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17 pages, 5822 KiB

Open AccessArticle

Selective Alkylation of Benzene with Methanol to Toluene and Xylene over H-ZSM-5 Zeolites: Impact of Framework Al Spatial Distribution

by Shu Ren, Fan Yang, Chao Tian, Yinghong Yue, Wei Zou, Weiming Hua and Zi Gao

Catalysts 2023, 13(9), 1295; https://doi.org/10.3390/catal13091295 - 14 Sep 2023

Cited by 5 | Viewed by 2738

Abstract

The alkylation of benzene with methanol can effectively generate high-value-added toluene and xylene out of surplus benzene, which is now achieved primarily using solid acids like H-ZSM-5 zeolites as catalysts. In this work, two H-ZSM-5 samples with distinct framework aluminum (Al_F) [...] Read more.

The alkylation of benzene with methanol can effectively generate high-value-added toluene and xylene out of surplus benzene, which is now achieved primarily using solid acids like H-ZSM-5 zeolites as catalysts. In this work, two H-ZSM-5 samples with distinct framework aluminum (Al_F) distributions, but otherwise quite similar textural and acidic properties, have been prepared by employing tetrapropylammonium hydroxide (TPAOH) and n-butylamine (NBA) as organic structure-directing agents (OSDAs). Systematical investigations demonstrate that Al_F is preferentially located at the intersections in MFI topology when TPAOH is adopted. In contrast, less Al_F is positioned therein as NBA is utilized. Density functional theory (DFT) calculations reveal that the transition-state complexes cannot be formed in the straight and sinusoidal channels due to their much smaller sizes than the dynamic diameters of transition states, whereas there are adequate spaces for the formation of transition states at the intersections. Benefitting from abundant Al_F at the intersections, which provides more acid sites therein, H-ZSM-5 synthesized from TPAOH is more active relative to the counterpart obtained from NBA. At a WHSV of 4 h⁻¹ and 400 °C, the former catalyst gives a 52.8% conversion, while the latter one affords a 45.9% conversion. Both catalysts display close total selectivity towards toluene and xylene (ca. 84%). This study provides an efficient way to regulate the distribution of acid sites, thereby enhancing the catalytic performance of H-ZSM-5 zeolite in the titled reaction. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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17 pages, 8326 KiB

Open AccessFeature PaperArticle

Effect of Different Zinc Species on Mn-Ce/CuX Catalyst for Low-Temperature NH₃-SCR Reaction: Comparison of ZnCl₂, Zn(NO₃)₂, ZnSO₄ and ZnCO₃

by Lin Chen, Shan Ren, Tao Chen, Xiaodi Li, Zhichao Chen, Mingming Wang, Qingcai Liu and Jie Yang

Catalysts 2023, 13(8), 1219; https://doi.org/10.3390/catal13081219 - 17 Aug 2023

Viewed by 1310

Abstract

The effects of four distinct zinc species (ZnCl₂, Zn(NO₃)₂, ZnSO₄, and ZnCO₃) on a Mn-Ce co-doped CuX (MCCX)catalyst were investigated and contrasted in the low-temperature NH₃-SCR process. Aqueous solutions of ZnCl [...] Read more.

The effects of four distinct zinc species (ZnCl₂, Zn(NO₃)₂, ZnSO₄, and ZnCO₃) on a Mn-Ce co-doped CuX (MCCX)catalyst were investigated and contrasted in the low-temperature NH₃-SCR process. Aqueous solutions of ZnCl₂, Zn(NO₃)₂, ZnSO₄, and ZnCO₃ were used to poison the catalysts. The catalytic activity of all catalysts was assessed, and their physicochemical properties were studied. There was a notable drop trend in catalytic activity in the low temperature range (200 °C) after zinc species poisoning on MCCX catalyst. Interestingly, ZnSO₄ and ZnCO₃ on MCCX catalyst had more serious effect on catalytic activity than Zn(NO₃)₂ and ZnCl₂ from 150 °C to 225 °C, in which NO conversion of the MCCX-Zn-S and MCCX-Zn-C catalysts dropped about 20–30% below 200 °C compared with the fresh MCCX catalyst. The zeolite X structure was impacted by Zn species doping on the MCCX catalyst, and the Zn-poisoned catalysts had less acidic and lower redox ability than fresh Mn-Ce/CuX catalysts. Through the results of in situ DRIFTS spectroscopy experiments, all catalysts were governed by both Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanisms, and the possible mechanism for poisoning the Mn-Ce/CuX catalyst using various zinc species was revealed. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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13 pages, 4294 KiB

