Cobalt ferrite for direct cracking of methane to produce hydrogen and carbon nanostructure: Effect of temperature and methane flow rate

Cobalt ferrite (CoFe2O4) was used as a catalyst for direct methane cracking. The reaction was accomplished in a fixed bed reactor at normal atmospheric pressure, while gas flow rate (20–50 mL/min) and reaction temperature (800–900 °C) were varied. The fresh CoFe2O4 morphology is sponge-like particle with inverse spinel structure as revealed from SEM and XRD results. The methane conversions and hydrogen formation rate were increased with reaction temperature, while catalyst stability and induction period decreased. Increases of gas flow rate > 20 mL/min led to a decrease the overall catalytic activity of CoFe2O4 for methane cracking. The XRD results of spent catalysts revealed that CoFe alloy was the active phase of methane cracking. TGA analysis showed that the largest amount of deposited carbon was 70.46 % at (20 mL/min, 900 °C), where it was 34.40 % at (50 mL/min, 800 °C). The deposited carbon has the shape of spherical carbon nanostructures and/or nano sprouts as observed with SEM. Raman data confirmed the graphitization type of the deposited carbon

Photocatalytic Synthesis of Coumarin Derivatives Using Visible-Light-Responsive Strawberry Dye-Sensitized Titanium Dioxide Nanoparticles

This study presents a novel method for the photocatalytic synthesis of 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones (a coumarin derivative) using strawberry dye-sensitized TiO2 (SD-TiO2) under visible light. The synthesis of 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones was achieved through a three-component, one-pot condensation reaction involving 3-acetyl coumarin, aldehydes, and urea, utilizing SD-TiO2 as a reusable and innovative photocatalyst at room temperature. The resulting SD-TiO2 photocatalyst was thoroughly characterized using FT-IR, XPS, XRD, SEM, and BET. The efficacy of SD-TiO2 was evaluated by comparing it to pristine TiO2 in terms of photocatalytic activity, and the optimal conditions for the synthesis process were determined. Notably, the SD-TiO2 photocatalyst exhibited a maximum yield of the compound, reaching up to 96% in just 30 min with a catalyst concentration of 1 mg/mL. This yield surpasses traditional thermal procedures employing reflux conditions, where 1 mg/mL of SD-TiO2 is sufficient to complete the reaction. The resulting 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones were further characterized using 1H-NMR and 13C-NMR. Moreover, the stability of the SD-TiO2 photocatalyst was confirmed through recyclability experiments and spectroscopic characterization, demonstrating its practicality for up to three consecutive reaction cycles

Structural diversity in pseudohalide complexes of cadmium(II) with N-methylthiourea (Metu) Polymeric [Cd(Metu)(2)(NCS)(2)](n) versus monomeric [Cd(Metu)(2)(CN)(2)]

International audienceCadmium(II) complexes, catena-poly[bis(thiocyanato-kappa N) bis(N-methylthiourea) cadmium(II)], [Cd(Metu)(2)(NCS)(2)](n) (1) and dicyanidobis(Nmethylthiourea) cadmium(II), [Cd(Metu)(2)(NCS)(2)] (2) were prepared and their structures were determined by single crystal X-ray analysis. In 1, the cadmium(II) ion is bound to four sulfur atoms of bridging Metu ligands and two nitrogen atoms of thiocyanate adopting a distorted octahedral environment. In 2, the geometry around cadmium is distorted tetrahedral attained by two cyanide ions and two methylthiourea molecules bound through the sulfur atoms. The crystal structures of both complexes show intra and intermolecular hydrogen bonding interactions. The complexes were also characterized by IR and NMR spectroscopy and the spectroscopic data were discussed in terms of the nature of bonding. [GRAPHICS]

Influence of Zn and Ni dopants on the physicochemical and activity patterns of CoFe2O4 derived catalysts for hydrogen production by catalytic cracking of methane

Zinc and nickel incorporated CoFe2O4 materials have been synthesized via a wet chemical method. Characterization of these cobalt ferrite based catalysts was undertaken using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and thermal gravimetric analysis (TGA). The catalytic activity of these materials was evaluated by monitoring the direct cracking of methane for the production of hydrogen and carbon. The XRD and SEM results indicated that Ni incorporation preserves the inverse spinel structure of CoFe2O4, whilst Zn incorporation changes its microstructure. The Co 2p, Fe 2p and O 1 s XP spectra confirm the expected oxidation states of the elements in the near surface region of the catalysts. Raman spectra indicate cation redistribution between tetrahedral and octahedral sites upon Ni and Zn incorporation into CoFe2O4. BET surface area analysis revealed Ni incorporation is more effective in increasing the surface area of CoFe2O4 compared to Zn incorporation. Indeed, catalytic activity evaluation showed that Ni incorporation into CoFe2O4 improved methane conversion and correspondingly the hydrogen formation rate. In contrast, Zn incorporation led to very low catalytic activity. The spent catalysts were further characterized and the results are strongly correlated with catalytic activity

