Search Results (333)

The development of multifunctional biodegradable materials with improved structural performance and antimicrobial functionality is essential for advancing sustainable packaging. This study evaluates the effect of copper-modified ZSM-5 zeolite (ZCu) concentration (0, 1, and 5 wt%) on thermoplastic starch/polylactic acid (TPS/PLA) blends. The TPS was derived from Ipomoea batatas (sweet potato, SP) and Dioscorea rotundata (diamond yam, DY) starches and compatibilized with 1 wt% citric acid. The ZCu response depended on both ZCu loading and the botanical starch source. Structural analyses showed that SP-based composites reached their highest crystallinity at 1 wt% ZCu (13.70%), whereas DY-based systems exhibited an initial decrease at 1 wt% followed by an increase to 12.75% at 5 wt%, reflecting distinct concentration-dependent crystallization trends. Thermal analyses demonstrated a substantial increase in the degradation onset temperature of SP-based composites, from 132.9 °C to 185.1 °C at 1 wt% ZCu, indicating an effective thermal barrier effect. Nanomechanical mapping revealed concentration- and starch-source-dependent changes in local hardness, reduced modulus, and elastic recovery, without evidence of uniform mechanical reinforcement across all formulations. Antibacterial activity was observed exclusively in composites containing 5 wt% ZCu, with inhibition zones of 5.3 mm against Staphylococcus aureus and 1.0 mm against Escherichia coli. These findings highlight how the structural, thermal, nanomechanical and antimicrobial responses of TPS/PLA blends vary with ZCu concentration and the botanical origin of the starch. Full article

This study focuses on the shaping of ZSM–5-based granules using conventional pseudoboehmite as well as aluminum hydroxynitrate precursors obtained by partial thermal treatment of Al(NO₃)₃·9H₂O. The starting materials and nitrate-derived precursors were characterized by X-ray diffraction, thermal analysis, infrared spectroscopy, scanning electron microscopy, and low-temperature nitrogen adsorption. Model pseudoboehmite systems were used to evaluate the effects of moisture, peptization equivalent, and HNO₃ concentration in the initial liquid portion on pore volume, apparent density, shrinkage, and axial and radial crushing strength. Acid peptization showed a strongly non-linear effect: small HNO₃ additions increased strength and densification, whereas excess acid promoted structural heterogeneity and granule disintegration during thermal treatment. Even at constant moisture and total acid dosage, strength depended markedly on the initial peptizer concentration. In unpeptized ZSM–5/pseudoboehmite composites, increasing zeolite content reduced pore volume but increased density and strength, indicating formation of a more compact framework. Aluminum hydroxynitrate precursors enabled effective shaping of ZSM–5-containing pastes, demonstrating their potential as alternative binder precursors, while the optimized pseudoboehmite systems provided the most favorable overall balance between porosity and mechanical stability. Full article

The morphology and pore structure of ZSM-48 zeolite are critical parameters determining the catalytic performance of bifunctional catalysts in the hydroisomerization of long-chain n-paraffins. This study investigates the effects of the Na₂O/SiO₂ molar ratio (0.02–0.12) in the synthesis gel and hydrothermal treatment duration (48–72 h) on the crystallization kinetics, phase purity, and physicochemical properties of ZSM-48. Low alkalinity (Na₂O/SiO₂ = 0.04–0.06) and shorter synthesis times (48 h) promote the formation of small aggregates composed of short needle-like crystals with enhanced intercrystalline mesoporosity. Conversely, increasing the alkalinity and crystallization duration accelerates crystal growth, resulting in dense pseudo-spherical aggregates (up to 4–7 μm in size) with restricted external surface area and increased diffusion limitations. Catalytic testing of Pt/ZSM-48 (0.5 wt.% Pt) in n-hexadecane hydroisomerization demonstrates that crystal morphology, size, and porosity significantly influence process selectivity. The catalyst based on nanosized ZSM-48 (Pt/Z48-06-2) effectively mitigates diffusion resistance, yielding a maximum isomer yield of 73% at 82% selectivity. In contrast, larger, densely packed aggregates with high but poorly accessible acidity intensify secondary hydrocracking reactions, reducing a maximum isomer yield to 46%. These results highlight the ability to tune the catalytic properties of ZSM-48 through careful control over gel alkalinity and crystallization kinetics. Full article

