Search Results (171)

Diesel-powered equipment is widely used in underground coal mines for auxiliary transportation, material handling, and equipment relocation because of its long operating endurance, convenient refueling, and strong adaptability to complex operating conditions. However, carbon monoxide (CO) emissions from such equipment can accumulate locally under restricted ventilation, idling, and frequent start–stop operation, thereby threatening occupational health and mine safety. This review focuses on CO purification technologies for diesel-powered mining equipment. The operating characteristics and influencing factors are analyzed, and different technical routes are compared, including in-cylinder control, wet scrubbing, adsorption, non-thermal plasma (NTP), and catalytic oxidation. Recent advances in noble-metal catalysts, transition-metal and CeO₂-based reducible oxide catalysts, and single-atom catalyst (SAC) design strategies are summarized. Research progress in exhaust aftertreatment systems is also discussed. Overall, CO purification for diesel-powered mining equipment requires coordinated optimization of low-temperature activity, safety-oriented thermal management, flow resistance, and long-term operational stability. Future research should focus on structured catalytic units, durability under coupled exhaust conditions, online monitoring, and field validation to improve the compatibility of CO purification systems with underground mining conditions. Full article

The great impact of carbon dioxide emissions on climate change motivates the development of technologies for carbon capture and utilization. CO₂ methanation, which transforms CO₂ into methane using renewable hydrogen, is a promising power-to-gas and carbon utilization pathway. Achieving high activity, strong CH₄ selectivity, and long-term stability remains challenging, as well as pushes to tailor catalyst properties for the methanation reaction. Cerium oxide is therefore widely explored as a support or promoter due to its redox behaviour and oxygen vacancy chemistry. This review surveys recent literature on catalysts based and containing CeO₂ applied for CO₂ methanation, covering not only thermal operation but also non-conventional catalytic routes as photothermal, electrocatalytic, and plasma-assisted, with emphasis on how synthesis and role of Ce tune physicochemical properties and catalytic activity. Across reported systems, dispersing active metals (notably Ni and Ru, Cu for electrochemical systems) on ceria frequently yields to high CH₄ selectivity. Redox properties of ceria enable optimal metal–support interactions and surface basicity to achieve effective CO₂ activation in thermo-catalytic route. Further enhancement of oxygen mobility is associated with doped CeO₂ and solid solutions such as Ce-Zr. The high oxygen storage capacity of CeO₂ promotes photogenerated charge separation for light-driven performance and optimal plasma–catalyst interactions. Full article

Carbon dioxide (CO₂) conversion in non-thermal plasma is a promising route for carbon utilisation under mild conditions. This study investigates the performance and dynamic behaviour of kaolin-based catalysts modified with Ni (nickel), Ni–Ce (nickel-cerium), and Fe–Cu (iron-copper) oxides in a Dielectric Barrier Discharge (DBD) reactor. Materials were characterised using X-ray diffraction, energy-dispersive X-ray fluorescence, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. CO₂ conversion was evaluated at varying Plasma Energy Numbers (PEN = 1.65–20) with time-resolved gas analysis over a 10 min period. Results demonstrate that the kaolin support is not inert; its dielectric properties actively influence discharge characteristics. Ni-based catalysts exhibited the highest stable activity, reaching ~53% conversion for samples calcined at 500 °C. Conversely, adding cerium oxide significantly decreased conversion and induced temporal instabilities, contrasting with its typical role in thermal catalysis. Time-resolved measurements revealed that Ni–Ce and Fe–Cu systems exhibit initial activity followed by gradual deactivation, suggesting plasma-induced surface restructuring. These findings highlight that catalyst performance in DBD is governed by a complex interplay of chemical activity and plasma–material interactions. The generated time-series data provide a robust foundation for machine learning applications in predictive modelling and stability classification of plasma-catalytic systems. Full article

