Catalysis Surveys from Asia最新文献

One of the most difficult gases to convert in automobiles exhaust is propane (P), which has a substantial impact on an after–treatment system’s ability to minimize emissions. To catalytically totally oxidize propane, silver nanoparticles (AgNPs) with mass loadings ranging from 1 to 3 weight percent (0–3AgNPs/CeO₂) were embedded on CeO₂ support. Because AgNPs and CeO₂ support have a strong metal support relationship, the dispersion of AgNPs on CeO₂ support significantly facilitates the reducibility of Ce (Ce⁴⁺ to Ce³⁺) and increases oxygen vacancies on the oxygen sublattice of Ce. With regard to the propane oxidation reaction, the 2Wt.% AgNPs loaded CeO₂ catalyst (2AgNPs/CeO₂) shows the maximum propane conversion (X_P), the lowest T₉₀ (temperature required to degrade 90% of P), the lowest T₅₀ (The required temperature to degrade 50% of P), and Ea(lowest activation energy).These benefits result in an excellent efficiency on Ag/CeO₂ when propane is completely oxidized at low temperatures.This study will provide a thorough understanding of the electronic relationships between the metal and the active surface of supports, which will aid in the development of more effective exhaust catalysts.

Rare-earth (RE) ion doping of spinel ferrite nanoparticles has emerged as a strategic route to tailor their physicochemical and photocatalytic properties for advanced wastewater treatment. In this study, nickel ferrite (NiFe₂O₄) nanoparticles doped with Neodymium (Nd^3⁺), Dysprosium (Dy^3⁺) and Praseodymium (Pr^3⁺) with the formula NiFe_1.90RE_0.1O₄ were synthesised via sol–gel auto-combustion method and systematically characterised using X-Ray Diffraction (XRD), Fourier-Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray (EDX) spectroscopy, Ultraviolet–Visible (UV–Vis) absorption spectroscopy and Vibrating Sample Magnetometry (VSM). RE doping induced lattice distortions, reducing crystallite size from 57.3 to 9.3 nm and enhancing surface reactivity. FTIR analysis revealed shifts in metal–oxygen vibrational modes, confirming the successful incorporation of RE ions. UV–Vis studies revealed a pronounced narrowing of the band gap from 2.44 to 1.36 eV, improving photon absorption and charge carrier excitation. Magnetic measurements revealed a decrease in saturation magnetisation and coercivity, indicating a soft magnetic behaviour suitable for facile catalyst recovery. Photocatalytic experiments under UV irradiation demonstrated an excellent enhancement in Crystal Violet dye degradation efficiency from 27 to 92%, within 90 min. This augmented catalytic performance is attributed to the synergistic effects of increased surface area, band gap tuning, oxygen vacancy formation and suppressed charge recombination. The catalysts retained over 88% efficiency after three cycles, underscoring their reusability and magnetic recoverability. These findings position RE-doped NiFe₂O₄ as scalable, high-performance photocatalysts for industrial wastewater remediation.

The present work reports the synthesis of heterogeneous catalyst from egg waste shell for biodiesel production from date seed oil to develop sustainable energy process and present viable solution for wastes management. Hydroxyapatite was successfully derived from the egg shells which was later modified with different loadings of Bismuth. The presence of various elements such as Calcium, Phosphorous and Bismuth in the catalyst plays a vital role in its activity. The various physiochemical properties of the designed catalyst (Bi-HAP) were thoroughly probed with different analytical techniques such as XRD, FTIR, FESEM and BET analysis. Amongst the designed catalysts, 10 wt% Bismuth loading provided highest FAME yield of 86% under the following optimum reaction conditions. i.e., 64 °C reaction temperature, 12:1 methanol to oil molar ratio, 5 wt% catalyst amount and 2-h reaction time. The results reveals that the synergism among the metals in 10 wt% Bi-HAP catalyst was more profound which provided greater number of active sites for efficient conversion of date seeds oil to biodiesel as compared to the other catalysts. Moreover, the designed catalyst showed multiple reused capability, indicating substantial chemical stability. The date seeds biodiesel also possessed good fuel characteristics complying with the ASTM standards. Thus, the designed catalyst provides cheap and sustainable approach for biodiesel production from the wastes.

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It is reported on the formation and functioning of platinum-containing nanoparticles generated in situ, which are active intransfer hydrogenation of model N- and O-heterocyclic compounds such as 1-methyl-1H-indole and furfural. The averagesize of the particles was determined by TEM, and their qualitative composition was established using electron diffractionand energy dispersive X-ray spectroscopy.

