Special Issue "Synthesis and Application of Zeolite Catalysts"

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

Deadline for manuscript submissions: closed (31 January 2020).

Special Issue Editors

Prof. Dr. Kyungsu Na
Website
Guest Editor
Department of Chemistry, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju, South Korea
Interests: heterogeneous catalysis; nanostructured materials; C1 conversion
Dr. Chang Hyun Ko

Guest Editor
School of Chemical Engineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju, South Korea
Interests: the heterogeneous catalysis using various nanostructured materials

Special Issue Information

Dear Colleagues,

Zeolites are central in many industrial and chemical engineering processes involving solid catalysts, which have attracted a great deal of attention from chemists, chemical engineers, and materials scientists. This family of nanoporous crystals was first discovered in 1756 and, since then, about 40 zeolites structures have been found in nature, and about 160 structures, to date, have been synthesized artificially in the lab. The regularly-arranged micropores within stable crystalline architectures afford useful functions to zeolite catalysts, such as size/shape selective catalytic ability and high thermal/hydrothermal/mechanical stabilities. In this regard, a great deal of research regarding the synthesis of zeolites, with better functions, as well as their catalytic applications, has been performed so far, and broad knowledge has been accumulated over the decades. For example, in addition to the aluminosilicate-type classical zeolites, various transition metal-incorporated zeolites have been synthesized, which is reminiscent of the heterogenized version of transition metal complexes. The tiny micropores often limit their catalytic regime to only sufficiently-small molecular species that can go through the pore aperture, but such a limited applicability has also been considerably improved by the generation of larger pores in a mesopore range.

The aforementioned research works on the development of various synthetic zeolites, having better catalytic performances, has guided current industrial society to a brighter and greener world. The aim of the present Special Issue is to report the latest research advances in the synthesis and characterization of zeolites and their catalytic applications in experimental and theoretical manners. Broad contributions, including other crystalline nanoporous materials and their catalytic applications, would also be valuable subjects to widen the scope of this Special Issue.

Dr. Kyungsu Na
Dr. Chang Hyun Ko
Guest Editors

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Keywords

  • Zeolite synthesis
  • Mesoporous zeolite
  • Hierarchical zeolite
  • Heterogeneous catalyst
  • Catalytic application

Published Papers (23 papers)