The development of sustainable electrocatalysts for clean energy by modifying biomass-derived activated carbon with nitrogen and transition metals is presented. Activated carbon (AWC) material was obtained using alder wood char as a precursor, while nitrogen and cobalt or copper nanoparticles were incorporated with the aim of creating efficient materials for hydrazine oxidation (HzOR) and direct hydrazine–hydrogen peroxide fuel cells (DHHPFC, N₂H₄–H₂O₂). The composition, structure, and surface morphology of the created materials were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES). The activity of the AWC, AWC–Co–N, and AWC–Cu–N catalysts for HzOR was investigated using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). N₂H₄–H₂O₂ fuel-cell tests were performed by applying the catalysts as both the anode and cathode. It was found that all materials retained a hierarchical porous carbon framework, while metal incorporation altered surface compactness. Cobalt doping produced well-dispersed Co nanoparticles and abundant Co–N–C coordination sites, whereas Cu introduction resulted in moderately compact structures with uniformly distributed Cu-based nanoparticles. Electrochemical measurements demonstrated that both metal dopants enhanced HzOR activity, with the catalytic performance following the order of AWC–Co–N > AWC–Cu–N > AWC. Fuel-cell testing further confirmed this trend: AWC–Co–N achieved the highest maximum power density (30.4 mW cm⁻²), outperforming AWC–Cu–N (17.7 mW cm⁻²). These results identify AWC–Co–N as a highly effective bifunctional electrocatalyst for DHHPFCs. Full article

The facet-dependent catalytic behavior of MgO in non-thermal plasma (NTP)-driven CO₂ decomposition is systematically investigated by combining experimental measurements and density functional theory (DFT) calculations. Three MgO catalysts with dominant exposure of the (100), (110), and (111) facets are synthesized. CO₂ temperature-programmed desorption (CO₂-TPD) shows that CO₂ adsorption capacity follows the order MgO(110) > MgO(111) > MgO(100), consistent with DFT-derived adsorption energies. DFT energy profiles reveal that although MgO(110) binds CO₂ most strongly, it suffers from excessively strong CO adsorption (5.84 eV), inhibiting product desorption. In contrast, MgO(111) offers a favorable CO₂ adsorption energy combined with a remarkably low CO desorption energy (0.71 eV), enabling rapid turnover. Electronic structure analyses demonstrate substantial charge transfer from MgO(111) to CO₂ (up to 1.76 |e|) and pronounced orbital hybridization near the Fermi level, which are further enhanced under plasma conditions. Plasma-catalytic tests at 0.8 W show that MgO(111) achieves the highest CO₂ conversion (60.7%) with excellent selectivity toward CO (95.3%) and O₂ (94.4%), outperforming MgO(110) and MgO(100). Increasing the input power from 0.8 to 2.5 W raises conversion to 78.1% but reduces energy efficiency due to increased gas heating or non-productive pathways. Overall, the (111)-enriched MgO is identified as an efficient and selective catalyst for NTP-based CO₂ splitting, owing to its optimal balance of adsorption strength, facile CO desorption, strong charge transfer, and plasma–catalyst synergy. This work highlights the importance of facet engineering and power optimization for designing oxide-based plasma catalysts toward energy-efficient CO₂ utilization. Full article

The potency of urate, an abundant human plasma antioxidant, in preventing oxidative damage caused by the carbonate radical anion CO₃^•−, was studied using quantum chemical calculations. The influence of microhydration of CO₃^•−/CO₃²⁻ and urate⁻/urate^• couples on the thermodynamic and kinetics of the one-electron oxidation process was investigated. Depending on the degree of microhydration, the estimated rate constant for one-electron transfer is in the range of 2.0–7.3 × 10⁹ M⁻¹ s⁻¹, in good agreement with the experimental value of 1.3 × 10⁹ M⁻¹ s⁻¹. Modeling using vertical detachment energy and electron affinity, the driving forces of single electron transfer revealed urate(H₂O)₆⁻ and CO₃(H₂O)₉^•− clusters as the most likely existing species in water. Molecular docking revealed a favorable interaction of urate with the catalytic pocket of SOD1. Urate binds more strongly to the anionic active center of SOD1 than the reference inhibitor LSC-1, indicating its potency to prevent HCO₃⁻-supported CO₃^•− formation. In contrast, the known OGG1 inhibitor TH13264 shows substantially stronger binding than urate, indicating urate’s weaker affinity toward the DNA repair enzyme catalytic pocket. The molecular dynamics data indicate that urate binding does not destabilize either SOD1 or OGG1. In light of increasing evidence that the major source of oxidative stress could be CO₃^•−, rather than the commonly assumed hydroxyl radical HO^•, the obtained results indicate the inherent ability of plasma to combat oxidative stress induced by this selective, milder oxidant. Such an ability with respect to the non-selective, highly reactive HO^• does not exist in vivo. Full article

