Search Results (4,166)

Carbon dioxide is naturally present in the Earth’s atmosphere and plays a role in regulating and balancing the planet’s temperature. However, due to various human activities, the amount of carbon dioxide is increasing beyond safe limits, disrupting the Earth’s natural temperature regulation system. Today, CO₂ is the most prevalent greenhouse gas; as its concentration rises, significant climate change occurs. Therefore, there is a need to utilize anthropogenically released carbon dioxide in valuable fuels, such as formic acid (HCOOH). Single-atom catalysts are widely used, where a single metal atom is anchored on a surface to catalyze chemical reactions. In this study, we investigated the potential of Cu@Phosphorene as a single-atom catalyst (SAC) for CO₂ reduction using quantum chemical calculations. All computations for Cu@Phosphorene were performed using density functional theory (DFT). Mechanistic studies were conducted for both bimolecular and termolecular pathways. The bimolecular mechanism involves one CO₂ and one H₂ molecule adsorbing on the surface, while the termolecular mechanism involves two CO₂ molecules adsorbing first, followed by H₂. Results indicate that the termolecular mechanism is preferred for formic acid formation due to its lower activation energy. Further analysis included charge transfer assessment via NBO, and interactions between the substrate, phosphorene, and the Cu atom were confirmed using quantum theory of atoms in molecules (QTAIM) and non-covalent interactions (NCI) analysis. Ab initio molecular dynamics (AIMD) calculations examined the temperature stability of the catalytic complex. Overall, Cu@Phosphorene appears to be an effective catalyst for converting CO₂ to formic acid and remains stable at higher temperatures, supporting efforts to mitigate climate change. Full article

Supports used in heterogeneous metallic catalysts serve as a structural skeleton across which metallic nanoparticles are dispersed, but specific properties of the supports may also determine the behavior of these nanoparticles in catalytic processes. For example, it is known that among various properties of crystalline alkaline earth metal oxides serving as supports, the ability of their surface sites to donate electrons, that is their basicity, has an influence on the characteristics of the adsorbed metal. In the present work, the influence of MeO (Me = Mg, Ca, and Sr) basicity on the adsorption of Pb on the (100) surface of MeO crystals is studied by means of a dispersion-corrected density functional theory (DFT-D) computational method. The DFT-D calculations have characterized essential structural parameters, energetics, and the distribution of the electron charge for the Pb atoms and Pb dimers adsorbed at the regular O²⁻ and defective F_s centers of MeO(100). It has been observed that an increase in the basicity of MeO(100) in the sequence MgO < CaO < SrO results in a more energetically favorable effect of Pb adsorption, a stronger interaction between Pb and the surface, and a greater amount of electron charge acquired by the adsorbed Pb atoms and dimers. These findings contribute to a better understanding of how support basicity may modulate certain characteristics of MeO-supported metallic catalysts containing Pb as an additive. From a computational viewpoint, this work shows that the inclusion of spin–orbit relativistic correction in the DFT-D calculations leads to a significant reduction in the strength of the interaction between Pb and MeO(100), but it does not change the aforementioned trend in the strength of this interaction as a function of support basicity. Full article

The efficient removal of elemental mercury (Hg⁰) from coal-fired flue gas is a critical challenge in environmental governance. This study proposes utilizing waste fluid catalytic cracking catalyst (WFCC) as the potential support for Hg⁰ catalytic oxidation. After activation (AFCC) via calcination decarbonization, a composite support (AFCC-PG) was fabricated using palygorskite (PG) as a binder. Subsequently, VO_x was loaded onto the support to form the VO_x/AFCC-PG catalyst for Hg⁰ removal. Experimental results demonstrate that the VO_x/AFCC-PG catalyst achieves >95% Hg⁰ removal efficiency under simulated flue gas conditions (150 °C, GHSV = 6000 h⁻¹) while maintaining excellent stability over 60 h. Furthermore, Hg-TPD and XPS analyses indicate that the synergistic lattice oxygen oxidation–adsorption established between VO_x and the AFCC-PG plays a key role in efficient Hg⁰ removal. This study proposes a cost-effective strategy for both the resource utilization of waste catalysts and the control of mercury pollution in coal-fired flue gas. Full article

