Search Results (715)

Plastic streams dominated by polyethylene (PE) including PE HD/MD (High Density/Medium Density) and PE LD/LLD (Low Density/Linear Low Density), polypropylene (PP), and polyvinyl chloride (PVC) across Europe demand a design framework that links synthesis with end of life reactivity, supporting circular economic goals and European Union waste management targets. This work integrates polymerization derived chain architecture and depolymerization mechanisms to guide selective valorization of commercial plastic wastes in the European context. Catalytic topologies such as Bronsted or Lewis acidity, framework aluminum siting, micro and mesoporosity, initiators, and strategies for process termination are evaluated under relevant variables including temperature, heating rate, vapor residence time, and pressure as encountered in industrial practice throughout Europe. The analysis demonstrates that polymer chain architecture constrains reaction pathways and attainable product profiles, while additives, catalyst residues, and contaminants in real waste streams can shift radical populations and observed selectivity under otherwise similar operating windows. For example, strong Bronsted acidity and shape selective micropores favor the formation of C₂ to C₄ olefins and Benzene, Toluene, and Xylene (BTX) aromatics, while weaker acidity and hierarchical porosity help preserve chain length, resulting in paraffinic oils and waxes. Increasing mesopore content shortens contact times and limits undesired secondary cracking. The use of suitable initiators lowers the energy threshold and broadens processing options, whereas diffusion management and surface passivation help reduce catalyst deactivation. In the case of PVC, continuous hydrogen chloride removal and the use of basic or redox co catalysts or ionic liquids reduce the dehydrochlorination temperature and improve fraction purity. Staged dechlorination followed by subsequent residue cracking is essential to obtain high quality output and prevent the release of harmful by products within European Union approved processes. Framing process design as a sequence that connects chain architecture, degradation chemistry, and operating windows supports mechanistically informed selection of catalysts, severity, and residence time, while recognizing that reported selectivity varies strongly with reactor configuration and feed heterogeneity and that focused comparative studies are required to validate quantitative structure to selectivity links. In European post consumer sorting chains, PS and PC are frequently handled as separate fractions or appear in residues with distinct processing routes, therefore they are not included in the polymer set analyzed here. Polystyrene and polycarbonate are outside the scope of this review because they are commonly handled as separate fractions and are typically optimized toward different product slates than the gas, oil, and wax focused pathways emphasized here. Full article

Coal mining releases large amounts of low-concentration methane. Its global warming potential per unit mass is about 21 times that of carbon dioxide. Approximately 13.5 billion cubic meters are directly emitted each year without utilization. This results in both energy waste and environmental issues. Technologies for utilizing methane with concentrations ≥8% are already mature. However, stable treatment of low-concentration methane remains challenging. Issues include unsustainable combustion and interference from impurities. This review provides a comprehensive overview of recent advances in the catalytic combustion of low-concentration methane, systematically examining reaction mechanisms, catalyst development (including noble metal catalysts, non-noble metal catalysts, and the role of supports), combustion methods, and numerical simulations. The analysis reveals that current research faces challenges such as mismatched catalyst performance under real conditions, insufficient combustion system stability, and gaps between numerical simulations and practice. Future work should focus on molecular-level catalyst design, integrated system innovation, and enhancing simulation predictive capabilities, thereby strengthening the link between basic research and engineering applications. This will promote the industrialization of efficient low-concentration methane utilization technologies, ultimately achieving both energy recovery and greenhouse gas emission reduction. Full article

