Search Results (265)

Hierarchical porous catalysts now benefit from intentional co-design of transport pathways and catalytic functionality. This review critically examines intelligent micro–mesoporous nanoarchitectures, emphasizing pore connectivity and active-site cooperativity as inseparable design principles. We first outline limitations of purely microporous systems (diffusion constraints, site inaccessibility, deactivation) and then show how multi-scale networks overcome these issues. Engineering strategies for pore connectivity involving bottom-up templating, post-synthetic reconstruction, top-down desilication/dealumination are systematically reviewed alongside metrics (tortuosity, connectivity, accessibility). Active-site cooperativity is examined via acid-based bifunctionality, metal-acid coupling, single-atom catalysis and compartmentalized architectures for cascade reactions. The central thesis is that optimal performance emerges when transport and catalytic site engineering are coupled, supported by evidence from zeolites, metal–organic frameworks, silica nanoreactors, heteroatom-doped carbons and advanced electrocatalysts. Applications include biomass upgrading, selective oxidation, and energy conversion. The review also covers stability, deactivation, and regeneration, suggests standardized reporting criteria, and highlights future challenges such as using AI for catalyst design, operando transport mapping, scalable catalyst synthesis, and programmable catalytic nanoarchitectures. This review offers a predictive design strategy for next-generation multifunctional catalytic materials by focusing on the integrated transport-reaction system instead of only focusing on the structure. Full article

Low-cost synthesis of ZSM-5 zeolite is critical for its large-scale industrial application. Herein, a seed-assisted low-template hydrothermal route was employed to fabricate ZSM-5 zeolites. The regulatory effects of gradient crystallization temperatures on the crystallization kinetics, morphology, pore structure and acid properties of ZSM-5 were systematically investigated, and the structure–activity relationship linking temperature-driven evolution and catalytic behavior in benzene alkylation with methanol was established. The results reveal that increasing the crystallization temperature shortens the amorphous induction period, facilitates framework aluminum (Al) incorporation and increases the concentration of Brønsted acid sites. Meanwhile, crystallization temperature modulates the specific surface area and intercrystalline mesopore volume, thereby tuning the accessibility of acid sites and the mass transfer efficiency of reactants and products. The sample synthesized at a moderate temperature of 170 °C achieves an optimal balance between textural properties and acid concentration. Benefiting from its large specific surface area, abundant intercrystalline mesopores and high Brønsted acid concentration, the catalyst affords a benzene conversion of 69.1% and a methanol utilization of 79.1%, and maintains stable operation over 135 h on stream. The temperature-dependent regulation insights uncovered in this work facilitate low-cost synthesis of ZSM-5 and rational design of high-performance catalysts for aromatic alkylation. Full article

Composites consisting of NaX and Na-LTA zeolites and mesoporous silica in different ratios were successfully synthesized from coal fly ash and rice husk, and subsequently modified with Ni and Mn using the incipient wetness impregnation method. The initial composite and the modified materials were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), N₂ physisorption, temperature-programmed reduction (TPR–TGA) and X-ray photoelectron spectroscopy (XPS). The formation of finely dispersed Ni, Fe spinel nanoparticles was registered in the Ni- and NiMn-containing catalysts. The presence of Mn has a favorable effect on the Ni dispersion. The support composition, including zeolite phases and the content of mesoporous silica phase, effects the formation of catalytically active metallic species for CO₂ hydrogenation to methane. The formation of Fe⁰ and FeNi₃ crystalline phases was detected for the reduced catalysts. Additionally, 3D printing technology was applied for the macrostructuring of the catalyst prior to the modification of the powdered supports with metal precursors, aiming to enhance their catalytic performance. The stabilization of Fe⁰ and FeNi₃ phase dispersion in the 3D-printed samples is beneficial for long-term catalytic performance. The advantage of the 3D-printed catalyst was demonstrated, showing its higher CO₂ consumption rate relative to the external geometric surface area compared to its powder analogue. Full article