Zeolites are porous aluminosilicate crystalline materials that are widely used for the adsorption of volatile organic compounds (VOCs). The synthesis of zeolites without organic structure-directing agents (OSDAs) is attractive because of its low cost and environmental friendliness. In this study, analcime and the ZSM-5 zeolite were synthesized from natural diatomite under OSDA-free conditions through different crystallization routes. Analcime was prepared by regulating the hydrothermal conditions, while the ZSM-5 zeolite was synthesized by combining hydrothermal condition regulation with seed-induced crystallization. Hydrochloric acid modification was further used to improve the pore structures and adsorption properties of the zeolites. The optimum acid treatment conditions were 1.0 mol·L⁻¹ HCl for analcime and 0.5 mol·L⁻¹ HCl for the ZSM-5 zeolite. After acid modification, the specific surface area and pore volume of analcime increased to 271.7 m²·g⁻¹ and 0.130 cm³·g⁻¹, respectively, and its tolune adsorption capacity increased from 18.3 mg·g⁻¹ to 23.2 mg·g⁻¹, corresponding to a 26.6% improvement. For the ZSM-5 zeolite, the optimal modified sample showed a specific surface area of 307.9 m²·g⁻¹, a pore volume of 0.172 cm³·g⁻¹, and a toluene adsorption capacity of 65.4 mg·g⁻¹, which was 5.5% higher than that of the unmodified sample. Adsorption kinetic analysis indicated that pore diffusion played an important role in toluene adsorption, while acid modification introduced additional acid sites that contributed to chemisorption. Overall, the ZSM-5 zeolite showed a higher adsorption capacity than analcime because of its larger surface area, higher pore volume, and more accessible adsorption sites. This study provides a low-cost and environmentally friendly route for preparing diatomite-derived zeolite adsorbents for VOC removal. Full article

To reduce environmental pollution caused by volatile organic compounds (VOCs) released during asphalt application, various porous materials have been used to adsorb asphalt VOCs due to their rich pore structures. However, asphalt VOCs are so complex that emission reduction mechanisms still require further study. In this study, Materials Studio was used to simulate the molecular dynamics of asphalt VOC adsorption by ZSM-5 zeolite. The adsorption heat, capacity, and energy of ZSM-5’s adsorption of the main asphalt VOCs was obtained by means of molecular simulation to reveal the adsorption rules and selectivity. Zeolite model simulations with different structures were run to investigate possibilities for the optimization of ZSM-5. In addition, the actual VOC emission reduction effects of ZSM-5 in asphalt were compared with the MS simulation results. The VOC emission reduction mechanism was discussed based on both microscopic simulations and macroscopic verification. The results show that hydrocarbon derivative VOCs are more likely to be adsorbed due to their higher polarity. The smaller molecules of these VOCs are easier to adsorb because they occupy a smaller pore volume. When several molecules are mixed, competitive adsorption occurs. The selective adsorption probabilities of n-hexane, 1-methylcyclopentene, and toluene increase. In relation to the structure of zeolites, the Si/Al ratio and pore size of zeolites can both affect adsorption ability. A low Si/Al ratio can increase the number of surface acid active sites, while a micro–mesoporous structure increases the pore volume. The actual emission reduction data confirm that computational simulation has high accuracy in evaluating VOC emission reduction based on physical adsorption. Low-Si/Al-ratio and micro–mesoporous zeolites show better emission reduction ability for non-benzene VOCs than high-Si/Al-ratio and microporous zeolites. The emission reduction efficiency is up to 44%. However, the aromatization reaction was more easily catalyzed by zeolites, leading to the discrepancy between the simulated adsorption data and the actual situation. In future work, the boundary conditions and parameter settings of the simulations should be changed to achieve greater accuracy. Full article

Fe-ZSM5 zeolite materials were prepared via solid-state ion exchange and comprehensively characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The XRD patterns confirm the successful loading of iron species onto the ZSM-5 support. These materials served as heterogeneous Fenton catalysts for the degradation of methyl orange in simulated wastewater. Key operational parameters—including initial pH, H₂O₂ concentration, catalyst dosage, and reaction temperature—were systematically evaluated to assess their effects on decolorization efficiency. The results indicated that under optimal conditions (initial pH of 3.0, H₂O₂ concentration of 0.3 mol/L, catalyst dosage of 1.6 g/L, reaction temperature of 30 °C), a decolorization efficiency of 92.58% was achieved within 60 min. This study demonstrates that Fe-ZSM5 zeolite is a robust and efficient catalyst for heterogeneous Fenton-based degradation of organic dyes in aqueous systems. Full article