Open AccessFeature PaperArticle

Mechanistic Insight into the Propane Oxidation Dehydrogenation by N₂O over Cu-BEA Zeolite with Diverse Active Site Structures

by Ruiqi Wu, Ning Liu, Chengna Dai, Ruinian Xu, Gangqiang Yu, Ning Wang and Biaohua Chen

Catalysts 2023, 13(8), 1212; https://doi.org/10.3390/catal13081212 - 15 Aug 2023

Cited by 3 | Viewed by 1420

Abstract

The present work theoretically investigated propane oxidation dehydrogenation by utilizing N₂O as an oxidant (N₂O-ODHP) over Cu-BEA with three different types of active site, including monomeric Cu ([Cu]⁺), dimeric Cu ([Cu−Cu]²⁺), and distant monomeric Cu [...] Read more.

The present work theoretically investigated propane oxidation dehydrogenation by utilizing N₂O as an oxidant (N₂O-ODHP) over Cu-BEA with three different types of active site, including monomeric Cu ([Cu]⁺), dimeric Cu ([Cu−Cu]²⁺), and distant monomeric Cu sites ([Cu]⁺—[Cu]⁺). Energetically, we calculated that the monomeric [Cu]⁺ is favorable for the αH dehydrogenation step (∆E = 0.05 eV), which, however, suffers from high barriers of N₂O dissociation and βH dehydrogenation steps of 1.40 and 1.94 eV, respectively. Although the dimeric [Cu−Cu]²⁺ site with a Cu—Cu distance of 4.91 Å is much more favorable for N₂O dissociation (0.95 eV), it still needs to overcome an extremely high barrier (∆E = 2.15 eV) for βH dehydrogenation. Interestingly, the distant [Cu]⁺—[Cu]⁺ site with the Cu—Cu distance of 5.82 Å exhibits low energy barriers for N₂O dissociation (0.89 eV) and ODHP steps (0.01 and 0.33 eV) due to the synergistic effect of distant [Cu]⁺. The microkinetic analyses quantitatively verified the superior activity of the distant [Cu]⁺—[Cu]⁺ site with a reaction rate being eight to nine orders of magnitude higher than those of the monomeric and the dimeric Cu sites, and this is related to its ready charge-transfer ability, as shown by the partial Density of State (PDOS) analysis and the static charge differential density analysis in this study. Generally, the present work proposes that the distance between the [Cu]⁺ sites plays a significant and important role in N₂O-ODHP over the Cu-based zeolite catalyst and modulates Cu—Cu distance, and this constitutes a promising strategy for highly-efficient Cu-zeolite catalyst design for N₂O-ODHP. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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12 pages, 4394 KiB

Open AccessFeature PaperArticle

Silver-Doped Zeolitic Imidazolate Framework (Ag@ZIF-8): An Efficient Electrocatalyst for CO₂ Conversion to Syngas

by Muhammad Usman and Munzir H. Suliman

Catalysts 2023, 13(5), 867; https://doi.org/10.3390/catal13050867 - 10 May 2023

Cited by 7 | Viewed by 3496

Abstract

To enable the reuse of carbon dioxide (CO₂), electrocatalytic reduction of CO₂ (CO₂RR) into syngas with a controllable H₂/CO ratio is considered a cost-effective and intriguing approach. Here, a number of silver (Ag)-doped, zeolitic imidazole framework [...] Read more.

