Search Results (10,633)

Here, we report a highly efficient and stable catalytic system based on monometallic oxides supported on HY zeolites for the catalytic oxidation of chlorobenzene (CB). Among the transition and rare-earth metal oxides screened, the 30Cu/HY catalyst demonstrates exceptional performance, achieving near 100% CB conversion at 300 °C (500 ppm CB, 10,000 h⁻¹) alongside outstanding 24 h continuous stability without deactivation. Quantitative Py-IR analysis reveals that this superior activity is fundamentally driven by extensive solid-state ion exchange, forming robust Lewis acid centers (Cu-Y structures) that synergize with zeolitic Brønsted acid sites to efficiently polarize and cleave C-Cl bonds. Through an integrated approach combining in situ DRIFTS, real-time mass spectrometry, TGA, and NLDFT pore size analysis, we elucidate that the exceptional deep-oxidation capability of Cu/HY continuously mineralizes carbonaceous intermediates. This property minimizes coke deposition (2.91 wt%) and preserves the hierarchical pore architecture, preventing the coverage of active sites and severe pore blockage by partially oxidized intermediates (such as phenolic, aldehydic, and quinonic species) and stable carbonate species responsible for the deactivation of other metal oxides. These insights provide a mechanistic framework for the rational design of robust, chlorine-resistant catalysts for the sustainable abatement of persistent organic pollutants. 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

Formic acid (FA) has emerged as a promising liquid hydrogen storage material, yet efficient photothermal dehydrogenation catalysts with high activity and H₂ selectivity remain challenging. Herein, a polymetallic synergistic PdCu/M-ZNC (where M represents the co-doped In, Sn and Mo species) is fabricated by molten-salt-assisted pyrolysis of ZIF-8 precursors followed by metal incorporation. The unique molten salt environment effectively preserves the porous architecture of ZIF-8, enabling the secure anchoring of PdCu alloy nanoparticles onto the carbonaceous matrix enriched with M-Nₓ coordination sites. Under light irradiation, the PdCu alloy sites kinetically accelerated the overall adsorption and activation of FA molecules. Based on empirical observations and corroborated by the established literature, this alloying effect was inferred to facilitate the C-H bond cleavage and HCOO* desorption processes. Concurrently, the M-Nₓ sites act as efficient electron transfer channels, facilitating the rapid coupling of photogenerated electrons with protons (H⁺) to evolve H₂. Consequently, the optimal catalyst exhibits an enhancement in gaseous product yield (404.46 mmol/g/h) and H₂ selectivity (67.49%) at 75 °C. This work offers a catalyst design that aligns with several principles of green chemistry: it maximizes the atom utilization of precious Pd, incorporates synergistic non-precious metals within MOF-derived frameworks to enhance stability, and leverages solar energy to drive hydrogen production under mild conditions, presenting a more sustainable pathway for hydrogen release from liquid carriers. 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

The COVID-19 pandemic has renewed interest in proximity tourism as a driver for culturally sustainable local development. Against this backdrop, this study examines the Province of Latina, Italy, evaluating the potential of proximity tourism flows originating from the Metropolitan City of Rome to reduce the socioeconomic and infrastructural disparities that affect the provincial territory. Using a multi-stage quantitative framework, the research identifies key determinants of municipal attractiveness and assesses the structural relationships between tourism activities, economic development, and demographic trends. Results reveal a clear spatial polarization: while coastal municipalities successfully leverage natural and cultural assets for development, they increasingly face challenges related to overtourism and gentrification. Conversely, marginalized hilly and mountainous peripheries remain underdeveloped despite their high heritage value. Empirical evidence suggests that while proximity tourism does not directly drive demographic growth, it acts indirectly as a catalyst by stimulating economic development. The study concludes that proximity tourism can foster territorial cohesion and socioeconomic resilience only when coupled within integrated strategies that improve accessibility, valorize peripheral assets, and keep the added value of tourism embedded within host communities. These findings offer actionable insights for policymakers aiming to transition toward more inclusive and culturally sustainable tourism models in the post-pandemic era. Full article