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Open AccessArticle
Copper-Iron Bimetal Ion-Exchanged SAPO-34 for NH3-SCR of NOx
Catalysts 2020, 10(3), 321; https://doi.org/10.3390/catal10030321 - 11 Mar 2020
Abstract
SAPO-34 was prepared with a mixture of three templates containing triethylamine, tetraethylammonium hydroxide, and morpholine, which leads to unique properties for support and production cost reduction. Meanwhile, Cu/SAPO-34, Fe/SAPO-34, and Cu-Fe/SAPO-34 were prepared through the ion-exchanged method in aqueous solution and used for [...] Read more.
SAPO-34 was prepared with a mixture of three templates containing triethylamine, tetraethylammonium hydroxide, and morpholine, which leads to unique properties for support and production cost reduction. Meanwhile, Cu/SAPO-34, Fe/SAPO-34, and Cu-Fe/SAPO-34 were prepared through the ion-exchanged method in aqueous solution and used for selective catalytic reduction (SCR) of NOx with NH3. The physical structure and original crystal of SAPO-34 are maintained in the catalysts. Cu-Fe/SAPO-34 catalysts exhibit high NOx conversion in a broad temperature window, even in the presence of H2O. The physicochemical properties of synthesized samples were further characterized by various methods, including XRD, FE-SEM, EDS, N2 adsorption-desorption isotherms, UV-Vis-DRS spectroscopy, NH3-TPD, H2-TPR, and EPR. The best catalyst, 3Cu-1Fe/SAPO-34 exhibited high NOx conversion (> 90%) in a wide temperature window of 250–600 °C, even in the presence of H2O. In comparison with mono-metallic samples, the 3Cu-1Fe/SAPO-34 catalyst had more isolated Cu2+ ions and additional oligomeric Fe3+ active sites, which mainly contributed to the higher capacity of NH3 and NOx adsorption by the enhancement of the number of acid sites as well as its greater reducibility. Therefore, this synergistic effect between iron and copper in the 3Cu-1Fe/SAPO-34 catalyst prompted higher catalytic performance in more extensive temperature as well as hydrothermal stability after iron incorporation. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Effect of Ethanol on the Morphology and Textual Properties of ZSM-5 Zeolite
Catalysts 2020, 10(2), 198; https://doi.org/10.3390/catal10020198 - 06 Feb 2020
Abstract
The morphology of ZSM-5 zeolite impacts the adsorption, separation and diffusion of molecules. The morphology and textural properties of ZSM-5 zeolites were adjusted by regulating the content of ethanol in the synthesis gel. When the ratio of ethanol/SiO2 was lower than 2, [...] Read more.
The morphology of ZSM-5 zeolite impacts the adsorption, separation and diffusion of molecules. The morphology and textural properties of ZSM-5 zeolites were adjusted by regulating the content of ethanol in the synthesis gel. When the ratio of ethanol/SiO2 was lower than 2, the obtained crystals were isolated particles. With higher ethanol concentration, the chainlike zeolite was generated due to the condensation of terminal Si-OH groups. The crystals stacked more and more compactly with the increase in ethanol concentration, resulting in decreased specific surface area, total volume and mesoporous volume. The crystal size increased gradually with the increase in the ethanol concentration. Moreover, some other small molecular alcohols could also induce the formation of chainlike morphology of ZSM-5. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessFeature PaperArticle
Structure and Activity of Ni2P/Desilicated Zeolite β Catalysts for Hydrocracking of Pyrolysis Fuel Oil into Benzene, Toluene, and Xylene
Catalysts 2020, 10(1), 47; https://doi.org/10.3390/catal10010047 - 01 Jan 2020
Cited by 1
Abstract
The effects of desilication (DS) of the zeolite β on the hydrocracking of polycyclic aromatics were investigated using the Ni2P/β catalysts. The Ni2P/β catalysts were obtained by the temperature-programmed reduction (TPR) method, and the physical and chemical properties were [...] Read more.
The effects of desilication (DS) of the zeolite β on the hydrocracking of polycyclic aromatics were investigated using the Ni2P/β catalysts. The Ni2P/β catalysts were obtained by the temperature-programmed reduction (TPR) method, and the physical and chemical properties were examined by N2 physisorption, X-ray diffraction (XRD), 27Al magic angle spinning–nuclear magnetic resonance (27Al MAS NMR), extended X-ray absorption fine structure (EXAFS), isopropyl amine (IPA) and NH3 temperature-programmed desorption (TPD), CO uptake, and thermogravimetric analysis (TGA). The catalytic activity was examined at 653 K and 6.0 MPa in a continuous fixed bed reactor for the hydrocracking (HCK) of model compounds of 1-methylnaphthalene (1-MN) and phenanthrene or a real feedstock of pyrolysis fuel oil (PFO). Overall, the Ni2P/DS-β was observed as more active and stable in the hydrocracking of polycyclic aromatics than the Ni2P/β catalyst. In addition, the Ni2P/β suffered from the coke formation, while the Ni2P/DS-β maintained the catalytic stability, particularly in the presence of large polycyclic hydrocarbons in the feed. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Removal of Banana Tree Fungi Using Green Tuff Rock Powder Waste Containing Zeolite
Catalysts 2019, 9(12), 1049; https://doi.org/10.3390/catal9121049 - 10 Dec 2019
Abstract
Hinai green tuff, which is found in Akita Prefecture, Japan, is used for the production of building materials, etc. About 60% of all stone is emitted as waste powder and therefore it is important to find ways for recycling it. In this work, [...] Read more.
Hinai green tuff, which is found in Akita Prefecture, Japan, is used for the production of building materials, etc. About 60% of all stone is emitted as waste powder and therefore it is important to find ways for recycling it. In this work, the characteristics of green tuff powder have been investigated. The results of scanning electron microscope (SEM) and elemental map observations indicate that the green tuff contains TiO2 on zeolite. The green tuff can therefore be used as a natural catalyst for producing hydrogen peroxide with moisture and oxygen with light. The optimum calcined temperature of the green tuff powder is about 800 °C, producing the hydroxyl radical from hydrogen peroxide decomposition without ultraviolet light (UV) and decomposition of the superoxide anion. As the application of green tuff powder, Cavendish banana trees found in the Philippines infected by a new Panama disease were treated with powder suspension in order to remove the fungus (a type of Fusarium wilt) due to the photocatalyst characteristics of powder. The suspension, prepared by using the powder was sprayed on the infected banana trees for about one month. Photograph observation indicated that the so-called 800 °C suspension spray was more effective in growing the infected banana trees. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Effect of Metal Oxide–Support Interactions on Ethylene Oligomerization over Nickel Oxide/Silica–Alumina Catalysts
