Catalysis Letters最新文献

WVO_x bi-metal oxides supported on the cost-effective industrial mesoprous Al₂O₃, SiO₂, active carbon (AC), and TiO₂–Al₂O₃ with different specific surface areas (WVO/Al₂O₃, WVO/SiO₂, WVO/AC, and WVO/TiO₂–Al₂O₃) were designed and prepared through co-impregnation method for large-scale bio-glycerol dehydration to acrolein. The XRD, BET, SEM–EDS, XPS, and NH₃-TPD characterization results revealed the WO₃–VO_x (V⁴⁺/V⁵⁺) species existed with better dispersion, lower molar ratio of V⁴⁺/V⁵⁺, and enhanced strength of surface acid sites on the developed mesoporous TiO₂–Al₂O₃ in comparison with that on the mesoporous Al₂O₃, SiO₂, and AC, demonstrating strong interaction of WO₃–VO_x species with the TiO₂–Al₂O₃ support and accounting for the acrolein selectivity over catalysts following the order of WVO/TiO₂–Al₂O₃ (75.8%) > WVO/AC (71.2%) > WVO/SiO₂ (55.3%) > WVO/Al₂O₃ (42.8%). Over the WVO/TiO₂–Al₂O₃, gas-glycerol conversion reached above 97.0% with acrolein selectivity of about 75.0% under the gas hourly space velocity (GHSV) of 120–360 h⁻¹, and maintained an improved catalytic stability.

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The acrolein selectivity over the prepared catalysts followed the order of WVO/TiO₂–Al₂O₃ > WVO/AC > WVO/SiO₂ > WVO/Al₂O₃, Among them, the WVO/TiO₂–Al₂O₃ catalyst demonstrated a low V⁴⁺/V⁵⁺ ratio, surface acid sites, and exceptional catalytic performance with a gas-glycerol conversion rate of 97.2% and an acrolein selectivity of 75.8%. Even after continuous reaction for 16 h, both gas-glycerol conversion and acrolein selectivity remained above 75% and 90%, respectively. This study presents a remarkable advancement in the development of industrial catalysts with outstanding performance in terms of efficiency, stability, and cost-effectiveness. Moreover, this catalyst shows great promise for its utilization in acrolein synthesis via glycerol dehydration.

Residual chlorine has a bactericidal effect, but it may react with natural organic matter in water to produce harmful substances. In this work, we report an efficient residual chlorine removal filter with activated carbon fiber (ACF) as adsorption carrier and CuO as residual chlorine degradation catalyst. Experimental results show that CuO has high catalytic efficiency and no attenuation of catalytic performance in 2924 h. The CuO is loaded on the surface of ACF by dipping-calcinating method. When the loading rate is 1.5%, the CuO distribution is uniform without defects and agglomeration. Continuous-flow experiment result shows that 1.5%-CuO/ACF filter can treat water amount 2.2 times as long as that for single ACF filter (residual chlorine concentration < 0.1 mg/L). Weak acidity and rising temperature can improve the reaction activity and increase the degradation amount of residual chlorine. The composite filter has excellent adsorption performance for Cu²⁺, showing the Cu²⁺ concentration in the produced water is less than 0.1 mg/L after filter treatment, which is in line with the National Drinking Water Standards, and in agreement with the Standard for Safety Assessment of Water Transmission and Distribution Equipment and Protective Materials for Drinking Water (GB/T17219-1998) of Immersion Experiment, indicating that 1.5%-CuO/ACF filter has good stability and safety.

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Efficient production of H₂ by combined (steam/CO₂; steam/O₂) reforming of CH₄ was comparatively studied over perovskite-derived promoted Ni catalysts. The process performance was improved by regulating the redox and structural properties of the LaNi_0.99M_0.01O₃ catalysts through promotion (M = Pt, Pd, Re, Mo, Sn). The catalysts were synthesized using the citrate sol–gel method, tested in combined reforming of methane and studied by X-ray fluorescence analysis, thermal analysis, N₂ adsorption, X-ray diffraction, electron microscopy, temperature-programed hydrogen reduction to elucidate the impact of catalyst properties on their activity and resistance to re-oxidation and formation of carbon deposits under reaction conditions. It was shown that LaNi_0.99M_0.01O₃ catalysts after calcination at 850 °C in air have a perovskite structure that was destroyed after reductive activation with formation of metal Ni^o particles with an average size of ~ 25 nm on the surface of lanthanum oxide/hydroxide. The resistance to re-oxidation of Ni^o particles depends on the type of promoter and is maximum in the case of M = Re. It was established that the type of promoter affects the conversion of reagents (CH₄, CO₂) and the H₂ yield, which at 700 °C increases in the series of promoters Sn < Mo < Pt < Pd < Re in the case of steam/CO₂ reforming and Pt < Sn < Mo < Pd < Re with steam/O₂ reforming. The optimal composition of catalyst was identified: among the studied samples, LaNi_0.99Re_0.01O₃ is characterized by a higher specific surface area, average reduction ability and high resistance to re-oxidation and coking. At 850 °C it provides the H₂ yield of 95 and 50% at complete CH₄ conversion in steam/CO₂ and steam/O₂ reforming, respectively.