This study reports a straightforward and controllable two-step hydrothermal synthesis of novel Ni₉S₈@NiMoO₄/NF nanospherical catalysts supported on nickel foam (NF), accompanied by a systematic evaluation of their performance in the electrochemical hydrogen evolution reaction (HER). Structural characterization revealed a well-defined Ni₉S₈–NiMoO₄ interfacial region, whose synergistic interaction, combined with the distinctive nanospherical morphology, substantially increased the electrochemically active surface area and the density of reactive sites, thereby optimizing HER kinetics. In alkaline media, the Ni₉S₈@NiMoO₄/NF catalyst demonstrated outstanding electrocatalytic performance, delivering an overpotential of only 64.2 mV at a current density of 20 mA cm⁻². The catalyst also exhibited a high double-layer capacitance of 22.2 mF cm⁻², reflecting a substantial active interfacial area. Long-term durability tests showed negligible performance degradation after 165 h of continuous operation at 10 mA cm⁻², underscoring the catalyst’s robust structural stability and durability. X-ray photoelectron spectroscopy confirmed a uniform distribution of Ni, Mo, and S across the NF framework and revealed optimized chemical states, providing material-level evidence for the enhanced performance. Collectively, this work proposes a viable strategy for designing efficient and stable HER catalysts, contributing to the advancement of green hydrogen production and clean energy technologies. Full article

Carbon monoxide (CO) is a highly toxic, colorless, and odorless gas posing significant risks to human health and the environment. Catalytic oxidation offers a promising, economically viable solution by converting CO into nontoxic CO₂ under mild conditions without energy-intensive regeneration. However, existing MnO₂-based catalysts often exhibit poor activity and stability in harsh environments, particularly at low temperatures and high humidity. In this study, we propose a Cu²⁺ ion-exchange modification strategy to activate lattice oxygen species in δ-MnO₂, thereby significantly enhancing its low-temperature CO oxidation performance. Structural characterization by XRD and SEM confirms that Cu-doped δ-MnO₂ retains its original birnessite-type structure and porous morphology. ICP-OES and XPS analyses verify that Cu²⁺ ions effectively replace interlayer K⁺ ions. The resulting MnO₂-150Cu catalyst demonstrates exceptional activity, achieving 100% CO conversion at 40 °C in dry air and maintaining full conversion at 80 °C in the presence of 1.3 vol.% H₂O at a weight hourly space velocity of 150 L/g·h. H₂-TPR and O₂-TPD results confirm that Cu doping enhances the reducibility and mobility of lattice oxygen. Furthermore, in situ DRIFTS analysis reveals that the migration of active oxygen species is the rate-limiting step at low temperatures. This work provides a novel and effective strategy for activating lattice oxygen in MnO₂-based catalysts, offering a promising pathway for developing high-performance materials for low-temperature CO oxidation under practical environmental conditions. Full article

A ligand-free Ni(acac)₂/EASC Ziegler–Natta catalytic system was developed for the efficient synthesis of low molecular weight liquid polybutadiene (LPB) featuring high 1,4 content. The influences of key polymerization parameters, including Al/Ni ratio, polymerization temperature, monomer-to-catalyst ratio ([Bd]/[Ni]), and external donors, were systematically investigated to elucidate structure–reactivity relationships. Increasing the Al/Ni ratio significantly enhances catalytic activity while promoting chain transfer reactions, leading to reduced molecular weights and broader molecular weight distributions, with minimal impact on overall 1,4 selectivity. Polymerization temperature strongly affects both activity and stereoselectivity; elevated temperatures accelerate chain transfer processes and broaden dispersity, while inducing a shift from kinetically favored cis-1,4 insertion toward increased trans-1,4 incorporation. Variation of the [Bd]/[Ni] ratio provides an effective handle for molecular weight regulation, where higher ratios favor chain propagation over chain transfer, affording higher molecular weights but lower monomer conversion. Notably, the system maintains consistently high 1,4 content (>98%) across a wide range of conditions. In contrast, the introduction of external donors markedly affects catalytic behavior depending on their coordination ability. Strongly coordinating O- and S-containing donors partially deactivate the catalyst and significantly shift regioselectivity toward 1,2-vinyl incorporation (up to ~20%), while N- and P-containing donors are well tolerated and can increase molecular weight by suppressing chain transfer pathways, which also results in products with higher 1,2 content. Full article

