Polyaniline-supported tungsten-catalyzed oxidative deoximation reaction with high catalyst turnover number

Sulfonated porous organic polymer supported Ziegler-Natta catalysts for the synthesis of ultra-high molecular weight polyethylene

Porous organic polymers (POPs) are attracting attention for their easy functionalization and potential as catalyst supports in olefin polymerization. In this study, sulfonated POP (s-POP) supported Ziegler-Natta catalysts were used for ethylene polymerization, producing ultra-high molecular weight polyethylene, with M ν reaching up to 6.83 × 106 g mol-1. The maximum M ν of polyethylene was achieved by Cat-3 with DIBP as the internal donor, albeit with a partial loss of catalytic activity. Polymerization conditions also play a pivotal role in determining the molecular weight of polyethylene. Hydrogen, being the most efficient chain transfer agent, can decrease the molecular weight to 9.68 × 104 g mol-1 at higher hydrogen concentrations ([H2] : [C2H4] = 0.83), and the s-POP-supported ethylene polymerization catalysts were observed to exhibit high sensitivity to hydrogen response. The effects of polymerization temperature, [Al] : [Ti] molar ratio, and ethylene pressure on ethylene polymerization were thoroughly investigated.

Selective and fast oxidation of alcohol to aldehyde using novel catalytic deep eutectic solvent surfactants

Deep eutectic solvent (DES) has been considered as a useful catalyst and reaction medium for various organic transformations. Herein, we report the catalytic application of novel deep eutectic solvent- based surfactant (DES surfactant) for the selective and fast oxidation of alcohols to aldehydes. The readily accessible DES surfactants (FeCl3/BHDC) was prepared using inexpensive ferric chloride (FeCl3) and benzyl hexadecyl dimethyl ammonium chloride in a simple manner. The synthesized FeCl3/BHDC was characterized using various techniques, including, FTIR spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and energy- dispersive X-ray spectroscopy (EDS) to determine its structure. The catalytic activity of FeCl3/BHDC in the selective oxidation of various alcohols to corresponding aldehyde derivative was investigated. The results showed the reaction could be completed within very short reaction times ranging from 2 to 15 min, while achieving good to excellent yields. This protocol offers a facile strategy and excellent efficiency in selectively oxidizing various alcohol derivatives to their respective aldehydes and ketones, utilizing hydrogen peroxide in the presence of catalytic DES surfactant.

Rational Design of Isolated Tetrahedrally Coordinated Ti(IV) Sites in Zeolite Frameworks for Methyl Oleate Epoxidation

The rational design of isolated metals containing zeolites is crucial for the catalytic conversion of biomass-derived compounds. Herein, we explored the insertion behavior of the isomorphic substitution of Ti(IV) in different zeolite frameworks, including ZSM-35 (FER), ZSM-5, and BEA. The different aluminium topological densities of each zeolite framework lead to the creation of different degrees of vacant sites for hosting the tetrahedrally coordinated Ti(IV) active sites. These observations show the precise control of the degree of four-coordinated Ti(IV) sites in a zeolite framework, especially in BEA topology, by tuning the degree of unoccupied sites in the host zeolite structure via dealumination. Interestingly, the more vacancies in the host zeolite structure, the more isolated tetrahedrally coordinated Ti(IV) can be increased, eventually enhancing the catalytic performance in methyl oleate (MO) epoxidation for producing methyl-9,10-epoxystearate (EP). The engineered Ti-β exhibits outstanding performances in bulky MO epoxidation with the amount of produced EP per number of Ti sites up to 17.1±1.8 mol mol-1. This observation discloses an alternative strategy for optimizing catalyst efficiency in the rational design of the Ti-embedding zeolite catalyst, endeavoring to reach highly efficient catalytic performance.