Plasma-catalytic oxidation is a promising approach for the abatement of volatile organic compounds (VOCs), yet its efficiency is often limited by the ineffective utilization of plasma-generated reactive oxygen species and incomplete oxidation pathways. In this work, a composite catalyst was constructed by integrating spinel-type NiCo₂O₄ with three-dimensional cubic mesoporous KIT-6 to couple efficient mass transfer with redox-active surface functionality for plasma-catalytic degradation of toluene. The performance of NiCo/KIT-6 was systematically evaluated in a dielectric barrier discharge (DBD) reactor and compared with Ni/KIT-6, Co/KIT-6, and NTP-only systems. XPS, O₂-TPD, H₂-TPR, and apparent dielectric measurements were employed to elucidate catalyst properties relevant to plasma–surface interactions. NiCo/KIT-6 exhibits superior overall performance in terms of toluene conversion, CO_x selectivity, and CO₂ selectivity over a wide range of specific input energies. This enhancement is closely associated with the integrated regulation of surface redox properties, oxygen activation capability, and apparent dielectric response by the NiCo₂O₄/KIT-6 composite structure, which may promote reactive oxygen utilization and facilitates effective plasma–surface redox processes. These results provide insights into the rational design of composite catalysts for plasma-assisted oxidation of aromatic VOCs. Full article

The vision for global net-zero carbon emissions by 2050 has intensified the demand for sustainable and low-carbon energy resources. Within this context, recent discoveries of substantial methane (CH₄) reserves, coupled with the rapidly growing interest in hydrogen (H₂) as a clean energy carrier, have underscored the strategic importance of developing efficient and economically viable technologies for methane conversion. This current review investigates hydrogen production specifically from coalbed methane (CBM), a methane-rich unconventional gas resource embedded in coal seams. Both catalytic and non-catalytic pathways for hydrogen generation are reviewed, including steam methane reforming (SMR), partial oxidation (POX), autothermal reforming (ATR), direct methane decomposition (DMD), and plasma-assisted pyrolysis. Catalytic processes such as SMR remain the most mature and cost-effective, though they emit significant CO₂ unless integrated with carbon capture and storage (CCS) technologies. Non-catalytic routes, including thermal and plasma-based decomposition, offer CO₂-free hydrogen generation while producing solid carbon byproducts with potential commercial value. Hybrid coal–CBM systems are also discussed as integrated approaches for improving energy efficiency and resource utilization. The techno-economic assessment compares hydrogen yield, production cost, and environmental impact across methods, emphasizing the advantages of CBM as a high-purity methane source. Case studies, particularly from China, highlight the practical potential of CBM in supporting hydrogen infrastructure. The paper concludes that catalytic routes such as SMR are the most commercially mature and cost-effective but remain CO₂-intensive unless coupled with carbon capture and storage. Non-catalytic approaches, including direct methane decomposition and plasma pyrolysis, enable CO₂-free hydrogen generation while yielding solid carbon byproducts of potential commercial value, though they are less developed. Hybrid coal–CBM systems offer a balanced pathway to improve efficiency, resource utilization, and sustainability in future hydrogen production strategies. Full article

