Catalyst For Synthesis Research Articles

Novel Biopolymer-Based Catalyst for the Multicomponent Synthesis of N-aryl-4-aryl-Substituted Dihydropyridines Derived from Simple and Complex Anilines.

Although Hantzsch synthesis has been an established multicomponent reaction method for more than a decade, its derivative, whereby an aniline replaces ammonium acetate as the nitrogen source, has not been explored at great length. Recent studies have shown that the products of such a reaction, N-aryl-4-aryldihydropyridines (DHPs), have significant anticancer activity. In this study, we successfully managed to synthesize a wide range of DHPs (18 examples, 8 of which were novel) using a metal-free, mild, inexpensive, recoverable, and biopolymer-based heterogeneous catalyst, known as piperazine, which was supported in agar-agar gel. In addition, 8 further examples (3 novel) of such dihydropyridines were synthesized using isatin instead of aldehyde as a reactant, producing spiro-linked structures. Lastly, this catalyst managed to afford an unprecedented product that was derived using an innovative technique-a combination of multicomponent reactions. Essentially, the product of our previously reported aza-Friedel-Crafts multicomponent reaction could itself be used as a reactant instead of aniline in the synthesis of more complex dihydropyridines.

Synthesis Catalyst of Loading Nano Platinum on Graphene Nanosheets and Photodegradation of Bromophenol blue in Ultra-violet light.

Synthesis Catalyst of Loading Nano Platinum on Graphene Nanosheets and Photodegradation of Bromophenol blue in Ultra-violet light.

VOx Matrix Confinement Approach to Generate Sub-3nm L10-Pt-Based Intermetallic Catalysts for Fuel Cell Cathode.

Pt-based intermetallic compounds (IMCs) are considered as a class of promising fuel cell electrocatalysts, owing to their outstanding intrinsic activity and durability. However, the synthesis of uniformly dispersed IMCs with small sizes presents a formidable challenge during the essential high-temperature annealing process. Herein, a facile and generally applicable VOx matrix confinement strategy is demonstrated for the controllable synthesis of ordered L10-PtM (M = Fe, Co, and Mn) nanoparticles, which not only enhances the dispersion of intermetallic nanocrystals, even at high loading (40 wt%), but also simplifies the oxide removal and acid-washing procedures. Taking intermetallic PtCo as an example, the as-prepared catalyst displays a high-performance oxygen reduction activity (mass activity of 1.52 A mgPt -1) and excellent stability in the membrane electrode assemblies (MEAs) (the ECSA has just 7% decay after durability test). This strategy provides an economical and scalable route for the controlled synthesis of Pt-based intermetallic catalysts, which can pave a way for the commercialization of fuel cell technologies.

Efficient hydrolysis of cellulose into sugars in aqueous systems using fibrous core-shell structure FS@C/HPW

Phosphotungstic acid hydrate (HPW)-doped hydroxyl-rich hydrothermal carbon-coated fibrous silica catalyst (FS@C/HPW) is fabricated to induce the highly efficient hydrolysis of cellulose to sugar in an ultra-low acid aqueous system. The obtained FS90@C/HPW12 owns good thermal stability under 200 °C and the highest specific surface area at 28 m2/g. Owing to its special fibrous microstructures, FS90@C/HPW12 can cause linear damage and structural fragmentation on the surface of cellulose during hydrolysis. Accordingly, rather highly efficient hydrolysis with the cellulose conversion of 100 %, total reducing sugar and glucose yields at 92.2 % and over 85 % is achieved in the aqueous system with FS90@C/HPW12 and 5 mmol/L H2SO4. FS90@C/HPW12 also exhibits good reusability in multiple hydrolysis. This research provides a particular way for the design and synthesis of solid catalysts to induce the highly efficient hydrolysis of cellulose to sugar by chemical catalysis in a full aqueous system.

Non-Isocyanate Synthesis of Aliphatic Polyurethane by BiCl3-Catalyzed Transurethanization Polycondensation.