Dry reforming of methane is an advantageous technique to produce syngas by using greenhouse gases like CO₂ and CH₄. This study investigated the stability, catalytic effectiveness, and physicochemical characteristics of mono- and trimetallic catalysts based on Ni and supported on γ-Al₂O₃. Adding Co and Fe has been found to modify the structure and surface through the characterizations, including XRD, SEM, TEM, BET, H₂-TPR, and XPS methods. Compared to the monometallic Ni catalyst, the trimetallic catalysts exhibited improved alloy formation, reduced particle size, increased metal dispersion, and enhanced surface area and pore structures. The 10% Ni, 2.5% Co, and 2.5% Fe-Al₂O₃ catalyst exhibits higher CH₄ conversion, surpassing 75%, and also CO₂ conversion around 85% at 700 °C, compared to 15% Ni-Al₂O₃, which showed CH₄ conversion of about 65% and CO₂ conversion of 70%. It also showed comparatively good stability in 24 h testing performed at 700 °C. According to the findings of the research on trimetallic catalysts, their capacity to improve dry reforming of methane (DRM) performance may be attributed to increased stability, which is a crucial challenge in the production of sustainable syngas, as well as higher activity and lower deactivation. Full article

The urgent need to address the climate crisis demands a swift transition from fossil fuels to renewable energy. Clean hydrogen, produced through ethanol steam reforming (ESR), offers a viable solution. Traditional ESR operates at atmospheric pressure, requiring costly separation and compression of hydrogen. High-pressure ESR, however, improves hydrogen purification, streamlines processes like pressure swing adsorption, and reduces operational costs while enhancing energy efficiency. High-pressure ESR also enables compact reactor designs, minimizing equipment size and land use by compressing reactants into smaller volumes. This study evaluates two nickel-based commercial catalysts, AR-401 and NGPR-2, under high-pressure ESR conditions. Key parameters, including reaction temperature, steam-to-ethanol ratio, and weight hourly space velocity, were optimized. At 30 bars, 700 °C, and a steam-to-ethanol ratio of 9, both catalysts demonstrated complete ethanol conversion, with hydrogen selectivity of 65–70% and yields of 4–4.5 moles of H₂ per mole of ethanol. Raising the temperature to 850 °C improved hydrogen selectivity to 74% and yielded 5.2 moles of H₂ per mole. High-pressure ESR using renewable ethanol provides a scalable, efficient pathway for hydrogen production, supporting sustainable energy solutions. Full article

This work presents an integrated experimental and machine learning study on the fire performance of sisal fiber-reinforced polyester composites treated with magnesium hydroxide as a flame retardant. A total of 43 small-scale fire resistance tests were conducted in a custom-built gas-fired furnace following ISO 834 and NCh935/2 standards. Key parameters—including fiber content, flame retardant proportion, catalyst, and accelerator—were correlated with burn time and mass loss. Linear regression revealed negligible to weak correlations, while nonlinear models (Random Forest, Support Vector Regression, and Deep Neural Network) showed improved predictive capacity. The Deep Neural Network achieved the best performance (MSE = 0.061, R² = 0.334). Experimental results confirm that magnesium hydroxide substantially increases burn time, whereas sisal fiber content alone has a minimal effect on fire resistance. This study highlights an affordable strategy for enhancing the fire safety of bio-based composites and demonstrates the potential of machine learning to optimize material formulations. Future research should expand the dataset and validate the models through standardized large-scale fire tests. However, the findings are limited to small-scale fire resistance tests under controlled laboratory conditions and should not be generalized to full-scale structural applications without further validation. Full article

