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Search Results (414)

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Keywords = ZSM-5

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21 pages, 3300 KiB  
Article
Catalytic Ozonation of Nitrite in Denitrification Wastewater Based on Mn/ZSM-5 Zeolites: Catalytic Performance and Mechanism
by Yiwei Zhang, Yulin Sun, Yanqun Zhu, Wubin Weng, Yong He and Zhihua Wang
Processes 2025, 13(8), 2387; https://doi.org/10.3390/pr13082387 - 27 Jul 2025
Viewed by 358
Abstract
In wet flue gas desulfurization and denitrification processes, nitrite accumulation inhibits denitrification efficiency and induces secondary pollution due to its acidic disproportionation. This study developed a Mn-modified ZSM-5 zeolite catalyst, achieving efficient resource conversion of nitrite in nitrogen-containing wastewater through an O3 [...] Read more.
In wet flue gas desulfurization and denitrification processes, nitrite accumulation inhibits denitrification efficiency and induces secondary pollution due to its acidic disproportionation. This study developed a Mn-modified ZSM-5 zeolite catalyst, achieving efficient resource conversion of nitrite in nitrogen-containing wastewater through an O3 + Mn/ZSM-5 catalytic system. Mn/ZSM-5 catalysts with varying SiO2/Al2O3 ratios (prepared by wet impregnation) were characterized by BET, XRD, and XPS. Experimental results demonstrated that Mn/ZSM-5 (SiO2/Al2O3 = 400) exhibited a larger specific surface area, enhanced adsorption capacity, abundant surface Mn3+/Mn4+ species, hydroxyl oxygen species, and chemisorbed oxygen, leading to superior oxidation capability and catalytic activity. Under the optimized conditions of reaction temperature = 40 °C, initial pH = 4, Mn/ZSM-5 dosage = 1 g/L, and O3 concentration = 100 ppm, the NO2 oxidation efficiency reached 94.33%. Repeated tests confirmed that the Mn/ZSM-5 catalyst exhibited excellent stability and wide operational adaptability. The synergistic effect between Mn species and the zeolite support significantly improved ozone utilization efficiency. The O3 + Mn/ZSM-5 system required less ozone while maintaining high oxidation efficiency, demonstrating better cost-effectiveness. Mechanism studies revealed that the conversion pathway of NO2 followed a dual-path catalytic mechanism combining direct ozonation and free radical chain reactions. Practical spray tests confirmed that coupling the Mn/ZSM-5 system with ozone oxidation flue gas denitrification achieved over 95% removal of liquid-phase NO2 byproducts without compromising the synergistic removal efficiency of NOx/SO2. This study provided an efficient catalytic solution for industrial wastewater treatment and the resource utilization of flue gas denitrification byproducts. Full article
(This article belongs to the Special Issue Processes in 2025)
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34 pages, 2026 KiB  
Review
Review of Applications of Zeolites in Dermatology: Molecular Perspectives and Translational Potentials
by James Curtis Dring, Matthew Kaczynski, Rina Maria Zureikat, Michael Kaczynski, Alicja Forma and Jacek Baj
Int. J. Mol. Sci. 2025, 26(14), 6821; https://doi.org/10.3390/ijms26146821 - 16 Jul 2025
Viewed by 482
Abstract
Zeolites, microporous aluminosilicates with tuneable physicochemical properties, have garnered increasing attention in dermatology due to their antimicrobial, detoxifying, and drug delivery capabilities. This review evaluates the structural characteristics, therapeutic mechanisms, and clinical applications of zeolites—including clinoptilolite, ZSM-5, ZIF-8, and silver/zinc-functionalized forms—across skin infections, [...] Read more.