Non-isocyanate polyurethane synthesis by non-Sn catalysis is an essential challenge toward green polyurethane synthesis. Bismuth compounds are attractive candidates due to their low cost, low toxicity, and availability to urethane chemistry. This work applied various Bi catalysts to the self-polycondensation of a bishydroxyurethane monomer and found BiCl3 to be an excellent catalyst through optimization. The catalytic activity and price of BiCl3 are comparable to those of Bu2SnO, while its toxicity is significantly low. BiCl3 is, therefore, a promising alternative to Sn-based catalysts in non-isocyanate polyurethane synthesis.

Development of single-atom Ru and N, S-Co-doped carbon catalyst for enhanced cycling stability of lithium-oxygen batteries

Li-oxygen (Li-O2) battery is a novel energy storage equipment. However, its poor reaction reversibility relating to the insoluble lithium peroxide (Li2O2) generated during the discharge process, limits its application and development for large scale use. Therefore, the design and synthesis of effective catalysts which can efficiently catalyze the production and decomposition of Li2O2 and exclude the generation of side-products has become the primary task to develop Li-O2 batteries. Herein, a new type of electrocatalyst based on single-atom Ru and N, S-co-doped carbon materials (Ru/CNS/CNT) is introduced to reduce the overpotential of the battery reaction and accelerate the formation and decomposition of Li2O2. Galvanostatic charge-discharge tests were performed on the Li-oxygen (Li-O2) battery with Ru/CNS/CNT as the cathode catalyst material. With a limited specific capacity of 1000 mA h g−1, the battery can stably cycle for 79 cycles at a current density of 200 mA g−1. Furthermore, the existence of the single atom of Ru was demonstrated according to the characterization of HAADF-STEM. The experimental results showed that composite material Ru/CNS/CNT can accelerate the formation and decomposition of lithium peroxide (Li2O2), thereby greatly improving the cycling stability of the battery.

Growth and Electrochemical Study of Bismuth Nanodendrites as an Efficient Catalyst for CO2 Reduction.

There is a growing interest in creating cost-effective catalysts for efficient electrochemical CO2 reduction to address pressing environmental issues and produce valuable products. A bimetallic ZnBi catalyst that enhances catalytic activity and stability toward the electrochemical reduction of CO2 is designed. It is based on bismuth nanodendrites grown using a facile, scalable, and low-cost method. The results have shown that the incorporation of bismuth can decrease the charge transfer resistance and facilitate CO2 reduction toward the formation of CO and formate. It was revealed that the ZnBi catalyst exhibited higher catalytic activity compared with that of the pure Zn catalyst for CO2 reduction, with a lower onset potential [-0.75 V vs a reversible hydrogen electrode (RHE) compared with -0.85 V vs RHE for Zn]. In situ electrochemical attenuated total internal reflection Fourier transform infrared spectroscopy was employed to study the reaction mechanism, showing the formation of CO and formate through the adsorbed *COO- intermediates. This study has demonstrated a new approach for the feasible synthesis of high-performance catalysts for large-scale electrochemical CO2 reduction.

Synthesis and Evaluation of Mesoporous Silica Nanoparticle Catalyst Supports Prepared from South African Coal Fly Ash

Synthesis and Evaluation of Mesoporous Silica Nanoparticle Catalyst Supports Prepared from South African Coal Fly Ash

Rational design of superaerophobic array electrode synergy enhanced by wettability engineering and doping engineering for HER catalytic performance