Renewable Energy Communities (RECs) are central to Europe’s strategy for reducing greenhouse gas emissions and advancing a sustainable, decentralized energy system. RECs aim to transform consumers into prosumers—individuals who both produce and consume energy—thereby enhancing energy efficiency, local autonomy, and citizen engagement. This study introduces a novel Geographic Information System (GIS)-based methodology that integrates socio-economic and spatial data to support the design of optimal REC configurations. QGIS 3.40.9 “Batislava” tool is used to simulate site-specific energy distribution scenarios, enabling data-driven planning. By combining a Composite Energy Vulnerability Index (CEVI), Rooftop Solar Potential (RSP), and the distribution of urban gardens (UGs), the approach identifies priority urban zones for intervention. Urban gardens offer multifunctional public spaces that can support renewable infrastructures while fostering local resilience and energy equity. Applied to the city of Rome, the methodology provides a replicable framework to guide REC deployment in vulnerable urban contexts. The results demonstrate that 11 of the 18 highest-priority areas already host urban gardens, highlighting their potential as catalysts for collective PV systems and social engagement. The proposed model advances sustainability objectives by integrating environmental, social, and spatial dimensions—positioning RECs and urban agriculture as synergistic tools for inclusive energy transition and climate change mitigation. Full article

This study presents a comparative investigation of 3Ni2Ce/Al catalysts synthesized via different methods dry impregnation (DI), capillary impregnation (CI), and solution combustion synthesis (SC) for the complete oxidation of methane. The aim was to elucidate the influence of the preparation method on the catalytic activity and reduction behavior of the catalysts. Among the samples tested, the catalyst prepared by the solution combustion method exhibited the highest activity: at 500 °C, the methane conversion reached 82%, compared to 43% and 41% for the 3Ni2Ce/Al (CI) and 3Ni2Ce/Al (DI) prepared catalysts, respectively. At 550 °C, the 3Ni2Ce/Al (SC) catalyst achieved 99% conversion, surpassing the 3Ni2Ce/Al (CI) (72.5%) and 3Ni2Ce/Al (DI) (95%) analogs. Hydrogen temperature-programmed reduction (H₂-TPR) analysis revealed that the 3Ni2Ce/Al (SC) catalyst exhibited enhanced hydrogen uptake in the range of 450–850 °C, indicating the presence of more easily reducible NiO species interacting with CeO₂ and the alumina support. Scanning electron microscopy (SEM) further confirmed a more uniform distribution of the active phase on the surface of the 3Ni2Ce/Al (SC) catalyst in comparison to the impregnated samples. Overall, the findings demonstrate that the preparation method has a significant impact on the development of a redox-active catalyst structure. The superior performance of the SC-derived catalyst in methane oxidation is attributed to its improved reducibility and homogenous morphology, making it a promising candidate for high-temperature catalytic applications. Full article

The selective dehydrogenation of ethanol to acetaldehyde is an efficient alternative to biomass valorization. Herein, a series of Cu catalysts supported on Silicalite-1 zeolites with tunable contents of surface silanols and the same Cu loading of 3 wt% were synthesized by an impregnation method. The parent Silicalite-1 supports and as-synthesized Cu/S-1 catalysts were characterized by N₂ adsorption, XRD, SEM, TEM, TGA, DRIFT, ²⁹Si MAS NMR, XPS, and TPR. The Cu dispersion and Cu species distribution of Cu/S-1 catalysts can be modulated by engineering the amount of silanol groups on the support. More silanols present on the surfaces of parent Silicalite-1 supports can promote the Cu dispersion, and lead to a higher Cu⁺/Cu⁰ molar ratio arising from strong interfacial interaction between Cu species and silanols on the Silicalite-1 support via the formation of Si-O-Cu bonds. Thus, higher catalytic activity is achieved. Full article

This short review provides a focused overview of recent advances in catalytic systems for water purification, with particular attention to photocatalysis, Fenton-like processes, and biocatalysis. While not intended as a comprehensive survey, this review is grounded primarily in recent work from our research group, supported by comparisons with relevant studies from the broader literature. Emphasis is placed on the role of graphene-based materials, particularly aerogels, hydrogels, and xerogels, as functional platforms for catalytic nanoparticles inclusion and enzyme immobilization. This review aims to highlight key insights, practical limitations, and emerging strategies to improve catalyst reusability, stability, and scalability for real-world water treatment applications. Full article