Probing the Catalytic Efficiency of Supported Heteropoly Acids for Esterification: Effect of Weak Catalyst Support Interactions

Supported heteropoly acids are an interesting class of solid acid catalysts which possess flexible structure and super acidic properties essentially required for the oil-based biodiesel production. In this study, a series of catalysts containing 25 wt.% of heteropolytungstate (HPW) supported on various clays or SiO2 were prepared, and their catalytic efficiency was evaluated for esterification of acetic acid with heptanol. The as-prepared catalysts were characterized by various techniques including FT-IR spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and BET. The catalytic efficiency of both bulk and supported HPW catalysts for the esterification activity strongly depends on the type of support and amount of catalyst; the bulk HPW catalyst and the catalyst supported by kaolinite with 25 wt.% of HPW exhibited highest activity. In order to study the effect of temperature on conversion, all the catalysts were subjected to different reaction temperatures. It was revealed that esterification activity of both bulk and supported HPW catalysts strongly depends upon the temperature variations of the reaction. Besides, the effect of leaching of active sites on the catalysts performance for biodiesel production was also evaluated by inductively coupled plasma studies (ICP). The kaolinite-supported catalyst (25% HPW/kaolinite) demonstrated higher amount of leaching which is also confirmed by the significant decrease in its catalytic activity when it is used for the second time. However, the higher activity demonstrated by HPW/kaolinite maybe because of some homogeneous reaction indicating a weak catalyst support interaction (WCSI) resulting in the leaching of the catalyst during the test. Furthermore, the effects of other reaction variables such as catalyst loading and reaction time on the conversion of acetic acid were also studied

Optimization of Postural Control, Balance, and Mobility in Children with Cerebral Palsy: A Randomized Comparative Analysis of Independent and Integrated Effects of Pilates and Plyometrics

The paradigm of comprehensive treatment approaches for children with cerebral palsy has gained traction, prompting clinicians to deliberate between independent and integrated treatment delivery. However, this decision-making process is often hindered by the dearth of empirical evidence available to inform optimal therapeutic strategies. This study, therefore, sought to compare the effects of Pilates-based core strengthening (PsCS), plyometric-based muscle loading (PlyoML), and their combination on postural control, balance, and mobility in children with unilateral cerebral palsy (ULCP). Eighty-one children with ULCP (age: 12–18 years) were randomized to PsCS (n = 27), PlyoML (n = 27), or a combined intervention (n = 27; equated for total sets/repetitions) group. The three interventions were applied twice/week over 12 successive weeks. Postural control (directional and overall limits of stability—LoS), balance, and mobility (Community Balance and Mobility Scale—CB&M; Functional Walking Test—FWT; Timed Up and Down Stair test—TUDS) were assessed pre- and post-intervention. The combined group exhibited greater increases in directional LoS compared to PsCS and PlyoML including the backward (p = 0.006 and 0.033, respectively), forward (p = 0.015 and 0.036, respectively), paretic (p = 0.017 and 0.018, respectively), and non-paretic directions (p = 0.006 and 0.004, respectively)], and this was also the case for overall LoS (p p = 0.037 and p = 0.002, respectively), FWT (p = 0.012 and p = 0.038, respectively), and TUDS (p = 0.046 and p = 0.021, respectively). In conclusion, the combined PsCS and PlyoML exercise program promotes considerably greater improvements in postural control, balance, and mobility compared to unimodal training in children with ULCP

Defects oriented hydrothermal synthesis of TiO2 and MnTiO2 nanoparticles as photocatalysts for wastewater treatment and antibacterial applications

Pure and manganese-doped titanium dioxide nanoparticles (MnTiO2-NPs) were synthesized by the defect-oriented hydrothermal approach. The synthesized material was then characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), and UV–visible spectroscopy (UV–Vis). The agar well diffusion method assessed the antibacterial efficiency of TiO2 and MnTiO2-NPs against E. coli and S. aureus. Zone of inhibition (ZOI) formed by pure TiO2 was observed as 12 mm and 11.5 mm against E. coli and S. aureus, while for MnTiO2-NPs it was observed as 19 mm (E. coli) and 21 mm (S. aureus). The concentration of synthesized nanoparticles (10 mg/ml, and 20 mg/ml) was used for antibacterial studies. The efficacy of the pure and MnTiO2-NPs as an active photocatalyst for the degradation of methylene blue (MB) dye was also assessed using a UV light. It was observed that the photodegradation efficiency of 1 g of MnTiO2-NPs was higher than the same amount of pure TiO2. The results suggest that the photocatalyst concentration directly impacts the photodegradation of MB dye. The pH value was found to influence the photodegradation of MB dye at higher pH values. Based on the obtained results, MnTiO2-NPs were observed as a promising agent for microbial resistance and water remediation