Zeolites, microporous aluminosilicates with tuneable physicochemical properties, have garnered increasing attention in dermatology due to their antimicrobial, detoxifying, and drug delivery capabilities. This review evaluates the structural characteristics, therapeutic mechanisms, and clinical applications of zeolites—including clinoptilolite, ZSM-5, ZIF-8, and silver/zinc-functionalized forms—across skin infections, wound healing, acne management, and cosmetic dermatology. Zeolites demonstrated broad-spectrum antibacterial and antifungal efficacy, enhanced antioxidant activity, and biocompatible drug delivery in various dermatological models. Formulations such as silver–sulfadiazine–zeolite composites, Zn–clinoptilolite for acne, and zeolite-integrated microneedles offer innovative avenues for targeted therapy. Zeolite-based systems represent a promising shift toward multifunctional, localized dermatologic treatments. However, further research into long-term safety, formulation optimization, and clinical validation is essential to transition these materials into mainstream therapeutic use. Full article
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11 pages, 2257 KiB  
Article
ZSM-5-Confined Fe-O4 Nanozymes Enable the Identification of Intrinsic Active Sites in POD-like Reactions
by Gaolei Xu, Yunfei Wu, Guanming Zhai and Huibin Ge
Nanomaterials 2025, 15(14), 1090; https://doi.org/10.3390/nano15141090 - 14 Jul 2025
Viewed by 271
Abstract
As widely used peroxidase-like nanozymes, Fe-based nanozymes still suffer from an unclear reaction mechanism, which limits their further application. In this work, through alkaline treatment and then the replacement or occupation of strong acid sites by isolated Fe species, porous ZSM-5-confined atomic Fe [...] Read more.
As widely used peroxidase-like nanozymes, Fe-based nanozymes still suffer from an unclear reaction mechanism, which limits their further application. In this work, through alkaline treatment and then the replacement or occupation of strong acid sites by isolated Fe species, porous ZSM-5-confined atomic Fe species nanozymes with separated medium acid sites (Al-OH) and isolated Fe-O4 sites were prepared. And the structure and the state of Fe-O4 confined by ZSM-5 were determined by AC-HAADF-STEM, XPS, and XAS. In the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) by the hydrogen peroxide (H2O2) process, the heterolysis of H2O2 to ∙OH mainly occurs at the isolated Fe-O4 sites, and then the generated ∙OH can spill over to the Al-OH sites to oxidize the adsorbed TMB. The synergistic effect between Fe-O4 sites and medium acid sites can significantly benefit the catalytic performance of Fe-based nanozymes. Full article
(This article belongs to the Section Biology and Medicines)
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19 pages, 3246 KiB  
Article
Direct Conversion of 1,3-Butanediol to 1,3-Butadiene over ZSM-22 Catalysts: Influence of the Si/Al Ratio
by Loïc Eloi, Jeroen Poissonnier, Arne De Landsheere, Dhanjay Sharma, Jaouad Al Atrach, Valérie Ruaux, Valentin Valtchev, Maarten K. Sabbe, Joris W. Thybaut and An Verberckmoes
Catalysts 2025, 15(7), 655; https://doi.org/10.3390/catal15070655 - 5 Jul 2025
Viewed by 558
Abstract
ZSM-22 zeolites with different Si/Al ratios (38, 50, 80) were prepared via a hydrothermal synthesis method, investigated for the catalytic dehydration of 1,3-butanediol (1,3-BDO) to butadiene (BD) at 300 °C. The catalytic performance of the synthesized materials was related to their properties and [...] Read more.
