogeneous Catalysis)

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