Search Results (401)

This study presents a comprehensive morphological and structural analysis of carbon materials produced via simple thermal methane pyrolysis conducted under laboratory conditions in a quartz reactor without the use of catalysts. The process, carried out at 1000 °C, achieved moderate methane conversion (36.5%), process efficiency (36.1%), and very high selectivity (98.9%) towards hydrogen production, highlighting its potential as a CO₂-free hydrogen generation method. Distinct carbon morphologies were observed depending on the formation areas within the reactor: a predominant flake-like silver carbon formed on reactor walls at temperatures between 600 and 980 °C (accounting for 91% of the solid product) and a minor powdery carbon formed near 980–1000 °C (9% of the solids). The powdery carbon exhibited a high specific surface area (125.3 m²/g), substantial mesoporosity (60%), and porous spherical aggregates, indicating an amorphous structure. In contrast, flake-like carbon demonstrated a low surface area (1.99 m²/g), high structural order confirmed by Raman spectroscopy, and superior thermal stability, making it suitable for advanced applications requiring mechanical robustness. Additionally, polycyclic aromatic hydrocarbons were detected in cooler zones of the reactor, suggesting side reactions in low-temperature areas. The study underscores the impact of temperature zones on carbon structure and properties, emphasizing the importance of precise thermal control to tailor carbon materials for diverse industrial applications while producing clean hydrogen. Full article

This paper provides a systematic review of the latest advancements in metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) for electrocatalytic carbon dioxide reduction. Both materials exhibit high specific surface areas, tunable pore structures, and abundant active sites. MOFs enhance CO₂ conversion efficiency through improved conductivity, optimized stability, and selective regulation—including bimetallic synergy, pulse potential strategies, and tandem catalysis. COFs achieve efficient catalysis through precise design of single or multi-metal active sites, optimization of framework conjugation, and photo/electro-synergistic systems. Both types of materials demonstrate excellent selectivity toward high-value-added products (CO, formic acid, C₂⁺ hydrocarbons), but they still face challenges such as insufficient stability, short operational lifespan, high scaling-up costs, and poor electrolyte compatibility. Future research should integrate in situ characterization with machine learning to deepen mechanistic understanding and advance practical applications. Full article

Indoor air pollution has become a significant concern, contributing to the decline in air quality through the presence of gaseous pollutants and particulate matter, especially under poor ventilation. Hospitals, functioning as non-industrial microenvironments, particularly in Thailand, face challenges due to insufficient and incomplete databases for effective air quality management. Within these environments, patients with heightened sensitivity, along with hospital staff who are predominantly exposed indoors, face increased risk of exposure to indoor air pollutants. This study aimed to review current evidence on VOCs in hospital settings in Thailand, identifying their sources, concentrations, and health impacts. It also aimed to provide recommendations for improved air quality monitoring and management. The review included studies published between 2008 and 2023 in English or Thai. Studies were selected based on relevance to VOCs in hospital environments, while excluding those lacking sufficient data or methodological rigor. Literature searches were conducted using Google Scholar, ScienceDirect, Scopus, and PubMed. Results from international studies were also considered to address gaps. Data extraction focused on VOC sources, concentrations, measurement methods, and associated health impacts. Results were synthesized into six thematic categories: characterization, health effects, control measures, etiological studies, monitoring systems, and comparative studies. The review identified 87 relevant studies. VOC exposure was associated with several adverse health impacts resulting from short- and long-term exposures, leading to an increased risk of cancer. Identified sources of VOC emissions within hospitals encompass anesthetic gases, sterilization processes, pharmaceuticals, laboratory chemicals, patient care, and household products, as well as building materials and furnishings. Commonly encountered VOCs include alcohols (e.g., ethanol, 2-methyl-2-propanol, isopropanol), ether, isoflurane, nitrous oxide, sevoflurane, chlorine, formaldehyde, aromatic hydrocarbons, limonene, and glutaraldehyde, among those commonly detected in hospital environments. Yet, limited knowledge exists regarding their source contributions, emissions, and concentrations associated with health impacts in Thai hospitals. Full article