Facile Preparation of Tannic Acid-Gold Nanoparticles for Catalytic and Selective Detection of Mercury(II) and Iron(II) Ions in the Environmental Water Samples and Commercial Iron Supplement

Tannic acid (TA), a plant-derived polyphenol rich in hydroxyl groups, serves as both a reducing agent and stabilizer for synthesizing gold nanoparticles (TA-AuNPs). This study presents a groundbreaking method that utilizes TA to fabricate TA-AuNPs and develop two distinct colorimetric detection systems for mercury (Hg2+) and iron (Fe2+) ions. The first detection system leverages the interaction between TA-AuNPs and Hg2+ to enhance the peroxidase-like activity of TA-AuNPs, facilitating the production of hydroxyl radicals upon reaction with hydrogen peroxide, which subsequently oxidizes 3,3',5,5'-tetramethylbenzidine (TMB) into a blue-colored product (ox-TMB). The second system capitalizes on TA-AuNPs to catalyze the Fenton reaction between Fe2+ and hydrogen peroxide in the presence of 2, 6-pyridinedicarboxylic acid, boosting the generation of hydroxyl radicals that oxidize TMB into a blue-colored ox-TMB. Absorbance measurements at 650 nm display a linear relationship with Hg2+ concentrations ranging from 0.40 to 0.60 μM (R2 = 0.99) and Fe2+ concentrations from 0.25 to 2.0 μM (R2 = 0.98). The established detection limits for Hg2+ and Fe2+ are 18 nM and 96 nM, respectively. Applications to real-world samples achieved an excellent spiked recovery, spanning 101.6% to 108.0% for Hg2+ and 90.0% to 112.5% for Fe2+, demonstrating the method's superior simplicity, speed, and cost-effectiveness for environmental monitoring of these ions compared to existing techniques.

Organic and Metal-Organic Polymer-Based Catalysts-Enfant Terrible Companions or Good Assistants?

This overview provides insights into organic and metal-organic polymer (OMOP) catalysts aimed at processes carried out in the liquid phase. Various types of polymers are discussed, including vinyl (various functional poly(styrene-co-divinylbenzene) and perfluorinated functionalized hydrocarbons, e.g., Nafion), condensation (polyesters, -amides, -anilines, -imides), and additional (polyurethanes, and polyureas, polybenzimidazoles, polyporphyrins), prepared from organometal monomers. Covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and their composites represent a significant class of OMOP catalysts. Following this, the preparation, characterization, and application of dispersed metal catalysts are discussed. Key catalytic processes such as alkylation-used in large-scale applications like the production of alkyl-tert-butyl ether and bisphenol A-as well as reduction, oxidation, and other reactions, are highlighted. The versatile properties of COFs and MOFs, including well-defined nanometer-scale pores, large surface areas, and excellent chemisorption capabilities, make them highly promising for chemical, electrochemical, and photocatalytic applications. Particular emphasis is placed on their potential for CO2 treatment. However, a notable drawback of COF- and MOF-based catalysts is their relatively low stability in both alkaline and acidic environments, as well as their high cost. A special part is devoted to deactivation and the disposal of the used/deactivated catalysts, emphasizing the importance of separating heavy metals from catalysts. The conclusion provides guidance on selecting and developing OMOP-based catalysts.

Dye degradation and antimicrobial efficacy of cesium-doped Y2O3 nanostructures: in silico docking study

Developing multifunctional nanomaterials is crucial to rising global concerns over environmental contamination caused by dye effluents and antibiotic resistance. This work presents cesium (Cs)-doped Y2O3 nanostructures (NSs) as viable options for catalytic dye degradation and antibacterial action. This study prepared yttrium oxide (Y2O3) and various (2, 4, and 6 wt%) concentrations of Cs-doped Y2O3 NSs via co-precipitation technique. The pure and Cs-doped Y2O3 NSs were used to degrade methylene blue (MB) at different pH levels and assess the antibacterial properties against multidrug-resistant (MDR) Escherichia coli (E. coli). The X-ray diffraction spectra of the pure and Cs-doped Y2O3 revealed the presence of cubic and monoclinic structures. The UV-vis absorption spectra displayed distinct peaks at 274 nm and a reduction in band gap energy (from 4.94 eV to 4.41 eV) upon incorporation of Cs. Maximum degradation efficiency of up to 99% attributed to 6% Cs-doped Y2O3. The bactericidal activity against MDR E. coli exhibited 4.15 mm inhibition zones at higher concentrations of Cs-doped Y2O3. The bactericidal mechanism of Cs-Y2O3 NSs was further investigated by molecular docking studies for β-lactamase and DNA gyrase enzymes.