The integration of non-thermal plasma (NTP) with heterogeneous catalysis has emerged as a promising strategy for the efficient abatement of industrial volatile organic compounds (VOCs), overcoming key limitations of conventional thermal and standalone plasma technologies. This review provides a comprehensive overview of the synergistic mechanisms in NTP-catalytic systems, with particular emphasis on the bidirectional interactions between plasma and the catalyst. Specifically, plasma can activate catalysts through surface defect generation and improved metal dispersion, while catalysts, in turn, modulate plasma characteristics via localized electric field enhancement and electron energy redistribution. Furthermore, this synergy spans multiple spatiotemporal scales, linking ultrafast electron dynamics with macroscopic catalytic performance, and atomic-scale active sites with reactor-level behavior. Based on these mechanistic insights, rational catalyst design strategies are systematically discussed, including transition metal oxides, noble metals, perovskites, and metal–organic frameworks. Finally, key challenges related to catalyst deactivation, energy efficiency, and process scalability are highlighted. Future perspectives are proposed, focusing on advanced in situ diagnostics and AI-assisted material discovery to accelerate the practical implementation of NTP-catalytic technologies for sustainable VOC removal. Full article

Plasma electrolytic oxidation (PEO) enables the fabrication of multifunctional oxide coatings with embedded active phases, offering a promising route for durable photocatalytic surfaces in water purification. This study examines how the electrical regime affects particle incorporation and photocatalytic performance. Coatings were produced under a 50% duty cycle in both unipolar mode and during the anodic part of the bipolar mode. A silicate-based electrolyte was modified with zeolites (Y and ZSM5), used in pristine form, Zn-loaded form, and combined with ZnO nanoparticles, to enhance catalytic activity. Photocatalytic performance was evaluated via methyl orange degradation under simulated solar irradiation for 6 h. The highest efficiency (~45%) was achieved with unipolar coatings containing Y zeolite and ZnO. In contrast, bipolar coatings with combined Y and ZnO showed lower efficiency (~35%). Although lower than typical powder photocatalysts, these results are notable since active phases are directly embedded in the coating, and both modes improve the photocatalytic activity by ~10% compared to the standard electrolyte. Microstructural analysis revealed that bipolar coatings were more compact, limiting access to active sites. Unipolar processing enabled better particle incorporation and a morphology more favorable for photocatalytic activity, making it the more effective regime for developing PEO-based photocatalytic coatings. Full article

The purpose of this work was to synthesize and study catalytic systems based on a carbon-containing support obtained from coke fines from the Shubarkol deposit as a waste product of the coal industry for the processing of phenolic compounds. Based on the obtained carbon sorbent, mono- and binary catalysts with active phases of transition metal oxides (Fe, Co, Ni) were synthesized by wet impregnation, followed by heat treatment at 500–700 °C, as well as the aluminum oxide compositions. The surface morphology and elemental composition of the samples were studied by scanning electron microscopy (SEM) with energy dispersion analysis and elemental mapping (EDS mapping), and the content of active phases was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The catalytic activity was studied in phenol hydrogenation reactions. The CoO/C catalyst demonstrated the greatest activity, providing a 62.36% benzene yield during phenol hydrogenation. The catalytic activity of the CoO/C catalyst has also been studied in the hydrogenation reactions of structurally and functionally more complex compounds, pyrocatechol and resorcinol. The yield of benzene was 63.16% in the hydrogenation of pyrocatechol and 48.64% in the hydrogenation of resorcinol. It was found that the CoO/C catalyst exhibits the highest efficiency at a temperature of 420 °C, a pressure of 6–6.5 MPa and a reaction duration of 120 min. The results obtained make it possible to evaluate the prospects of using a carbon sorbent obtained from coke fines from the Shubarkol deposit as a support for CoO as part of an active and stable catalytic system designed for deep processing of phenolic compounds. Full article

N₂O (Nitrous oxide) is a potent greenhouse gas with a global warming potential nearly 300 times that of CO₂ and poses a critical environmental challenge, particularly in semiconductor and display manufacturing, where it is emitted during plasma processes. However, catalytic N₂O abatement in O₂-rich environments remains inefficient because O₂ competitively occupies active sites and hinders the turnover of surface oxygen species. To clarify how support properties govern this inhibition, Co-based catalysts supported on beta zeolite, CeO₂, and TiO₂, together with unsupported Co₃O₄, were comparatively evaluated for direct N₂O decomposition. Among them, Co/Beta exhibited the highest performance, achieving >95% N₂O conversion at 450 °C in the presence of 5% O₂ with excellent long-term stability. Co/Beta possessed a high specific surface area (649 m² g⁻¹) and a mesoporous framework that favored uniform Co dispersion and reactant accessibility, while its high Co²⁺/(Co²⁺ + Co³⁺) ratio (75.5%) and large fraction of chemisorbed oxygen species (79.9%) promoted oxygen-vacancy formation and facile oxygen exchange. These results indicate that the ability of Co/Beta to maintain high activity in the presence of oxygen stems from support-modulated cobalt surface states and enhanced oxygen turnover behavior. These findings provide a support-design principle for stable N₂O decomposition under oxygen-containing exhaust conditions. Full article