Multistage hydraulic fracturing significantly increased oil and gas production in the past two decades. After drilling, fracturing fluids are pumped into the formation to create fractures that provide pathways to the hydrocarbon. These fluids are usually viscous to provide the mechanical power to frack the formation and carry the proppants, which keep the fractures open. After fracking, the viscous gel should be broken to allow the flowback of the fluid to avoid formation damage. The key player in the fracturing fluid system is the polymer, which is responsible for the fluid viscosity of the system. All other additives are added to improve the polymer’s performance under different conditions and reduce formation damage. The formation damage appears as fine migration, residue precipitation, adsorption, and wettability alteration. All of these types are affected by the polymer types and behavior. This paper reviews the polymers used in fracturing treatments, their classifications, preparations, mechanisms, degradation behavior, and interactions with other fracturing fluid additives. It also covers their impact on the formation damage and environmental concerns raised with fracturing treatments, including spills and flaring activities. The paper discussed the cost of the main polymers used in fracturing fluids and suggested practical recommendations to select a robust, cost-effective polymer. By integrating these concepts, the review gives the researcher the necessary knowledge to design and prepare effective fracturing fluids tailored to a wide range of operational scenarios. Full article

Zeolites are widely used as solid acid catalysts and also as supports in complex multifunctional heterogeneous systems. In recent years, there has been an increase in the development of zeolite-based catalysts with hierarchical porosity combined with metal dopants (modifiers or catalysts). These modifications can significantly improve the catalytic characteristics of such materials. In this review, we discuss the application of hierarchically porous zeolites, including metal-doped ones, in catalytic reactions employed in the production and upgrading of liquid fuels, i.e., pyrolysis of biomass and polymeric wastes; conversion of alcohols to fuel hydrocarbons, aromatics and olefins; cracking and hydrocracking of polymeric wastes and hydrocarbons; and hydroisomerization. It is revealed that, in many cases, higher activity, selectivity and stability can be achieved for metal-doped hierarchical zeolites in comparison with parent ones due to control over the diffusion, surface acidity and coke deposition processes. Full article

Petroleum hydrocarbons (PHC) are organic pollutants that pose serious health risks to humans and the environment. Treating soils contaminated with these persistent pollutants is a global concern that is challenging to implement effectively. Synergistic remediation strategies, particularly those involving plants and functional endophytic bacteria, offer ecologically sustainable approaches for remediating PHC-contaminated soil and thus hold broad application prospects. This review collected the literature from databases including Elsevier, Web of Science, PubMed, and CNKI, using keywords such as endophytic bacteria, petroleum hydrocarbons, plants, microorganisms, polycyclic aromatic hydrocarbons, and alkanes. After screening the titles, abstracts, and secondary headings, 123 articles were selected for narrative synthesis. It systematically elaborates on the types, functions, sources, and distribution characteristics within plants of hydrocarbon-degrading endophytic bacteria. It comprehensively summarizes the key molecular pathways involved in the bacterial degradation of alkanes and polycyclic aromatic hydrocarbons (PAHs). Furthermore, from four dimensions—PHC metabolism modes, plant growth promotion (PGP), production of biosurfactants (PBS), and horizontal gene transfer—this article innovatively analyzes the mechanisms underlying the synergistic remediation of petroleum hydrocarbon-contaminated soil through functional bacterium–plant interactions. Finally, the review outlines future research directions in the field, providing a theoretical foundation and practical pathways for advancing green remediation strategies for PHC-polluted soil. Full article