Defect engineering has been demonstrated to be an attractive strategy to improve the catalytic performance of g−C₃N₄−based catalysts. Herein, three graphite carbon nitrides (labeled “CN”) containing a certain number of cyano groups and nitrogen vacancies are prepared successfully by calcination of the dicyandiamide−based CN in the presence of KOH, and the performances of the corresponding Pd−based catalysts are evaluated by using the formic acid (FA) dehydrogenation as a probe reaction. The characterizations of X−ray diffraction (XRD), scanning transmission electron microscopy (STEM), X−ray photoelectron spectra (XPS), hydrogen temperature−programmed desorption (H₂−TPD), and hydrogen spillover experiments indicate that the high catalytic activity of Pd/CNK−0.5 is mainly attributed to its high efficient hydrogen spillover, relatively high dispersity of Pd species, and basicity due to the introduction of a proper amount of cyano groups and nitrogen vacancies. The low initial activity of Pd/CNK−0.75 may mainly be ascribed to its low hydrogen spillover ability and the strongly chemisorbed hydrogen on Pd single atoms or small clusters. Full article

Feedstock quality has been proven to be the single variable that most affects fluid catalytic cracking (FCC) unit performance, but catalyst characteristics have also been reported in the literature to have a considerable effect on cracking process performance. How these two main variables of the FCC process complement each other in the search for ways to optimize the performance of the FCC unit is the subject of current research. Twenty-one feedstocks with K_W-characterizing factors ranging from 11.08 to 12.06, Conradson carbon contents ranging from 0.05 to 12.8 wt.%, and nitrogen contents ranging from 800 to 3590 ppm (wt/wt) (basic nitrogen from 172 to 1125 ppm (wt/wt)) were cracked on 21 catalysts with micro-activity between 67% and 76% (wt/wt) in a laboratory-based advanced catalytic evaluation (ACE) unit at a reaction temperature of 527 °C, catalyst–to-oil ratios between 3.5 and 12.0 wt/wt, and a catalyst time on stream of 30 s. Some of the feeds and catalysts tested in the laboratory FCC ACE unit were also examined in a commercial short-contact-time FCC unit resembling a UOP side-by-side design. It was found that conversion can be very well predicted in both the laboratory ACE and the commercial FCC units using multiple linear correlations developed in this work from information about the following feed properties: K_W-characterizing factor, nitrogen content, and micro-activity of the catalyst. The coke on the catalyst that controls the catalyst-to-oil ratio and the regenerator temperature in the commercial FCC unit could be calculated using the correlations developed in this work for the laboratory ACE and commercial FCC units, based on feed characteristics and catalyst micro-activity. Due to the greater slope of the Δ coke/Δ micro-activity dependence observed in the ACE FCC unit, the more active catalysts show weaker results compared to the less active catalysts at a constant coke yield. In contrast, catalysts with higher activity are preferable for operation in the commercial FCC plant because they provide higher conversion at the same coke yield due to the lower slope of the Δ coke/Δ micro-activity relationship. Full article

In the context of green transition and digital transformation, forestry is becoming a strategic area of application of current modern technologies. The Internet of Things (IoT), artificial intelligence (AI), big data analysis (Big Data) and Digital Twins define the basic infrastructure of smart forestry. By connecting sensors, drones and satellites, IoT allows for continuous monitoring of forest ecosystems, risk anticipation and decision optimization in real-time. The purpose of this study is to perform a comprehensive narrative analysis of the relevant scientific literature from the recent period (2020–2025) regarding the application of IoT in forestry, highlighting the conceptual, technological and institutional developments. Based on a selection of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (29 full-text articles), four major axes are analyzed: (A) forest fire detection and prevention; (B) climate-smart forestry and carbon accounting; (C) forest digitalization through the concepts of Forest 4.0, Forest 5.0 and Digital Twins; (D) sustainability and digital forest policies. The results show that IoT is a catalyst for the sustainable transformation of the forest sector, supporting carbon accounting, climate-risk reduction and data-driven governance. The analysis highlights four major developments: the consolidation of IoT–AI architectures, the integration of IoT and remote sensing, the emergence of Forest 4.0/5.0 and Digital Twins and the growing role of governance and data standards. These findings align with the objectives of the EU Forest Strategy 2030 and the European Green Deal. Full article