CO₂ methanation with renewable hydrogen is a promising strategy for carbon valorization and synthetic natural gas (SNG) production. However, the molecular mechanisms behind catalyst-dependent adsorption and mass transport in zeolite-confined spaces are still not fully elucidated. Herein, we performed comparative molecular simulations on HZSM-5, Ni/ZSM-5 and Ru/ZSM-5 by combining density functional theory (DFT), grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) methods, aiming to clarify the thermodynamic and mass transport mechanisms of reactant enrichment and product desorption in CO₂ methanation. The electronic structures of the three systems were systematically evaluated via Mulliken charge analysis, differential charge density mapping, and frontier molecular orbital calculations. We further quantified the adsorption thermodynamics and diffusion kinetics of reactants and products, focusing specifically on the effects of temperature and framework Si/Al ratio for Ni/ZSM-5. The results show that Ni doping greatly modulates the local electronic environment of the ZSM-5 framework, enhancing the adsorption of CO₂ (−121.9 kJ·mol⁻¹) and H₂ (−81.6 kJ·mol⁻¹) and weakening the adsorption of CH₄ and H₂O. A higher Si/Al ratio reduces CO₂ adsorption capacity, while elevated temperatures inhibit reactant adsorption and lower the diffusion selectivity of CH₄. This demonstrates that moderately low temperatures and moderate Si/Al ratios can optimize the adsorption and diffusion behaviors of reactants and products. This work provides molecular-level insights into the adsorption and diffusion behaviors of Ni/ZSM-5 and offers theoretical references for the rational development of high-performance CO₂ methanation catalysts. Full article

Zeolites, both natural (e.g., clinoptilolite) and synthetic (e.g., FAU, ZSM-5), provide robust, tunable platforms for the removal of air pollutants and process-stream contaminants via adsorption and catalysis. This author-led article integrates experimental and theoretical insights on the adsorption of odorous compounds and ammonia (NH₃) and the catalytic abatement of nitrogen oxides (NOx) and nitrous oxide (N₂O), highlighting how topology, acidity, and metal speciation jointly control performance. Representative theoretical results show that adsorption on Brønsted acid sites is significantly more favorable (≈−1.1 eV for NH₃ and −0.37 eV for acetaldehyde) than on Na⁺ sites (≈0.02 eV and 1.22 eV, respectively), demonstrating the critical role of acid site distribution in adsorption selectivity. We dissect structure–function relationships encompassing pore size and connectivity, Si/Al ratio, Brønsted/Lewis site distribution, hydrophilicity/hydrophobicity, and the role of water, with emphasis on hierarchical porosity to alleviate transport limitations. Metal exchange and surface functionalization are discussed as levers to tailor adsorption strength and redox activity, supported by density functional theory (DFT) analyses and reaction pathways. We propose practical design descriptors (acid strength metrics, metal nuclearity, and confinement factors) that enable faster iteration of zeolite architecture for targeted separations and reactions. Sustainability considerations include the use of abundant natural zeolites, low-energy regeneration, stability under humid, mixed-stream conditions that minimize pressure drop and waste. The article closes with a forward look at data-guided optimization to accelerate “engineering zeolites” for durable, selective, and energy-efficient clean-air and process-intensification applications. Full article

Plasma electrolytic oxidation (PEO) enables the fabrication of multifunctional oxide coatings with embedded active phases, offering a promising route for durable photocatalytic surfaces in water purification. This study examines how the electrical regime affects particle incorporation and photocatalytic performance. Coatings were produced under a 50% duty cycle in both unipolar mode and during the anodic part of the bipolar mode. A silicate-based electrolyte was modified with zeolites (Y and ZSM5), used in pristine form, Zn-loaded form, and combined with ZnO nanoparticles, to enhance catalytic activity. Photocatalytic performance was evaluated via methyl orange degradation under simulated solar irradiation for 6 h. The highest efficiency (~45%) was achieved with unipolar coatings containing Y zeolite and ZnO. In contrast, bipolar coatings with combined Y and ZnO showed lower efficiency (~35%). Although lower than typical powder photocatalysts, these results are notable since active phases are directly embedded in the coating, and both modes improve the photocatalytic activity by ~10% compared to the standard electrolyte. Microstructural analysis revealed that bipolar coatings were more compact, limiting access to active sites. Unipolar processing enabled better particle incorporation and a morphology more favorable for photocatalytic activity, making it the more effective regime for developing PEO-based photocatalytic coatings. Full article