The photocatalytic conversion of CO₂ into value-added hydrocarbons offers a sustainable route for mitigating carbon emissions. In this study, we synthesized MoSe₂/g-C₃N₄ heterostructured composites through a hydrothermal method and used these composites in the photocatalytic reduction of CO₂ in the presence of ultraviolet radiation. Photoluminescence characterization, photocurrent analysis, and electrochemical impedance spectroscopy confirmed improved charge separation and interfacial transfer as a result of the composites’ heterojunction structure. The MoSe₂/10 wt% g-C₃N₄ composite exhibited a CH₄ production rate of 1.38 μmol g⁻¹ h⁻¹ and a CO₂ consumption rate of 2.22 μmol g⁻¹ h⁻¹, which are 4.2 and 3.1 times, respectively, higher than those of pure MoSe₂. Gas chromatography revealed the selective formation of C₁–C₅ hydrocarbons, with minimal oxygenated by-products. Band structure analysis conducted through ultraviolet photoelectron spectroscopy and ultraviolet–visible/near-infrared spectroscopy confirmed the proposed charge transfer pathway and enhanced C–C coupling efficiency. Overall, these results demonstrate the potential of the as-prepared heterojunction composites for highly selective CO₂-to-CH₄ conversion under mild conditions, with CH₄ as the dominant product (80%) among the generated hydrocarbons. Full article

With the rapid evolution of 5G wireless communications, millimeter-wave (mmWave) technology has become a crucial enabler for high-speed, low-latency, and large-scale connectivity. As the critical interface for signal transmission, mmWave antennas directly affect system performance, reliability, and application scope. This paper reviews the current state of mmWave antenna technologies in 5G systems, focusing on antenna types, design considerations, and integration strategies. We discuss how the multiple-input multiple-output (MIMO) architectures and advanced beamforming techniques enhance system capacity and link robustness. State-of-the-art integration methods, such as antenna-in-package (AiP) and chip-level integration, are examined for their importance in achieving compact and high-performance mmWave systems. Material selection and fabrication technologies—including low-loss substrates like polytetrafluoroethylene (PTFE), hydrocarbon-based materials, liquid crystal polymer (LCP), and microwave dielectric ceramics, as well as emerging processes such as low-temperature co-fired ceramics (LTCC), 3D printing, and micro-electro-mechanical systems (MEMS)—are also analyzed. Key challenges include propagation path limitations, power consumption and thermal management in highly integrated systems, cost–performance trade-offs for mass production, and interoperability standardization across vendors. Finally, we outline future research directions, including intelligent beam management, reconfigurable antennas, AI-driven designs, and hybrid mmWave–sub-6 GHz systems, highlighting the vital role of mmWave antennas in shaping next-generation wireless networks. Full article

The electrochemical reduction in CO₂ (CO2RR) to syngas and value-added hydrocarbons offers a promising route for sustainable CO₂ utilization. This work develops tuneable Cu-Sn bimetallic catalysts via electrodeposition, optimized for CO2RR in a zero-gap flow cell fed with CO₂-saturated KHCO₃ solution, a configuration closer to industrial scalability than conventional H-cells. By varying electrodeposition parameters (pH, surfactant DTAB, and metal precursors), we engineered catalysts with distinct selectivity profiles: Cu-Sn(B), modified with DTAB, achieved 50% Faradaic efficiency (FE) to CO at −2.2 V and −50 mA·cm⁻², outperforming Ag-based systems that require higher overpotentials. Meanwhile, Cu-Sn(A) favoured C₂H₄ (35% FE at −100 mA·cm⁻²), and Cu-Sn(C) shifted selectivity to CH₄ (26% FE), demonstrating product tunability. The catalysts’ performance stems from synergistic Cu-Sn interactions and DTAB-induced morphological control, as revealed by SEM/EDX and electrochemical analysis. Notably, all systems operated at lower voltages than literature benchmarks while maintaining moderate CO₂ utilization (32–49% outlet). This study highlights the potential of electrodeposited Cu-Sn catalysts for energy-efficient CO2RR, bridging the gap between fundamental research and industrial application in syngas and hydrocarbon production. Full article