Catalytic transfer hydrogenation (CTH) provides a practical and sustainable approach for reducing unsaturated compounds, serving as an alternative to high-pressure H₂ in laboratory and fine chemical contexts. This broad reaction class includes asymmetric transfer hydrogenation (ATH), a key strategy in enantioselective synthesis due to its operational simplicity, high stereocontrol, and compatibility with sensitive functional groups. A central variable governing CTH efficiency is the role of bases, which may function as essential activators, co-hydrogen donors, or be entirely absent depending on the catalytic system. This review provides a comparison of base-assisted, base-free, and base-as-co-hydrogen-donor CTH methodologies across diverse metal catalysts and substrates. We highlight how bases such as triethylamine, K₂CO₃, and NaOH facilitate catalyst activation, modulate hydride formation, and tune reactivity and selectivity. The dual function of bases in formic-acid-driven systems is examined alongside synergistic effects observed with mixed-base additives. In contrast, base-free CTH platforms demonstrate how tailored ligand frameworks, metal-ligand cooperativity, and engineered surface basicity can eliminate the need for external additives while maintaining high activity. Through mechanistic analysis and cross-system comparison, this review identifies the key structural, electronic, and environmental factors that differentiate base-assisted from base-free pathways. Emerging trends—including greener hydrogen donors, advanced catalyst architectures, and additive-minimized protocols—are discussed to guide future development of sustainable CTH processes. Full article

Graph neural networks (GNNs) have rapidly matured into a unifying, end-to-end framework for energy-materials discovery. By operating directly on atomistic graphs, modern angle-aware and equivariant architectures achieve formation-energy errors near 10 meV atom⁻¹, sub-0.1 V voltage predictions, and quantum-level force fidelity—enabling nanosecond molecular dynamics at classical cost. In this review, we provide an overview of the basic principles of GNNs, widely used datasets, and state-of-the-art architectures, including multi-GPU training, calibrated ensembles, and multimodal fusion with large language models, followed by a discussion of a wide range of recent applications of GNNs in the rapid screening of battery electrodes, solid electrolytes, perovskites, thermoelectrics, and heterogeneous catalysts. Full article

The selective decomposition of formic acid to hydrogen gas represents a highly promising strategy for sustainable energy production. The influence of solvent effects on the selective decomposition of formic acid into H₂ and CO₂ or H₂O and CO was investigated. A variety of solvents, including polar protic solvents (e.g., water, ethanol, methanol), polar aprotic solvents (e.g., tetrahydrofuran, dimethyl sulfoxide), and ionic liquids, were employed in conjunction with a 5 wt% Pd/C catalyst. The yield of formic acid decomposition and the turnover number (TON) were found to be dependent on the choice of solvent. To elucidate the solvent effects, classical solvent parameters and Kamlet–Taft solvatochromic parameters were studied. The study revealed correlations between the TON and the solubility of hydrogen, Kamlet–Taft parameters (acidity, basicity, and polarity/dipolarity), hydrogen bond donor (HBD) capability, and hydrogen bond acceptor (HBA) capacity. The solvent identity was found to play a dominant role in both the polarity/dipolarity and the catalytic mechanism of formic acid decomposition. Full article

