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Metal-Exchanged Zeolite Catalysts
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Metal-Exchanged Zeolite Catalysts

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

Deadline for manuscript submissions: closed (15 July 2020) | Viewed by 13858

Special Issue Editors

Prof. Dr. Oliver Kröcher

E-Mail Website
Guest Editor
Bioenergy and Catalysis Laboratory, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
Interests: heterogeneous catalysis; environmental catalysis; exhaust gas catalysis; biofuels; thermochemical biomass conversion
Special Issues, Collections and Topics in MDPI journals
Dr. Davide Ferri

E-Mail Website
Guest Editor
Catalysis for Energy, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
Interests: heterogeneous catalysis; environmental catalysis; operando spectroscopy; IR spectroscopy; perovskite-type oxides; functional materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Zeolites are workhorses of the chemical industry and are also heavily exploited in pollution control technologies. Numerous zeolite framework structures are currently used, developed and investigated for an incredible number of chemical processes. The exchange with various transition and post-transition metals functionalizes zeolites and makes them potent heterogeneous catalysts.

This Special Issue on “Metal-Exchanged Zeolite Catalysts” will provide updates on recent advances in synthesis methods, characterization, catalytic performance and degradation of transition metal-exchanged zeolites for catalytic applications. We expect contributions to the Special Issue to include structural analysis of the active metal phase using various characterization methods and measurements of the catalytic performance. Determination of the working structure during reaction would be ideal.

Submissions to this Special Issue are welcome in the form of original research papers or short reviews reflecting the knowledge in the field of zeolite materials within the following thematic subjects: heterogeneous catalysis, biomass valorization, catalytic pollution control, and structure by operando methods.

Prof. Dr. Oliver Kröcher
Dr. Davide Ferri
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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. Catalysts is an international peer-reviewed open access monthly 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 2700 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

  • zeolites
  • transition metals
  • precious metals
  • synthesis
  • characterization
  • novel structures
  • aging
  • acid-base catalysis
  • pollution control
  • synthesis of fine chemicals
  • biomass applications

Published Papers (4 papers)