This research article discussed the synthesis of bimetallic Pd-Cu/CeO₂ catalysts for NO removal using selective catalytic reduction (SCR) and H₂ as a reducing agent. The CeO₂ support was synthesized using both hydrothermal and precipitation methods. The catalysts were characterized through several analytical techniques, including X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The catalysts consisted of 25 wt% Cu and 0.4–1.2 wt% Pd. Among the catalysts, the one supported on CeO₂ prepared via the hydrothermal method exhibited the highest catalytic activity for NO reduction. Incorporating Pd and Cu into the CeO₂ support significantly improved NO conversion and selectivity. The optimal performance was observed with the bimetallic catalyst containing 0.4 wt% Pd and 25 wt% Cu on hydrothermally synthesized CeO₂, achieving a NO conversion rate of 45.64% at 250 °C. As the Pd content increased, NO conversion and N₂ selectivity reached 80% and 90% for the Pd-Cu/CeO₂ catalyst.

Developing active lower Mn −based metal oxides through the addition of non−noble metal oxides like Fe₂O₃ as a promoter is the most cost−effective technique for generating active heterogeneous catalysts for diverse oxidation processes. In this paper, we provide Fe₂O₃−Mn₂O₃ mixed oxides for the aerobic oxidation of benzyl alcohol (BA) into benzaldehyde (BZA) in the absence of a solvent, using molecular O₂. The insertion of Fe₂O₃ on Mn₂O₃ support improves the reducibility of Mn and surface adsorbed oxygen (O_ads) by forming crystal defects on the Mn₂O₃ surface via Mn and Fe atom exchanges. Fe₂O₃ significantly increases the Mn₂O₃ catalytic activity of the BA catalytic oxidation process. The conversion rate of benzyl alcohol (X_BA) is 3.2 times that of bare Mn₂O₃. The structural development of bare Mn₂O₃ and its varied Fe₂O₃−loaded catalysts has been thoroughly studied using spectroscopic techniques such as XPS, P−XRD, BET, and SEM examination. Furthermore, the effect of reaction parameters such as temperature, different wt% of Fe₂O₃ loading, catalyst quantity, and O₂ flow rates on the BA oxidation reaction has been carefully examined.

Cobalt phosphate Co₃(PO₄)₂ (CoPO) was synthesized by wet chemical method in the presence of oxalate for its application as a heterogeneous Fenton-like catalyst to remove Basic Yellow 28 (BY-28) dye from water. The formation of the CoPO phase was confirmed by XRD analysis, revealing a crystallite size of 27  nm. The optimal synthesis temperature was found to be 800 °C based on thermal analysis. The modified synthesis method allows for obtaining a homogeneous distribution of spherical grains with surface area of 3.78 m² g⁻¹. The catalytic activity is attributed to hydroxyl radicals (HO·) generated through the activation of hydrogen peroxide (H₂O₂). The degradation rate decreased to 10% after 300 min in the presence of 500 mM tert-butyl alcohol (TBA), a well-known HO· scavenger. Several reaction parameters influencing the Fenton-like process were investigated and the highest BY-28 degradation yield was achieved under neutral pH with a CoPO dose of 1.25 g/L and H₂O₂ concentration of 50 mM. The catalyst was successfully reused five times, maintaining a removal efficiency of 80% after 60 min with a good crystallinity revealed by XRD analysis. Moreover, other organic dyes commonly found in the textile wastewater were also degraded. The kinetic study revealed that the degradation reaction of BY-28 follows the Behnajady-Modirshahla-Ghanbery (BMG) model, while the thermodynamic analysis indicated that the process is non-spontaneous and endothermic. This study offers valuable insights into the performance, kinetics, and thermodynamics of cobalt phosphate-based Fenton-like catalysts for the degradation of organic dyes, highlighting their potential as effective candidates for such applications.