The synthesis of nitrogen-containing heterocycles remains a subject of significant interest due to their applications in medicinal chemistry and materials science. This paper describes the preparation of imidazo[1,2-a]pyridine using a catalytic system consisting of the deep eutectic solvent (DES) choline chloride (ChCl)–tartaric acid (1:2) and I₂ by reaction between 2-aminopyridines and chalcones (1,3-diphenylprop-2-en-1-ones). The proposed mechanism suggests the activation of the chalcone carbonyl by the DES, enhancing the polarization of the conjugated system which suffers electrophilic addition by I₂ to the C=C bond. The resulting intermediate undergoes a nucleophilic attack by 2-aminopyridine followed by cyclization and iodine-promoted oxidation and aromatization to yield the corresponding imidazo[1,2-a]pyridine products. The role of the DES is crucial, as it facilitates carbonyl activation through hydrogen bond interactions, stabilizes reactive intermediates, and promotes protonation–deprotonation steps, thereby eliminating the need for metal catalysts or toxic organic solvents. Theoretical calculations at the PM6 level of theory suggest that the DES acts as a catalyst in this reaction, due to the nature of its components enabling the development of more sustainable synthetic strategies. Full article

This work investigates the behavior of carbon dioxide (CO₂) near the surface of different single-atom alloys to evaluate their potential as catalysts for decarbonization processes. Specifically, 26 transition metals from the first three transition series, alloyed with three low Miller index copper supports, were considered. Adsorption energies and distances of linear CO₂, trigonal CO₂, and CO* + O* on the surfaces were calculated using the semiempirical computational method MOPAC-PM7. Additionally, activation energies were determined from previously published research. The proposed methodology is less computationally demanding than DFT studies, and results show good agreement with both experimental and simulated data. This approach provides a computationally efficient methodology for screening promising materials that convert CO₂ into valuable products, such as methane and methanol. Full article

The widespread presence of ciprofloxacin (CIP) in aquatic environments threatens ecological and public health, yet conventional treatment processes fail to remove such persistent contaminants. Conventional solvothermal synthesis of Bi-doped g-C₃N₄ photocatalysts involves complicated procedures and low productivity. Herein, we employ a single-step, template-free and solvent-free green calcination method to construct Bi³⁺-modified g-C₃N₄ with strong Bi-N coordination interactions. A series of Bi/g-C₃N₄ photocatalysts with Bi-doping mass ratios of 0.09–0.34 wt% was prepared, and the structure–performance relationship as well as the surface–interface reaction mechanism for ciprofloxacin (CIP) degradation were systematically elucidated. Experimental results confirm that Bi³⁺ incorporates into the lattice via Bi-N coordination bonds with nitrogen in the g-C₃N₄ framework, which narrows the band gap, suppresses photogenerated carrier recombination, and constructs a loose porous morphology beneficial for increasing specific surface area and active sites. Under optimal conditions, 15Bi/g-C₃N₄ achieves 97.6% degradation of 15 mg L⁻¹ CIP within 90 min, which is 13.7% higher than that of pristine g-C₃N₄. The effects of catalyst dosage, initial pH, CIP concentration, common coexisting ions, and different real water matrices on the degradation performance were systematically investigated. Radical quenching experiments combined with ESR characterization confirm that h⁺ is the dominant reactive species responsible for CIP degradation. This green, simple and scalable method yields uniform products, and the resulting materials exhibit high efficiency, economic feasibility and environmental safety, demonstrating promising potential for antibiotic wastewater treatment. Full article

This study addressed the issue of insufficient activity in CALB lipase during the catalytic synthesis of key chiral intermediates for moxifloxacin. A structure-guided protein engineering strategy was employed to systematically modify its functional domains. Through molecular dynamics simulations of CALB-I189K, multiple regions exhibiting high conformational flexibility were preliminarily identified. Subsequently, by integrating 3D structural alignment with active site pocket distance analysis, the functionally most critical region (143–146) was selected. A site-directed saturation mutation library was constructed specifically targeting this region. Building upon the previously reported CALB-I189K, a mutant I189K/L144R/A146K was ultimately obtained through high-throughput screening combined with chiral HPLC validation. This mutant maintains excellent stereoselectivity (E = 206.52) while enhancing catalytic efficiency (k_cat/Κ_m) to 273.73 min⁻¹·mM⁻¹, approximately 4.5-fold that of I189K. At a substrate concentration of 1 M, it achieves 50% conversion within 2.6 h, demonstrating kinetic resolution capabilities approaching industrial standards. Molecular simulation analysis indicates that the L144R and A146K mutations synergistically enhance catalytic performance primarily by optimizing spatial distances between catalytic residues. This study not only provides a high-performance catalyst for the efficient biosynthesis of moxifloxacin chiral intermediates but also offers new insights for enzyme rational design based on dynamic structural information. Full article