ZSM-22 zeolites with different Si/Al ratios (38, 50, 80) were prepared via a hydrothermal synthesis method, investigated for the catalytic dehydration of 1,3-butanediol (1,3-BDO) to butadiene (BD) at 300 °C. The catalytic performance of the synthesized materials was related to their properties and compared to a commercial ZSM-22 zeolite (Si/Al = 30). ZSM-22 (50) exhibited a quick decline in conversion, a lower BD selectivity, and higher propylene selectivity compared to the other materials, which could be attributed to the presence of strong Lewis acid sites and silanol nests. The Lewis sites favor the cracking of the intermediate 3-buten-1-ol (3B1OL) into propylene, while the silanol nests interact with the free hydroxyl group of 3B1OL, potentially inhibiting further dehydration towards BD. The highest initial BD yield of 74% was observed over ZSM-22 (80), while the highest initial BD productivity of 2.7 gBD·g−1cata·h−1 was achieved over ZSM-22 (38). After 22 h time on stream (TOS), c-ZSM-22 and ZSM-22 (38) outperformed previously reported catalysts from the literature, with productivities amounting to 1.3 gBD·g−1cata·h−1 and 1.2 gBD·g−1cata·h−1, respectively, at a site time of 6.6 molH+·s·mol−11,3-BDO. Full article
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9 pages, 2979 KiB  
Proceeding Paper
Utilizing ZSM-5 Zeolite, Synthesized from Kaolin Clay, as a Catalyst Presents an Efficient Approach for Reducing Emissions in Compression Ignition (CI) Engines
by Sethuraman Narayanan, Karthikeyan Duraisamy and Aasthiya Bharanitharan
Eng. Proc. 2025, 93(1), 16; https://doi.org/10.3390/engproc2025093016 - 30 Jun 2025
Viewed by 155
Abstract
This investigation focuses on synthesizing ZSM-5 zeolite from kaolin clay and its application as a catalytic converter to reduce NOx emissions in CRDI diesel engines. By doping the synthesized zeolite with CuCl2 and AgNO3 and coating it on a ceramic monolith, [...] Read more.
This investigation focuses on synthesizing ZSM-5 zeolite from kaolin clay and its application as a catalytic converter to reduce NOx emissions in CRDI diesel engines. By doping the synthesized zeolite with CuCl2 and AgNO3 and coating it on a ceramic monolith, this study demonstrated superior catalytic activity for NOx reduction compared to conventional converters. A set of experimental trials conducted by using a diesel engine with an AVL DI-gas analyzer showed that CuCl2-ZSM5 and AgNO3-ZSM5 catalysts reduced the NOx conversion efficiencies to 72% and 66%. Additionally, these catalysts effectively reduced CO and HC emissions. The results highlight the potential of kaolin-derived zeolites with copper and cobalt dopants as efficient catalysts for emission control in internal combustion engines, offering a promising, sustainable solution for improving air quality and environmental sustainability. Full article
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22 pages, 5253 KiB  
Article
On the Deactivation Analysis of IM-5 Zeolite in Pseudocumene Methylation with Methanol
by Shumin Hao, Yongrui Wang, Enhui Xing and Xuhong Mu
Crystals 2025, 15(7), 598; https://doi.org/10.3390/cryst15070598 - 25 Jun 2025
Viewed by 385
Abstract
In the methylation of pseudocumene with methanol over IM-5 zeolite, the yield of durene can be enhanced. However, poorer stability of the catalytic activity was observed, especially at a higher methanol/pseudocumene ratio. In this paper, conventional characterization methods (XRD, XRF, TGA, SEM, physical [...] Read more.