Catalysts 2019, 9(11), 933; https://doi.org/10.3390/catal9110933 - 08 Nov 2019
Abstract
We investigated the interactions between nickel oxide and silica–alumina supports, which were applied to the catalytic oligomerization of ethylene by powder X-ray diffraction, UV diffuse reflectance spectroscopy, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy. The catalytic activity was also correlated with the [...] Read more.
We investigated the interactions between nickel oxide and silica–alumina supports, which were applied to the catalytic oligomerization of ethylene by powder X-ray diffraction, UV diffuse reflectance spectroscopy, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy. The catalytic activity was also correlated with the acidity of catalysts determined by NH3 temperature-programmed desorption and pyridine FT-IR spectroscopy. Although all the catalysts had similar Ni contents, their catalytic performances were strongly influenced by the strength of the metal oxide–support interaction. Strong interaction promoted the formation of nickel aluminate on the catalyst surface, and resulted in low catalytic activity due to reducing the amount of nickel oxide active sites. However, weak interaction favored the aggregation of nickel oxide species into larger particles, and thus resulted in low ethylene conversion and selectivity to oligomers. Eventually, the optimal activity was realized at the medium interaction strength, preserving a high amount of both active nickel oxides and acid sites. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessFeature PaperCommunication
Selective Catalytic Transfer Hydrogenolysis of Glycerol to 2-Isopropoxy-Propan-1-Ol over Noble Metal Ion-Exchanged Mordenite Zeolite
Catalysts 2019, 9(11), 885; https://doi.org/10.3390/catal9110885 - 25 Oct 2019
Abstract
This study investigated the selective conversion of glycerol to 2-isopropoxy-propan-1-ol over noble metal ion-exchanged mordenite zeolites (RuMOR, RhMOR, and PdMOR) as heterogeneous catalysts via catalytic transfer hydrogenolysis (CTH) using propan-2-ol as the solvent, hydrogen supplier, and reactive coupling reagent with glycerol. The catalytic [...] Read more.
This study investigated the selective conversion of glycerol to 2-isopropoxy-propan-1-ol over noble metal ion-exchanged mordenite zeolites (RuMOR, RhMOR, and PdMOR) as heterogeneous catalysts via catalytic transfer hydrogenolysis (CTH) using propan-2-ol as the solvent, hydrogen supplier, and reactive coupling reagent with glycerol. The catalytic reactions were performed at 140 °C under inert conditions with a 0.5 MPa initial pressure of N2. A single product, 2-isopropoxy-propan-1-ol, was catalytically generated without any appreciable by-products. The catalytic results were reproducible, and the catalysts exhibited good recyclability. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Facile Synthesis of Co3O4 Nanoparticle-Functionalized Mesoporous SiO2 for Catalytic Degradation of Methylene Blue from Aqueous Solutions
Catalysts 2019, 9(10), 809; https://doi.org/10.3390/catal9100809 - 27 Sep 2019
Cited by 1
Abstract
In this study, a series of Co3O4 nanoparticle-functionalized mesoporous SiO2 (Co–SiO2) were successfully synthesized via a spontaneous infiltration route. Co species were firstly infiltrated into the confined spaces between the surfactant and silica walls, with the assistance [...] Read more.
In this study, a series of Co3O4 nanoparticle-functionalized mesoporous SiO2 (Co–SiO2) were successfully synthesized via a spontaneous infiltration route. Co species were firstly infiltrated into the confined spaces between the surfactant and silica walls, with the assistance of grinding CoCl3·6H2O and the as-prepared mesoporous SiO2. Then, Co3O4 nanoparticles (NPs) were formed and grown in the limited space of the mesopores, after calcination. Structures, morphologies, and compositions of the materials were characterized by X-ray diffraction, transmission electron microscopy, energy dispersion spectrum, N2 adsorption, and Fourier transform infrared spectra. Results showed that the high content of Co (rCo:Si = 0.17) can be efficiently dispersed into the mesoporous SiO2 as forms of Co3O4 NPs, and the structural ordering of the mesoporous SiO2 was well-preserved at the same time. The Co3O4 NP functionalized mesoporous SiO2 materials were used as Fenton-like catalysts for removing methylene blue (MB) from aqueous solutions. The catalyst prepared at rCo:Si = 0.17 could completely remove the high-concentration of MB (120 mg·L−1), and also showed an excellent performance with a removal capacity of 138 mg·g−1 to 180 mg·L−1 of MB. Catalytic mechanisms were further revealed, based on the degradation results. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Synthesis of ZSM-5 Zeolite Using Coal Fly Ash as an Additive for the Methanol to Propylene (MTP) Reaction
Catalysts 2019, 9(10), 788; https://doi.org/10.3390/catal9100788 - 22 Sep 2019
Cited by 3
Abstract
Using ZSM-5 zeolites as catalysts for the methanol to propylene (MTP) reaction is being widely investigated and has been industrially applied. In this study, pure ZSM-5 zeolite was successfully synthesized by a direct hydrothermal method using the fly ash of coal gasification as [...] Read more.