This article elucidates the synthesis of NiMoO4-based catalysts with different arrays and crystal structures, including nanowires (nw), nanoplates (ns), and nanocolumns (nc). Subsequently, a high-temperature phosphorization method was employed to generate the corresponding P-NiMoO4 catalysts. The study investigates the structural evolution of the catalysts and changes in the active species under operational conditions. Concurrently, density functional theory (DFT) calculations provide a more in-depth description of the HER reaction mechanism, considering d-band centers and adsorption energies. Experimental results demonstrate that phosphorized NiMoO4 with a nanowire array structure and crystal structures of NiMoO4 and MoO3 exhibit the optimal HER performance, displaying superhydrophilic and underwater superaerophobic behaviors. The hydrophilic contact angle is 0°, and the aerophobic contact angle is 156.8° This array electrode achieves a current density of 10 mA·cm−2 at an overpotential as low as 73.97 mV. The experiments indicate that through doping and morphology control engineering, catalytic performance can be further synergistically enhanced, providing a new perspective for preparing HER catalytic electrodes with potential applications.

Activation of calcium sulfite by bismuth cobalt-copper perovskite-manganese dioxide composite for efficient degradation of metronidazole

The highly efficient BiCo0.5Cu0.5O3-MnO2 catalyst was prepared using the hydrothermal method and utilized for the first time to activate sulfite for degrading metronidazole (MNZ) in this study. Physicochemical analysis of the BiCo0.5Cu0.5O3-MnO2 catalyst was performed using XRD, FTIR, BET, SEM, TEM, and XPS, confirming the successful synthesis of catalyst. BiCo0.5Cu0.5O3-MnO2 demonstrated a larger specific surface area, a more uniform pore structure, and prevented perovskite agglomeration. The catalyst effectively activated CaSO3, resulting in the degradation of 99.94 % of MNZ within 30 min, showing excellent catalytic performance. Quenching experiments and EPR tests indicated that SO•-4, SO•-5 and 1O2 were the main reactive species, with the oxygen vacancy on the catalyst surface playing a crucial role in accelerating the formation of reactive species and electron transfer. Moreover, the valence transformation of Co, Cu, and Mn was identified as the main contributor to the activation of CaSO3, demonstrating significant synergistic effects. Liquid chromatography-mass spectrometry detected eleven intermediates, revealing that the BiCo0.5Cu0.5O3-MnO2/CaSO3 system could convert MNZ into low-toxicity products through three potential degradation pathways. Density functional theory (DFT) calculations showed that higher Fukui indices of MNZ sites were more susceptible to free radical attack. The BiCo0.5Cu0.5O3-MnO2/CaSO3 system also exhibited excellent degradability to different natural water bodies and other pollutants. Furthermore, the catalyst displayed strong stability and outstanding catalytic performance after 5 cycles. This study presents a versatile strategy for developing highly efficient green catalysts, which could be utilized in organic wastewater treatment.

A Low-Cost and Non-Noble Metal Catalyst Synthesis of Phenothiazine-Based Polymer HTM for Efficient and Stable Perovskite Solar Cells

A Low-Cost and Non-Noble Metal Catalyst Synthesis of Phenothiazine-Based Polymer HTM for Efficient and Stable Perovskite Solar Cells

Unveiling synergy of strain and ligand effects in metallic aerogel for electrocatalytic polyethylene terephthalate upcycling

Recently, there has been a notable surge in interest regarding reclaiming valuable chemicals from waste plastics. However, the energy-intensive conventional thermal catalysis does not align with the concept of sustainable development. Herein, we report a sustainable electrocatalytic approach allowing the selective synthesis of glycolic acid (GA) from waste polyethylene terephthalate (PET) over a Pd67Ag33 alloy catalyst under ambient conditions. Notably, Pd67Ag33 delivers a high mass activity of 9.7 A mgPd-1 for ethylene glycol oxidation reaction (EGOR) and GA Faradaic efficiency of 92.7 %, representing the most active catalyst for selective GA synthesis. In situ experiments and computational simulations uncover that ligand effect induced by Ag incorporation enhances the GA selectivity by facilitating carbonyl intermediates desorption, while the lattice mismatch-triggered tensile strain optimizes the adsorption of *OH species to boost reaction kinetics. This work unveils the synergistic of strain and ligand effect in alloy catalyst and provides guidance for the design of future catalysts for PET upcycling. We further investigate the versatility of Pd67Ag33 catalyst on CO2 reduction reaction (CO2RR) and assemble EGOR//CO2RR integrated electrolyzer, presenting a pioneering demonstration for reforming waste carbon resource (i.e., PET and CO2) into high-value chemicals.