In the methylation of pseudocumene with methanol over IM-5 zeolite, the yield of durene can be enhanced. However, poorer stability of the catalytic activity was observed, especially at a higher methanol/pseudocumene ratio. In this paper, conventional characterization methods (XRD, XRF, TGA, SEM, physical adsorption, OH-IR, NH3-TPD, and Py-IR) were used to characterize fresh and deactivated IM-5 zeolite and ZSM-5. FT-IR, XPS, TG-MS, GC-MS, FT-ICR MS, and NMR were employed to characterize deactivated IM-5 zeolite. It was found that the deactivation of IM-5 zeolite was mainly due to the severe coverage of acidic sites and pore channels by carbon deposits. The carbon deposits within the internal surface had a higher abundance, mainly in the form of linear unsaturated chain-like structures with a high degree of unsaturation. The carbon deposits on the external surface were mainly polycyclic aromatic hydrocarbons with alkyl side chains and a high degree of saturation, accompanied by unreacted methanol. Moreover, graphitized carbon existed on both the internal and external surfaces, which made the conventional coke-burning regeneration method unable to restore the activity of the post-reaction IM-5 zeolite. This work had certain reference significance for modulating the acidity and pore channels of zeolite catalysts, thus improving the activity and stability of the catalysts and extending their service life. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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23 pages, 4126 KiB  
Article
Enhanced Hydrothermal Stability and Propylene Selectivity of Electron Beam Irradiation-Induced Hierarchical Fluid Catalytic Cracking Additives
by Nguyen Xuan Phuong Vo, Thuy Phuong Ngo, Van Tri Tran, Ngoc Thuy Luong, Phuc Nguyen Le and Van Chung Cao
Catalysts 2025, 15(7), 620; https://doi.org/10.3390/catal15070620 - 24 Jun 2025
Viewed by 1665
Abstract
A cheap, environmentally friendly, easily scalable post-treatment of Na-ZSM-5 (Si/Al molar ratio = 20 or 30) via electron-beam irradiation to produce hierarchical H-ZSM-5 as a propylene-increasing fluid catalytic cracking additive was performed. Higher specific surface areas and highly accessible porous systems were obtained [...] Read more.
A cheap, environmentally friendly, easily scalable post-treatment of Na-ZSM-5 (Si/Al molar ratio = 20 or 30) via electron-beam irradiation to produce hierarchical H-ZSM-5 as a propylene-increasing fluid catalytic cracking additive was performed. Higher specific surface areas and highly accessible porous systems were obtained among the irradiated samples. A combination of 27Al, 1H magic angle spinning nuclear magnetic resonance and NH3-temperature-programmed desorption methods showed that upon irradiation, some of the framework’s tetrahedral Al atoms were removed as non-framework Al atoms via flexible coordination with Si-OH groups (either framework or non-framework defects), thus increasing the H-ZSM-5 acidity and stability during hydrothermal dealumination. The enhanced selectivity and stability toward propylene production over the irradiated H-ZSM-5 samples were attributed to the integration of the reserved population of medium acid sites into the highly accessible hierarchical network. N2 adsorption–desorption isotherm data showed that the Si-rich H-ZSM-5 samples possessed an obvious ink-bottle-shaped micro-mesopore network and a greater degree of disordered orientation of the straight pore systems toward the exterior surfaces. Micro-activity test data suggested that with an increasing Si/Al ratio, the H-ZSM-5 additives lost some extent of their cracking activity due to the constricted hierarchical pore network toward the exterior surface but gained more stability and selectivity for propylene due to the reserved medium acid sites. Full article
(This article belongs to the Section Industrial Catalysis)
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8 pages, 906 KiB  
Proceeding Paper
Ion Exchange of Na+ Ions with H+ Ions on ZSM-5 Zeolite Using Acetic Acid
by Aleksandar Došić, Milomirka Obrenović, Zoran Obrenović, Jelena Vuković and Ivan M. Savić
Eng. Proc. 2025, 99(1), 17; https://doi.org/10.3390/engproc2025099017 - 20 Jun 2025
Viewed by 360
Abstract
ZSM-5 zeolites are primarily used in acid-catalyzed hydrocracking reactions in the petrochemical industry, and it is very important to ensure an adequate number of acidic sites for more efficient catalytic activity. This study investigated the possibility of exchanging sodium ions with hydrogen ions [...] Read more.