Using ZSM-5 zeolites as catalysts for the methanol to propylene (MTP) reaction is being widely investigated and has been industrially applied. In this study, pure ZSM-5 zeolite was successfully synthesized by a direct hydrothermal method using the fly ash of coal gasification as an additional raw material. Various analysis methods such as X-ray diffraction, N2 sorption, scanning electron microscopy, and infrared spectroscopy, were employed to characterize the physicochemical properties of parent and modified zeolites. Then, the prepared ZSM-5 catalysts were tested in the MTP reaction. The results showed that pure ZSM-5 could be directly synthesized in the optimized conditions using fly ash as additional silicon and aluminum sources, and those ZSM-5 catalysts turned out to be candidate catalysts for the MTP reaction. Whereas their catalytic lifetimes were not good enough due to the strong acid sites and needed improving. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Influence of the Brønsted Acidity on the Ring Opening of Decalin for Pt-USY Catalysts
Catalysts 2019, 9(10), 786; https://doi.org/10.3390/catal9100786 - 20 Sep 2019
Abstract
A challenging hot topic faced by the oil refinery industry is the upgrading of low-quality distillate fractions, such as light cycle oil (LCO), in order to meet current quality standards for diesel fuels. An auspicious technological alternative entails the complete saturation of the [...] Read more.
A challenging hot topic faced by the oil refinery industry is the upgrading of low-quality distillate fractions, such as light cycle oil (LCO), in order to meet current quality standards for diesel fuels. An auspicious technological alternative entails the complete saturation of the aromatic structures followed by the selective cleavage of endocyclic carbon-carbon bonds in the formed naphthenic rings (selective ring opening—SRO). This work reports the influence of Brønsted acid sites of platinum-ultra stable Y zeolite (Pt-USY) catalysts in the SRO of decalin as a model naphthenic feed. A maximum combined yield to selective ring opening products (ROP: C10-alkylcycloalkanes + OCD: C10-alkanes) as high as 28.6 wt% was achieved for 1.6Pt-NaUSY-im catalyst. The molar carbon distribution curve of the hydrocracked (C9-) products varied from M-shaped for 1.4Pt-USY-im catalyst, indicating mainly C–C bond cleavage of the ring opening products with one remaining naphthenic ring via carbocations and the paring reaction, to not M-shaped for the 1.6Pt-NaUSY-im catalyst, where carbon-carbon bond cleavage occurs preferentially through a hydrogenolysis mechanism on metal sites. High (hydro)thermal stability and secondary mesoporosity of the 1.6Pt-NaUSY-im catalysts make this system highly prospective for upgrading low-quality real distillate feeds. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Effect of Chlorine-Containing VOCs on Silver Migration and Sintering in ZSM-5 Used in a TSA Process
Catalysts 2019, 9(8), 686; https://doi.org/10.3390/catal9080686 - 14 Aug 2019
Cited by 1
Abstract
Silver nanoparticles are currently one of the most studied nanostructured nanomaterials. Because nanoparticle size and dispersion act together in determining a material’s physical and chemical properties, there is a continuous quest to develop size-controlled synthesis methods. Nonetheless, the instability of the nanometer-sized particles, [...] Read more.
Silver nanoparticles are currently one of the most studied nanostructured nanomaterials. Because nanoparticle size and dispersion act together in determining a material’s physical and chemical properties, there is a continuous quest to develop size-controlled synthesis methods. Nonetheless, the instability of the nanometer-sized particles, which is caused by their tendency to aggregate irreversibly into larger particles, remains a recurrent problem. The use of confining scaffolds, such as the regular system of cages in a crystalline zeolite-type material, is often reported in the literature as an efficient solution to overcome particle migration at the surface. Silver nanoparticles encapsulated in ZSM-5 ([email protected]) represent a new generation of adsorbent for Xe enrichment from the atmosphere that is currently being developed at the pilot scale in a Temperature Swing Adsorption (TSA) process. In this study, we have found that the presence of Cl-containing compounds in the air (VOCs) leads to a poisoning of the active silver phase by the formation of silver chloride. By a careful study of process parameters, we have found that most of the chlorine can be removed by heat treatment above 573 K so that the adsorption properties of silver are regenerated. That said, when applying 573 K temperature regeneration at the pilot scale, we observe a very minor but observable decay of xenon adsorption capacity that continues cycle after cycle. The mechanism of capacity decay is discussed in terms of (i) the residual presence of Cl at the surface of silver nanoparticles, (ii) the aggregation of silver nanoparticles into larger particles (sintering mechanism), and (iii) the acceleration of silver particle migration to the surface and sintering. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessCommunication
Synthesis of Hierarchical Titanium Silicalite-1 Using a Carbon-Silica-Titania Composite from Xerogel Mild Carbonization
Catalysts 2019, 9(8), 672; https://doi.org/10.3390/catal9080672 - 07 Aug 2019
Cited by 1
Abstract
Hierarchical titanium silicalite-1 (HTS-1) zeolites are an important class of catalytic materials due to their enhanced mass transfer and improved catalytic performance. In this study, HTS-1 zeolites have been successfully prepared by the hydrothermal crystallization of carbon-silica-titania (CST) composites. Compared with the direct [...] Read more.
Hierarchical titanium silicalite-1 (HTS-1) zeolites are an important class of catalytic materials due to their enhanced mass transfer and improved catalytic performance. In this study, HTS-1 zeolites have been successfully prepared by the hydrothermal crystallization of carbon-silica-titania (CST) composites. Compared with the direct carbonization method, the mild carbonization of SiO2-TiO2/Tween 40 xerogel in the presence of sulfuric acid can effectively improve both the content and mesoporous structure of carbon material in the CST composites, which enables carbon materials to better play the role of a mesoporous template during the crystallization process. The resultant zeolite has both ordered micropores and interconnected mesopores and macropores, which are similar to the skeleton of the carbon template trapped in the TS–1 crystals. Moreover, the HTS–1 zeolite displays outstanding catalytic performance in oxidative desulfurization of bulky sulfur compounds. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Catalytic Dehydration of Ethanol over WOx Nanoparticles Supported on MFI (Mobile Five) Zeolite Nanosheets