Ball-milling preparation of ZnFe2O4/AgI nanocomposite with enhanced photocatalytic activity

Semiconductor photocatalytic technology is increasingly being utilized in wastewater treatment due to its high efficiency, low energy consumption and environmental friendliness. However, single photocatalysts often exhibit low catalytic performance. In this study, a ZnFe2O4/AgI composite photocatalyst was initially prepared using a high-energy ball-milling method. For the first time, it was applied to the photocatalytic dehydrogenation of diethyl 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate (1,4-DHP), as well as photocatalytic degradation of harmful substances such as amaranth (AM), methyl orange (MO) and indole present in wastewater. The composite photocatalyst exhibited superior catalytic performance compared to ZnFe2O4 and AgI under visible light irradiation (λ ≥ 400 nm). With optimized composition, the pseudo-first-order rate constants of ZnFe2O4/AgI-50% were approximately 6, 20, 64 and 38 times higher than that of AgI for the photooxidation of 1,4-DHP, AM, MO and indole, respectively. The enhanced catalytic activity of the composite was attributed to the formation of heterojunction between ZnFe2O4 and AgI, which facilitated the separation and transfer of photogenerated charge carriers. Mechanism studies revealed that photogenerated holes (h+) and superoxide radical anions (˙O2 -) played pivotal roles in the photocatalytic reaction process.

Photocatalyzed Synthesis of a Schiff Base via C-N Bond Formation: Benzyl Alcohol as Sustainable Surrogates of Aryl Aldehydes

The advancement of photocatalytic techniques has enabled green chemical synthesis through visible-light-mediated photochemical oxidation under mild conditions. A novel approach under visible-light conditions was facilitated by eosin-Y for the reaction between substituted benzyl alcohols and anilines, resulting in the synthesis of diverse Schiff bases. This innovative method is emphasized for its environmentally friendly nature, lack of metal catalysts, cost-effectiveness, and nontoxic characteristics.

Removal of mercury and lead ions from water using bioinspired N3Se3 type small sized moieties

Mercury and lead toxicity in water has serious repercussions on human health. There is an urgent need to develop effective and efficient small moieties for their removal. The convenient one-pot synthesis of a few N3Se3 type small sized moieties is reported herein. The highest metal ion uptake capacity of Hg(II) and Pb(II) ions was found to be 314.3 mg g-1 and 93.5 mg g-1, respectively, by ICP-MS analysis. These ion uptake values are the highest for small sized moieties known in the literature to date.

Photoinduced Ordered Growth of Copper-Doped Polyaniline Nanotubes: A Method to Improve the Catalytic Activity for C-N Coupling Reactions

Polyaniline-supported metal nanoparticles (M@PANIs) have been widely employed as catalysts for organic reactions. Traditionally, the catalytic activities of the materials can be improved by introducing functional groups onto the aniline monomers, but it may enhance the catalyst cost and reduce the production yield of the material. This work reports a new strategy for improving the catalytic activity of M@PANIs. It was found that induced by visible light in the presence of a polymeric carbon nitride catalyst and copper dopant, the oxidative polymerization of simple aniline occurred slowly and orderly to produce the copper-doped polyaniline nanotubes. The unique tubular structure protected the catalytically active Cu(I) inside and endowed even more sufficient contact of the catalytic sites with reactants so that the material exhibited excellent catalytic performances in C-N coupling reactions.

Dodecahedral hollow multi-shelled Co3O4/Ag:ZnIn2S4 photocatalyst for enhancing solar energy utilization efficiency

Employing semiconductor photocatalysts featuring a hollow multi-shelled (HoMs) structure to establish a heterojunction is an effective approach to addressing the issues of low light energy utilization and severe recombination of photogenerated charge carriers. To take advantage of these key factors in semiconductor photocatalysis, here, a dodecahedral HoMs Co3O4/Ag:ZnIn2S4 photocatalyst (denoted as Co3O4/AZIS) was firstly synthesized by coupling Ag+-doped ZnIn2S4 (AZIS) nanosheets with dodecahedral HoMs Co3O4. The unique HoMs structure of the photocatalyst can not only effectively promote the separation and transfer of photo-induced charge, but also improve the utilization rate of visible light, exposing rich active sites for the photocatalytic redox reaction. The photocatalytic experiment results showed that the Co3O4/90.0 wt% AZIS photocatalyst has a high hydrogen (H2) production rate (695.0 μmol h-1 g-1) and high methyl orange (MO) degradation rate (0.4243 min-1). This work provides a feasible strategy for the development of HoMs heterojunction photocatalysts with enhanced H2 production and degradation properties of organic dyes.