Electrocatalytic water splitting offers a viable route to sustainable hydrogen generation, yet the development of non-noble metal catalysts that combine high efficiency with long-term stability remains a significant hurdle. Zeolitic imidazolate framework-67 (ZIF-67) has emerged as a potential electrocatalyst, but its activity is often limited by insufficient active sites and poor conductivity. In this study, Mn, Fe, and Ni doped derivatives of ZIF-67 (ZIF-67/M, M = Mn, Fe, Ni) were synthesized via a post-synthetic modification method to improve the electrocatalytic performance. The effects of metal doping on structure, morphology, and water splitting activity were systematically investigated. XRD and FTIR confirmed the successful incorporation of heteroatoms without destroying the crystalline framework, while TGA revealed altered thermal stability. BET measurements showed a transformation from microporous to mesoporous structures upon doping, and SEM exhibited crystal distortion, aggregation, and increased surface roughness. Electrochemical tests demonstrated that doping significantly enhanced both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performances. At 10 mA cm⁻², ZIF-67/Fe exhibited the lowest overpotentials for OER (271 mV) and HER (338 mV), outperforming ZIF-67/Mn, ZIF-67/Ni, and pristine ZIF-67. Overall water splitting tests on ZIF-67/Fe showed negligible overpotential change after 24 h, confirming good ambient stability. In summary, metal doping effectively enhances the electrocatalytic water splitting performance of ZIF-67 by modulating its coordination environments and active site distribution, with ZIF-67/Fe exhibiting the best overall performance as a promising bifunctional electrocatalyst. Full article

Mesoporous nanoscale HZSM-5 zeolites were prepared by alkali treatment and characterized by XRD, SEM, NMR, ICP-OES, N₂ adsorption/desorption, NH₃-TPD, Py-IR, and TG techniques. The effects of NaOH concentration on pore structure, acidity, and catalytic performance of nanoscale HZSM-5 zeolites were systematically investigated for selective conversion of aqueous ethanol to propylene. The results showed that the newly developed mesopores on HZSM-5 zeolite were enhanced with increasing NaOH concentrations. By treating nanoscale HZSM-5 zeolite using NaOH solutions with appropriate concentrations (0.2 mol/L), AZ-0.2 showed simultaneously higher propylene selectivity and better stability because of its larger mesopore volume, higher B/L ratios, and suitable acidity. However, excessive treatment by a high-concentration NaOH (0.4 mol/L) solution led to serious desilication, which remarkably increased the strength and amount of strong acid sites on AZ-0.4, resulting in a remarkable decrease in propylene selectivity and catalyst stability. Full article

Hierarchical zeolites have emerged as an effective strategy to mitigate diffusional limitations and catalyst deactivation during the catalytic cracking of heavy feedstocks. However, conventional alkaline desilication often lacks selectivity, leading to partial loss of crystallinity and unfavorable alterations in acidic properties. In this work, microwave-assisted desilication is explored as an alternative route to engineer hierarchical Y zeolites with improved structural control and catalytic performance. A systematic comparison between conventional and microwave-assisted treatments was carried out using a 0.20 mol L⁻¹ NaOH solution, followed by hydrothermal stabilization. The resulting materials were comprehensively characterized by X-ray diffraction, nitrogen physisorption, scanning electron microscopy, ICP–OES, and pyridine-adsorbed FTIR. Catalytic performance was evaluated in the cracking of nitrogen-containing vacuum gas oil under microactivity test conditions representative of FCC operation. Microwave-assisted desilication promotes a more homogeneous development of mesoporosity, yielding higher mesopore volumes and larger pore diameters while preserving a greater fraction of the FAU crystalline structure and Brønsted acidity compared to conventional treatment. These features translate into enhanced catalytic behavior, including higher and more stable conversions, increased gasoline selectivity (up to 63 wt%), and significantly reduced coke yields. In addition, spectroscopic and thermal analyses reveal that coke formed on the microwave-treated zeolite is less condensed and more readily oxidizable, indicating a reduced propensity for irreversible deactivation. Finally, the results demonstrate that the mode of energy input during desilication plays a critical role in dictating the balance between pore architecture and acidity, ultimately governing catalytic performance. Microwave-assisted desilication emerges as an efficient strategy for designing hierarchical Y zeolites with improved accessibility, selectivity, and resistance to deactivation under severe FCC conditions. Full article

