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Zeolites and Related Materials for Biocatalysis, Heterogeneous Catalysis and Sustainable Applications

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Catalytic Materials".

Deadline for manuscript submissions: closed (20 December 2023) | Viewed by 4368

Special Issue Editors

Department of Applied Science and Technology, Polytechnic University of Turin, Turin, Italy
Interests: heterogeneous catalysis; biocatalysis; sustainable materials; biotechnology; environmental applications
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue aims to provide a range of selected contributions on both natural and synthetic zeolites, mesoporous materials, and hierarchical systems for biocatalysis (supported enzymes), heterogeneous catalysis, and sustainable applications.

Porous materials are particularly interesting for the immobilization of enzymes and cells. Then, it is possible to design promising biocatalytic systems. Similarly, micro- and mesoporous materials can be used to prepare heterogeneous catalysts with highly dispersed active sites, such as the Single-Site Heterogeneous-Catalysts proposed by Sir John Meurig Thomas, that are the inorganic analogues of enzymes.

On the other hand, zeolites and related materials are effective for a large number of environmental and sustainable processes, including wastewater treatment, capture and storage of gases, development of sustainable agriculture, etc. Therefore, we strongly encourage researchers and scientists, from academia and industry, to submit their scientific work for this Special Issue. Full papers, communications, and reviews are all welcome.

Prof. Dr. Debora Fino
Dr. Marco Piumetti
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • synthetic zeolite
  • natural zeolite
  • hierarchical zeolite
  • catalysis
  • biocatalysis, biotechnology
  • sustainability

Published Papers (3 papers)

