Search Results (3,500)

Interzeolite transformation (IZT) has emerged as a versatile strategy for accessing zeolite frameworks through controlled framework reorganization under comparatively simplified synthesis conditions. Unlike traditional synthesis approaches that frequently require organic structure-directing agents (OSDAs), highly alkaline media, and prolonged thermal treatment, IZT converts pre-existing zeolite into a new topology, enabling direct reuse of crystalline matter while reducing synthesis complexity. This review examines how structural drivers, including framework density, structural memory, and building-unit compatibility, govern transformation pathways and phase selectivity across five principal transformation approaches: (i) solution-mediated, (ii) assembly–disassembly–organization–reassembly (ADOR), (iii) mechanically assisted, (iv) steam-assisted, and (v) fully solid-state systems. These approaches promote distinct transformation pathways that govern framework reconstruction, structural inheritance, and phase selectivity. Recent advances in solvent-free, mechanochemical, steam-assisted, and microwave-assisted synthesis demonstrate the potential of IZT to reduce solvent consumption, template usage, and crystallization times. Despite these advances, major challenges remain in predicting transformation outcomes, controlling transient intermediates, and establishing scalable and quantitatively validated sustainability metrics. Collectively, these developments position IZT as a promising platform for the rational and sustainable design of next-generation zeolitic materials. Full article

Zeolite morphology strongly determines its performance. Herein, Silicalite-1 was synthesized in a low-template system (TPA⁺/Si = 0.007) via a synergistic strategy using potassium bisulfate and seed suspension. The seeds supply abundant structural units to reduce nucleation barrier and accelerate crystallization, while KHSO₄ facilitates silicate polycondensation and suppresses non-MFI impurities. Sulfate ions selectively adsorb on specific crystal facets via hydrogen bonding and induce preferential crystal growth along the c-axis. The c-axis size of Silicalite-1 can be precisely regulated by adjusting dosages of seeds and KHSO₄. Well-defined plate-like crystals were obtained under the conditions of K⁺/Si = 0.25, a seed content of 2.42 wt%, and hydrothermal treatment at 180 °C for 8 h. Scale-up synthesis in a 2 L autoclave verifies its industrial potential. The product exhibits excellent adsorption capacity and cyclic stability toward methylene blue. This work provides a low-cost and green route for morphology-controlled synthesis of MFI-type zeolites. Full article

This review examines the scientific basis and technological development of natural zeolites, focusing particularly on deposits and research from Bulgaria and Turkey. It traces the transformation of zeolites from conventional industrial minerals into advanced, high-performance functional materials. A stepwise methodological framework was employed to conduct a bibliometric assessment of research and review articles published between 2015 and 2025, primarily focusing on contributions from researchers in Bulgaria and Turkey. In parallel, the study evaluates historical industrial data and the foundational literature. Beyond its regional focus, the bibliometric analysis reveals that Turkey ranks among the world’s leading contributors to zeolite research after Iran, China, and Indonesia, while Bulgaria maintains significant presence within the global network of active researchers in the field. The findings suggest that zeolite science in the region is expanding rapidly and dynamically, with current research increasingly focused on modifying, functionalizing, and diversifying zeolitic materials for a wide range of scientific and technological applications, including wastewater treatment, environmental remediation, construction materials production, agriculture, animal husbandry, and healthcare enhancement. The growing demand for effective adsorbents, therapeutic agents, and nutritional supplements, coupled with the critical need to reduce manufacturing costs, serves as a primary driver for accelerated zeolite research. Full article

This study investigates potassium-L zeolite (K-L) as an adsorbent for the removal of thallium (Tl⁺) from aqueous solutions, focusing on the relationship between cation exchange and framework structural response. X-ray powder diffraction (XRPD), thermal analysis, and Rietveld refinements were employed to monitor structural modifications upon Tl⁺ uptake, combined with batch adsorption experiments to evaluate the removal performance. At low Tl⁺ uptake, only minor structural perturbations occur, mainly involving slight shifts in extra-framework cation positions and limited rearrangement of channel water molecules. At higher Tl⁺ concentrations, a measurable anisotropic expansion of the zeolite framework is observed, consistent with partial substitution of K⁺ by Tl⁺ and progressive modification of the hydration environment within the pores. Moreover, the crystallographic distribution of Tl⁺ differs from that of the original K⁺ cations, suggesting a specific site preference during the uptake process. Batch experiments reveal rapid uptake kinetics, with equilibrium reached within minutes, and high removal efficiency up to 99.5%. The adsorption behaviour is well described by the Langmuir model, with a maximum adsorption capacity of 631 mg g⁻¹. These findings highlight the coupling between ion exchange and structural flexibility in K-L zeolite and support its potential application for efficient thallium removal from contaminated water. Full article