Highly efficient visible-light induced N-doped ZnO@g-C3N4 and S-doped ZnO@g-C3N4 photocatalysts for environmental remediation

Facile, cost-effective and eco-friendly synthesis of N-doped ZnO@g-C3N4 and S-doped ZnO@g-C3N4 photocatalysts towards efficient degradation of environmental pollutants was achieved. The as-synthesized 2 wt% N-doped ZnO@g-C3N4 and 2 wt% S-doped ZnO@g-C3N4 achieved 96.2% and 90.4% degradation efficiencies towards crystal violet (100 ppm) within 45 min irradiation and 99.3% and 92.3% photocatalytic degradation efficiencies towards brilliant green (100 ppm) dye within 30 min irradiation, respectively, under a normal 90 W LED light instead of an expensive commercial light source. Moreover, the N-doped ZnO@g-C3N4 and S-doped ZnO@g-C3N4 nanocomposites showed excellent stability in the photodegradation of crystal violet and brilliant green dyes. The modification made on ZnO by doping with nitrogen and sulphur enhances the visible-light absorption as well as the separation of photoexcited charge carriers. The active radicals ˙OH and ˙O2- are both identified to play important roles in the photodegradation of crystal violet and brilliant green.

Polyaniline-Supported Tungsten-Catalyzed α-H Alkylation Reaction of Ketone with Alcohol

α-H alkylation of carbonyls is a significant reaction in the pharmaceutical industry because it can directly form a C-C bond in an environmentally benign manner. Thus, developing a novel catalyst for this reaction is a hot and practical topic in catalysis, organic synthesis, and materials science. In this paper, we found that polyaniline-supported tungsten could catalyze the α-H alkylation reaction of ketone with alcohol generating water as the only byproduct. Polyaniline support is the key for promoting the catalytic activity of tungsten, which is relatively cheaper than the traditionally employed noble metals. The reaction occurred under mild conditions with a wide substrate scope. The substrate initial concentration was enhanced to 1 mol/L, while the reaction speed was accelerated to reduce the reaction time to only 6 h; these improvements could significantly enhance the production capacity. The advantages make this reaction practical for synthesis with industrial purposes.

Iron-Promoted Catalytic Activity of Selenium Endowing the Aerobic Oxidative Cracking Reaction of Alkenes

Oxidative cracking of alkenes is a significant process in industry. In this work, it was found that catalyzed by Se/Fe via hybrid mechanisms, the carbon-carbon double bond in alkenes can break to produce carbonyls under mild conditions. Since O2 can be used as a partial oxidant, the employed H2O2 amount can be reduced (90 mol % vs 250 mol %) to avoid the peroxide residues, making the process even safer for operation.

A study on rapid and stable catalytic reduction of 4-nitrophenol by 2-hydroxyethylamine stabilized Fe3O4@Pt and its kinetic factors

The successful development of efficient and stable catalysts for 4-NP reduction reactions is beneficial to the environment and ecology. Fe3O4@Pt exhibits excellent catalytic performance for 4-NP reduction reaction due to the synergistic effect between Fe and Pt. But its structure and catalytic performance are extremely unstable. Here, we utilized the small-scale organic compound 2-hydroxyethylamine as surfactant to construct a stable composite nanomaterial. Then investigated the influence of monochromatic light (650 nm, 808 nm and 980 nm) and temperature on the kinetics of 4-NP reduction reaction by 2-hydroxyethylamine stabilized Fe3O4@Pt. The results indicate that both temperature and monochromatic light radiation can affect kinetic regulation. Increasing temperature can promote the catalytic rate, while monochromatic light radiation can induce agglomeration and inhibit the catalytic rate. This study opens up a new way for developing and regulating catalysts for heterogeneous catalysis reactions.