To enable the reuse of carbon dioxide (CO₂), electrocatalytic reduction of CO₂ (CO₂RR) into syngas with a controllable H₂/CO ratio is considered a cost-effective and intriguing approach. Here, a number of silver (Ag)-doped, zeolitic imidazole framework composites were prepared by a facile method. The outcomes demonstrate that CO₂ electroreduction on Ag-doped ZIF-8 catalysts produces just CO and H₂, without having any liquid fuel, resulting in a total faradaic efficiency approaching 100%. The most optimal Ag-Zn-ZIF-8 (10% Ag, 90% Zn) demonstrates good selectivity for syngas (CO and H₂) that can be easily adjusted from 3:1 to 1:3 (H₂/CO) by changing the applied voltage during the CO₂ conversion process. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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16 pages, 10654 KiB

Open AccessArticle

Positive Effect of Ce Modification on Low-Temperature NH₃-SCR Performance and Hydrothermal Stability over Cu-SSZ-16 Catalysts

by Yuqian Liang, Rui Li, Ruicong Liang, Zhanhong Li, Xiangqiong Jiang and Jiuxing Jiang

Catalysts 2023, 13(4), 742; https://doi.org/10.3390/catal13040742 - 13 Apr 2023

Cited by 6 | Viewed by 1827

Abstract

Cu-exchanged SSZ-16 zeolite catalysts exhibit outstanding NH₃-SCR activity, but their catalytic performance after hydrothermal treatments is not ideal. In order to improve the hydrothermal stability of Cu-SSZ-16, CuCe_x-SSZ-16 series catalysts were prepared via an ion exchange process, and the [...] Read more.

Cu-exchanged SSZ-16 zeolite catalysts exhibit outstanding NH₃-SCR activity, but their catalytic performance after hydrothermal treatments is not ideal. In order to improve the hydrothermal stability of Cu-SSZ-16, CuCe_x-SSZ-16 series catalysts were prepared via an ion exchange process, and the effect of Ce modification on the hydrothermal stability was investigated. In addition, increasing Ce contents significantly improved the hydrothermal stability, and CuCe_0.87-SSZ-16 showed the best hydrothermal stability. The effects of adding Ce to active species and the AFX framework were studied by various characterization measurements. The ²⁷Al MAS NMR results reveal that Ce modification can strengthen the structural stability of the CuCe_x-SSZ-16 catalysts. Furthermore, the combined results of XPS, H₂-TPR, and in situ DRIFTS confirm that the introduction of Ce markedly increases the active Cu²⁺-2Z species, contributing to the remarkable hydrothermal stability. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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19 pages, 3026 KiB

Open AccessArticle

CO₂-Assisted Dehydrogenation of Propane to Propene over Zn-BEA Zeolites: Impact of Acid–Base Characteristics on Catalytic Performance

by Svitlana Orlyk, Pavlo Kyriienko, Andriy Kapran, Valeriy Chedryk, Dmytro Balakin, Jacek Gurgul, Malgorzata Zimowska, Yannick Millot and Stanislaw Dzwigaj

Catalysts 2023, 13(4), 681; https://doi.org/10.3390/catal13040681 - 31 Mar 2023

Cited by 11 | Viewed by 2172

Abstract

Research results about the influence of BEA zeolite preliminary dealumination on the acid–base characteristics and catalytic performance of 1% Zn-BEA compositions in propane dehydrogenation with CO₂ are presented. The catalyst samples, prepared through a two-step post-synthesis procedure involving partial or complete dealumination [...] Read more.

Research results about the influence of BEA zeolite preliminary dealumination on the acid–base characteristics and catalytic performance of 1% Zn-BEA compositions in propane dehydrogenation with CO₂ are presented. The catalyst samples, prepared through a two-step post-synthesis procedure involving partial or complete dealumination of the BEA specimen followed by the introduction of Zn²⁺ cations into the T-positions of the zeolite framework, were characterized using XRD, XPS, MAS NMR, SEM/EDS, low-temperature N₂ ad/desorption, C₃H₈/C₃H₆ (CO₂, NH₃)-TPD, TPO-O_2, and FTIR-Py techniques. Full dealumination resulted in the development of a mesoporous structure and specific surface area (BET) with a twofold decrease in the total acidity and basicity of Zn-BEA, and the formation of Lewis acid sites and basic sites of predominantly medium strength, as well as the removal of Brønsted acid sites from the surface. In the presence of the ZnSiBEA catalyst, which had the lowest total acidity and basicity, the obtained selectivity of 86–94% and yield of 30–33% for propene (at 923 K) exceeded the values for ZnAlSiBEA and ZnAlBEA. The results of propane dehydrogenation with/without carbon dioxide showed the advantages of producing the target olefin in the presence of CO₂ using Zn-BEA catalysts. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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17 pages, 6325 KiB

