Search Results (259)

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

Direct air capture (DAC) of CO₂ via temperature-swing adsorption (TSA) can support sustainable carbon dioxide removal, but only if sorbents regenerate with low energy demand and maintain performance under humid ambient air. In this paper, we evaluate three commercial molecular sieves (JLPM3, 13X, and 4A) in packed-bed tests using humid ambient air. We compared 40 g samples as received with 200 g samples conditioned for 12 days at 100 °C to emulate prolonged exposure to regeneration temperature (the cumulative effect of many heating/desorption cycles); all cycle-stabilized uptake values are reported from the conditioned materials. JLPM3 delivered the highest stabilized CO₂ uptake (0.24 ± 0.01 mmol·g⁻¹), consistent with a combined physisorption/chemisorption mechanism. Its higher total porosity (26.190%) and smaller mesopores (7.569 nm width) promoted rapid mass transfer and site accessibility, while slightly greater micropore area (710.285 m²·g⁻¹) and volume (0.267 cm³·g⁻¹) than 13X supported its marginally higher capacity. Evidence of partial structural degradation under mechanical and thermal stress indicates that minimizing strain during cycling will be important for scale-up and for reducing sorbent replacement. Conditioning at 100 °C activated additional chemisorption sites across all sieves but reduced physisorption capacity. Importantly, a ~100 °C desorption step fully regenerated physisorbed CO₂ while purging moisture from zeolite pores, indicating that low-temperature TSA (compatible with low-grade or waste heat) can replace harsher 300 °C regeneration and lower energy demand. CO₂–H₂O competition experiments confirmed substantial site occupancy by water vapor, which limits capture under humid conditions and motivates water management strategies. Overall, maximizing DAC performance requires tailoring pore structure and operating conditions while preserving sorbent integrity; JLPM3 emerges as a promising candidate for more energy- and resource-efficient DAC. 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

Methane (CH₄) is the second-largest contributor to climate change after carbon dioxide (CO₂) and has a global warming potential about 72 times greater than CO₂ over a 20-year timescale. A possible solution to mitigate CH₄ emissions from diluted sources is direct removal of CH₄ through tailored sorbents. In this work, ion-exchanged zeolites have been investigated, owing to their low cost, excellent chemical stability, and ease of production. The impact of barium, lithium, and nickel exchange was investigated, along with one, three, and five ion-exchange sequences. XRD analysis confirmed that the structure remained intact after ion exchange. However, nitrogen physisorption revealed that nickel- and barium-exchanged zeolites had reduced pore volume and surface area compared to the parent zeolite, possibly due to mesopore formation from lattice strain relaxation. ICP-OES and SEM-EDX confirmed the successful incorporation of metals into the zeolite. Finally, breakthrough experiments were carried out to assess the saturation capacity of the synthesized sample. The results demonstrated that the lithium-exchanged samples provided the highest saturation capacity, namely 1.58 ± 0.05 mmol g⁻¹ for the Li-13X-3 and 1.76 ± 0.07 mmol g⁻¹ for the Li-SAPO34-5 over 10 adsorption cycles. Furthermore, the stability of the Li-SAPO34-5 was confirmed over 100 adsorption cycles. Full article

Linear alkylbenzene (LAB) is the main raw material used to make biodegradable detergents, and its production process is based on aromatic alkylation. HY zeolites that have undergone controlled dealumination and desilication have led industrial standards amongst solid acid catalysts because of their controllable acidity and hierarchical pore structure. Coke formation in such systems can assume a dual role, which is dependent on its condition. Though the over-deposition is known to cause deactivation by blocking the micropores, Bronsted acid-site masking, and diffusion collapse, the low-level deposition could also be done to increase the monoalkylate selectivity by the pore mouth catalysis, steric modulation, and selective suppression of secondary alkylation pathways. The critical review is done on the structural-kinetic interaction that determines the coke evolution in HY-based catalysts. In order to moderate the acid-site density and enhance hydrothermal stability, dealumination (Si/Al optimization of about 2.5 to 30–100) occurs, but to reduce deep-pore coke formation, desilication (interconnected mesopores) is created. The bimodal porosity and regulated acidity are found to be synergistic, as hierarchical HY zeolites produced through successive cycles of steam and alkaline treatments not only show LAB selectivity in excess of 90% but also exhibit much longer catalyst lifetimes. Quantitative research on the beneficial coke regime revealed that it was composed of about 36 wt% hydrogen-rich species, which were localized at the pore mouths, hence enhancing monoalkylation selectivity by 15–40%. Beyond a critical transition window (e.g., 8–12 wt.%), coke formation to condensed polyaromatic and graphitic products leads to fast deactivated coke formation, which is due to percolation limits and transport-controlled kinetics. More advanced techniques of characterization of the coke, e.g., temperature-programmed oxidation (TPO), ²⁷Al MAAS NMR, and UV-Raman spectroscopy, indicate how the coke is changed to highly structured graphitic deposits of high oxidation activation energy. Activity recovery of 85–98% is obtained in regeneration processes, including controlled oxidative calcination, microwave-based and plasma-based processes, and thermal management protocols, and it would be determined by the chemistry of the coke, its spatial distribution, and the regeneration protocols. This paper has developed a mechanistic coke control system by cross-tuning the acidity and development of an effective pore network, which led to a sustainable aromatic alkylation reaction with minimal activity loss, high selectivity, and long life. Full article

Reforming processes are key technologies for the production of hydrogen and synthesis gas from hydrocarbon feedstocks, with steam reforming and dry reforming being the most extensively studied routes. Steam reforming remains the dominant industrial process due to its high efficiency and economic viability; however, its associated CO₂ emissions raise environmental concerns, partially mitigated through an integration with carbon capture and storage technologies. Dry reforming has emerged as an attractive alternative, although it requires high operating temperatures and suffers from catalyst deactivation. Catalyst design is therefore critical for improving process efficiency and stability. Supported metal catalysts, particularly Ni-based systems, are widely employed, with the support material playing a decisive role in metal dispersion, resistance to sintering and coking, and reaction selectivity. Microporous and mesoporous silica-based materials, including zeolites and ordered mesoporous silicas, offer tunable structural and surface properties that enhance catalytic performance. The novelty of this work lies in its holistic approach to reforming catalysis, where the catalytic performance is not discussed solely in terms of active metals, but is systematically correlated with the surface properties, chemical composition, and structural features of silica-based supports. Moreover, this study expands the perspective to alternative and less-explored feedstocks. By considering multiple fuels and support types, the study provides new design guidelines for developing more efficient and sustainable reforming catalysts. Full article