Topics in Catalysis最新文献

Ammonia, essential for agriculture fertilizers and as an energy carrier, is traditionally produced by the energy-intensive Haber–Bosch process, which is a significant energy consumer and a notable contributor to CO₂ emissions. The electrochemical nitrate reduction reaction (NO₃RR) to produce ammonia presents a promising and environmentally friendly solution, allowing to reduce NO₃⁻ contamination in waste water resources. This review covers recent trends in noble and non-noble metal-based catalysts, single-atomic metal catalysts, and metal-free catalysts for NO₃RR. Specifically, it was found that transition metals were effective in enhancing electron transfer in the NO₃RR due to their d-orbital energy levels. Furthermore, alloys or single atomic catalysts with transition metals have been studied to improve NO₃RR performance by adjusting the crystal plane or generating oxygen vacancies. Metal-free catalysts have been investigated and have exhibited great potentials in the NO₃RR. It was revealed that tuning the electronic properties can effectively suppress the side reactions and increase the ammonia yield and Faradaic efficiency. This review aims to provide guidance for catalyst design and performance improvement in future NO₃RR research.

Abstract

In this work, a convenient, low cost and fast detection of glucose (GO) in human blood has been investigated. For this purpose, a non-enzymatic sensor based on the hydrothermally prepared cobalt hydroxide nano-catalyst was fabricated and used for analysis of GO level in biological fluids. The electrochemical ability of the modified glassy carbon electrode (GCE) for GO measuring was studied by cyclic voltammetry and chronoamperometry assays. The chronoamperometric data indicate that the proposed sensing platform is capable of measuring changes in GO levels within a linear range of 1.5–460 µM and low detection limit of 0.8 µM. The cobalt hydroxide modified GCE depicts a significant resistant versus common interfering species such as fructose, cholesterol, ascorbic acid, l-cysteine and uric acid. In addition, the suggested GO sensor was employed for determination of analyte concentration in blood samples from athletes. This novel platform is characterized by its low price, simple operation, high anti-interference property and high sensitivity. The experimental results proved that the cobalt hydroxide modified GCE is an effective strategy for non-enzymatic GO detection in clinical applications.

NiMoS/TiMg and NiWS/TiMg nanocatalysts were synthesized, characterized by various techniques and tested in the hydrodesulphurization (HDS) of dibenzothiophene (DBT). TiMg mixed oxides containing 5, 10 or 15 wt% of MgO were prepared by sol–gel and then used as catalyst supports. A constant atomic ratio of Ni/(Ni + M) = 0.5 was kept for all the catalysts (M = Mo or W). The catalysts were first prepared by sequential-wet impregnation. Then, after an ex-situ sulfidation process, they were characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), and physisorption of N₂ following the BET method. The presence of MgO in the NiMoS/TiMg and NiWS/TiMg catalysts resulted in an enhancement in the HDS activity of DBT. In addition, their HDS activities were higher than those observed in the NiMoS/Ti and NiWS/Ti catalysts. Furthermore, higher HDS activity was found for the NiMoS/TiMg compared with their NiWS/TiMg catalysts counterpart.

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Abstract

Dimethyl ether (DME), one of the proposed targets for CO₂ recycling, is a very attractive renewable energy source due to its non-toxic nature, low environmental impact, and hydrogen (H₂)-carrying abilities. The thermal catalyzed reaction of CO₂ to DME requires two steps with different catalysts, and the combination and optimization of these catalysts are of great importance for achieving viable DME yield that would make future industrial implementation possible. The thermodynamics and reaction mechanisms of the CO₂ conversion to DME were discussed. The metallic and acidic catalyst functions utilized for this reaction are analyzed in this review, and the different methods of combination are presented with a focus on hybrid catalysts to achieve successful and efficient catalyzed reactions with optimized DME yield. Additionally, an outlook for future directions in catalyst development and mechanistic understanding in this largely overlooked area are provided.

Nitrogen and phosphorous compounds are significant pollutants in urban stormwater runoff. In this study, three lab-scale bioretention cells, namely a control reactor CM, and reactors M1 and M2 containing Scrap Iron Filings (SIF) with granulated brick (M1) and pumice pellets (M2), respectively, were used to evaluate the simultaneous removal of nitrate, nitrite, ammonia, total nitrogen, phosphorous, and COD using simulated runoff. Under unsaturated conditions, M1 with the ZVI-brick combination removed 91.37% TP, while M2 with the ZVI-pumice combination removed 89.76% TP. Under saturated conditions, M2 removed 72.02% TN, and M1 removed 66.1% TN. It was found that the presence of saturation zones benefitted TN removal which can be attributed to the creation of anoxic conditions within saturation zones, which favoured denitrification, as well as the prolongation of influent retention and reaction time, while it hindered TP removal. TP removal percentages for CM, M1, and M2 declined from 86.77%, 91.37%, and 89.76% in unsaturated conditions to 63.99%, 83.67%, and 71.74% in saturated conditions due to the propensity of soil-bound P to leach in anoxic environments. The media amendments were further characterized using Scanning Electron Microscopy (SEM) and X Ray Diffraction analysis (XRD), as well as adsorption and leaching tests. Significantly, the highest pollutant leaching was observed in the assessed conditions for CM, underscoring the usefulness of including media like ZVI, brick powder, and pumice pellets. This incorporation not only heightened the effectiveness of pollutant removal but also fortified their retention in potential future stormwater events. In consideration of this, M1 emerged as the preferred design option, as its non-leaching characteristics were verified through flushing with distilled water after post-stormwater influent loading cycles when compared to traditional designs.