While the petroleum industry undergoes structural adjustments in supply and demand alongside a green and low-carbon transition, water drilling mud generated during oil extraction poses severe environmental challenges. Consequently, addressing the solid waste pollution and disposal issues associated with drilling mud has become critical. In this study, ZSM-5 zeolite was synthesized using water drilling mud as a silicon and aluminum source, inexpensive n-butylamine as a template agent, and a combined approach of alkali-melting activation pre-treatment and seed-directed hydrothermal synthesis. By adjusting key parameters such as water content, template agent dosage, and seed addition, optimal synthesis conditions were determined. Based on these conditions, a series of ZSM-5 zeolites with varying silicon-to-aluminum ratios were synthesized. Characterization results from XRD, TEM, SEM, and N₂ adsorption–desorption experiments revealed that all prepared samples exhibited high crystallinity, regular morphology, and high specific surface area. ²⁷Al MAS NMR results indicated that almost aluminum species were located at the framework structures with four-coordination. In the 1,3,5-triisopropylbenzene cracking reaction, the conversion rate increased with decreasing silicon-to-aluminum ratio, consistent with variations in acid amount. These findings achieve high-value utilization of waste drilling mud, offering a novel pathway for low-cost synthesis of high-performance ZSM-5 zeolite. This breakthrough injects fresh momentum into the petroleum refining industry’s green sustainable development, fostering a win–win scenario that harmonizes ecological conservation with industrial profitability. Full article

Energy-efficient microwave technologies for the synthesis of zeolites and zeolite-like materials are considered. The use of microwave radiation in the process of material synthesis has a number of advantages, but also some disadvantages in comparison with the traditional hydrothermal synthesis method. The advantages and disadvantages of microwave synthesis of zeolites and zeolite-like materials are presented in the review. The use of microwave synthesis makes it possible to significantly reduce synthesis time, reduce energy costs, and obtain particles with a narrow distribution, usually in the nanoscale range (50–500 nm). The groups of zeolites considered include LTA, BEA, MOR, MFI, MEL, FAU, F, P, T, FER, ANA, MTT, ZSM–22, ZSM-48, SOD, SSZ-11, SSZ-13, SSZ-51, SSZ-54, and others. Among the zeolite-like materials synthesized using microwave radiation, mesoporous silicates MCM-41, SBA-15, alumophosphates, and metallaluminophosphates (AlPO-5, AlPO-11, AlPO-18, SAPO-5, SAPO-11, SAPO-34, SAPO-35) are considered. The proposed methods (microwave processing) significantly expand the range of methods for synthesizing new materials. These methods can reduce the synthesis temperature and affect the structure of the resulting materials. The proposed methods increase the likelihood of obtaining new nanomaterials and hybrid materials, as well as improving the properties of existing ones. Full article

Utilizing the pyrolysis reaction of endothermic hydrocarbon fuels to provide thermal protection for hypersonic vehicles is a feasible approach. The introduction of catalysts or cracking-initiating additives could promote hydrocarbon fuel cracking and increase the reaction heat sink. Catalysts such as ZSM-5 zeolite, Al₂O₃, and precious metals were commonly used for hydrocarbon fuel cracking. By optimizing their pore structure and acidity, their catalytic cracking performance can be effectively improved. These catalysts can function not only as catalytic coatings but also be dispersed in the fuel to act via quasi-homogeneous catalytic cracking. Additionally, small-molecule and macromolecular additives could crack at lower temperatures to generate active free radicals, thereby initiating the cracking of hydrocarbons and increasing the reaction heat sink. Under the conditions of a reaction temperature of 650–750 °C, a pressure of 3–5.5 MPa, and a fuel flow rate of 1 g/s, quasi-homogeneous catalysts can enhance the heat sink of hydrocarbon fuel cracking by 5–21%, while cracking-initiating additives can enhance it by 5.6–8.6%. Therefore, based on the different action modes of catalysts or additives, this review summarizes the recent research on improving the cracking of endothermic hydrocarbons from three aspects: coating catalysts, quasi-homogeneous catalysts, and cracking-initiating additives. Subsequently, the potential challenges of each approach in practical applications are analyzed. Furthermore, based on the current research findings, we outline future research directions with the expectation of facilitating the advancement of efficient cracking technologies for endothermic hydrocarbons. Full article