Corrosion-protective coatings have progressed from passive barrier systems and chromate-based technologies toward multifunctional materials that integrate barrier durability, interfacial adhesion, active inhibition, electrochemical response, and self-healing capabilities. However, the intellectual framework connecting these technological developments remains fragmented, as most reviews focus on specific material families rather than on the broader evolution of the field. This study examines technological paradigms in corrosion-protective coatings through a citation network analysis of highly cited publications retrieved from Web of Science and processed with CitNetExplorer. The most influential publications were thematically reviewed to identify dominant materials, coating architectures, protection mechanisms, seminal contributions, and bridge articles. Four principal paradigms were identified: smart and self-healing coatings based on nanocontainers, layered double hydroxides, mesoporous silica, halloysite, zeolites, hydroxyapatite reservoirs, and microcapsules; chromate-free sol–gel and silane pretreatments based on organic–inorganic hybrid matrices, organosilanes, rare-earth inhibitors, and oxide nanoparticles; graphene and graphene oxide-based nanocomposite coatings in which two-dimensional fillers enhance tortuosity, reduce water uptake, and reinforce polymer matrices and coating–substrate interfaces; and electroactive coatings based mainly on polyaniline and polypyrrole, where protection is associated with passivation, redox mediation, and dopant-controlled inhibition. The findings indicate that corrosion-protective coatings have evolved through partially overlapping and increasingly integrated paradigms rather than through a single technological trajectory. This citation network analysis clarifies the transition from chromate replacement toward active, nanostructured, electroactive, and self-healing corrosion-protective systems. 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

In this study, lamellar MFI (Mobile Five-membered ring Intergrowth) zeolites pillared with TiO₂ were synthesized using tetraethyl orthotitanate (TEOTi) as titanium precursor and evaluated as photocatalysts for Rhodamine B (RhB) degradation under UV irradiation. The materials were characterized by X-ray diffraction (XRD), UV–Vis spectroscopy, N₂ adsorption–desorption, photoluminescence spectroscopy (PL), and transmission electron microscopy (TEM). XRD confirmed the preservation of the lamellar MFI structure and the formation of anatase TiO₂ pillars within the interlayer space. The composites exhibited hierarchical micro/mesoporosity, high surface areas (>320 m² g⁻¹), and mesopore sizes of approximately 4.1–4.2 nm. Photocatalytic experiments revealed that the incorporation of TiO₂ into the lamellar MFI framework significantly enhanced the degradation kinetics of RhB compared with bare TiO₂. The apparent pseudo-first-order rate constants followed the order MFIPTi-6 > MFIPTi-3 > MFIPTi-12 > TiO₂ > MFIPTi-24, with MFIPTi-6 exhibiting the highest activity (k_app = 0.049 min⁻¹), approximately 1.6 times higher than that of pure TiO₂. Scavenger experiments identified hydroxyl radicals as the predominant reactive species involved in the degradation process. TOC (Total Organic Carbon) measurements showed approximately 80% organic carbon removal, while recyclability tests demonstrated stable photocatalytic performance over six consecutive cycles. These results highlight the potential of lamellar TiO₂/MFI composites as efficient and reusable photocatalysts for water treatment applications. Full article

The nanoconfinement effect is crucial in unconventional oil and gas development, yet the regulatory mechanism of wettability on it remains unclear. In this study, three SBA type molecular sieves with different pore sizes were used as model materials. Isothermal adsorption experiments were conducted using a BET analyzer, and pore size distributions were determined using the BET method and the DFT method, to systematically investigate the influence of wettability on the nanoconfinement effect. The results show that SBA molecular sieves with different pore sizes exhibit significantly different propane adsorption behaviors. SBA-15-4.2 with smaller pore sizes undergo capillary condensation at lower pressures, while SBA-15 and SBA-15-18 with larger pore sizes require higher pressures. The pore size distribution of the mixed SBA molecular sieve system exhibits a weighted superposition characteristic of the individual material pore size distributions, with each material contributing differently in different pore size ranges. Wettability significantly affects gas adsorption, diffusion, and condensation processes: unmodified SBA molecular sieves are highly hydrophilic and unfavorable for propane adsorption; shale pore surfaces have complex wettability and exhibit unique adsorption preferences for propane. After hydrophobic modification, the isothermal adsorption curve of the oil-wet SBA composite system is closer to that of shale, and the shale isothermal adsorption curve can be well fitted by adjusting the proportion of SBA molecular sieves in the mixture. This study provides a theoretical basis and experimental means for understanding the production mechanisms of unconventional reservoirs and optimizing production technologies. Full article