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Emerging pollutants, also referred to as emerging contaminants, are substances that have recently been recognized or are gaining attention due to their potential adverse impacts on the environment, human health, or ecosystems. These pollutants present a significant threat to both environmental and human well-being and are challenging to eliminate using conventional remediation methods. Extremophiles, organisms adapted to extreme environmental conditions like high or low temperatures, high pressure, and elevated salt concentrations, play a crucial role in this context. They produce a diverse array of enzymes capable of breaking down complex organic compounds, some of which remain stable and functional even in harsh environmental conditions, making extremophiles well-suited for use in bioremediation applications. Numerous studies have demonstrated the capability of extremophiles to degrade various pollutants, including toxic solvents, heavy metals, and industrial chemicals. Halophilic archaea, a type of extremophile, have particularly shown promise in degrading emerging contaminants in salt marsh sediments. Despite their potential, there are challenges associated with using extremophiles in bioremediation, such as the limited availability of extremophilic microorganisms capable of degrading specific pollutants and a reduction in enzyme stability when operating outside their optimum range. Nevertheless, ongoing research in this field is anticipated to result in the development of new and innovative bioremediation strategies for effectively removing emerging pollutants from the environment.

The ever-increasing demand for sustainable diesel production, driven by depleting fossil fuel reserves, escalating prices, and environmental concerns has led to an intensive exploration of biodiesel as an alternative. Although chemical catalysis has been a dominant strategy for biodiesel synthesis due to its rapid reaction rates, its limitations in handling low-grade feedstock, susceptibility to product contamination, and high-temperature and pressure demands have prompted a paradigm shift toward lipase catalysis. Lipases, renowned for their ability to function under moderate conditions and prevent product contamination, present an appealing substitute. However, their extensive adoption is hindered by their inherent high cost. To address this challenge, investigators have turned their attention to immobilizing lipases on various support materials, aiming to enhance stability and recyclability and ultimately make lipase-catalyzed biodiesel economically viable on a commercial level. This review provides a comprehensive overview of the raw materials employed, the lipase action mechanism at the interfacial level, and a detailed discussion of the recent works carried out in both traditional and innovative immobilization techniques. The discussion encompasses diverse support materials and factors influencing biodiesel manufacturing, thereby illuminating the dynamic landscape of immobilized lipases in the synthesis of biodiesel. Throughout this paper, our objective is to furnish insights into the current state of the field, pinpoint key challenges, and articulate a roadmap for future research endeavors in the pursuit of sustainable and economically viable biodiesel production.

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Quercetin (QCT), as an important flavonoid, has different properties including neuroprotective, anti-hyperlipidemia, decreasing blood pressure and neuroprotective effects. Hence precise determination of quercetin is noteworthy. Herein, a fast, simple, highly sensitive, and new fluorescent sensor was prepared based on Achillea Millefolium extract carbon dots stabilized on sodium alginate structure (CD/Na-Al). For confirm the reliability of synthesized sensor some characterization analysis were performed such as FT-IR and TEM. The CD/Na-Al was applied for the accurate recognition and measurement of QCT molecule. The operation mechanism for the analytical procedure was based on ‘‘turn-off’’ the fluorescence emission signal in 440 nm. The dynamic linear range was obtained in the range of 1–25 and 25–110 µM, with detection of limits equal to 0.32 and 3.9 µM respectively. The observations confirmed that the present method was able to detect trace amounts of quercetin in black tea and sur cherry with satisfy results.

Abstract

Enzymes are essential biological catalysts that can accelerate multiple reactions. Their outstanding catalytic properties make them highly valuable in different research fields and industries including pharmaceutical, sensing, food, and agriculture. However, the catalytic attributes of free enzymes are limited by their poor stability and resistance to harsh conditions. Recently, the conjugation of different enzymes with carbon dots (CDs) has been explored as a novel strategy for tuning their catalytic properties. CDs possess unique and tunable characteristics such as light stability, electron transfer properties, lower toxicity, cost-efficiency, and outstanding biocompatibility; thus, they represent excellent options for the conjugation of different enzymes to improve their stability, selectivity, and catalytic efficiency. Recently, various CDs-based nano-biocatalysts have been successfully prepared with superior performances compared to their free enzymes. Therefore, this review aims to discuss the most recent reported studies in the synthesis of CDs-based nano-biocatalysts providing an overview of current methodologies and recent research applications. Lastly, we delve into the prospects and the future possibilities of such innovative conjugates that entail an exploration of the faced challenges and their untapped potential for various applications.

In this work, CuFe₂O₄ nanoparticles (NPs) were created using a hydrothermal process. The form and size of the obtained CuFe₂O₄ NPs were characterized using XRD and TEM techniques. The Scherrer equation and XRD measurements revealed that the crystal size of nanoparticles was 10.79 nm. The TEM study of nanoparticles with an average size of 7.673.75 nm revealed a distinctive core–shell structure. The methanolysis on NaBH₄ at various parameters was used to assess the catalytic activity of NPs. The results showed that CuFe₂O₄ NPs are an effective catalyst for the methanolysis of NaBH₄ in alkaline solutions, as demonstrated by the activation energy of 33.31 kJ/mol and turnover frequency (TOF), which was estimated as 2774.61 min⁻¹ under ambient circumstances. These obtained NPs also showed an excellent (92%) reusability. A deep neural network architecture was determined using a neuro-evolutive approach based on a genetic algorithm to model the process and predict the catalyst performance in changing operating conditions. The determined models had a correlation > 0.9 and a mean squared error in the testing phase < 7.5%, indicating their capacity to capture the process dynamic effectively.