Open AccessArticle

Effects of Synthesis Variables on SAPO-34 Crystallization Templated Using Pyridinium Supramolecule and Its Catalytic Activity in Microwave Esterification Synthesis of Propyl Levulinate

by Yik-Ken Ma, Taghrid S. Alomar, Najla AlMasoud, Zeinhom M. El-Bahy, Stephen Chia, T. Jean Daou, Fitri Khoerunnisa, Tau Chuan Ling and Eng-Poh Ng

Catalysts 2023, 13(4), 680; https://doi.org/10.3390/catal13040680 - 30 Mar 2023

Cited by 4 | Viewed by 2143

Abstract

A detailed investigation of the hydrothermal crystallization of SAPO-34 in the presence of the novel 1-propylpyridinium hydroxide ([PrPy]OH) organic structural directing agent is presented. The synthesis conditions are systematically tuned to investigate the effects of various parameters (viz. concentrations of each reactant, crystallization [...] Read more.

A detailed investigation of the hydrothermal crystallization of SAPO-34 in the presence of the novel 1-propylpyridinium hydroxide ([PrPy]OH) organic structural directing agent is presented. The synthesis conditions are systematically tuned to investigate the effects of various parameters (viz. concentrations of each reactant, crystallization time, and temperature) on the nucleation and crystallization of SAPO-34. The results show that a careful variation in each of the synthesis parameters results in the formation of competing phases such as SAPO-5, SAPO-35, and SAPO-36. Pure and fully crystalline SAPO-34 can be crystallized using a precursor hydrogel of a molar ratio of 2.0 Al: 4.7 P: 0.9 Si: 6.7 [PrPy]OH: 148 H₂O at 200 °C for only 19 h, which is a shorter time than that found in previous studies. The prepared SAPO-34 is also very active in the esterification of levulinic acid and 1-propanol. By using microwave heating, 91.5% conversion with 100% selectivity toward propyl levulinate is achieved within 20 min at 190 °C. Hence, the present study may open a new insight into the optimum synthesis study of other zeolites using novel pyridinium organic moieties and the opportunity of replacing conventional harmful and non-recyclable homogeneous catalysts in levulinate biofuel synthesis. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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22 pages, 5950 KiB

Open AccessFeature PaperArticle

Evidence of Synergy Effects between Zinc and Copper Oxides with Acidic Sites on Natural Zeolite during Photocatalytic Oxidation of Ethylene Using Operando DRIFTS Studies

by Norberto J. Abreu, Héctor Valdés, Claudio A. Zaror, Tatianne Ferreira de Oliveira, Federico Azzolina-Jury and Frédéric Thibault-Starzyk

Catalysts 2023, 13(3), 610; https://doi.org/10.3390/catal13030610 - 17 Mar 2023

Cited by 2 | Viewed by 2119

Abstract

In this article, the role of surface sites of modified zeolites with semiconductor nanoparticles as alternative photocatalyts for protecting post-harvest foodstuff from the detrimental effects of ethylene is addressed. Two single and one double catalyst based on zinc and copper oxides supported over [...] Read more.

In this article, the role of surface sites of modified zeolites with semiconductor nanoparticles as alternative photocatalyts for protecting post-harvest foodstuff from the detrimental effects of ethylene is addressed. Two single and one double catalyst based on zinc and copper oxides supported over modified zeolite samples were prepared. Physical, chemical, and surface properties of prepared materials were studied by several characterization methods. UV-Vis absorption spectra show that the applied modification procedures increase the optical absorption of light in the UV and visible regions, suggesting that an increase in the photocatalytic activity could take place mainly in the obtained co-impregnated catalyst. An ethylene conversion around 50% was achieved when the parent natural zeolite support was modified with both transition metal oxides, obtaining higher removal efficiency in comparison to single oxide catalysts. Adsorption and photocatalytic oxidation experiments were also performed using single and double catalysts supported over fumed silica, attaining lower ethylene conversion and thus highlighting the role of zeolite surfaces as adsorption sites for ethylene during photocatalytic reactions. Operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies reveal that a synergistic mechanism occurs, involving ethylene adsorption at acidic sites of zeolite and its photocatalytic oxidation due to the generation of radicals by the light activation of nanoparticles of zinc and copper oxides. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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20 pages, 3959 KiB