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Research

13 pages, 2258 KiB  
Article
Effects of Framework Disruption of Ga and Ba Containing Zeolitic Materials by Thermal Treatment
by Siyabonga S. Ndlela, Holger B. Friedrich and Mduduzi N. Cele
Catalysts 2020, 10(9), 975; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10090975 - 30 Aug 2020
Cited by 2 | Viewed by 1900
Abstract
The effect of the thermal treatment of some zeolitic materials was studied on oxidative dehydrogenation (ODH) of n-octane. Gallium containing faujasite catalysts were synthesized using isomorphic substitution, specifically, a galosilicalite (Ga-BaY(Sil)) and an aluminosilicalite substituted with gallium (Ga-BaY(IS)), with constant Si/M ratio. [...] Read more.
The effect of the thermal treatment of some zeolitic materials was studied on oxidative dehydrogenation (ODH) of n-octane. Gallium containing faujasite catalysts were synthesized using isomorphic substitution, specifically, a galosilicalite (Ga-BaY(Sil)) and an aluminosilicalite substituted with gallium (Ga-BaY(IS)), with constant Si/M ratio. The catalysts were thermally treated at different temperatures (250, 550, and 750 °C) before catalytic testing. The quantification of total and strength of acid sites by FT-IR (O-H region), pyridine-IR, and NH3-temperature-programmed desorption (TPD) confirmed a decrease in the number of Brønsted acid sites and an increase in the number of Lewis acid sites upon increasing the calcination temperature. Isothermal n-octane conversion also decreased with the catalysts’ calcination temperature, whereas octene selectivity showed the opposite trend (also at iso-conversion). The COx selectivity showed a decrease over the catalysts calcined from 250 to 550 °C and then an increase over the 750 °C calcined catalysts, which was due to the strong adsorption of products to strong Lewis acid sites on the catalysts leading to the deep oxidation of the products. Only olefinic-cracked products were observed over the 750 °C calcined catalysts. This suggested that the thermal treatment increases Lewis acid sites, which activate n-octane using a bimolecular mechanism, instead of a monomolecular mechanism. Full article
(This article belongs to the Special Issue Metal-Exchanged Zeolite Catalysts)
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11 pages, 3027 KiB  
Article
In-Exchanged CHA Zeolites for Selective Dehydrogenation of Ethane: Characterization and Effect of Zeolite Framework Type
by Zen Maeno, Xiaopeng Wu, Shunsaku Yasumura, Takashi Toyao, Yasuharu Kanda and Ken-ichi Shimizu
Catalysts 2020, 10(7), 807; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10070807 - 20 Jul 2020
Cited by 15 | Viewed by 3829
Abstract
In this study, the characterization of In-exchanged CHA zeolite (In-CHA (SiO2/Al2O3 = 22.3)) was conducted by in-situ X-ray diffraction (XRD) and ammonia temperature-programmed desorption (NH3-TPD). We also prepared other In-exchanged zeolites with different zeolite structures (In-MFI [...] Read more.
In this study, the characterization of In-exchanged CHA zeolite (In-CHA (SiO2/Al2O3 = 22.3)) was conducted by in-situ X-ray diffraction (XRD) and ammonia temperature-programmed desorption (NH3-TPD). We also prepared other In-exchanged zeolites with different zeolite structures (In-MFI (SiO2/Al2O3 = 22.3), In-MOR (SiO2/Al2O3 = 20), and In-BEA (SiO2/Al2O3 = 25)) and different SiO2/Al2O3 ratios (In-CHA(Al-rich) (SiO2/Al2O3 = 13.7)). Their catalytic activities in nonoxidative ethane dehydrogenation were compared. Among the tested catalysts, In-CHA(Al-rich) provided the highest conversion. From kinetic experiments and in-situ Fourier transform infrared (FTIR) spectroscopy, [InH2]+ ions are formed regardless of SiO2/Al2O3 ratio, serving as the active sites. Full article
(This article belongs to the Special Issue Metal-Exchanged Zeolite Catalysts)
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21 pages, 2972 KiB  
Article
Nanosized Cu-SSZ-13 and Its Application in NH3-SCR
by Ana Palčić, Paolo Cleto Bruzzese, Kamila Pyra, Marko Bertmer, Kinga Góra-Marek, David Poppitz, Andreas Pöppl, Roger Gläser and Magdalena Jabłońska
Catalysts 2020, 10(5), 506; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10050506 - 04 May 2020
Cited by 23 | Viewed by 4852
Abstract
Nanosized SSZ-13 was synthesized hydrothermally by applying N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) as a structure-directing agent. In the next step, the quantity of TMAdaOH in the initial synthesis mixture of SSZ-13 was reduced by half. Furthermore, we varied the sodium hydroxide concentration. After ion-exchange with [...] Read more.
Nanosized SSZ-13 was synthesized hydrothermally by applying N,N,N-trimethyl-1-adamantammonium hydroxide (TMAdaOH) as a structure-directing agent. In the next step, the quantity of TMAdaOH in the initial synthesis mixture of SSZ-13 was reduced by half. Furthermore, we varied the sodium hydroxide concentration. After ion-exchange with copper ions (Cu2+ and Cu+), the Cu-SSZ-13 catalysts were characterized to explore their framework composition (XRD, solid-state NMR, ICP-OES), texture (N2-sorption, SEM) and acid/redox properties (FT-IR, TPR-H2, DR UV-Vis, EPR). Finally, the materials were tested in the selective catalytic reduction of NOx with ammonia (NH3-SCR). The main difference between the Cu-SSZ-13 catalysts was the number of Cu2+ in the double six-membered ring (6MRs). Such copper species contribute to a high NH3-SCR activity. Nevertheless, all materials show comparable activity in NH3-SCR up to 350 °C. Above 350 °C, NO conversion decreased for Cu-SSZ-13(2–4) due to side reaction of NH3 oxidation. Full article
(This article belongs to the Special Issue Metal-Exchanged Zeolite Catalysts)
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13 pages, 1927 KiB  
Article
Effects of Modifying Acidity and Reducibility on the Activity of NaY Zeolite in the Oxidative Dehydrogenation of n-Octane
by Siyabonga S. Ndlela, Holger B. Friedrich and Mduduzi N. Cele
Catalysts 2020, 10(4), 363; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10040363 - 27 Mar 2020
Cited by 9 | Viewed by 2551
Abstract
Non-coking stable alkaline earth metal (M = Mg, Sr, and Ba) modified Ga-NaY catalysts were prepared by ionic-exchange and tested in oxidative dehydrogenation (ODH) of n-octane using air as the source of oxygen. The role of the alkaline earth metals in NaY [...] Read more.
Non-coking stable alkaline earth metal (M = Mg, Sr, and Ba) modified Ga-NaY catalysts were prepared by ionic-exchange and tested in oxidative dehydrogenation (ODH) of n-octane using air as the source of oxygen. The role of the alkaline earth metals in NaY was to poison the acid sites while enhancing the basic sites responsible for ODH. The exception was the calcium modified NaY, which was more acidic than the parent NaY, coking and unstable under the ODH conditions used in this study. The role of gallium was to enhance the dehydrogenation pathway and improve the stability of NaY. The sequence of increasing selectivity to octenes followed the order: CaGa-NaY < Ga-NaY< MgGa-NaY < SrGa-NaY < BaGa-NaY. The highest octene selectivity obtained was 37% at iso-conversion of 6 ± 1% when BaGa-NaY was used at a temperature of 450 °C. The activity of the catalysts was directly proportional to the reducibility of the catalysts, which is in agreement with expectations. Full article
(This article belongs to the Special Issue Metal-Exchanged Zeolite Catalysts)
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