Noncovalent interaction with a spirobipyridine ligand enables efficient iridium-catalyzed C–H activation

Exploitation of noncovalent interactions for recognition of an organic substrate has received much attention for the design of metal catalysts in organic synthesis. The CH–π interaction is especially of interest for molecular recognition because both the C–H bonds and the π electrons are fundamental properties of organic molecules. However, because of their weak nature, these interactions have been less utilized for the control of organic reactions. We show here that the CH–π interaction can be used to kinetically accelerate catalytic C–H activation of arenes by directly recognizing the π-electrons of the arene substrates with a spirobipyridine ligand. Computation and a ligand kinetic isotope effect study provide evidence for the CH–π interaction between the ligand backbone and the arene substrate. The rational exploitation of weak noncovalent interactions between the ligand and the substrate will open new avenues for ligand design in catalysis.

Synthesis of a cobalt catalyst supported by graphene oxide modified perlite and its application on the hydrolysis of sodium borohydride

In this work, a novel catalyst for the hydrolysis reaction of sodium borohydride to produce hydrogen—graphene oxide modified perlite supported cobalt—was produced. After being exposed to 98 % H2SO4, the natural mineral perlite was calcined and then mixed with graphene oxide. To create the Co@Perlite-GO catalyst, the synthesized Perlite-GO was added to the cobalt catalyst as a supporting material. The morphological layout and nature of the sample were evaluated using different spectroscopic techniques. Comparative analysis was carried out to investigate the catalytic effects of Co@Perlite-GO and Co@Perlite catalysts on the sodium borohydride (SBH) hydrolysis reaction. When the Co@Perlite-GO catalyst containing 4 mg Co was utilized, the hydrogen production rate was 12401 ml g−1 min−1 as a consequence of the optimization procedures carried out at 298 K. Under room conditions, the reaction occurred as catalyst control (0th degree), and the standard turnover frequency (TOF) was measured to be 8615 s−1. The activation energy, enthalpy, and entropy of the reaction were measured as 53.35 kJ mol−1, 50.77 kJ mol−1, and −58 J/(mol.K) respectively. It was found that the catalyst maintained 100 % efficiency even after being used six times.

Boosting electrocatalytic nitrogen fixation on Ni-P codoped MoS2 nanosheets

Electrocatalytic nitrogen fixation in an aqueous solution is considered a promising approach to ammonia synthesis. Still, this process has low Faraday efficiency and ammonia yield, so it is necessary to develop an efficient, clean, and safe catalyst to promote nitrogen reduction process. Doping can be easily carried out during the crystal growth owing to the weak interaction between the sandwiched layers (due to van der Waals forces) of MoS2. Here, a Ni-P codoped MoS2 nanosheets is designed as a highly efficient catalyst for electrochemical nitrogen fixation with superior selectivity. Especially, the doping of Ni achieved the transformation of MoS2 from 2 H phase to 1 T phase, improving the conductivity of the material. In addition, the doping of P creates more sulfur vacancies in the catalyst, thereby producing more H*, which promotes the adsorption and activation of nitrogen. The as-synthesized Ni-P codoped MoS2 nanosheets show excellent catalytic performance with a high yield of electrocatalytic ammonia synthesis (84.29 μgNH3 h−1 mgcat−1) and Faraday efficiency (2.39 %) at −0.5 V versus reversible hydrogen electrode in acidic electrolytes (0.005 M H2SO4), which outperformed most electrocatalytic ammonia synthesis catalysts. Furthermore, the Ni-P codoped MoS2 catalyst also shows outstanding electrochemical stability and durability. This work may offer a hopeful lead for designing effective non-noble-metal NRR electrocatalysts.