Open AccessFeature PaperArticle

Catalytic Characterization of Synthetic K⁺ and Na⁺ Sodalite Phases by Low Temperature Alkali Fusion of Kaolinite during the Transesterification of Spent Cooking Oil: Kinetic and Thermodynamic Properties

by Mohamed Adel Sayed, Jamaan S. Ajarem, Ahmed A. Allam, Mostafa R. Abukhadra, Jianmin Luo, Chuanyi Wang and Stefano Bellucci

Catalysts 2023, 13(3), 462; https://doi.org/10.3390/catal13030462 - 22 Feb 2023

Cited by 1 | Viewed by 2131

Abstract

The mineral raw Egyptian kaolinite was used as a precursor in the synthesis of two sodalite phases (sodium sodalite (Na.SD) and potassium sodalite (K.SD)) according to the low alkali fusion technique. The synthesized Na.SD phase demonstrates enhanced total basicity (6.3 mmol OH/g), surface [...] Read more.

The mineral raw Egyptian kaolinite was used as a precursor in the synthesis of two sodalite phases (sodium sodalite (Na.SD) and potassium sodalite (K.SD)) according to the low alkali fusion technique. The synthesized Na.SD phase demonstrates enhanced total basicity (6.3 mmol OH/g), surface area (232.4 m²/g), and ion exchange capacity (126.4 meq/100 g) compared to the K.SD phase (217.6 m²/g (surface area), 96.8 meq/100 g (ion exchange capacity), 5.4 mmol OH/g (total basicity). The catalytic performance of the two sodalite phases validates the higher activity of the sodium phase (Na.SD) than the potassium phase (K.SD). The application of Na.SD resulted in biodiesel yields of 97.3% and 96.4% after 90 min and 60 min, respectively, while the maximum yield using K.SD (95.7%) was detected after 75 min. Robust base-catalyzed reactions using Na.SD and K.SD as catalysts were suggested as part of an operated transesterification mechanism. Moreover, these reactions exhibit pseudo-first order kinetics, and the rate constant values were estimated with consideration of the change in temperature. The estimated activation energies of Na.SD (27.9 kJ.mol⁻¹) and K.SD (28.27 kJ.mol⁻¹) reflected the suitability of these catalysts to be applied effectively under mild conditions. The essential thermodynamic functions, such as Gibb’s free energy (65.16 kJ.mol⁻¹ (Na.SD) and 65.26 kJ.mol⁻¹ (K.SD)), enthalpy (25.23 kJ.mol⁻¹ (Na.SD) and 25.55 kJ.mol⁻¹ (K.SD)), and entropy (−197.7 J.K⁻¹.mol⁻¹ (Na.SD) and −197.8 J.K⁻¹.mol⁻¹ (K.SD)), display the endothermic and spontaneous nature of the two transesterification systems. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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12 pages, 2577 KiB

Open AccessFeature PaperArticle

Facial One-Pot Synthesis, Characterization, and Photocatalytic Performance of Porous Ceria

by Amal A. Atran, Fatma A. Ibrahim, Nasser S. Awwad, Mohd Shkir and Mohamed S. Hamdy

Catalysts 2023, 13(2), 240; https://doi.org/10.3390/catal13020240 - 20 Jan 2023

Cited by 7 | Viewed by 2069

Abstract

A facial one-step synthesis procedure was applied to prepare porous sponge-like ceria (CeO₂). The synthesis was performed by mixing cerium nitrate with citric acid, followed by thermal treatment. The produced solid material was characterized by several techniques, such as XRD, SEM, [...] Read more.

A facial one-step synthesis procedure was applied to prepare porous sponge-like ceria (CeO₂). The synthesis was performed by mixing cerium nitrate with citric acid, followed by thermal treatment. The produced solid material was characterized by several techniques, such as XRD, SEM, N₂ sorption measurement, DR-UV-vis, and Raman spectroscopy. The characterization data showed that the nanoparticles of the porous ceria were formed with a three-dimensional pore system. Moreover, the measured surface area of the porous sample was eight times higher than the commercially available ceria. The photocatalytic performance of the porous ceria was investigated in two different applications under visible light illumination. The first was the decolorization of a methyl green aqueous solution, while the second was the photocatalytic elimination of a gaseous mixture consisting of five short-chain hydrocarbons (C1–C3). The obtained results showed that the photocatalytic activity of porous ceria was higher than that of the commercial sample. Finally, the recycling of porous ceria showed low deactivation (less than 9%) after four consecutive runs. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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Review