Catalysts 2019, 9(8), 670; https://doi.org/10.3390/catal9080670 - 06 Aug 2019
Abstract
Ethylene can be synthesized in a renewable manner by dehydrating bioethanol over supported metal oxide nanoparticle catalysts. Here, a series of nanoparticulate tungsten oxides supported on MFI (Mobil five) zeolite nanosheets was prepared at different W loadings (1 to 6 mol %) using [...] Read more.
Ethylene can be synthesized in a renewable manner by dehydrating bioethanol over supported metal oxide nanoparticle catalysts. Here, a series of nanoparticulate tungsten oxides supported on MFI (Mobil five) zeolite nanosheets was prepared at different W loadings (1 to 6 mol %) using the incipient wetness method and investigated with respect to the ability to catalyze the dehydration of ethanol. The resulting samples were characterized by X-ray diffraction, electron microscopy, N2 isotherms, X-ray absorption fine structures, and by the temperature-programmed desorption of NH3. The results obtained showed that WOx nanoparticles were homogeneously distributed over the entire void space of nanosheet samples up to a loading of 2 mol %, after which large WOx nanoparticles with needle-like morphology were formed on the surface of the zeolite nanosheet beyond 2mol%. The number of acid sites increased with WOx loading and, as a result, EtOH conversion progressively increased with WOx loading up to 6 mol %. At reaction temperatures of >390 °C, homogeneously distributed WOx nanoparticles showed slightly higher ethylene selectivity than nano-needle structured WOx. However, nano-needle structured WOx exhibited greater catalytic stability. In terms of ethylene yield over 8 h, needle-like WOx nanoparticles were found to be more suitable for the acid-catalyzed dehydration of ethanol than small-sized WOx nanoparticles. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Ring Enlargement of Methylcyclopentane over Pt/(HZSM-48+pseudoboehmite) Catalysts
Catalysts 2019, 9(6), 531; https://doi.org/10.3390/catal9060531 - 13 Jun 2019
Cited by 1
Abstract
Platinum catalysts loaded on a hybrid support, composed of HZSM-48 and pseudoboehmite, were applied to the synthesis of benzene through methylcyclopentane (MCP) reforming in order to investigate the effect of the addition of pseudoboehmite to Pt/HZSM-48 for ring-enlargement reaction. A total of 0.5 [...] Read more.
Platinum catalysts loaded on a hybrid support, composed of HZSM-48 and pseudoboehmite, were applied to the synthesis of benzene through methylcyclopentane (MCP) reforming in order to investigate the effect of the addition of pseudoboehmite to Pt/HZSM-48 for ring-enlargement reaction. A total of 0.5 wt% of platinum was impregnated on the hybrid support by using the incipient wetness method. Catalyst characterization was performed with nitrogen sorption, X-ray diffraction, temperature-programmed desorption of NH3, and infrared spectroscopy of adsorbed pyridine. It was found that mesoporous structures were well-developed in Pt/(HZSM-48 + pseudoboehmite) catalyst as a result of the pseudoboehmite addition, of which the average pore size was in the range of 7–8 nm. The presence of pseudoboehmite in the catalyst increases the total amount of acid sites and weakens the acid strength, compared with those of the Pt/HZSM-48 catalyst. Lewis acid sites were more abundant than Brönsted acid sites over the Pt/(HZSM-48+pseudoboehmite) catalysts. It was found that selectivity to the ring-enlargement reaction is dominant over selectivity to the ring-opening reaction over the Pt/(HZSM-48 + pseudoboehmite) catalysts. The benzene yield over Pt/(HZSM-48 + pseudoboehmite, 1:1) catalyst reached 65.1% at 450 °C and 0.3 h−1. As well as being influenced by the mesoporous structure, the higher activity and selectivity in MCP reforming was also determined by appropriate acidity of the Pt/(HZSM-48 + pseudoboehmite) catalysts. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Acidic and Catalytic Properties of Zeolites Modified by Zinc in the Conversion Process of Lower C3–C4 Alkanes
Catalysts 2019, 9(5), 421; https://doi.org/10.3390/catal9050421 - 05 May 2019
Abstract
The acid and catalytic properties of the modified MFI zeolite catalysts during the conversion of the propane–butane fraction of the associated petroleum gases into the aromatic hydrocarbons were studied. It was established that the high-silica zeolites synthesized with the new structure-forming additive of [...] Read more.
The acid and catalytic properties of the modified MFI zeolite catalysts during the conversion of the propane–butane fraction of the associated petroleum gases into the aromatic hydrocarbons were studied. It was established that the high-silica zeolites synthesized with the new structure-forming additive of the alcohol fraction (ZKE-AF) belong to the high-silica MFI zeolites. The resulting zeolites were modified by 1–5 wt. % additives consisting of zinc oxide and sulfide. The influence of the modifying additive concentration containing zinc oxides and sulfides in an amount of 1–5% on the acid and catalytic properties of the catalysts in the conversion process of lower C3–C4 alkanes into liquid hydrocarbons was studied. The research of the acid properties of the modified zeolite catalysts by thermal desorption of ammonia showed that the total concentrations of the acidic centers of H-ZKE-AF modified by 3% and 5% ZnO increased. It was found that the highest yield of liquid hydrocarbons was on the zeolite catalysts modified by 3% and 5% ZnS, and is 60.6% and 60.5%, respectively, which is 9% more than in the initial H-ZKE-AF. The activity of the zeolite catalysts modified by zinc oxide and zinc sulfide was in correlation with their acid properties. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Effect of Mg/Al2O3 and Calcination Temperature on the Catalytic Decomposition of HFC-134a
Catalysts 2019, 9(3), 270; https://doi.org/10.3390/catal9030270 - 16 Mar 2019
Abstract
This paper evaluated the effect of calcination temperature and the use of Mg/Al2O3 on the decomposition of HFC-134a. Two commercialized catalysts, Al2O3 and Mg/Al2O3, were calcined at two different temperatures (500 and 650 [...] Read more.
