Topics in Catalysis最新文献

This work investigates the stability and electron transport kinetics of lindane, a persistent organic contaminant, as it adsorbs onto graphene. The most stable configuration comprises strong interactions between the chlorine atoms of lindane and the (Pi )-electron-rich surface of graphene, as seen by a dominant Boltzmann population (X(_{i})=0.8157 at 298.15 K). By looking at overall reactivity measures like electronegativity, hardness, and electrophilicity, along with specific measures like the Fukui function, this study seeks to understand the interactions at the molecular level that influence how sensors work. dipole moment ((mu )=2.02 D). Fukui function analysis shows that these interactions lead to a significant redistribution of charge, with chlorine atoms acting as the main redox-active sites. The results highlight graphene’s capacity to stabilise adsorbed molecules and promote electron transport, increasing its potential for use in environmental remediation and pollution sensing. Important information about the design of graphene-based sensors for the efficient detection of persistent organic pollutants is provided by the study.

Amides, which contain both oxygen and nitrogen, are present in many potential feedstocks for renewable fuels. There is a consequent need to study the hydrodenitrogenation (HDN) and hydrodeoxygenation (HDO) of amides. This work studies the HDN and HDO of hexadecanamide with sulfided NiMo/(gamma )-(hbox {Al}_2hbox {O}_3) and NiMo/(hbox {TiO}_2) catalysts. The experiments are conducted in a batch reactor, with decalin as a solvent. Hexadecanamide is found to easily undergo either dehydration into hexadecanenitrile or deammonization into palmitic acid. Hydrotreating of hexadecanamide consequently occurs either through an initial HDO step (dehydration) into hexadecanonitrile, followed by reduction and HDN of the resulting hexadecylamine, or through an initial HDN step (deammonization) followed by HDO of the resulting palmitic acid. On both NiMo/(gamma )-(hbox {Al}_2hbox {O}_3) and NiMo/(hbox {TiO}_2), HDN of the amide is slower than HDO. The secondary amine, dihexadecylamine, is a major intermediate, formed through condensation reactions between hexadecylamine and palmitic acid or by the self-condensation of hexadecylamine. Thus, after the initial dehydration or deammonization step, hydrotreating of the primary amide follows the pathways associated with the HDN of primary amines and the HDO of primary carboxylic acids. NiMo/(hbox {TiO}_2) is a more active amide hydrotreating catalyst than NiMo/(gamma )-(hbox {Al}_2hbox {O}_3). This is attributed to (hbox {TiO}_2) catalyzing the initial dehydration (HDO) step, as well as to more complete sulfidation of Mo and the better incorporation of the Ni promoter in the (hbox {MoS}_2) phase on (hbox {TiO}_2).

Ni supported on SiO₂ with various morphologies such as nanocubes, nanorods, nanospheres and dendritic mesoporous silica (DMS) are prepared and employed for zero emission hydrogen production (Turquoise hydrogen). The fresh calcined catalysts possessed NiO (200) planes predominantly while in the reduced samples Ni⁰ (111) planes are majorly exposed irrespective of SiO₂ morphology. Among these the Ni-DMS demonstrated a higher rate of H₂ production while, the Ni/nanorods showed inferior activity. Formation of Ni silicate was found only in case of Ni/nanorods. Ionic Ni reduced below 600 °C seems to exhibit better CH₄ cracking rate, as was depicted from H₂-TPR results. Variation in graphitic carbon was found due to difference in SiO₂ morphology as well as the reducibility of nickel interacted with SiO₂.

Using an annular structured reactor the oxidation of CO and H₂ over silver was studied at temperatures employed during the industrial partial oxidation of methanol to formaldehyde. Silver tubes were systematically exposed to different atmospheres and imaged at regular intervals using scanning electron microscopy to gain insight into both reaction activity and catalyst restructuring. The reactant feed has a profound effect on restructuring, and a “dynamic steady-state morphology” is identified for each gas mixture. The exposed catalysts show clear signs of stepped surface faceting, grain growth and formation of small pinholes (< 1 μm). H₂ oxidation conditions promote the formation of numerous angular surface cavities (> 3 μm). Addition of steam to the feed, however, inhibits the formation of stepped facets. Silver is active towards both CO and H₂ oxidation, and co-feeding both reactants has a synergistic effect. Addition of steam leaves the H₂ oxidation activity unaffected but completely inhibits the formation of CO₂ via CO oxidation. The results clearly show that the effects of H₂O formation are very different from those of H₂O addition and that CO is not a precursor towards CO₂ in the silver-catalysed methanol to formaldehyde system, in which steam is usually co-fed. The systematic approach taken here allows the effects of temperature and gas composition to be decoupled, and the results can be used in future studies to ascribe restructuring features to various reactants.

Calcium Zirconium Titanium Oxide Multiwalled Carbon nanotubes nanocomposites was synthesized by solution combustion method. A carbon paste electrode was used to create a Voltammetric resolution for Copper Zirconium Titanium Oxide Multiwalled Carbon nanotubes nanocomposites. The electrochemical oxidation was carried out in 0.2 M Phosphate buffer solution at scan rate 0.05Vs⁻¹. Electrochemical investigation of L-Dopa, Uric Acid and Tyrosine was studied by scan rate varation by this it has confirmed all analytes shows diffusion controlled process, by varying the concentration of the analytes limit of detection and quantification are obtained and by pH studies number of protons and electron are obtained. Simultaneous study was carried out for L-Dopa, Uric Acid and L-Tyrosine. The CZTO MWCNT nanocomposites MCPE was used for investigation of UA in real sample.