Photocatalytic degradation of imidacloprid using Ag2O/CuO composites

Imidacloprid is one of the most commonly used neonicotinoid pesticides that has been identified as a neurotoxin for various non-target organisms. It binds to the central nervous system of organisms, causing paralysis and eventually death. Thus, it is imperative to treat waterwaters contaminated with imidacloprid using an efficient and cost effective method. The present study presents Ag₂O/CuO composites as excellent catalysts for the photocatalytic degradation of imidacloprid. The Ag₂O/CuO composites were prepared in different compositions by adopting the co-precipitation method and used as a catalyst for the degradation of imidacloprid. The degradation process was monitored using UV-vis spectroscopy. The composition, structure, and morphologies of the composites were determined by FT-IR, XRD, TGA, and SEM analyses. The effect of different parameters i.e time, concentration of pesticide, concentration of catalyst, pH, and temperature on the degradation was studied under UV irradiation and dark conditions. The results of the study evidenced the 92.3% degradation of imidacloprid in only 180 minutes, which was 19.25 hours under natural conditions. The degradation followed first-order kinetics, with the half life of the pesticide being 3.7 hours. Thus, the Ag₂O/CuO composite was an excellent cost-effective catalyst. The non-toxic nature of the material adds further benefits to its use. The stability of the catalyst and its reusability for consecutive cycles make it more cost effective. The use of this material may help to ensure an immidacloprid free environment with minimal use of resources. Moreover, the potential of this material to degrade other environmental pollutants may also be explored.

Fabrication and characterization of mesoporous yolk-shell nanocomposites as an effective reusable heterogeneous base catalyst for the synthesis of ortho-aminocarbonitrile tetrahydronaphthalenes

Mesoporous yolk-shell nanocomposites (MYSNs) were loaded with a mobile CaMg core inside the silica shell. CaMg@MYS nanocomposites have been effectively prepared inside the inner cavity of a novel structure that consists of hollow mesoporous silica spheres. Tetraethyl orthosilicate (TEOS) and an amount of cetyltrimethylammonium bromide (CTAB) are coated on the carbon spheres used as a hard template in the multi-step synthetic procedure. In this method, the target products were obtained in high to excellent yields between 87-96% and quick response times between 10-20 minutes under mild conditions. The CaMg@MYS catalyst shows promise as an efficient and reusable catalyst in multicomponent processes. The CaMg@MYS multi-yolk spheres compared to metal oxide nanostructures indicated both high catalytic performance and a significant factor as a novelty. To identify each product, FT-IR, ¹H NMR, and melting point techniques were applied. Also, in order to characterize the prepared catalysts, FT-IR, XRD, FE-SEM, EDS, elemental mapping, and HR-TEM techniques were applied.

Conversion of 5-hydroxymethylfurfural to furan-2,5-dicarboxylic acid by a simple and metal-free catalytic system

A simple and metal-free catalytic system composed of NaOtBu/DMF and an O2 balloon efficiently converted 5-hydroxymethylfurfural (5-HMF) to furan-2,5-dicarboxylic acid with an 80.85% yield. 5-HMF analogues and various types of alcohols were also transformed to their corresponding acids in satisfactory to excellent yield by this catalytic system.

Sonocatalytic Degradation of Chrysoidine R Dye Using Ultrasonically Synthesized NiFe2O4 Catalyst

The novel ultrasound-assisted co-precipitation method was successfully applied for the synthesis of the NiFe2O4 catalyst, which offered the advantages of lower particle size and better crystalline structure without affecting the phase planes. Furthermore, the efficacy of synthesized catalysts was evaluated using ultrasound-assisted catalytic degradation of Chrysoidine R dye. The study was designed to evaluate the effect of different parameters, such as pH, duty cycle, power output, and catalyst loading on Chrysoidine R dye degradation using a 5 wt% NiFe2O4 catalyst synthesized ultrasonically. At the optimized condition of 120 W ultrasonic power, 70% duty cycle, 3 pH, 0.5 g/L catalyst loading, and 160 min of reaction time, the best degradation of 45.01% was obtained. At similar conditions, the conventionally synthesized catalyst resulted in about 15% less degradation. Chrysoidine R dye degradation was observed to follow second-order kinetics. To accelerate the degradation, studies were performed using hydrogen peroxide at various loadings where it was elucidated that optimum use of 75 ppm loading showed the maximum degradation of 92.83%, signifying the important role of the co-oxidant in ultrasound-assisted catalytic degradation of Chrysoidine R dye. Overall, the present study clearly demonstrated the potential benefits of ultrasound in catalyst synthesis as well as in catalytic degradation.