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A modified two-step coprecipitation method has been formulated to prepare a series of model CuZnO/Al₂O₃ catalysts for methanol synthesis from syngas. Evaluation at industrially relevant condition showed slightly higher activity and much higher stability for model catalysts than for a commercial catalyst. Due to the same CuZn-binary precursor, the model catalysts had similar structural properties with large specific surface area and pore volume, small CuO crystallites and good reducibility, resembling that of the commercial catalyst. However, the model catalysts showed much better uniformity of alumina distribution, which accounted for their better performance. Strong positive correlation between the deactivation rate and the coefficient of variation of Al/Zn indicates the uniformity of alumina distribution plays an important role in determining stability. Specifically, CuZnO/Al₂O₃ catalysts with alumina distributed more uniformly had higher stability. This work demonstrated that the formulated modified two-step coprecipitation could provide excellent CuZnO/Al₂O₃ catalysts for industrial applications. Additionally, it also affords new clues for the development of even better industrial catalysts.

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Remediation of antibiotics by photocatalysis technique has been regarded as a promising route to tackle with the environmental pollution affecting human survival and development. In this work, brookite TiO₂ nanorods with different oxygen vacancy have been synthesized through tailoring the volume of ethylene glycol by hydrothermally treatment with NaTiOx-nanoassembly. After constitute and morphology confirmation with different characterizations, their photocatalytic performances are evaluated via ciprofloxacin (CIP) antibiotic degradation experiments. The result shows that the TiO₂-0 has the highest photocatalytic efficiency towards CIP degradation, comparing with TiO₂-15 and TiO₂-30 samples. Although the TiO₂-30 has high concentration oxygen vacancy, it exhibits excellent adsorption ability in the dark, rather than CIP degradation rate. The photo/electrochemical tests suggest the photo-generated electron lifetime, charge transfer ability, and the effective active sites on the material’s surface are inversely proportional to the concentration of oxygen vacancies. It also concludes that rational fabrication conditions tailoring of the photocatalyst could optimize the corresponding capability in the antibiotic degradation process. In addition, the possible degradation pathway is also proposed based on the high resolution mass spectrometry (HRMS), and the acute toxicity changes in the degradation process are also predicted.

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The increasing global demand for fuel, along with pressing environmental regulations and concerns, and the need for energy security, all point to the biofuel industry seeing rapid growth in the near future. The objective of this study was to study the performance of a series of activated carbon (AC) supported La and Ce oxide catalysts in the catalytic cracking of waste cooking oil into alkane-based hydrocarbon. Coconut-shell activated carbon was loaded with various amounts of lanthanum and cerium were prepared via wet impregnation. The catalytic cracking activity was evaluated in a fixed bed reactor under N₂ flow at 450 °C and a weight hourly space velocity of 8 h⁻¹ at 60 min. The physical and chemical properties of the prepared catalysts were characterized by BET, SEM–EDX, XRD, TPD-NH₃/CO₂, FTIR, and TGA. The results indicated that 5 wt% La/AC performed superiorly with a liquid product of 87.03% which composed of 99.09% hydrocarbons, that were mostly alkane (79.89%) with n-(C₁₅ + C₁₇) 66% selectivity (66.13%).