A series of clay–spinel nanocomposites reinforced by tungstophosphoric acid (TPA) were prepared and examined for the esterification of oleic acid. The type of spinel (ZnAl₂O₄ and CuAl₂O₄) and the weight ratio of clay-to-spinel were evaluated. The characterization results revealed that the clay–ZnAl₂O₄ nanocomposite formed better than the clay–CuAl₂O₄, with fewer other phases, such as ZnO or CuO. Moreover, clay–ZnAl₂O₄ showed higher pore volume and pore size, which led to higher conversion of oleic acid to biodiesel. The nanocomposite exhibited a good interaction between the spinel phase and clay, preventing the agglomeration of TPA. Assessing the weight ratio of clay-to-ZnAl₂O₄ (0.5, 1, and 1.5) showed that the same ratio of clay-to-spinel provided higher activity. It can be attributed to its rough surface, which facilitates vortex flow on the catalyst surface, its high pore volume (0.122 cc/g), and pore size (24.6 nm), enabling the diffusion of reactants and the egression of products, as well as its high acidic (453.9 μmol/g) and basic (731.6 μmol/g) properties. The clay–ZnAl₂O₄(1)–TPA with the largest particle size in the range of 10–30 nm converted 81.9% of oleic acid under the conditions of 120 °C, a 12 molar ratio of methanol-to-oleic acid, 4 wt.% of catalyst, and 4 h of reaction time. Due to both acidic and basic properties, along with its good reusability, the clay–ZnAl₂O₄(1)–TPA nanocatalyst can be a suitable catalyst for industrial biodiesel production via esterification and transesterification reactions. Full article

Since the discovery of carbon nanotubes (CNTs), extensive and comprehensive research has been conducted in many areas of materials science. Due to their structural and chemical properties, they can be an important part of electronic devices and structural materials that surround us. In this work, we focused on the preparation and basic analysis of vertically aligned CNTs. An aluminum oxide carrier layer and bimetallic iron–cobalt catalyst layers of different compositions were fabricated on the surface of a silicon substrate using a pulsed laser deposition method. Then, vertically aligned CNTs were grown using a catalytic chemical vapor deposition method based on the thermal decomposition of ethylene. During the experiments, the effect of water vapor and hydrogen gas was investigated on the structure of as-prepared carbon nanotubes. CNT forest samples were characterized by scanning electron microscopy and Raman spectroscopy. One of the most important findings of this research is that the presence of hydrogen gas in the CCVD system is essential, but high-quality vertically aligned CNTs can be produced on silicon substrates even without water vapor. Full article

Amine-functionalized polysiloxanes, due to the presence of amino moieties, can be used for the extraction of toxic metal ions from wastewater, as supports for metallic catalysts, stabilizers for metal nanoparticles, macromolecular biocides, or as self-healing materials. In the present work, we studied poly(hydromethylsiloxane) (PHMS) networks functionalized with three amines: N-allyaniline (Naa), N-allylcyclohexylamine (Nach), and N-allylpiperidine (Nap). They were prepared using two procedures. The first one was a two-step process in which the previously cross-linked PHMS was reacted with the amine. The second, one-step method involved simultaneous PHMS cross-linking and reaction with the amine. FTIR and ²⁹Si MAS-NMR spectroscopic investigations, as well as elemental analysis, allowed us to conclude that the one-step method was more advantageous. It ensured higher PHMS networks functionalization degrees and hindered hydrolysis/condensation of Si-H/SiOH groups side processes, which were related to the basicity of the studied amines and significant in the two-step procedure. Full article

Research has shown that attention plays a crucial role in developing mathematical problem-solving skills, particularly for students who struggle with non-routine tasks. Even basic operations require shifts in attention, underscoring the deep connection between attention and mathematical cognition. Attentional strategies are observable and can be developed with targeted scaffolding. This study aimed to enhance high school students’ attentional engagement in problem-solving through a structured intervention. Over an academic year, twelve struggling students in Grades 11 and 12 participated in three one-on-one sessions with a researcher, receiving focused instruction. These sessions encouraged reflection and attention by using the “CCRSRC” model: Connections (identifying similarity connections among the problems presented); Choice (the student deciding which problem to solve); Reflection (explaining the choice); Solving (an attempt is made); Repetition (repeating steps 1–4 as often as wished); and Choice (to end the repetition and move on). Mason’s theory of shifts of attention was used to examine learners’ attentional development. This article provides a detailed analysis of one intervention case, offering insight into how CCRSRC actions serve as catalysts for fostering learner attention. In addition to describing and characterizing a single case, the article summarizes the attention data of all learners involved in the individual intervention. Full article