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Research

18 pages, 2938 KiB  
Article
Natural Zeolite Clinoptilolite Application in Wastewater Treatment: Methylene Blue, Zinc and Cadmium Abatement Tests and Kinetic Studies
Materials 2022, 15(22), 8191; https://doi.org/10.3390/ma15228191 - 18 Nov 2022
Cited by 6 | Viewed by 1487
Abstract
In recent decades, several abatement techniques have been proposed for organic dyes and metal cations. In this scenario, adsorption is the most known and studied. Clinoptilolite was considered, since it is a zeolite with a relatively low cost (200–600 $ tons−1) [...] Read more.
In recent decades, several abatement techniques have been proposed for organic dyes and metal cations. In this scenario, adsorption is the most known and studied. Clinoptilolite was considered, since it is a zeolite with a relatively low cost (200–600 $ tons−1) compared to the most well-known adsorbent used in wastewater treatment. In this work, Clinoptilolite was used for the adsorption of Methylene Blue (MB) at three different concentrations, namely, 100, 200, and 250 ppm. Furthermore, the adsorption capacity of the natural zeolite was compared with that of Activated Charcoal (250 ppm of MB). The two adsorbents were characterized by complementary techniques, such as N2 physisorption at −196 °C, X-ray diffraction, and field emission scanning electron microscopy. During the adsorption tests, Clinoptilolite exhibited the best adsorption capacities at 100 ppm: the abatement reached 98% (t = 15 min). Both Clinoptilolite and Activated Charcoal, at 250 ppm, exhibited the same adsorption capacities, namely, 96%. Finally, at 250 ppm MB, the adsorption capacity of Clinoptilolite was analyzed with the copresence of Zn2+ and Cd2+ (10 ppm), and the adsorption capacities were compared with those of Activated Charcoal. The results showed that both adsorbents achieved 100% MB abatement (t = 40 min). However, cation adsorption reached a plateau after 120 min (Zn2+ = 86% and 57%; Cd2+ = 53% and 50%, for Activated Charcoal and Clinoptilolite, respectively) due to the preferential adsorption of MB molecules. Furthermore, kinetic studies were performed to fully investigate the adsorption mechanism. It was evidenced that the pseudo-second-order kinetic model is effective in describing the adsorption mechanism of both adsorbents, highlighting the chemical interaction between the adsorbent and adsorbate. Full article
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25 pages, 4352 KiB  
Article
Hydrotalcite-Modified Clinoptilolite as the Catalyst for Selective Catalytic Reduction of NO with Ammonia (NH3-SCR)
Materials 2022, 15(22), 7884; https://doi.org/10.3390/ma15227884 - 08 Nov 2022
Cited by 1 | Viewed by 1211
Abstract
A series of clinoptilolite-supported catalysts, modified with hydrotalcite-like phase (HT) by co-precipitation, were prepared and tested in NH3-SCR reactions. It was found that deposition of HT on clinoptilolite increased conversion of NO within 250–450 °C, and that the positive impact on [...] Read more.
A series of clinoptilolite-supported catalysts, modified with hydrotalcite-like phase (HT) by co-precipitation, were prepared and tested in NH3-SCR reactions. It was found that deposition of HT on clinoptilolite increased conversion of NO within 250–450 °C, and that the positive impact on the catalytic activity was independent of HT loading. The promoting effect of clinoptilolite was attributed to Brönsted acid sites present in the zeolite, which facilitated adsorption and accumulation of ammonia during the catalytic process. Concentration of N2O in the post-reaction gas mixture reached its maximum at 300 °C and the by-product was most likely formed as a consequence of NH4NO3 decomposition or side reaction of NH3 oxidation in the high-temperature region. The gradual elimination of nitrous oxide, noticed as the material with the highest concentration of hydrotalcite phase, was attributed to the abundance of oligomeric iron species and the superior textural parameters of the material. UV-Vis experiments performed on the calcined samples indicated that Fe sites of higher nuclearity were generated by thermal decomposition of the hydrotalcite phase during the catalytic reaction. Therefore, calcination of the materials prior to the catalytic tests was not required to obtain satisfactory overall catalytic performance in NO reductions. Full article
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22 pages, 4388 KiB  
Article
Physico-Chemical Modifications Affecting the Activity and Stability of Cu-Based Hybrid Catalysts during the Direct Hydrogenation of Carbon Dioxide into Dimethyl-Ether
Materials 2022, 15(21), 7774; https://doi.org/10.3390/ma15217774 - 04 Nov 2022
Cited by 4 | Viewed by 1040
Abstract
The direct hydrogenation of CO2 into dimethyl-ether (DME) has been studied in the presence of ferrierite-based CuZnZr hybrid catalysts. The samples were synthetized with three different techniques and two oxides/zeolite mass ratios. All the samples (calcined and spent) were properly characterized with [...] Read more.
The direct hydrogenation of CO2 into dimethyl-ether (DME) has been studied in the presence of ferrierite-based CuZnZr hybrid catalysts. The samples were synthetized with three different techniques and two oxides/zeolite mass ratios. All the samples (calcined and spent) were properly characterized with different physico-chemical techniques for determining the textural and morphological nature of the catalytic surface. The experimental campaign was carried out in a fixed bed reactor at 2.5 MPa and stoichiometric H2/CO2 molar ratio, by varying both the reaction temperature (200–300 °C) and the spatial velocity (6.7–20.0 NL∙gcat−1∙h−1). Activity tests evidenced a superior activity of catalysts at a higher oxides/zeolite weight ratio, with a maximum DME yield as high as 4.5% (58.9 mgDME∙gcat−1∙h−1) exhibited by the sample prepared by gel-oxalate coprecipitation. At lower oxide/zeolite mass ratios, the catalysts prepared by impregnation and coprecipitation exhibited comparable DME productivity, whereas the physically mixed sample showed a high activity in CO2 hydrogenation but a low selectivity toward methanol and DME, ascribed to a minor synergy between the metal-oxide sites and the acid sites of the zeolite. Durability tests highlighted a progressive loss in activity with time on stream, mainly associated to the detrimental modifications under the adopted experimental conditions. Full article
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