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Copper-Nitrogen-Carbon (Cu-N-C) materials, derived from zeolite imidazolium frameworks, serve as promising carriers for catalyzing glycerol carbonylation reactions due to their modifiable pore size structure, enhanced catalytic selectivity, and stability. However, conventional palladium loading often results in the susceptibility of Cu-Pd co-catalysis loss, impeding practical application. In this investigation, we employed an in-situ confinement technique to embed polyvinylpyrrolidone (PVP)-modified palladium nanoparticles within the Cu-ZIF-8 metal framework, followed by direct calcination under a nitrogen atmosphere. This method yielded uniform-sized and shaped copper-palladium alloy catalysts, denoted as Pd@Cu-NC. Comparative analysis with catalysts prepared via impregnation followed by calcination revealed significantly enhanced stability of the resulting Pd@Cu-NC catalysts, with improved selectivity and stability of the active components. Notably, catalyst stability was markedly improved, and active component loss was mitigated. Under optimized conditions, a remarkable yield of 90.14% and selectivity of 99.91% were achieved, while retaining 77.43% activity after five cycles. Furthermore, density functional theory (DFT) calculations were employed to simulate the kinetics of carbon monoxide adsorption and glycerol dimethyl acetal (DMA) solution on various substrates. The presence of copper oxide notably reduced the adsorption energy of substrates to carbon monoxide and reaction solutions, thereby lowering the reaction activation energy and enhancing the reaction rate. This computational analysis provides further evidence of the beneficial role of copper oxide in facilitating the carbonylation reaction.

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CO₂ regeneration and reutilization is considered to be a green and effective route with highly potential for development. CeO₂ showed high catalytic activity for the production of N,N′-dibutylurea through n-butyl amine and CO₂. Herein, V-doped CeO₂ with different molar ratios of V/Ce (V_x%-CeO₂, x = 0, 0.4, 0.6, 0.8 and 1.0) were further successfully synthesized and firstly applied to the reaction of CO₂ with n-butyl amine. The reaction results displayed the catalytic performance of CeO₂ were prominently enhanced by doping V⁵⁺ and followed an order of V_0.8%-CeO₂ > V_0.6%-CeO₂ > V_1.0%-CeO₂ > V_0.4%-CeO₂ > CeO₂. The reason for the changes in the catalytic activities of CeO₂ with different doping amounts of V⁵⁺ could be closely related to the surface oxygen vacancy and surface weak acidity and weak basicity based on specific analysis of relevant characterization including XRD, BET, Raman, XPS, EPR and NH₃/CO₂-TPD.

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The decomposition mechanism of dyes under the synergistic effect of pyroelectric catalysis and photocatalysis was systematically investigated using a BaTiO₃/NiB catalyst in this paper, and the degradation efficiency of BaTiO₃/NiB was 97.5% under light and 24 cycles of hot and cold at 25 ~ 65 °C, showing high pyroelectroic catalytic RhB decomposition activity and excellent recoverability. The degradation rate constants of RhB chromophore degradation by Pyro-photocatalytic coupled were 3.2 times as high as those of photocatalysis and 11.8 times as high as those of pyroelectric catalysis. In this study, we used light-assisted electrodeposition to deposit a thin layer of amorphous NiB acid salts onto the surface of a BaTiO₃ photoelectrode aiming to explore its influence on photocharge separation and the catalytic mechanism of NiB in the context of pollutant degradation. The synergies between the pyroelectric internal field and the amorphous Ni–B acid salt thin layer during photogenerated charge separation were extensively explored in this paper, including the introduction of a port for pyroelectric polarization.

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The Co/Co-Nx-embedded mesoporous 3D flower-like carbon sheet (Co/Co-N-MC-800) catalyst is successfully prepared from high N content H-1,2,4-Triazol-3-amine organic-ligand at different pyrolysis temperatures based on in situ pyrolysis Co-metal organic frame (MOF) (Co-PTA-MOF) precursor under nitrogen. The metal active center of the mesoporous Co/Co-N-MC-800 catalyst with more defect sites is situated in the positively charged 0 ~ + 2, and the bond spacing is consistent with the Co-N₄ plane structure of the co-porphyrin. The obtained Co/Co-N-MC-800 possesses an excellent oxygen reduction reaction performance with a higher onset potential (0.92 V vs RHE) and half-wave potential (0.76 V vs RHE), which is closer to Pt/C and outstanding long-term stability with 89.1% current retention after 89 h and displays an optional power density of 1079.3 ± 22.5mW·m⁻² in air-breath cathode microbial fuel cell (MFC). The improved catalytic performance maybe attributes to combination of the special 3D nanostructure, embedded cobalt nanoparticles (forming Co-N_x) and N-doped mesoporous carbon sheet material. The present study provides the technical and theoretical basis for the ORR through the cathode modification of MOF prepared from non-precious metal and N content organic-ligand.

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