The purpose of this study is the exploration of the catalytic performance of a ZSM-5 zeolite produced from iron-rich fly ash, without any additional iron loading, in removing paracetamol via a heterogenous Fenton reaction. The structural and textural characterization by powder X-ray diffraction and N₂ adsorption isotherms showed that a pure ZSM-5 phase was synthesized, but lower crystallinity and textural parameters were obtained when compared with commercial ZSM-5. The XPS analysis revealed significant amounts of iron and yttrium, which enhanced the electronic properties of the samples’ surface when compared with iron-impregnated commercial ZSM-5. The catalytic reaction was followed through UV-spectroscopy and kinetic models were applied to the data; the best fit was obtained for a pseudo-first-order model. All fly ash-based zeolites showed increased paracetamol removal when compared with commercial iron-loaded ZSM-5, which may be attributed to the more disordered structure, able to accommodate large paracetamol species (dimers). On the other hand, the effect of yttrium on the electronic properties of iron sites may increase the ^●OH radical formation, thus increasing the paracetamol removal rate, despite the progressive drop on paracetamol removal upon regeneration–reuse cycles due to Fe leaching. Full article

CO₂-assisted catalytic pyrolysis presents a viable and promising approach to addressing plastic waste pollution and mitigating climate change. However, the effects of the metal–catalyst combination mode and the spatial distance between metal–acid sites on catalytic performance remain unclear. In this study, the reaction behaviors of the configurations, Fe₃O₄ and ZSM-5 in tandem catalysis (Fe₃O₄&HZ), their physical mixture (Fe₃O₄-HZ), and Fe-loaded ZSM-5 (Fe/HZ), were compared in polypropylene pyrolysis under a CO₂ atmosphere. The aromatic contents followed this order: Fe/HZ > Fe₃O₄-HZ > Fe₃O₄&HZ > ZSM-5 > Fe₃O₄. Specifically, Fe/HZ with the highest degree of metal–zeolite proximity achieved an aromatic content of 66.1%, significantly higher than the 34.2% obtained with Fe₃O₄&HZ, demonstrating that closer metal–acid proximity promoted aromatic formation. Moreover, Fe/HZ significantly reduced coke deposition. Based on characterization results from XRD, SEM, TEM, XPS, and NH₃-TPD, the enhanced spatial proximity between metal and acid sites strengthened the functional synergy between iron-based redox sites and zeolitic Brønsted acid sites. This synergy facilitated the reverse water–gas shift reaction of CO₂, which consumed hydrogen generated during aromatization and shifted the reaction equilibrium toward enhanced aromatic production. These findings would offer theoretical and strategic insights into the optimization of CO₂-assisted catalytic pyrolysis systems for the sustainable upcycling of plastic waste. Full article

While temperature and acidity dominate the design of zeolite catalysts for olefin cracking, the role of reaction time as an independent variable governing pathway dynamic remains elusive. This study integrates experimental and simulation methods to unravel the dynamic competition among carbenium ion cracking, thermal cracking and Confined Catalytic Radical (CCR) pathways during 1-pentene cracking on H-ZSM-5 zeolite at 650 °C. Analysis of the optimum performance envelope (OPE) curves for cracking products revealed that, in the initial reaction stage, the CCR mechanism significantly enhances ethylene yield. As the reaction time prolongs, C₅+ olefins in the gas phase undergo further cracking on the zeolite surface, markedly increasing the contribution of the carbenium ion pathway. Molecular simulations indicate that C₅+ olefins exhibit stronger adsorption capacity but lower diffusion coefficients on H-ZSM-5, and this adsorption–diffusion disparity is a key factor influencing the evolution of 1-pentene cracking pathways. Concurrently, thermal cracking reactions are also enhanced with increasing residence time, which is unfavorable for ethylene formation. This work elucidates the time-dependent evolution of 1-pentene cracking pathways and the regulatory role of intraparticle mass transfer, providing a theoretical basis for optimizing light olefin selectivity through the adjustment of reaction time and catalyst structure. Full article