Jump to: Research

20 pages, 3931 KiB

Open AccessFeature PaperReview

Research Progress of the Selective Catalytic Reduction with NH₃ over ZSM-5 Zeolite Catalysts for NO_x Removal

by Wangxiang Pan, Jingping He, Guanlin Huang, Wentao Zhang and De Fang

Catalysts 2023, 13(10), 1381; https://doi.org/10.3390/catal13101381 - 19 Oct 2023

Cited by 5 | Viewed by 2417

Abstract

Nitrogen oxides (NO_x) are very common air pollutants that are harmful to the environment and human bodies. Selective catalytic reduction with ammonia (NH₃-SCR) is considered an effective means to remove NO_x emissions due to its good environmental adaptability, [...] Read more.

Nitrogen oxides (NO_x) are very common air pollutants that are harmful to the environment and human bodies. Selective catalytic reduction with ammonia (NH₃-SCR) is considered an effective means to remove NO_x emissions due to its good environmental adaptability, high catalytic activity, and remarkable selectivity. In this paper, the preparation methods, types, advantages, and challenges of ZSM-5 catalysts are reviewed. Special attention is paid to the catalytic properties and influence factors of ZSM-5 catalysts for NH₃-SCR. The SCR performances of ZSM-5 catalysts doped with single or multiple metal ions are also reviewed. In addition, the environmental adaptabilities (sulfur resistance, alkali resistance, water resistance, and hydrothermal stability) of ZSM-5 catalysts are discussed, and the development of ZSM-5 catalysts in denitrification is summarized. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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19 pages, 4512 KiB

Open AccessFeature PaperReview

Research and Application Development of Catalytic Redox Technology for Zeolite-Based Catalysts

by Wentao Zhang, De Fang, Guanlin Huang, Da Li and Yun Zheng

Catalysts 2023, 13(8), 1197; https://doi.org/10.3390/catal13081197 - 10 Aug 2023

Cited by 4 | Viewed by 2471

Abstract

Zeolites are porous materials with plentiful and adjustable pore structures, which are widely applied in various fields such as fossil fuel energy conversion, preparation of clean energy, chemical product conversion, CO₂ capture, VOC treatment, and so on. Zeolites exhibited advantageous adsorption compared [...] Read more.

Zeolites are porous materials with plentiful and adjustable pore structures, which are widely applied in various fields such as fossil fuel energy conversion, preparation of clean energy, chemical product conversion, CO₂ capture, VOC treatment, and so on. Zeolites exhibited advantageous adsorption compared with traditional adsorbents such as activated carbon; in addition, they can also provide abundant reaction sites for various molecules. The chemical composition, structural acidity, and distribution of pore size can distinctly affect the efficiency of the reaction. The modification of zeolite structure, the development of novel and efficient preparation methods, as well as the improvement of reaction efficiency, have always been the focus of research for zeolites. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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14 pages, 698 KiB

Open AccessEditor’s ChoiceReview

Research Progress in Gas Separation and Purification Based on Zeolitic Materials

by Kai Qi, Lili Gao, Xuelian Li and Feng He

Catalysts 2023, 13(5), 855; https://doi.org/10.3390/catal13050855 - 8 May 2023

Cited by 4 | Viewed by 2697

Abstract

The characteristics and preparation methods of zeolite-based adsorbents and membranes were reviewed and their applications in gas separation and purification were introduced according to classification. The effects of framework structure, equilibrium cations and pore size of zeolites as well as temperature and pressure [...] Read more.

The characteristics and preparation methods of zeolite-based adsorbents and membranes were reviewed and their applications in gas separation and purification were introduced according to classification. The effects of framework structure, equilibrium cations and pore size of zeolites as well as temperature and pressure of the system on gas adsorption and separation were discussed, and the separation mechanisms were also summarized. The main defects and improved methods of zeolite-based adsorbents and membranes were briefly described, and their future trend for gas separation and purification was finally prospected. Full article

(This article belongs to the Special Issue Zeolites as Catalysts: Applications in Chemical Engineering, Energy Sources and Environmental Protection)

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