Kumquat peel-derived biochar to support zeolitic imidazole framework-67 (ZIF-67) for enhancing peracetic acid activation to remove acetaminophen from aqueous solution

This study presents the synthesis of a novel composite catalyst, ZIF-67, doped on sodium bicarbonate-modified biochar derived from kumquat peels (ZIF-67@KSB3), for the enhanced activation of peracetic acid (PAA) in the degradation of acetaminophen (APAP) in aqueous solutions. The composite demonstrated a high degradation efficiency, achieving 94.3% elimination of APAP at an optimal condition of 200 mg L−1 catalyst dosage and 0.4 mM PAA concentration at pH 7. The degradation mechanism was elucidated, revealing that superoxide anion (O2•−) played a dominant role, while singlet oxygen (1O2) and alkoxyl radicals (R–O•) also contributed significantly. The degradation pathways of APAP were proposed based on LC-MS analyses and molecular electrostatic potential calculations, identifying three primary routes of transformation. Stability tests confirmed that the ZIF-67@KSB3 catalyst retained an 86% efficiency in APAP removal after five successive cycles, underscoring its durability and potential for application in pharmaceutical wastewater treatment.

Using red mud to prepare the iron-bearing catalyst for the efficient degradation of phenol in the Fenton-like process

Phenol pollution is widely environmental and health problems that require new insights and urgent attention. A iron-bearing catalyst (FRM/2%A) was prepared with red mud by HCl dissolution, ascorbic acid reducing and precipitation of filter liquor, and activated H2O2 to degrade the phenol in synthetic wastewater. Results show that FRM/2%A had the highest degradation efficiency (99.3 %) in the reaction time of 5 min among investigative samples, due to the production of ferrous polymetallic oxides on the catalyst and the formation of mesoscopic particles and microcellular structures. The optimal conditions were 1 g/L of catalyst dosage, 5 mM of H2O2 concentration, 3–6 of initial pH and 100 mg/L of initial concentration of phenol in the FRM/2%A/H2O2 system. The degradation data fit into the pseudo-first-order kinetics model and the reaction rate constant (k) of FRM/2%A was 0.865 min−1. The removal efficiency (77 %) of COD below the value (99.3 %) of phenol degradation implied the intermediates generating during the phenol degradation. The possible degradation pathway was proposed as phenol → catechol → benzoquinone → muconic acid → small molecular organic acids → CO2 and H2O. The findings suggested a new way for the synthesis of the efficient catalyst with RM and optimal operating strategies for the treatment of phenol wastewater.

Polymer Supported Nitrogen-Bridged Symmetrical Binuclear Dioxidomolybdenum(VI) Complexes and Their Homogeneous Analogues as Potential Catalysts for Efficient Synthesis of 2-Amino-3-Cyano-4H-Chromenes/Pyrans.