This study investigates the effect of nano-zeolite and lime on the resistance of reconstituted soil using an integrated experimental and explainable machine learning framework. Soil samples were prepared with varying proportions of nano-zeolite, lime, and fines, and cured under controlled temperature and time conditions. Soil resistance (q) was measured to evaluate the mechanical performance of each mixture. Eight machine learning models, including artificial neural networks (ANN), random forest (RF), random tree (RT), random committee–random tree (RC-RT), M5Rules, KStar, RBFS, and additive regression–decision stump (AR-DS), were developed using Weka 3.8.6 to predict soil resistance based on the input parameters. Model performance was assessed using SSE, MAE, MSE, RMSE, Error %, Accuracy %, R², correlation coefficient, Willmott Index, Nash–Sutcliffe Efficiency, Kling–Gupta Efficiency, and SMAPE. ANN and RF achieved superior accuracy (R² ≥ 0.98) with minimal prediction error, effectively capturing the nonlinear interactions between stabilizer content, curing time, and environmental conditions. Sensitivity analyses using the analysis index and SHAP values revealed that nano-zeolite, lime, and curing time were the dominant factors influencing soil resistance, while fines content and curing temperature had secondary effects. The results demonstrate that nano-zeolite and lime significantly enhance soil resistance and that explainable machine learning models can reliably predict and interpret soil performance, providing a data-driven framework for optimized soil stabilization in geotechnical engineering applications. Full article

In the Arabian Gulf region, saltwater desalination is considered to be a significant process in producing clean water. This paper presents a sustainable, combined process for upgrading a Doha reverse osmosis (RO) plant in Kuwait. A pilot-scale microbial desalination cell (MDC) stack is proposed as a pre-treatment unit prior to the RO process in order to improve plant performance. A cost–benefit analysis is conducted for the combined system to emphasize the significance of the MDC–RO process. In RO, the expected energy consumption is 2.6–13 kWh per m³ of desalinated water, whereas using MDC can reduce this to about 0.52–5.3 kWh/m³. Moreover, this new technology using catalytic MDCs can help in improving electric current production and reducing the amount of rejected brine and membrane fouling in the RO process. The electric current is improved by reducing MDCs’ internal resistance using a reduced graphene oxide/polyaniline composite-coated stainless steel mesh cathode electrode. Layer-by-layer electro-deposition can be applied to achieve these coatings. An intermediate zeolite filter is proposed to mitigate RO membrane fouling. The combined system’s natural zeolite-membrane filter improves water purification. In this study, we assessed the combined MDC–RO process for upgrading the Doha plant’s performance in terms of quality, cost, and time. The suggested catalytic MDC, using efficient, low-cost materials as cathode electrodes with an equivalent daily cost of 0.01 USD/m³ and a desalination efficiency of about 40%, acts as an alternative to high-cost platinum metal electrodes. The results also indicate that the equivalent daily cost of energy consumption using the MDC process is about 0.03 USD/m³, whereas the investment cost is about 0.4 USD/m³ daily for one year of cell operation. Full article