Against the backdrop of increasing global warming, exploring sustainable pathways to mitigate the greenhouse effect has become a central issue for the ecological and energy future. Photocatalytic reduction of CO₂ technology shows a broad application prospect due to its ability to directly convert CO₂ into high-value-added hydrocarbon fuels and to use solar energy, a clean energy source, to drive the reaction. However, traditional semiconductor catalysts generally suffer from insufficient activity and poor product selectivity in the actual reaction, which cannot meet the requirements of practical applications. In recent years, sulfur vacancy, as an effective material modulation strategy, has demonstrated a remarkable role in enhancing photocatalytic performance. This paper reviews a series of research reports on sulfur vacancies in recent years, introduces the methods of preparing sulfur vacancies, and summarizes the commonly used characterization methods of sulfur vacancies. Finally, the mechanism of introducing sulfur vacancies to promote CO₂ reduction is discussed, which improves the photocatalytic activity and selectivity by enhancing light absorption, facilitating carrier separation, improving CO₂ adsorption and activation, and promoting the stability of reaction intermediates. This review aims to provide theoretical support for an in-depth understanding of the role of sulfur vacancies in photocatalytic systems and to provide a view on the future direction and potential challenges of sulfur vacancies. Full article

Background: Surgical resection remains central to the curative treatment of locally advanced gastric cancer (GC), yet global variability persists in defining resectability, particularly in complex scenarios such as multivisceral invasion, positive peritoneal cytology (CY1), or oligometastatic disease. The Intercontinental Criteria of Resectability for Gastric Cancer (ICRGC) project was developed to address this gap by combining expert surgical input with artificial intelligence (AI)-based reasoning. Methods: A two-stage prospective survey was conducted during the 2024 European Gastric Cancer Association (EGCA) meeting. Fifty-eight surgical oncologists completed a 36-item questionnaire on resectability, strategy, and quality metrics. Subsequently, they reviewed AI-generated responses based on current clinical guidelines and completed a second round. Concordance between human and AI responses was classified as full, partial, or discordant, and changes in surgeon opinions were statistically analyzed. Results: Substantial agreement was observed in evidence-based domains. Seventy-nine percent of surgeons agreed with AI on distinguishing technical from oncological resectability. In cT4b cases, 61% supported restricting multivisceral resection to high-volume centers. Similar alignment was found in CY1 (54%) and N3 nodal disease (63%). Partial concordance appeared in areas requiring individualized judgment, such as peritonectomy or bulky-N disease. After AI exposure, surgeon responses shifted toward guideline-consistent decisions, including increased support for cytoreductive surgery only when CC0/1 was achievable and stricter classification of R2 resections as unresectable. Following AI exposure, 27.1% of surgeons changed at least one answer in alignment with AI recommendations, with statistically significant shifts observed in items related to surgical margin definition (p = 0.015), anatomical resection criteria (p < 0.05), and hospital stay benchmarks (p = 0.031). Conclusions: The ICRGC study demonstrates that AI-driven consensus modeling can replicate expert reasoning in complex surgical oncology and serve as a catalyst for harmonizing global practice. These findings suggest that AI-supported consensus modeling may complement expert surgical reasoning and promote greater consistency in decision-making, particularly in controversial or ambiguous cases. Full article

The conversion of cellulosic biomass into renewable chemicals can serve as a sustainable resource for levulinic acid (LA) production. LA yield is significantly influenced by reaction temperature, reaction time, substrate concentration, active sites, catalyst amount, catalyst porosity, and durability. Beyond the features of the catalyst, such as acidity, porosity, functional groups, and catalytic efficiency, the contact between the solid acid catalyst and the solid substrate is of vital importance. Solid-based catalysts show remarkable catalytic activity for cellulose-derived LA production, thanks to the incorporation of functional groups. For a solid carbon-based catalyst to be effective, a synergistic interaction between the binding domain (functional groups capable of anchoring cellulose to the catalyst surface, such as chloride groups, COOH, or OH) and the hydrolysis domain (due to their ability to cleave glycosidic bonds, such as in SO₃H) is essential. As a relatively new market niche, carbon-based catalyst supports are projected to reach a market value of nearly USD 125 million by 2030. This review aims to highlight the advantages and limitations of carbon-based materials compared to conventional catalysts (including metal oxides or supported noble metals, among others) in features like catalytic activity, thermal stability, and cost, examine recent advancements in catalyst development, and identify key challenges and future research directions to enable more efficient, sustainable, and scalable processes for LA production. The novelty of this review lies in its focus on carbon-based catalysts for LA production, emphasizing their physical and chemical characteristics. Full article