ZSM-5 zeolites are primarily used in acid-catalyzed hydrocracking reactions in the petrochemical industry, and it is very important to ensure an adequate number of acidic sites for more efficient catalytic activity. This study investigated the possibility of exchanging sodium ions with hydrogen ions on ZSM-5 zeolite with a molar ratio of (SiO2/Al2O3 = 1000) using an ion-exchange process with acetic acid. By employing the XRD and FT-IR methods, along with chemical analysis of ZSM-5 zeolite samples, the influence of hydrogen ion concentration on the chemical composition and structural characteristics of ZSM-5 zeolite was monitored at different acid concentrations and exchange times. It was shown that ion exchange with acetic acid leads to a significant reduction in sodium content even with less concentrated solutions while maintaining the stability of the crystal structure of ZSM-5 (SiO2/Al2O3 = 1000) and a high degree of crystallinity. Full article
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12 pages, 2545 KiB  
Article
Rapid Fabrication of ZSM-5/AlPO4-5 Composites via Microwave-Ionothermal Strategy for Enhanced Methanol-to-Olefins Catalysis
by Li Han, Mengting Zhang, Hao Li, Huiru Ding, Jingjing Zhao, Yujia Zhang, Lang Wu, Changzhou Jiao, Jie Feng and Zhikun Peng
Catalysts 2025, 15(6), 605; https://doi.org/10.3390/catal15060605 - 19 Jun 2025
Viewed by 503
Abstract
Microwave-assisted ionothermal strategies offer an effective pathway for rapid zeolite crystallization under mild conditions, while conventional ionothermal approaches are still constrained by prolonged crystallization cycles that limit their industrial applicability. Herein, we report a microwave-activated, ionic liquid-mediated synthesis strategy that enables the precise [...] Read more.
Microwave-assisted ionothermal strategies offer an effective pathway for rapid zeolite crystallization under mild conditions, while conventional ionothermal approaches are still constrained by prolonged crystallization cycles that limit their industrial applicability. Herein, we report a microwave-activated, ionic liquid-mediated synthesis strategy that enables the precise modulation of crystallization kinetics and composite assembly. By introducing ZSM-5 seeds into the ionic liquid system, the nucleation and growth of AlPO4-5 were significantly accelerated, reducing crystallization time by up to 75% (optimal condition: 60 min). Among various imidazolium-based ionic liquids, [BMMIm]Br demonstrated an optimal balance of hydrophilic and hydrophobic interactions, yielding composite zeolites with high surface area (350 m2·g−1) and large pore volume (0.28 cm3·g−1). Comprehensive characterization (XRD, SEM-EDX, NH3-TPD) confirmed the formation of well-defined ZSM-5/AlPO4-5 core–shell structures and revealed tunable acid site distributions depending on the ionic liquid used. In methanol to olefins (MTO) reactions, the composite catalyst exhibited outstanding selectivity towards light olefins (C2=–C4=: 72.84%), markedly outperforming the individual ZSM-5 and AlPO4-5 components. The superior catalytic behavior is primarily attributed to the synergistic effect of hierarchical acid site tuning and the integrated core–shell architecture, which together optimize reaction selectivity. This strategy provides a promising route for the rational design of high-performance zeolites with significant industrial applicability. Full article
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14 pages, 1670 KiB  
Article
Inhibiting the Production of Polychlorinated Organic Pollutants in the Hydrolysis Oxidation Process of 1,2-Dichlorobenzene
by Yuqing Li, Bisi Lv, Na Li, Yingjie Li, Wenjie Song and Jiahui Zhou
Atmosphere 2025, 16(6), 750; https://doi.org/10.3390/atmos16060750 - 19 Jun 2025
Viewed by 353
Abstract
The hydrolysis oxidation of 1,2-chlorobenzene (1,2-DCB) over Pd-Ti-Ni/ZSM-5(25) catalysts has been investigated as a safe and environmentally friendly method for the removal of chlorinated aromatic organic compounds. Experimental results demonstrate that hydrolysis oxidation technology can effectively suppress the formation of polychlorinated organic compounds. [...] Read more.