The selective conversion of high-molecular-weight paraffins (C₂₀–C₄₀) into linear alpha-olefins is often hindered by severe diffusion limitations and secondary over-cracking. This study addresses these challenges by transforming low-value natural minerals into sophisticated catalytic systems. We present a “top-down” engineering strategy for designing hierarchical catalysts based on natural Kazakhstani clinoptilolite. The multi-stage modification involves synergistic demineralization and precision chelation (EDTA, sulfosalicylic acid) to generate a tailored mesoporous architecture. This framework serves as a host for the sub-nanometric immobilization of Keggin-type heteropolyacids (PW₁₂, PMo₁₂), ensuring optimal active-phase dispersion. The innovative dual-step modification successfully bypassed the “micropore barrier”, creating a high-surface-area hierarchical network that facilitates the transport of bulky paraffinic molecules. Precise localization of heteropolyacid clusters within the created mesopores resulted in the formation of superstrong Lewis acid sites, as confirmed via temperature-programmed ammonia desorption. These sites triggered a highly efficient monomolecular beta-scission mechanism, suppressing undesirable hydrogen transfer reactions. The resulting catalysts achieved a breakthrough in technical paraffin cracking, delivering a 70% liquid product yield with an unprecedented >50% selectivity toward the C₇–C₁₄ α-olefin fraction. This work demonstrates a sustainable pathway for upgrading natural zeolites into high-performance, green catalysts that rival expensive analogs in precision and efficiency. Full article

The presence of residual moisture in tetrahydrofuran (THF) greatly limits its suitability for moisture-sensitive processes, including polymerization, Grignard chemistry, and fine-chemical production, where the allowable water concentration is generally lower than 10 mg/kg. Here, a hierarchical microporous/mesoporous composite adsorbent was prepared via extrusion molding, combining an LTA-type zeolite microporous framework with an amorphous mesoporous matrix. Characterization by XRD, FTIR, SEM, and pore analysis confirmed that the LTA crystal structure was retained while mesopores provided channels for mass transport. Static dehydration tests showed that the composite reduced THF water content from 70 mg/kg to 8.3 mg/kg, compared to 23.4 mg/kg for commercial 3A molecular sieves. The enhanced performance arises from micropores supplying uniform adsorption sites for deep dehydration and mesopores accelerating diffusion. Water vapor adsorption, kinetic and isotherm analyzes, regeneration, and competitive adsorption experiments indicated improved water accessibility and high selectivity, with kinetics described by a double-exponential model. The adsorbent remained stable over six adsorption–regeneration cycles. These results demonstrate that hierarchical microporous/mesoporous structures effectively achieve deep THF dehydration. Full article