Iron is a crucial trace element in DNA synthesis, oxygen transport and various biological processes. However, iron overdose can result in health issues like liver damage and neurodegenerative disorders. The present study reports a green and eco-friendly route for biosynthesis of lead oxide nanoparticles using Bougainvillea flower extract. The structural and chemical composition of lead oxide was investigated by XRD and XPS methods, respectively. The average diameter size of lead oxide was ~ 400 nm. The lead oxide-modified glassy carbon electrode (GCE) was investigated for electrochemical sensing of iron (III) ions in aqueous solutions. The lead oxide electrodes show a nearly linear increase in peak current density with varying iron concentrations, indicating effective detection capabilities. The lead oxide displayed high sensitivity, selectivity and durability for detecting iron (III) ions with a detection limit of 8.22 mM in the linear detection range of 0-0.1 M. The results highlight oxide-based electrochemical sensors as a promising candidate for real-time detection and quantification of iron (III) ions in aqueous environments.

The selection of appropriate catalysts is critical for the efficient operation of hydrotreaters, due to the diverse types of reactions inherent to the process. In this study, various Type I and Type II sulfided NiMo/γ-Al₂O₃ hydrotreating catalysts were prepared using chelating agents and support modification, and the apparent activity differences were evaluated using step response experiments. The experiments were conducted in a trickle bed reactor at 300 °C and 120 barg using phenanthrene and carbazole as model compounds while the apparent activities were elucidated using dynamic reactor modelling. It was found that the addition of citric acid to the impregnation solution to chelate the Ni leads to an average 30% increase in the active site density for hydrogenation (HDA) and hydrodenitrogenation (HDN), without significantly affecting the reaction rate coefficients suggesting similar activity per active site. Phosphorus modification of the support, however, results in larger reaction rate coefficients for both hydrogenation of phenanthrene as well as adsorption and reaction coefficients for carbazole, resulting in more active catalysts both for HDA and HDN. This enhanced activity is accompanied by increased selectivity to HDN suggesting that catalysts exhibiting higher activity for HDA reactions are more susceptible to inhibition by organonitrogen compounds. In addition, dynamic activity testing indicated that catalysts with superior HDN activity attain their new steady state in the shortest time. Thus, the selection of catalysts for efficient hydrotreater operation necessitates activity testing under dynamic conditions to account for competing and inhibitory reactions, rather than relying solely on steady-state activity. Such an approach, allows for the elucidation of the differences in HDA and HDN activity, providing valuable insights to support the catalyst selection process.

Nepafenac (NPC) is a topical nonsteroidal anti-inflammatory drug used to treat postoperative eye pain and inflammation following cataract surgery. It is also effective against photophobia, intraocular pressure, hyperemia, and itching. However, NPC has side effects, such as dry eyes, eye itching, eyelid flaking or drooping, eye discharge, dizziness, nausea, hypersensitivity, and allergic conjunctivitis (eye allergy). Therefore, the detection of NPC in physiological and biological samples is of great importance. Rapid, inexpensive, and practical advanced analytical methods are required for routine analysis. To date, there have been very few studies on NPC analysis. In this study, a sensitive and reproducible electrochemical sensor was developed for the determination of NPC. Voltammetric measurements were carried out using paste electrodes modified with multi-walled carbon nanotubes (MWCNTs: MWCNT, MWCNT-NH₂, MWCNT-COOH) and polymer-based sensors using monomers (phenylalanine, lysine, glycine, and proline). Among these, MWCNT-NH₂ modified paste electrode (PE) and poly(glycine)-modified glassy carbon electrode (GCE) showed the highest sensitivity and were selected for detailed analysis. Electrochemical behavior and electrode mechanisms of NPC were studied using different voltammetric methods. The optimum signals were observed at pH 9.0 for MWCNT-NH₂PE and pH 10.0 for poly(glycine)/GCE in Britton–Robinson buffer. The linear detection range was 0.4–128.0 µM for MWCNT-NH₂ PE and 1.18–12.98 µM for poly(glycine)/GCE. The limit of detection values (LOD and LOQ) were calculated as 0.025 µM and 0.41 µM, respectively. This work presents an electrochemical method and a new generation sensor that is more sensitive, selective and easy to fabricate than existing analytical techniques for NPC detection.

The urgent demand for high-performance and sustainable energy storage solutions necessitates the development of advanced electrolytes with superior electrochemical properties. Hybrid lithium electrolytes, which integrate the advantages of inorganic and organic ionic conductors, have emerged as promising candidates for next-generation energy storage devices. This review presents a comprehensive bibliometric analysis of 1569 research articles from 2019 to 2024, sourced from Scopus and Web of Science (WOS) databases, highlighting the rising research focus on hybrid electrolytes. Key material properties such as wide electrochemical windows, thermal and chemical stability, low toxicity, and reduced volatility are critical for enhancing battery performance. The discussion encompasses recent advancements in solid-state, polymer, and hybrid electrolytes, emphasizing their role in improving energy density, cycling stability, and safety. Furthermore, this study examines the challenges associated with hybrid electrolytes, including ionic conductivity limitations, interfacial compatibility, and scalability for industrial applications. The integration of novel materials such as NASICON-type ceramics, perovskites, sulfides, and garnet-based electrolytes is explored for their potential to revolutionize lithium-ion battery technologies. By bridging the gap between fundamental research and practical implementation, this review provides insights into the future directions of hybrid electrolytes, paving the way for more efficient and sustainable energy storage systems.

Graphical Abstract