The hydrolysis oxidation of 1,2-chlorobenzene (1,2-DCB) over Pd-Ti-Ni/ZSM-5(25) catalysts has been investigated as a safe and environmentally friendly method for the removal of chlorinated aromatic organic compounds. Experimental results demonstrate that hydrolysis oxidation technology can effectively suppress the formation of polychlorinated organic compounds. Among the catalysts studied, the 0.5%Pd-2%Ti-8%Ni/ZSM-5(25) catalyst exhibited optimal hydrolysis oxidation performance, achieving complete conversion of 1,2-DCB at 425 °C. Notably, this technology significantly inhibits the formation of polychlorinated organic by-products during the catalytic degradation of 1,2-DCB. Although trace amounts of chlorobenzene were still detected, the overall reduction in hazardous by-products is remarkable. Characterization techniques, including X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Pyridine adsorption infrared Spectroscopy (pyridine IR) and Fourier transform infrared spectroscopy (FT-IR) analysis, revealed that the acidity and redox properties of the catalyst surface play a pivotal role in the hydrolysis oxidation process. The hydrolysis oxidation of chlorinated volatile organic compounds not only effectively reduces pollutant concentrations but also prevents the generation of more toxic by-products. This dual benefit not only protects the environment but also minimizes ecological risks, highlighting the potential of this technology for sustainable environmental remediation. Full article
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15 pages, 2200 KiB  
Article
In Situ DRIFTS Study of Na-Promoted Pt/ZSM5 Catalysts for H2-SCR
by Stefano Cimino, Elisabetta Maria Cepollaro, Michele Emanuele Fortunato and Luciana Lisi
Catalysts 2025, 15(6), 598; https://doi.org/10.3390/catal15060598 - 17 Jun 2025
Viewed by 421
Abstract
Platinum was supported on ZSM5 at loadings from 0.1 to 1 wt% and tested for the Selective Catalytic Reduction of NO with H2 under excess O2 in a fixed bed reactor to address the issue of NOx emission abatement from [...] Read more.
Platinum was supported on ZSM5 at loadings from 0.1 to 1 wt% and tested for the Selective Catalytic Reduction of NO with H2 under excess O2 in a fixed bed reactor to address the issue of NOx emission abatement from H2-fueled internal combustion engines avoiding the additional devices for urea storage and injection. To reduce the undesired NO oxidation to NO2, which is activated by platinum at T > 200 °C, the 0.1%Pt/ZSM5 catalyst was further promoted with sodium. 5 wt% loading of Na strongly inhibited the NO oxidation while giving only a limited impact on the H2-SCR activity. Unpromoted and Na-promoted catalysts were characterized by XRD, SEM/EDX, N2 physisorption, and NH3-TPD to investigate the morphological, structural, and acid properties; H2 pulse chemisorption and DRIFTS of CO chemisorption were used to investigate the nature of Pt active species. Steady-state and transient operando DRIFTS experiments under NO+H2+O2 flow were employed to identify the adsorbed NOx species interacting with H2, and reaction intermediates as a function of the reaction conditions. The formation of ammonium intermediates via the reduction of surface nitrate species, playing a key role in H2-SCR catalyzed by 0.1Pt/ZSM5, was preserved at low Na load whilst NO2 formation was largely inhibited. Full article
(This article belongs to the Special Issue Spectroscopy in Modern Materials Science and Catalysis)
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15 pages, 5342 KiB  
Article
Synthesis of Dimethyl Terephthalate from Terephthalic Acid Esterification over the Zeolite Catalysts
by Ningyu Jia, Haoyu Han, Tao Yang, Meng Zhang and Zhongyi Liu
Inorganics 2025, 13(6), 184; https://doi.org/10.3390/inorganics13060184 - 5 Jun 2025
Viewed by 581
Abstract
The esterification of terephthalic acid (PTA) with methanol to dimethyl terephthalate (DMT) was investigated using commercially available zeolite catalysts as the eco-friendly solid acids. Six typical zeolites (ZSM-5-25, ZSM-5-50, ZSM-5-100, ZSM-35, MOR, and β) were systematically evaluated. Among them, β zeolite showed excellent [...] Read more.