This study presents a novel approach to the parametrization of 3D PETRO FACIES and SEISMO FACIES using supervised and unsupervised learning, supported by a coherent structural and stratigraphic framework, to enhance understanding of the presence of hydrocarbons in the Dzików–Uszkowce region. The prediction relies on selected seismic attributes and well logging data, which are essential in hydrocarbon exploration. Three-dimensional seismic data, a crucial source of information, reflect the propagation velocity of elastic waves influenced by lithological formations and reservoir fluids. However, seismic response similarities complicate accurate seismic image interpretation. Three-dimensional seismic data were also used to build a structural–stratigraphic model that partitions the study area into coeval strata, enabling spatial analysis of the machine learning results. In the 3D seismic model, PETRO FACIES classification achieved an overall accuracy of 80% (SD = 0.01), effectively distinguishing sandstone- and mudstone-dominated facies (RT1–RT4) with F1 scores between 0.65 and 0.85. RESERVOIR FACIES prediction, covering seven hydrocarbon system classes, reached an accuracy of 70% (SD = 0.01). However, class-level performance varied substantially. Non-productive zones such as HNF (No Flow) were identified with high precision (0.82) and recall (0.84, F1 = 0.83), while mixed-saturation facies (HWGS, BSWGS) showed moderate performance (F1 = 0.74–0.81). In contrast, gas-saturated classes (BSGS and HGS) suffered from extremely low F1 scores (0.08 and 0.12, respectively), with recalls as low as 5–7%, highlighting the model’s difficulty in discriminating these units from water-saturated or mixed facies due to overlapping seismic responses and limited training data for gas-rich intervals. To enhance reservoir characterization, SEISMO FACIES analysis identified 12 distinct seismic facies using key attributes. An additional facies (facies 13) was defined to characterize gas-saturated sandstones with high reservoir quality and accumulation potential. Refinements were performed using borehole data on hydrocarbon-bearing zones and clay volume (VCL), applying a 0.3 VCL cutoff and filtering specific facies to isolate zones with confirmed gas presence. The same approach was applied to PETRO FACIES and a new RT facie was extracted. This integrated approach improved mapping of lithological variability and hydrocarbon saturation in complex geological settings. The results were validated against two blind wells that were excluded from the machine learning process. Knowledge of the presence of gas in well N-1 and its absence in well D-24 guided verification of the models within the structural–stratigraphic framework. Full article

This research explores the effect of a composite support of SiO₂ and Al₂O₃ with Fe and Co incorporated as catalysts for Fischer–Tropsch synthesis (FTS) using a 3D-printed stainless steel (SS) microchannel microreactor. Two mesoporous catalysts, FeCo/SiO₂Al₂O₃ and Co/SiO₂Al₂O₃, were synthesized via a one-pot (OP) method and extensively characterized using N₂ physisorption, XRD, SEM, TEM, H₂-TPR, TGA-DSC, FTIR, and XPS. H₂-TPR results revealed that the synthesis method significantly affected the reducibility of metal oxides, thereby influencing the formation of active FTS sites. SEM-EDS and TEM further revealed a well-defined hexagonal matrix with a porous surface morphology and uniform metal ion distribution. FTS reactions, carried out in the 200–350 °C temperature range at 20 bar with a H₂/CO molar ratio of 2:1, exhibited the highest activity for FeCo/SiO₂Al₂O₃, with up to 80% CO conversion. Long-term stability was evaluated by monitoring the catalyst performance for 30 h on stream at 320 °C under identical reaction conditions. The catalyst was initially active for the methanation reaction for up to 15 h, after which the selectivity for CH₄ declined. Correspondingly, the C₄⁺ selectivity increased after 15 h of time-on-stream, indicating a shift in the product distribution toward longer-chain hydrocarbons. This trend suggests that the catalyst undergoes gradual activation or restructuring under reaction conditions, which enhances chain growth over time. The increase in C₄⁺ products may be attributed to the stabilization of the active sites and suppression of methane or light hydrocarbon formation. 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