Reaction of 2-chloromethyl-1H-benzimidazole with known intermediates (i-iii), prepared from diaminoguanidine hydrochloride with salicylaldehyde, 5-bromosalicylaldehyde or 3,5-di-tert-butylsalicylaldehyde, in the presence of triethylamine (NEt3) led to the formation of benzimidazole appended new ligands, H4L1-H4L3 (I-III). The homogeneous nitrogen-bridged symmetrical binuclear complexes, [(MoVIO2)2(L1)(H2O)2] (1), [(MoVIO2)2(L2)(H2O)2] (2) and [(MoVIO2)2(L3)(MeOH)2] (3) have been isolated by reacting these ligands with [MoVIO2(acac)2] in a 1 : 2 molar ratio in refluxing methanol. Using 1 : 1 (ligand to Mo precursor) molar ratio under above reaction conditions resulted in the corresponding mononuclear complexes, [MoVIO2(H2L1)(MeOH)] (4), [MoVIO2(H2L2)(H2O)] (5) and [MoVIO2(H2L3)(MeOH)] (6). The binuclear heterogeneous compounds [(MoVIO2)2(L1)(DMF)2]@PS (PS-1), [(MoVIO2)2(L2)(DMF)2]@PS (PS-2) and [(MoVIO2)2(L3)(DMF)2]@PS (PS-3) have been obtained by immobilization of 1-3 onto chloromethylated polystyrene (PS) beads. All synthesized ligands, homogeneous as well as supported compounds have been characterized by elemental analyses and various spectroscopic methods. Single crystal X-ray diffraction study of complexes 1 and 3 confirms their nitrogen-bridged symmetrical binuclear structures while 4 is mononuclear. Heterogeneous compounds (PS-1-PS-3) have further been studied by microwave plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy along with energy dispersive spectroscopy. These compounds (homogeneous and heterogeneous) were explored for catalytic applications to one-pot multicomponent reactions (MCRs) for efficient synthesis of biologically active 2-amino-3-cyano-4H-chromenes/pyrans (21 examples). Optimising various reaction parameters helped in achieving as high as 97 % yields of products. Though, only half equivalent of the binuclear complexes (1-3) was required compared to mononuclear analogues (4-6) to achieve comparable yields, heterogeneous catalysts have an added advantage due to their stability and recyclability. Suitable reaction mechanism has also been proposed based on isolated intermediates.

Efficient degradation of m-cresol by MnO-doped red mud catalyst activating peroxymonosulfate process: Performance and mechanism

M-cresol, one of phenolics, is highly toxic, refractory, and threatens human health and ecological safety. The study on the efficient m-cresol degradation technologies is crucial and helpful to restrain its discharge into water body. A composite of MnO-doped red mud (RM) to activate peroxymonosulfate (PMS) for the m-cresol degradation was fabricated and employed, favorable to the recycling and utilization of RM. Considering the catalytic activity and cost, 0.1 M/RM@G exhibited an excellent degradation capacity attributing to strong Fe3O4 and MnO synergy and was considered as the best catalyst among the investigative catalysts. 100 % of m-cresol and 71.4 % of COD could be degraded within 90 min under 2 g/L catalyst, 10 mM of PMS, 3-8 of initial pH and 50 mg/L m-cresol in the 0.1 M/RM@G/PMS system. The reaction rate constant (0.045 min−1) of 0.1 M/RM@G was much larger than RM@G (0.012 min−1), ARM (0.0048 min−1) and WRM (0.0028 min−1). Main Mn and Fe active components and abundant mesoporous structures on the catalyst surface could efficiently drove electron transfers, and further accelerated the redox cycles of Mn(III)Mn(II) and Fe(III)Fe(II) for activating PMS. 1O2 played a crucial role in degrading m-cresol. Based on the experiment data, the generation mechanism of radicals and the possible pathways of m-cresol degradation were proposed in the 0.1 M/RM@G/PMS system. This finding provides a new way for the synthesis of the efficient catalyst with RM and optimal operating strategies for the treatment of m-cresol wastewater.

Preparation of nanodiamond anchored on copper tannic acid as a heterogenous catalyst for synthesis of 1,4-benzodiazepines derivatives

In this research, a new and eco-friendly heterogeneous catalyst (ND@Tannicacid-Cu) was synthesized based on nanodiamond and copper tannic acid via esterification process. The as-prepared catalyst was characterized by Fourier transforms infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD) methods. The catalytic efficacy of the intended catalyst was examined by one-step three-component reaction of 1,4-benzodiazepine derivatives from a mixture of ortho-phenylenediamine, aromatic aldehydes, and dimedone under mild conditions. In all instances, corresponding 2,4-benzodiazepines derivatives were synthesized with high efficiency, short reaction time, straightforward work up procedure, no requirement for column-chromatography, and cost-effective catalyst. The heterogeneous catalyst was easily recycled using fillers, and it can be reused for eight cycles without significantly diminishing its performance.