This paper evaluated the effect of calcination temperature and the use of Mg/Al2O3 on the decomposition of HFC-134a. Two commercialized catalysts, Al2O3 and Mg/Al2O3, were calcined at two different temperatures (500 and 650 °C) and their physicochemical characteristics were examined by X-ray diffraction, Brunauer–Emmett–Teller analysis, and the temperature-programed desorption of ammonia and carbon dioxide analysis. The results show that, in comparison to Al2O3, 5% Mg/Al2O3 exhibited a larger Brunauer–Emmett–Teller surface area and higher acidity. The relative amount of strong acid sites of the catalysts decreased with increasing calcination temperature. Although a more than 90% decomposition rate of HFC-134a was achieved over all catalysts during the sequential decomposition test of HFC-134a using a vertical plug flow reactor connected directly to a gas chromatography/mass spectrometry system, the lifetime of the catalyst differed according to the catalyst type. Compared to Al2O3, Mg/Al2O3 revealed a longer lifetime and less coke formation due to the increased Brunauer–Emmett–Teller surface area and weak Lewis acid sites and basic sites arising from Mg impregnation. Higher temperature calcination extended the catalyst lifetime with the formation of less coke due to the smaller number of strong acid sites, which can lead to severe coke formation. A valuable by-product, trifluoroethylene, was formed as a result of the decomposition. Based on the experimental results, a reaction is proposed which reasonably explains the decomposition reaction. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Dehydration of Bioethanol to Ethylene over H-ZSM-5 Catalysts: A Scale-Up Study
Catalysts 2019, 9(2), 186; https://doi.org/10.3390/catal9020186 - 16 Feb 2019
Cited by 1
Abstract
Bioethanol dehydration was carried out in a bench scale reactor-loaded H-ZSM-5 molded catalyst, which increased by tens of times more than at lab scale (up to 60 and 24 times based on the amount of catalyst and ethanol flow rate, respectively). From the [...] Read more.
Bioethanol dehydration was carried out in a bench scale reactor-loaded H-ZSM-5 molded catalyst, which increased by tens of times more than at lab scale (up to 60 and 24 times based on the amount of catalyst and ethanol flow rate, respectively). From the results of the lab scale reaction, we confirmed the optimum Si/Al ratio (14) of H-ZSM-5, reaction temperature (~250 °C), and weight hourly space velocity (WHSV) (<5 h−1) indicating high ethanol conversion and ethylene selectivity. Five types of cylindrical shaped molded catalysts were prepared by changing the type and/or amount of organic solid binder, inorganic solid binder, inorganic liquid binder, and H-ZSM-5 basis catalyst. Among them, the catalyst exhibiting the highest compression strength and good ethanol dehydration performance was selected. The bench scale reaction with varying reaction temperature of 245–260 °C and 1.2– 2.0 h−1 WHSV according to reaction time showed that the conversion and ethylene selectivity were more than 90% after 400 h on stream. It was also confirmed that even after the successive catalyst regeneration and the reaction for another 400 h, both the ethanol conversion and ethylene selectivity were still maintained at about 90%. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Dehydrogenation of Propane to Propylene Using Promoter-Free Hierarchical Pt/Silicalite-1 Nanosheets
Catalysts 2019, 9(2), 174; https://doi.org/10.3390/catal9020174 - 13 Feb 2019
Cited by 4
Abstract
Propane dehydrogenation (PDH) is the extensive pathway to produce propylene, which is as a very important chemical building block for the chemical industry. Various catalysts have been developed to increase the propylene yield over recent decades; however, an active site of monometallic Pt [...] Read more.
Propane dehydrogenation (PDH) is the extensive pathway to produce propylene, which is as a very important chemical building block for the chemical industry. Various catalysts have been developed to increase the propylene yield over recent decades; however, an active site of monometallic Pt nanoparticles prevents them from achieving this, due to the interferences of side-reactions. In this context, we describe the use of promoter-free hierarchical Pt/silicalite-1 nanosheets in the PDH application. The Pt dispersion on weakly acidic supports can be improved due to an increase in the metal-support interaction of ultra-small metal nanoparticles and silanol defect sites of hierarchical structures. This behavior leads to highly selective propylene production, with more than 95% of propylene selectivity, due to the complete suppression of the side catalytic cracking. Moreover, the oligomerization as a side reaction is prevented in the presence of hierarchical structures due to the shortening of the diffusion path length. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Phase Controlled Synthesis of Pt Doped Co Nanoparticle Composites Using a Metal-Organic Framework for Fischer–Tropsch Catalysis
Catalysts 2019, 9(2), 156; https://doi.org/10.3390/catal9020156 - 05 Feb 2019
Cited by 2
Abstract
Recently, metal nanoparticles embedded in porous carbon composite materials have been playing a significant role in a variety of fields as catalyst supports, sensors, absorbents, and in energy storage. Porous carbon composite materials can be prepared using various synthetic methods; recent efforts provide [...] Read more.
Recently, metal nanoparticles embedded in porous carbon composite materials have been playing a significant role in a variety of fields as catalyst supports, sensors, absorbents, and in energy storage. Porous carbon composite materials can be prepared using various synthetic methods; recent efforts provide a facile way to prepare the composites from metal-organic frameworks (MOFs) by pyrolysis. However, it is usually difficult to control the phase of metal or metal oxides during the synthetic process. Among many types of MOF, recently, cobalt-based MOFs have attracted attention due to their unique catalytic and magnetic properties. Herein, we report the synthesis of a Pt doped cobalt based MOF, which is subsequently converted into cobalt nanoparticle-embedded porous carbon composites ([email protected]/C) via pyrolysis. Interestingly, the phase of the cobalt metal nanoparticles (face centered cubic (FCC) or hexagonal closest packing (HCP)) can be controlled by tuning the synthetic conditions, including the temperature, duration time, and dosage of the reducing agent (NaBH4). The Pt doped Co/C was characterized using various techniques including PXRD (powder X-ray diffraction), XPS (X-ray photoelectron spectroscopy), gas sorption analysis, TEM (transmission electron microscopy), and SEM (scanning electron microscopy). The composite was applied as a phase transfer catalyst (PTC). The Fischer-Tropsch catalytic activity of the [email protected]/C (10:1:2.4) composite shows 35% CO conversion under a very low pressure of syngas (1 MPa). This is one of the best reported conversion rates at low pressure. The 35% CO conversion leads to the generation of various hydrocarbons (C1, C2–C4, C5, and waxes). This catalyst may also prove useful for energy and environmental applications. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Fabrication of the Hierarchical HZSM-5 Membrane with Tunable Mesoporosity for Catalytic Cracking of n-Dodecane
Catalysts 2019, 9(2), 155; https://doi.org/10.3390/catal9020155 - 05 Feb 2019
Cited by 5
Abstract
Hierarchical HZSM-5 membranes were prepared on the inner wall of stainless steel tubes, using amphiphilic organosilane (TPOAC) and mesitylene (TMB) as a meso-porogen and a swelling agent, respectively. The mesoporosity of the HZSM-5 membranes were tailored via formulating the TPOAC/Tetraethylorthosilicate (TPOAC/TEOS) ratio and [...] Read more.
Hierarchical HZSM-5 membranes were prepared on the inner wall of stainless steel tubes, using amphiphilic organosilane (TPOAC) and mesitylene (TMB) as a meso-porogen and a swelling agent, respectively. The mesoporosity of the HZSM-5 membranes were tailored via formulating the TPOAC/Tetraethylorthosilicate (TPOAC/TEOS) ratio and TMB/TPOAC ratio, in synthesis gel, and the prepared membranes were systematically characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2 adsorption–desorption, N2 permeation, inductively coupled plasma (ICP), in situ fourier transform infrared (FT-IR), ammonia temperature-programmed desorption (NH3-TPD), etc. It was found that the increase of the TPOAC/TEOS ratio promoted a specific surface area and diffusivity of the HZSM-5 membranes, as well as decreased acidity; the increase of the TMB/TPOAC ratios led to an enlargement of the mesopore size and diffusivity of the membranes, but with constant acid properties. The catalytic performance of the prepared HZSM-5 membranes was tested using the catalytic cracking of supercritical n-dodecane (500 °C, 4 MPa) as a model reaction. The hierarchical membrane with the TPOAC/TEOS ratio of 0.1 and TMB/TPOAC ratio of 2, exhibited superior catalytic performances with the highest activity of up to 13% improvement and the lowest deactivation rate (nearly a half), compared with the microporous HZSM-5 membrane, due to the benefits of suitable acidity, together with enhanced diffusivity of n-dodecane and cracking products. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
A Hybrid Reactor System Comprised of Non-Thermal Plasma and Mn/Natural Zeolite for the Removal of Acetaldehyde from Food Waste
Catalysts 2018, 8(9), 389; https://doi.org/10.3390/catal8090389 - 10 Sep 2018
Cited by 4
Abstract
The degradation of low concentrations of acetaldehyde while using a non-thermal plasma (NTP)/catalyst hybrid reactor system was investigated while using humidified air at ambient temperature. A series of highly active manganese-impregnated natural zeolite (Mn/NZ) catalysts were synthesized by the incipient wetness method using [...] Read more.
The degradation of low concentrations of acetaldehyde while using a non-thermal plasma (NTP)/catalyst hybrid reactor system was investigated while using humidified air at ambient temperature. A series of highly active manganese-impregnated natural zeolite (Mn/NZ) catalysts were synthesized by the incipient wetness method using sonication. The Mn/NZ catalysts were analyzed by Brunauer-Emmett-Teller surface area measurements and X-ray photoelectron spectroscopy. The Mn/NZ catalyst located at the downstream of a dc corona was used for the decomposition of ozone and acetaldehyde. The decomposition efficiency of ozone and acetaldehyde was increased significantly using the Mn/NZ catalyst with NTP. Among the various types of Mn/NZ catalysts with different Mn contents, the 10 wt.% Mn/NZ catalyst under the NTP resulted the highest ozone and acetaldehyde removal efficiency, almost 100% within 5 min. Moreover, this high efficiency was maintained for 15 h. The main reason for the high catalytic activity and stability was attributed to the high dispersion of Mn on the NZ made by the appropriate impregnation method using sonication. This system is expected to be efficient to decompose a wide range of volatile organic compounds with low concentrations. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessArticle
Catalytic Copyrolysis of Cork Oak and Waste Plastic Films over HBeta
Catalysts 2018, 8(8), 318; https://doi.org/10.3390/catal8080318 - 03 Aug 2018
Cited by 2
Abstract
The catalytic fast copyrolysis (CFCP) of cork oak (CoOak) and waste plastic films (WPFs) over HBeta(25) (SiO2/Al2O3: 25) was investigated using a thermogravimetric (TG) analyzer and a tandem micro reactor-gas chromatography/mass spectrometry (TMR-GC/MS) to determine the effectiveness [...] Read more.
The catalytic fast copyrolysis (CFCP) of cork oak (CoOak) and waste plastic films (WPFs) over HBeta(25) (SiO2/Al2O3: 25) was investigated using a thermogravimetric (TG) analyzer and a tandem micro reactor-gas chromatography/mass spectrometry (TMR-GC/MS) to determine the effectiveness of WPFs as the hydrogen donating cofeeding feedstock on the CFCP of biomass. By applying CFCP, the maximum decomposition temperatures of CoOak (373.4 °C) and WPFs (487.9 °C) were reduced to 364.5 °C for CoOak and 436.5 °C for WPFs due to the effective interaction between the pyrolysis intermediates of CoOak and WPFs over HBeta(25), which has strong acidity and an appropriate pore size. The experimental yields of aromatic hydrocarbons on the CFCP of CoOak and WPFs were higher than their calculated yields concluded from the yields obtained from the individual catalytic fast pyrolysis (CFP) of CoOak and WPFs. The coke amount produced from the CFP of CoOak and WPFs over HBeta(25) were also decreased by applying CFCP. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Review