This work focuses on the fabrication, characterization, and performance of a structured iron catalyst to produce hydrocarbons by the Fischer–Tropsch synthesis (FTS). The structured catalyst enhances the heat and mass transfer and provides a larger surface area and lower pressure drop. Iron-based structured catalysts indicate more activity in lower H₂/CO ratios and improve carbon conversion as compared to other metals. These catalysts were manufactured using the sponge replication method (powder metallurgy). The performance of the structured iron catalyst was assessed in a fixed-bed reactor under industrially relevant conditions (250 °C and 20 bar). The feed gas was a synthetic syngas with a H₂/CO ratio of 1.2, simulating a bio-syngas derived from lignocellulosic biomass gasification. Notably, the best result was reached under these conditions, obtaining a CO conversion of 84.8% and a CH₄ selectivity of 10.4%, where the catalyst exhibited a superior catalytic activity and selectivity toward desired hydrocarbon products, including light olefins and long-chain paraffins. The resulting structured catalyst reached a one-pass CO conversion of 84.8% with a 10.4% selectivity to CH₄ compared to a traditionally produced catalyst, for which the conversion was 18% and the selectivity was 19%, respectively. The results indicate that the developed structured iron catalyst holds considerable potential for efficient and sustainable hydrocarbon production, mainly C10–C20 (diesel-range hydrocarbons), via Fischer–Tropsch synthesis. The catalyst’s excellent performance and improved stability and selectivity offer promising prospects for its application in commercial-scale hydrocarbon synthesis processes. Full article

Catalytic upgrading of pyrolysis oils is an important step for producing replacement hydrocarbon-rich liquid biofuels from biomass and can help to advance pyrolysis technology. Catalysts play a pivotal role in influencing the selectivity of chemical reactions leading to the formation of main compounds in the final upgraded liquid products. The present work involved a systematic study of solvent-free catalytic reactions of cyclohexanone in the presence of hydrogen gas at 160 °C for 3 h in a batch reactor. Cyclohexanone can be produced from biomass through the selective hydrogenation of lignin-derived phenolics. Three types of catalysts comprising undoped NbOPO₄, 10 wt% NiO/NbOPO₄, and 30 wt% NiO/NbOPO₄ were studied. Undoped NbOPO₄ promoted both aldol condensation and the dehydration of cyclohexanol, producing fused ring aromatic hydrocarbons and hard char. With 30 wt% NiO/NbOPO₄, extensive competitive hydrogenation of cyclohexanone to cyclohexanol was observed, along with the formation of C₆ cyclic hydrocarbons. When compared to NbOPO₄ and 30 wt% NiO/NbOPO₄, the use of 10 wt% NiO/NbOPO₄ produced superior selectivity towards bi-cycloalkanones (i.e., C₁₂) at cyclohexanone conversion of 66.8 ± 1.82%. Overall, the 10 wt% NiO/NbOPO₄ catalyst exhibited the best performance towards the production of precursor compounds that can be further hydrodeoxygenated into energy-dense aviation fuel hydrocarbons. Hence, the presence and loading of NiO was able to tune the activity and selectivity of NbOPO₄, thereby influencing the final products obtained from the same cyclohexanone feedstock. This study underscores the potential of lignin-derived pyrolysis oils as important renewable feedstocks for producing replacement hydrocarbon solvents or feedstocks and high-density sustainable liquid hydrocarbon fuels via sequential and selective catalytic upgrading. Full article

(1) Background: This study investigated changes in bioactive components and volatile compounds (VCs) during the production of red millet by comparing two varieties: Miao Xiang glutinous millet (waxy) and Jigu-42 (non-waxy). The samples were solid-state-fermented with “Red Ferment” and evaluated for bioactive components. (2) Methods: Multiple analytical methods—including principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA) and orthogonal PLS-DA (OPLS-DA), cluster analysis, and correlation analysis—were employed to systematically compare bioactive components and VCs. (3) Results: Significant varietal differences were observed: (1) Miao Xiang glutinous millet showed higher monacolin K (MK) and fatty acid contents; (2) Jigu-42 contained significantly more polyphenols; (3) linoleic acid dominated the fatty acid profiles of two varieties; and (4) a total of twenty-seven VCs were identified, including six alcohols, four aldehydes, seven ketones (corrected from duplicated count), two aromatic hydrocarbons, three heterocycles, one acid, three furans, and one ether. (4) Conclusions: The two varieties exhibited significant differences in MK, pigment profiles, fatty acid composition, polyphenol content, and volatile-compound profiles. These findings provide scientific guidance for the selection of the appropriate millet varieties in functional food production. Full article