Essential oils (EOs) are widely studied as natural antimicrobial and antioxidant agents in food systems. However, their high volatility, low water solubility, instability, phytotoxicity, and strong aroma often limit their consistent applicability for food preservation. This review critically examines the literature and synthesizes current essential oil stabilization and delivery strategies in food systems, integrated with a bibliometric analysis of Scopus-indexed literature published before June 2025. The bibliometric findings showed an expanding research field, supported by 543 authors and 54 journals, revealing the disciplinary diversity of research on essential oil-based preservation systems. In addition, the review highlights a significant focus of studies on nanoemulsions, encapsulation, and active packaging in essential oil applications. Interestingly, the study also reveals the emergence of non-contact, or vapor-phase, technologies with improved release management. Furthermore, the review shows that essential oils’ functionality depends not only on major bioactive compounds but also on chemical class, oxidative sensitivity, release behavior, interactions with the food matrix, and the delivery platform. Mechanistically, stabilization technologies such as emulsions, encapsulation, and coatings/films can improve the protection, dispersion, and release of essential oils; however, their effectiveness strongly relies on formulation variables, matrix composition, and the regulatory framework. Emerging platforms such as nanofibers, zeolites, and metal–organic frameworks offer promising routes for vapor-phase or non-contact delivery systems, ensuring improved release control, functionality, and sensory quality, but may be limited by their scalability and production cost. However, a major research gap identified by this review is the imbalance between extensive “in vitro” studies and limited studies on real food matrices, which impedes understanding of the impacts of food matrices and packaging materials on essential oil release kinetics, antimicrobial efficacy, and sensory quality. Therefore, future research should integrate real-food applications, consumer acceptability, shelf-life performance, release-kinetic modeling, and techno-economic analysis to advance essential-oil-based technologies in food systems. Full article

Background: Conventional and refractory wounds frequently remain in a prolonged inflammatory phase associated with excessive reactive oxygen species (ROS) accumulation and disruption of endogenous electrical cues. Methods: A multifunctional nanocomposite hydrogel was fabricated via an amidation condensation reaction, utilizing 3-amino-4-methoxybenzoic acid (AMB)-modified carboxymethyl chitosan (PAMB-CMCS) and decellularized extracellular matrix (dECM) as macromolecular networks, integrated with Astragaloside IV-Loaded Polydopamine/Zeolitic Imidazolate Framework-8 (AS@PDA/ZIF-8) nanoparticles. Results: The hydrogel provided a biomechanically supportive scaffold with compressive strength of 27.24 ± 1.9 kPa and breaking strength of 28.2 ± 2.8 kPa and exhibited electrical conductivity of 29.84 mS/cm, ROS-scavenging activity, and near-infrared (NIR)-responsive photothermal behavior reaching 62.55 °C. The integrated PDA@ZIF-8 nanoplatform further contributed to antibacterial performance and localized AS release, thereby improving the wound microenvironment and accelerating full-thickness cutaneous defect repair. Conclusions: This macromolecule-based composite hydrogel offers a promising therapeutic strategy for complex wound management. Full article

An efficient catalyst for the reaction of ethanol–acetaldehyde into 1,3-butadiene (EATB) is prepared through the grafting of zirconia into a zeolite Beta lattice. The grafting is achieved through the dealumination of a zeolite framework by acid treatment followed by zirconia impregnation, leading to the substitution of aluminum in the zeolite framework by zirconia. The catalyst with zirconia grafted into the zeolite framework promotes desirable catalyst properties like high zirconium dispersion, stability, and the close proximity of Lewis acid, Bronsted acid, and medium basic sites. The phase, the coordination of zirconia, the location of the active center and the cooperative synergism were elucidated through various characterization techniques, including X-ray diffraction, Raman spectroscopy, N₂ adsorption, UV–vis spectroscopy, XPS, ²⁹Si MAS NMR, NH₃-TPD, Py-IR, CO-IR and CO₂-TPD. The catalytic results show that a suitable phase and content of zirconia were needed to improve the ethanol–acetaldehyde conversion, butadiene selectivity and catalyst stability. Among the catalysts, m+t-ZrO_x-Beta-H₂O-9020 (m = monoclinic, t = tetragonal ZrO₂ phase) achieved the best butadiene selectivity of 82–73% at the conversion of 100–66%, run over 200 h. The results allow us to propose a Lewis acid–medium basic pairing for the Si–O–Zr–O–Si group, where the adjacent Si-OH is the active center for reactions. Full article

The selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) is of great importance for the production of dyes, pesticides, and pharmaceuticals, but it is often plagued by the undesired hydrodechlorination side reaction. In this work, we report a PtNi bimetallic catalyst supported on nano-sized LTL zeolite (PtNi/Nano-HL) for the selective hydrogenation of p-chloronitrobenzene under mild conditions. The catalyst was systematically characterized by X-ray diffraction (XRD), nitrogen sorption (N₂ sorption), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and ammonia temperature-programmed desorption (NH₃-TPD). The results reveal abundant oxygen vacancies (RIR = 0.73) and an optimized distribution of medium–strong acid sites on the catalyst surface, as well as electronic interaction between Pt and Ni, which collectively enhance the catalytic performance. Remarkably, the PtNi/Nano-HL catalyst achieves 100% conversion and over 99% selectivity for p-chloroaniline under ambient conditions (30 °C, 0.1 MPa H₂) using ethanol as a solvent. Even after 24 recycling runs, it retains 100% conversion and >93% selectivity, demonstrating excellent stability. Moreover, the catalyst requires an extremely low Pt loading (only 0.11 wt%) and exhibits good substrate universality for various substituted nitroarenes. This work provides a promising strategy for designing high-performance bimetallic catalysts on nano-zeolite supports for the selective hydrogenation of halonitrobenzenes. 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

The integration of artificial intelligence (AI), machine learning (ML), and computational modeling with experimental catalysis is reshaping materials design and chemical process development. Tailored heterogeneous catalysts including supported metals, zeolites, defect-engineered materials, and multi-element systems exhibit enhanced activity, selectivity, and stability through engineered active sites and porosity. AI and ML approaches enable predictive modeling, high-throughput screening, mechanistic insight, and rational catalyst design by linking synthesis conditions, structural features, and performance metrics across scales. Applications span CO₂ conversion, methane reforming, hydrogen production, polymer recycling, and photocatalysis, with platforms such as PHOTOREAC, QMOF, and PhotoCatDB facilitating the translation from laboratory experiments to reactor-scale processes. Hybrid strategies that combine mechanistic understanding with data-driven models improve interpretability, predictive accuracy, and process optimization. These advances underscore a paradigm shift toward data-driven catalysis, accelerating discovery, supporting sustainable chemical technologies, and emphasizing the role of human expertise in guiding responsible AI deployment. Full article

Chemical recycling of polyolefins is essential to mitigate plastic waste accumulation and promote circular economy strategies. Among the various chemical recycling pathways, catalytic pyrolysis, tandem catalyst systems, ethenolysis, hydrocracking, and hydrogenolysis have emerged as promising approaches for converting polyolefin waste into valuable hydrocarbons, including gaseous, liquid, and solid products. This review provides a comprehensive survey of recent research on these methodologies, with a particular focus on the production of light gaseous hydrocarbons (C2–C4), bypassing the intermediate pyrolysis oil stage, potentially reducing contamination issues and simplifying downstream processing. In contrast to conventional reviews focused primarily on liquid products, the present work emphasizes strategies for enhancing the selective production of light gaseous hydrocarbons due to their potential application in circular monomer manufacturing. Aspects such as catalyst selection, reaction conditions, and product distribution are analyzed. Additionally, the current Technology Readiness Level (TRL) of the studied processes and their relative advantages, limitations, and perspectives for industrial applications are discussed. The analysis highlights catalytic pyrolysis with zeolites as the most mature and scalable technological alternative for manufacture of light compounds directly from polyolefin waste, while tandem catalyst systems and ethenolysis constitute promising but still emerging alternatives for targeted gas production. Full article

This study experimentally evaluates hydrogen recovery from synthetic syngas and water–gas shift (WGS) syngas using a laboratory-scale pressure swing adsorption (PSA) unit equipped with layered activated carbon/zeolite 5A beds. Breakthrough tests were first performed to determine adsorption-time limits and identify the critical impurity controlling product quality. Continuous PSA experiments were then carried out using two cycle configurations: a two-bed Berlin-type cycle and a four-bed Linde-type cycle. CO was the first impurity breakthrough experimentally detected and it therefore defined the practical adsorption-time cut-off, whereas CO₂ exhibited the strongest retention, especially in beds with an increased activated-carbon fraction. The results showed a clear trade-off between purity and recovery. The four-bed Linde-type cycle provided a wider operating window than the two-bed Berlin-type cycle, owing to pressure equalization and product-purge steps. The best overall performance was obtained for WGS syngas with the 1.6:1 AC:zeolite bed, reaching 99.5 vol.% H₂ at 84% recovery and maintaining 99.2 vol.% H₂ at 86% recovery. The tail gas was enriched in CO₂ up to approximately 72 vol.%, indicating potential for integration with downstream CO₂ management. Full article