The esterification of terephthalic acid (PTA) with methanol to dimethyl terephthalate (DMT) was investigated using commercially available zeolite catalysts as the eco-friendly solid acids. Six typical zeolites (ZSM-5-25, ZSM-5-50, ZSM-5-100, ZSM-35, MOR, and β) were systematically evaluated. Among them, β zeolite showed excellent catalytic performance, achieving nearly 100% PTA conversion and 76.1% DMT selectivity under the conditions of 200 °C, of 0.5 MPa N2 pressure, m(PTA):V(methanol) of 1:40 (g/mL), m(PTA):m(catalyst) of 10:1 over 4 h. The characterization results show that the catalytic efficiency was correlated with acid site strength, specific surface area, and mesoporous structure of the zeolite. After optimization, β zeolite achieved 100% PTA conversion and 94.1% DMT selectivity under the conditions of 200 °C, of 1 MPa N2 pressure, m(PTA)/V(methanol) of 1:30 (g/mL), m(PTA)/m(catalyst) of 8:1 over 8 h. Moreover, β zeolite exhibited superior stability, maintaining over 92% of its initial activity after five cycles, highlighting its potential for sustainable DMT production. Full article
(This article belongs to the Special Issue Inorganics Emerging Investigators Themed Collection 2024/2025)
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14 pages, 1634 KiB  
Article
Modified Fischer–Tropsch Pathway for CO2 Hydrogenation to Aromatics: Impact of Si/Al Ratio of H-ZSM-5 Zeolite on Light Aromatics Selectivity
by Shaocong Wang, Yu Sun, Shiyuan Lin, Zhongxu Bian, Yuanyuan Han, Xinze Bi, Zhaorui Zhang, Xiaojie Liu, Dandan Liu, Yang Wang and Mingbo Wu
Catalysts 2025, 15(6), 557; https://doi.org/10.3390/catal15060557 - 4 Jun 2025
Viewed by 714
Abstract
Despite significant advancements in designing tandem catalysts for CO2 hydrogenation to aromatics, the role of zeolite acid property in regulating the selectivity of light aromatics (benzene, toluene, and xylene, abbreviated as BTX) remains unclear. Herein, we report H-ZSM-5 zeolite (denoted as HZ-X, [...] Read more.
Despite significant advancements in designing tandem catalysts for CO2 hydrogenation to aromatics, the role of zeolite acid property in regulating the selectivity of light aromatics (benzene, toluene, and xylene, abbreviated as BTX) remains unclear. Herein, we report H-ZSM-5 zeolite (denoted as HZ-X, where X represents the Si/Al ratio) integrated with a Na-promoted FeCo-based catalyst (NaFeCo) for CO2 hydrogenation into aromatics via a modified Fischer–Tropsch synthesis pathway. This study systematically modulates the Si/Al ratio of acidic zeolite and examines its critical role in influencing the light aromatics selectivity. The optimized NaFeCo/HZ-50 catalyst achieves a CO2 conversion of 43% with an aromatics selectivity of 41%, including a BTX fraction of 57% in total aromatics. Multiple characterization techniques (NH3-TPD, Py/DTBPy-IR, 27Al NMR, etc.) clarify that acidic zeolite HZ-50 exhibits appropriate acid density and lower external surface acid sites, which synergistically boost the efficient aromatics and BTX synthesis while suppressing the undesirable alkylation and isomerization reactions on the external acid sites. This work develops a highly efficient multifunctional catalyst for CO2 hydrogenation to light aromatics, especially offering guidance for the rational design of acidic zeolite with unique shape-selective functions. Full article
(This article belongs to the Special Issue Catalysis on Zeolites and Zeolite-Like Materials, 3rd Edition)
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20 pages, 2037 KiB  
Article
Catalytic Transformation of LDPE into Aromatic-Rich Fuel Oil
by Muhammad Naseem Akhtar, Nabeel Ahmad and Feras Alqudayri
Catalysts 2025, 15(6), 532; https://doi.org/10.3390/catal15060532 - 27 May 2025
Viewed by 563
Abstract
The present study investigates the catalytic conversion of low-density polyethylene (LDPE) into high-grade fuel oil using a semi-batch reactor at 350 °C under ambient pressure, with a catalyst-to-LDPE ratio of 1:20. Zeolite-based catalysts were synthesized by impregnating different metals (Fe, Zn, Cr, Mn, [...] Read more.