Ventilation air methane (VAM) has an extremely low concentration, making its abatement exceptionally challenging. Catalytic oxidation offers a promising route for VAM treatment, but industrial application requires integrated catalysts with high activity and efficient mass transfer. In this study, a novel straight-channel NiO/CeO₂ ceramic reactor was fabricated via mesh-assisted phase inversion, with NiO content systematically optimized to screen the optimal ratio. The 60 wt% NiO was the optimal composition, exhibiting excellent VAM oxidation performance. Brunauer–Emmett–Teller (BET) analysis confirmed that this optimal ratio yielded the largest specific surface area. Furthermore, H₂-temperature-programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS) confirmed that this optimal ratio facilitated the formation of abundant NiO–CeO₂ active interfaces, effectively inducing surface Ce³⁺ species and oxygen vacancies. These merits significantly enhanced the reactor’s oxygen adsorption capacity and redox properties, thus realizing efficient methane activation in catalytic oxidation. Moreover, the optimal reactor successfully passed 10 thermal cycle tests, further verifying the thermal stability of the catalytic structure. In addition, it exhibited outstanding long-term stability during a 100 h test, with no carbon deposition or active phase sintering observed. This work develops an optimized straight-channel NiO/CeO₂ ceramic reactor and offers a practical and scalable design strategy for VAM oxidation. Full article

The CO₂ storage–regeneration (CO₂-SR) process represents a promising strategy for integrating CO₂ capture and catalytic conversion within a single cyclic operation using multifunctional catalysts. In this concept, CO₂ is first stored on basic sites and subsequently converted through methane activation, enabling the coupling of CO₂ capture and reforming reactions in a single reactor. In this work, a series of unsupported Ni–Ba catalysts were investigated as model multifunctional materials for the CO₂-SR process. Catalysts with different Ni/Ba ratios were prepared to analyze how the distribution of storage and catalytic sites influences the cyclic CO₂ capture–conversion behavior. In addition, Rh was introduced as a promoter either during synthesis by co-precipitation or ex situ by impregnation, allowing to evaluate the influence of Rh location and surface enrichment on the catalytic properties. Rh incorporation in the NiBa catalyst (Ni/Ba = 10/1 and Ni/Rh = 100/1) increased the specific surface area (BET area 64 m²·g⁻¹ vs. 55 m²·g⁻¹ for NiBa) and reduced the NiO crystallite size from 250.4 Å to 231.5 Å, indicating improved dispersion of the metallic phase. XPS analysis revealed the coexistence of Rh⁰ and Rh³⁺ species, suggesting that Rh acts as a redox mediator that facilitates hydrogen activation and promotes hydrogen spillover to neighboring Ni sites. Raman and CO₂-TPD results show that Ba-derived domains stabilize carbonate species responsible for CO₂ storage, while Rh enhances catalyst reducibility and modifies the kinetics of carbonate decomposition during the regeneration stage. Transient CO₂–CH₄ pulse experiments demonstrate that the CO₂-SR process proceeds through a dynamic surface cycle involving reversible carbonate formation on Ba-derived basic sites coupled with methane activation on Ni-containing interfacial sites. The results indicate that catalyst performance is governed by a hierarchical surface architecture composed of Ni–O–Ba interfacial domains, reversible Ba–O–Ba carbonate storage sites, and more stable Ba-rich domains. The distribution of these domains, controlled by the Ni/Ba ratio and the dispersion of the metallic phase, determines the reversibility of carbonate formation and the efficiency of the cyclic CO₂ storage–regeneration process. Full article

The Activators Regenerated by Electron Transfer Atom Transfer Radical Polymerization (ARGET-ATRP) of vanillin methacrylate (VMA), a bio-based methacrylic monomer derived from vanillin, was systematically studied for the first time. The reaction conditions were optimized aiming at achieving good monomer conversions while preserving the antimicrobial aldehyde functionality. Bipyridine-based catalysts showed limited effectiveness, whereas polydentate aliphatic amines displayed higher activity. Kinetic studies showed linear profiles during the early stages of the polymerization before reaching a conversion plateau accountable to the depletion of the reducing agent, as confirmed by reactivation experiments. The resulting polymer (PVMA) exhibited a glass transition temperature comparable to that of poly(styrene), emerging as a potential bio-derived alternative to fossil-based thermoplastic materials. Furthermore, preliminary in vitro tests demonstrated that PVMA has potential antimicrobial activity against both Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive). Full article