In this study, a magnetic TiO₂/Co_0.6Cu_0.25Zn_0.15Fe₂O₄ heterostructure was developed in an attempt to degrade pharmaceutical drugs and to enable separation of the catalyst from the wastewater after the process. Magnetic nanoparticles Co_0.6Cu_0.25Zn_0.15Fe₂O₄ are obtained by co-precipitation method using (cetyltrimethylammonium bromide, CTAB) as surfactant. Further, the Co_0.6Cu_0.25Zn_0.15Fe₂O₄ nanoparticles are mixed from the very beginning with the titanium precursor solution. The calcination crystallizes the TiO₂ and promotes the jonction of magnetic nanoparticles to the surface of titania. X-ray diffraction and Raman confirm that the TiO₂/Co_0.6Cu_0.25Zn_0.15Fe₂O₄ heterostructure consists of consists of Co_0.6Cu_0.25Zn_0.15Fe₂O₄ and TiO₂ phases without any additional peaks, indicating a successful integration of the two materials. The integration of Co_0.6Cu_0.25Zn_0.15Fe₂O₄ with TiO₂ leads to non-uniform distribution of spherical particles. Spectra of UV-Vis absorption of the TiO₂/Co_0.6Cu_0.25Zn_0.15Fe₂O₄ displays a notable redshift compared to pure TiO₂. The photocatalytic effect of the TiO₂/Co_0.6Cu_0.25Zn_0.15Fe₂O₄ in two applied pharmaceutical drugs was higher than in commercial Degussa P-25 and TiO₂ under real sunlight. It was reported that TiO₂/Co_0.6Cu_0.25Zn_0.15Fe₂O₄ had 94.2% degradation on paracetamol and complete degradation for ofloxacin within 150 min. The improvement in the photocatalytic activity can be attributed to the efficient charge carrier separation at the interface of TiO₂/Co_0.6Cu_0.25Zn_0.15Fe₂O₄ heterostructure. A possible photocatalytic mechanism for drugs degradation by TiO₂/Co_0.6Cu_0.25Zn_0.15Fe₂O₄ was proposed based on the results of trapping experiments and the energy bands of TiO₂ and Co_0.6Cu_0.25Zn_0.15Fe₂O₄. The recyclability of the photocatalyst was ascertained over five consecutive cycles, indicating the stability of the catalyst.

The need for sustainable and eco-friendly fuel alternatives has grown due to practical considerations in recent years. Biodiesel has garnered significant interest as a promising petroleum diesel substitute due to its renewability, biodegradability, and free of sulfur. However, developing advanced and highly efficient heterogeneous catalysts is crucial in the biodiesel production. Among various heterogeneous catalysts, metal–organic frameworks (MOFs) have become the key catalytic materials because of their distinctive and fascinating characteristics. Among the currently explored MOFs, ZIFs have undergone many studies, including catalysis, separation, and sensing, owing their simple and fast preparation process, ultrahigh surface areas, and well-defined active sites. In this review article, the current advances of different types of MOF-based catalysts to accelerate biodiesel production have been discussed. More importantly, it aims to summarize critically the performance, characterization, and reusability of various ZIFs-based catalysts (single ZIFs catalysts, supported ZIFs-based catalysts, and ZIFs-derived catalysts) in catalyzing the production of sustainable biodiesel. Finally, the limitations, the challenges, and future developments of ZIFs-based hybrid catalysts are also proposed, hoping that this timely review can be useful for researchers in promoting sustainable biodiesel generation and other relevant biorefineries using ZIFs-based catalysts.

This study involved the fabrication of a novel catalyst based on natural clay via straightforward co-precipitation technique. Fe₃O₄ magnetic nanoparticles and cellulose covalently grafted onto the Halloysite nanotubes (HNTs) after being functionalized with perchloric acid (Fe₃O₄@HNTs-Cellulose-HClO₄). It was characterized by using different analytical techniques to confirm its formation, including Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) pattern, Energy dispersive X-ray (EDAX) analysis, Thermogravimetric analysis (TGA), and Scanning electron microscopy (SEM). This novel heterogeneous catalyst was effectively applied in the synthesis of 4-aryl-4H-pyran-3-carboxylate using an aromatic aldehyde, ethyl acetoacetate and malononitrile and Tetrahydro-4H-chromene using an aromatic aldehyde, dimedone and ethyl cyanoacetate. Gentle reaction parameters, minimal catalyst costs, environmental friendliness, and excellent product yields (97 & 96% respectively) are some of the primary advantages of this approach. The catalyst is easily separated and can be recycled five times without experiencing a noticeable decrease in activity and the hot filtration test demonstrated the catalyst’s heterogeneity. With mild reaction conditions and room temperature, easy purification, simple workup, and excellent yields this heterogeneous catalyst demonstrated high efficiency in green media.

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