The present study investigates the catalytic conversion of low-density polyethylene (LDPE) into high-grade fuel oil using a semi-batch reactor at 350 °C under ambient pressure, with a catalyst-to-LDPE ratio of 1:20. Zeolite-based catalysts were synthesized by impregnating different metals (Fe, Zn, Cr, Mn, and Ga) onto ZSM-5 with a silica-to-alumina ratio of 30 (Z30). These catalysts were characterized using BET, XRD, and NH3-TPD techniques to evaluate their physicochemical properties. The results showed that catalytic pyrolysis of LDPE yielded less pyrolytic oil compared to non-catalytic pyrolysis. The obtained pyrolytic oil was analysed through elemental composition, gross calorific value (GCV), Simulated Distillation, and GC-DHA. The elemental analysis revealed a high carbon (85–86%) and hydrogen (13–14%) content, resulting in a high GCV of approximately 42 MJ/kg. GC-DHA analysis indicated that the pyrolytic oil was rich in aromatic and olefinic compounds. Among the catalysts, 5Fe/Z30 exhibited the highest aromatic selectivity (35%), a research octane number of 91, and 100% LDPE conversion. These findings underscore the potential of low-cost iron-based catalysts for efficiently converting LDPE waste into valuable chemicals and fuels. Full article
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19 pages, 6839 KiB  
Article
Acoustic Enhancement Performance of Hierarchical ZSM-5 Zeolites with Different Si/Al Ratios
by Mingbo Guo, Yijun Wang, Lei Zhang, Junran Lu, Chang Gong, Wanning Zhang, Yuxi Fang, Xinyuan Zhu and Shunai Che
Nanomaterials 2025, 15(11), 797; https://doi.org/10.3390/nano15110797 - 26 May 2025
Viewed by 566
Abstract
Size restrictions pose increasing challenges to the acoustic performance of microspeakers in portable devices as the size of such devices, and thus the back volume of microspeakers, continues to shrink. Filling the back volume with porous materials, such as zeolites, has been proved [...] Read more.
Size restrictions pose increasing challenges to the acoustic performance of microspeakers in portable devices as the size of such devices, and thus the back volume of microspeakers, continues to shrink. Filling the back volume with porous materials, such as zeolites, has been proved to be an effective strategy for improving acoustic performance. In this work, hierarchically structured ZSM-5 zeolites with abundant mesopores were synthesized via the traditional hydrothermal method by adjusting the SiO2/Al2O3 ratios (SAR), and their pore structures and morphologies were systematically investigated. Their acoustic enhancement performance was evaluated using a commercial microspeaker. Based on their acoustic properties, the influence of pore structure on acoustic performance was further studied. The ZSM-5 zeolite sample with an SAR of 614, which exhibited the maximum mesopore volume, demonstrated exceptional acoustic enhancement performance with a resonance offset of 199.53 Hz and an enhanced sound pressure level of 4.74 dB at 500 Hz. The presence of mesopores significantly facilitates diffusion within the zeolite crystals, enabling air molecules to access more micropores for efficient sorption–desorption processes during diaphragm vibration in microspeakers. Furthermore, supermicropores were found to contribute to improved performance by adsorbing air molecules during diaphragm vibration, complementing the role of micropores. Full article
(This article belongs to the Section Nanocomposite Materials)
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