The dehydrogenation of cyclohexane is of vital importance for the production of Nylon-6 and Nylon-66, as it enhances atom utilization efficiency. Ca-doped platinum catalysts have been employed in alkane dehydrogenation due to their ability to selectively activate C–H bonds while minimizing C–C bond cleavage. However, owing to their limited selectivity toward cyclohexene, Pt-Ca/Al₂O₃ catalysts have not been widely adopted in the field of partial dehydrogenation to alkenes. In this work, Al₂O₃ supports are fabricated using the direct ink writing (DIW) 3D printing technique, incorporating designed channels. After impregnation and calcination at 550 °C, the distribution of active species, surface acidity, and basicity are optimized, resulting in a cyclohexene yield of 8.9%. The cyclohexene yield and stability of the 3D-printed catalysts are significantly higher than those of the granular catalyst, attributed to enhanced heat and mass transfer performance facilitated by the internal channels. Full article

The increasing atmospheric CO₂ concentration is one of the major environmental challenges, necessitating not only emission reduction but also effective carbon utilization. Non-thermal plasma-catalytic CO₂ conversion offers an efficient pathway under mild conditions by synergistically combining plasma activation with catalytic surface reactions. In this study, mesoporous ceria catalysts were synthesized by different methods and characterized using N₂ adsorption–desorption, SEM, XRD, XPS, CO₂-TPD, and XRF techniques. The materials exhibited distinct textural and electronic properties, including variations in surface area, pore structure, and basicity. Plasma-catalytic CO₂ dissociation experiments were conducted in a dielectric barrier discharge reactor at near-room temperature. Among the synthesized catalysts, Ce(mp)-4 demonstrated the highest CO₂ conversion of 32.3% at a 5 kV input voltage and superior energy efficiency, which can be attributed to its meso-macroporous structure that promotes microdischarge formation and enhances CO₂ adsorption–desorption dynamics. CO was the only product obtained, with near-100% selectivity. Catalyst stability testing showed no deactivation while spent catalyst characterization indicated carbon-containing species. The findings in this study highlight the critical role of tailored pore structure and basic-site distribution in optimizing plasma-catalytic CO₂ dissociation performance, offering a promising strategy for energy-efficient CO₂ utilization. Full article

Biodiesel is an alternative, sustainable, renewable, and environmentally friendly energy source, which has generated interest from the scientific community due to its low toxicity, rapid biodegradability, and zero carbon footprint. Biodiesel is a biofuel produced by the transesterification of triglycerides or the esterification of free fatty acids (FFA). Both reactions require catalysts with numerous active sites (basic, acidic, bifunctional, or enzymatic) for efficient biodiesel production. On the other hand, since the late 1990s, metal–organic frameworks (MOFs) have emerged as a new class of porous materials and have been successfully used in various fields due to their multiple properties. For this reason, MOFs have been used as heterogeneous catalysts or as a platform for designing active sites, thus improving stability and reusability. This literature review presents a comprehensive analysis of using MOFs as heterogeneous catalysts or supports for biodiesel production. The optimal parameters for transesterification/esterification are detailed, such as the alcohol/feedstock molar ratio, catalyst amount, reaction time and temperature, conversion percentage, biodiesel yield, fatty acid and water content, etc. Additionally, novel methodologies such as ultrasound and microwave irradiation for obtaining MOF-based catalysts are described. It is important to note that most studies have shown biodiesel yields >90% and multiple reuse cycles with minimal activity loss. The bibliographic analysis was conducted using the American Chemical Society (ACS) Scifinder^® database, the Elsevier B.V. Scopus^® database, and the Clarivate Analytics Web of Science^® database, under the institutional license of the Universidad Veracruzana. Keywords were searched for each section, generally limiting the document type to “reviews” and “journals,” and the language to English, and published between 2000 and 2025. Full article