Sustainable management of industrial solid waste is critical for a circular economy. This study presents a novel approach for valorizing blast furnace slag (BFS) into NaA zeolite through selective acetic acid leaching followed by hydrothermal crystallization. The leaching step selectively extracts Ca²⁺ and Mg²⁺ while efficiently retaining silicon and aluminum in the solid residue, producing a reactive aluminosilicate precursor that facilitates zeolite nucleation and growth. The effects of the silicon-to-aluminum molar ratio (n(Si)/n(Al)), crystallization temperature, and duration on the phase evolution and morphology were systematically investigated. The results demonstrate that phase-pure NaA zeolite with high crystallinity and a uniform cubic morphology can be obtained from precursor gels with n(Si)/n(Al) ratios of 0.5–1.25. Optimal synthesis conditions were identified as n(Na):n(Si):n(Al):n(H₂O) = 6:1:1:240 at 373 K for 8 h. The resulting zeolites exhibit a BET specific surface area of 52.1 m²/g, a micropore volume of 0.016 cm³/g, an average adsorption pore size of 4.7 nm, and an external specific surface area of 12.8 m²/g. It achieved near-complete removal of Cu²⁺ and high adsorption efficiencies for Pb²⁺ (77.78%) and Ni²⁺ (71.79%) from 250 mg/L solutions at 298 K with a dosage of 4.0 g/L, following the affinity sequence Cu²⁺ > Pb²⁺ > Ni²⁺, with all pairwise differences statistically significant at p < 0.001, using one-way ANOVA and Tukey’s HSD tests. The adsorption of three metal ions was most accurately described by the Freundlich isotherm and pseudo-second-order kinetic models, indicating heterogeneous multilayer chemisorption. The theoretical maximum monolayer adsorption capacities (q_max) were 307.67 mg/g for Cu²⁺, 246.09 mg/g for Pb²⁺, and 173.79 mg/g for Ni²⁺, whereas the kinetic equilibrium adsorption capacities (q_e) reached 62.69, 48.85 and 41.69 mg/g, respectively. This study demonstrates a value-added strategy for valorizing BFS into a micro-mesoporous adsorbent, advancing both circular resource utilization and environmental remediation. Full article

The fast growth of the aviation sector has intensified the need for sustainable alternatives to conventional fossil-based jet fuels. Sustainable aviation fuel (SAF) has emerged as one of the most promising strategies to reduce greenhouse gas emissions while remaining compatible with existing aviation infrastructure. Among the different feedstocks explored for SAF production, lipid-based resources such as vegetable oils, animal fats, and waste cooking oil have received considerable attention due to their high content of triglycerides and free fatty acids. Additionally, the increasing generation of plastic waste has stimulated interest in its catalytic valorization as an alternative carbon source for hydrocarbon fuel production. This mini-review summarizes recent advances in catalytic pathways for producing jet-fuel-range hydrocarbons (C₈–C₁₆) from lipid-based feedstocks and polyolefins. Particular emphasis is given on hydroprocessing reactions, including deoxygenation, cracking, and isomerization, which are essential to adjust fuel properties and meet aviation specifications. In this context, bifunctional heterogeneous catalysts play a crucial role, particularly regarding the influence of the metal phase and catalyst support on catalytic activity and stability. Different support classes, including metal oxides, mesoporous silicas, and zeolites, are discussed. Carbon-based materials, especially carbon nanotubes (CNT), are also highlighted due to their outstanding chemical and textural properties. Full article

N₂O (Nitrous oxide) is a potent greenhouse gas with a global warming potential nearly 300 times that of CO₂ and poses a critical environmental challenge, particularly in semiconductor and display manufacturing, where it is emitted during plasma processes. However, catalytic N₂O abatement in O₂-rich environments remains inefficient because O₂ competitively occupies active sites and hinders the turnover of surface oxygen species. To clarify how support properties govern this inhibition, Co-based catalysts supported on beta zeolite, CeO₂, and TiO₂, together with unsupported Co₃O₄, were comparatively evaluated for direct N₂O decomposition. Among them, Co/Beta exhibited the highest performance, achieving >95% N₂O conversion at 450 °C in the presence of 5% O₂ with excellent long-term stability. Co/Beta possessed a high specific surface area (649 m² g⁻¹) and a mesoporous framework that favored uniform Co dispersion and reactant accessibility, while its high Co²⁺/(Co²⁺ + Co³⁺) ratio (75.5%) and large fraction of chemisorbed oxygen species (79.9%) promoted oxygen-vacancy formation and facile oxygen exchange. These results indicate that the ability of Co/Beta to maintain high activity in the presence of oxygen stems from support-modulated cobalt surface states and enhanced oxygen turnover behavior. These findings provide a support-design principle for stable N₂O decomposition under oxygen-containing exhaust conditions. Full article