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Open AccessReview
A Comprehensive Review of the Applications of Hierarchical Zeolite Nanosheets and Nanoparticle Assemblies in Light Olefin Production
Catalysts 2020, 10(2), 245; https://doi.org/10.3390/catal10020245 - 18 Feb 2020
Cited by 1
Abstract
Light olefins including ethylene, propylene and butylene are important building blocks in petrochemical industries to produce various chemicals such as polyethylene, polypropylene, ethylene oxide and cumene. Traditionally, light olefins are produced via a steam cracking process operated at an extremely high temperature. The [...] Read more.
Light olefins including ethylene, propylene and butylene are important building blocks in petrochemical industries to produce various chemicals such as polyethylene, polypropylene, ethylene oxide and cumene. Traditionally, light olefins are produced via a steam cracking process operated at an extremely high temperature. The catalytic conversion, in which zeolites have been widely used, is an alternative pathway using a lower temperature. However, conventional zeolites, composed of a pure microporous structure, restrict the diffusion of large molecules into the framework, resulting in coke formation and further side reactions. To overcome these problems, hierarchical zeolites composed of additional mesoporous and/or macroporous structures have been widely researched over the past decade. In this review, the recent development of hierarchical zeolite nanosheets and nanoparticle assemblies together with opening up their applications in various light olefin productions such as catalytic cracking, ethanol dehydration to ethylene, methanol to olefins (MTO) and other reactions will be presented. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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Open AccessReview
Advances in the Green Synthesis of Microporous and Hierarchical Zeolites: A Short Review
Catalysts 2019, 9(3), 274; https://doi.org/10.3390/catal9030274 - 17 Mar 2019
Cited by 7
Abstract
Hierarchical zeolites have been extensively studied due to their enhancement of intra-crystalline diffusion, which leads to the improved catalytic activity and resistance to coking-deactivation. Traditional synthesis strategies of hierarchical zeolites via post-treatment or directing synthesis with the aid of mesoporous template are often [...] Read more.
Hierarchical zeolites have been extensively studied due to their enhancement of intra-crystalline diffusion, which leads to the improved catalytic activity and resistance to coking-deactivation. Traditional synthesis strategies of hierarchical zeolites via post-treatment or directing synthesis with the aid of mesoporous template are often characterized by high energy consumption and substantial use of expensive and environmentally unfriendly organic templates. In the recent decade, new green synthesis protocols have been developed for the effective synthesis of conventional and hierarchical zeolites. In this review, the latest advancements on the green synthesis of hierarchical zeolites are summarized and discussed in detail. Full article
(This article belongs to the Special Issue Synthesis and Application of Zeolite Catalysts)
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