Geospatial sensing and data-driven technologies (GSDDTs) are playing an increasingly important role in transforming (agro)forestry practices across the Western Balkans 6 region (WB6). This review critically examines the current state of GSDDT application in six WB countries (also known as the WB6 group)—Albania, Bosnia and Herzegovina, Kosovo*, Montenegro, North Macedonia, and Serbia—with a focus on their contributions to sustainable (agro)forest management. The analysis explores the use of unmanned aerial vehicles (UAVs), light detection and ranging (LiDAR), geographic information systems (GIS), and satellite imagery in (agro)forest monitoring, biodiversity assessment, landscape restoration, and the promotion of circular economy models. Drawing on 25 identified case studies across WB6—for example, ALFIS, Forest Beyond Borders, ForestConnect, Kuklica Geosite Survey, CREDIT Vibes, and Project O₂ (including drone-assisted reforestation in Kosovo*)—this review highlights both technological advancements and systemic limitations. Key barriers to effective GSDDT deployment across WB6 in the (agro)forestry sector and its cross-border cooperation initiatives include fragmented legal frameworks, limited technical expertise, weak institutional coordination, and reliance on short-term donor funding. In addition to mapping current practices, this paper offers a comparative overview of UAV regulations across the WB6 region and identifies six major challenges influencing the adoption and scaling of GSDDTs. To address these, it proposes targeted policy interventions, such as establishing national LiDAR inventories, harmonizing UAV legislation, developing national GSDDT strategies, and creating dedicated GSDDT units within forestry agencies. This review also underscores how GSDDTs contribute to compliance with seven European Union (EU) acquis chapters, how they support eight Sustainable Development Goals (SDGs) and their sixteen targets, and how they advance several EU Green Agenda objectives. Strengthening institutional capacities, promoting legal alignment, and enabling cross-border data interoperability are essential for integrating GSDDTs into national (agro)forest policies and research agendas. This review underscores GSDDTs’ untapped potential in forest genetic monitoring and landscape restoration, advocating for their institutional integration as catalysts for evidence-based policy and ecological resilience in WB6 (agro)forestry systems. Full article

Biomass gasification represents a pivotal technology for sustainable energy and chemical production, yet its efficiency and product quality are critically dependent on catalyst performance. This comprehensive review systematically synthesizes recent advancements in catalyst design, mechanistic insights, and process integration in biomass gasification. Firstly, it details the development and performance of catalysts in diverse categories, including metal-based catalysts, Ca-based catalysts, natural mineral catalysts, composite/supported catalysts, and emerging waste-derived catalysts. Secondly, this review delves into the fundamental catalytic reaction mechanisms governing key processes such as tar cracking/reforming, water–gas shift, and methane reforming. It further explores sophisticated strategies for catalyst structure optimization, focusing on pore structure/surface area control, strong metal–support interactions (SMSIs), alloying effects, nanodispersion, and crystal phase design. The critical challenges of catalyst deactivation mechanisms and the corresponding activation, regeneration strategies, and post-regeneration performance evaluation are thoroughly discussed. Thirdly, this review addresses the crucial integration of zero CO₂ emission concepts, covering in situ CO₂ adsorption/conversion, carbon capture and storage (CCS) integration, catalytic CO₂ reduction/valorization, multi-energy system synergy, and environmental impact/life cycle analysis (LCA). By synthesizing cutting-edge research, this review identifies key knowledge gaps and outlines future research directions towards designing robust, cost-effective, and environmentally benign catalysts for next-generation, carbon-neutral biomass gasification systems. Full article