Methane, as an abundant and relatively clean resource, has primarily been converted into various chemical products via indirect conversion through synthesis gas, a mixture of CO and H₂. Recently, interest in direct methane conversion technologies with lower energy consumption has increased. Compared to research on methanol production via selective oxidation of methane, studies on the direct conversion of methane to acetic acid have been relatively scarce, but significant research progress has been made recently. This review classifies reports on the direct conversion of methane into acetic acid according to catalyst type (homogeneous vs. heterogeneous catalysts) and reaction conditions, and discusses the advantages and disadvantages of each approach. A relatively high yield of acetic acid can be achieved using CO as a carbonylating agent. However, the direct conversion of methane and CO₂ into acetic acid is more attractive from an environmental perspective. Recent advances in the field of electrocatalysis for this purpose are noteworthy. Other non-thermal catalytic methods, including photocatalysis, photoelectrocatalysis, and plasma processes, are also included. Based on the current state-of-the-art research trends in this field, future research directions are proposed. Full article

The study investigates the catalytic activity of vanadium-containing catalysts in the selective oxidation of 4-methylpyridine (4-MP) in the gas phase. V-Cr, V-Ti, and V-Ti-Cr catalysts were synthesised and studied. The phase composition and structural features of the catalysts were determined by X-ray diffraction (XRD) and Raman spectroscopy, and their thermal stability was investigated using thermogravimetric analysis (TGA/DTA). Textural characteristics were evaluated by low-temperature nitrogen adsorption–desorption (BET, BJH), surface morphology was studied using scanning electron microscopy (SEM), and the distribution of elements was investigated using energy-dispersive X-ray spectroscopy (EDX). The chemical composition of the catalysts was determined using inductively coupled plasma atomic emission spectrometry (ICP-OES) and catalytic activity was evaluated in the selective gas-phase oxidation reaction of 4-methylpyridine in the temperature range 280–380 °C. It was found that an increase in temperature is accompanied by an increase in the conversion of 4-methylpyridine, but at the same time, deep oxidation reactions intensify. The best result is achieved on the V-Ti-Cr catalyst, for which the conversion of 4-MP reaches 86.88% and the selectivity is 73.06% at 320 °C. However, V-Ti provides moderate stable performance, while V-Cr demonstrates relatively low efficiency. Thus, it can be concluded that the nature of the temperature dependence of 4-methylpyridine conversion reflects the different nature of the active centres and their stability. Full article

In this study, a series of Ag/Co-HA catalysts were synthesized using a plasma-assisted method. Plasma is a partially ionized gas composed of electrons, ions, neutral molecules, free radicals, photons, and excited-state substances, which can serve as a highly reactive medium for catalyst modification. Its unique discharge characteristics can effectively regulate the dispersion of active sites, electronic structure, and metal–support interactions. The study compared the performance of catalysts prepared by the traditional high-temperature calcination method with those treated by rapid plasma in the toluene oxidation removal reaction. The results showed that the catalyst treated by dielectric barrier discharge (DBD) plasma exhibited excellent low-temperature catalytic activity, achieving 100% toluene conversion and approximately 75% CO₂ selectivity at 275 °C, while the catalyst prepared by traditional calcination only achieved 73% toluene conversion and approximately 50% CO₂ selectivity at 285 °C. This study provides a simple preparation method for the Ag/5Co-HA-P catalyst. Due to the plasma treatment’s ability to precisely control the catalyst structure, along with advantages such as low energy consumption, short processing time, and environmental friendliness, it holds significant application prospects in the field of VOCs treatment. Full article