Catalytic Preparation Research Articles

UiO-66 with Both Brønsted and Lewis Acid Sites for Catalytic Synthesis of Biodiesel.

In the present study, an acid catalyst (UiO-66-SO3H) with Brønsted and Lewis acid sites was synthesised for the preparation of highly efficient biodiesel from oleic acid and methanol using chlorosulphonic acid sulfonated metal-organic frameworks (UiO-66) prepared with acetic acid as a moderator. The prepared catalysts were characterised using XRD, SEM, FT-IR and BET. The catalytic efficiency of the sulfonated catalysts was significantly improved and successful sulfonation was demonstrated by characterisation techniques. Biodiesel was synthesised by the one-pot method and an 85.0% biodiesel yield was achieved under optimum conditions of the reaction. The esterification reaction was determined to be consistent with a proposed primary reaction and the kinetics of the reaction was investigated. A reusability study of the catalyst (UiO-66-SO3H) was also carried out with good reproducibility. In conclusion, the present study provides some ideas for the synthesis of catalysts with high catalytic activity for the application in the catalytic preparation of biodiesel.

A review of the catalytic preparation of mesophase pitch

A review of the catalytic preparation of mesophase pitch

Influence of loading method on the performance of Zn/SAPO-34 catalysts and its catalytic preparation of 5-Hydroxymethylfurfural from fructose dehydration

A diverse suite of Zn-SAPO-34 catalysts was synthesized employing three distinct methodologies for the incorporation of zinc species: thermal ion exchange, wet impregnation, and physical mixing. The catalysts were characterized using various analytical techniques including XRD, FT-IR, BET, SEM, XRF, XPS, NH3-TPD, and Py-IR, to elucidate the crystal structure, morphology, surface acidity, and the presence of zinc species within the catalysts. The study showed that the method of zinc introduction markedly impacts the physicochemical properties of the catalysts. Different approaches to introducing zinc species significantly influence the acid strength and type on the catalyst surface, with variations in the existing states of zinc across the catalysts. Specifically, zinc species introduced via thermal ion exchange coexist as ZnOH+ and ZnO within the catalyst, whereas those from wet impregnation and physical mixing are individually present as either ZnOH+ or ZnO. Furthermore, the study examined the catalytic performance of these Zn-SAPO-34 catalysts in the dehydration of fructose to produce 5-hydroxymethylfurfural (HMF). Catalysts prepared via thermal ion exchange exhinited superior performance, achieving an remarkable HMF yield of 94.6 %. Additionally, in situ infrared technology was used to investigate the effect of zinc species introduction on the fructose dehydration process, indicating suggesting that the introduction of zinc species enhances the transformation of fructose molecules.

Microwave-Induced Synthesis of Bioactive Nitrogen Heterocycles.

There are many different applications of heterocyclic molecules in the pharmaceutical and materials science fields, which make them an important family of compounds. Among these heterocyclic compounds, nitrogen-containing heterocyclic (N-heterocyclic) compounds have attracted a lot of interest among researchers due to their various applications across a wide variety of fields. Many studies have been performed over the past few years to study the synthesis of N-heterocycles under different reaction conditions, such as solvent-free, catalytic, reactants immobilized on a solid support, one-pot synthesis, and microwave irradiation. It has been demonstrated by our research group that microwaves can be utilized for rapid and efficient synthesis of biologically active compounds. In this review, we provide an overview of the microwave-assisted non-catalytic and catalytic preparation of nitrogen-containing heterocycles, mostly polycyclic N-heterocycles, five-membered N-heterocycles, six-membered N-heterocycles, and fused N-heterocycles. Mostly in this article, we explore the microwave-assisted preparation of biologically important compounds, such as pyrimidines, thiazoles, imines, tetrazoles, steroidal derivatives, quinolines, indolizine, triazoles, beta-lactams, pyrroles and quinoxalines.

Spatially selective catalysis of OSA starch for preparation of Pickering emulsions with high emulsification properties

The traditional strategies of chemical catalysis and biocatalysis for producing octenyl succinic anhydride modified starch can only randomly graft hydrophobic groups on the surface of starch, resulting in unsatisfactory emulsification performance. In this work, a lipase-inorganic hybrid catalytic system with multi-scale flower like structure is designed and applied to spatially selective catalytic preparation of ocenyl succinic anhydride modified starch. With the appropriate floral morphology and petal density, lipases distributed in the “flower center” can selectively catalyze the grafting of hydrophobic groups in a spatial manner, the hydrophobic groups are concentrated on one side of starch particles. The obtaining OSA starch exhibits excellent emulsifying property, and the pickering emulsion has good protective effect on the embedded curcumin. This work provides a direction for the development of high-performance starch-based emulsifiers for the food and pharmaceutical industries, which is of great significance for improving the preparation and emulsification theory research of modified starch.

Biomimetic immobilization of α-glucosidase inspired by antibody-antigen specific recognition for catalytic preparation of 4-methylumbelliferone

Immobilization technology plays an important role in enhancing enzyme stability and environmental adaptability. Despite its rapid development, this technology still encounters many challenges such as enzyme leakage, difficulties in large-scale implementation, and limited reusability. Drawing inspiration from natural paired molecules, this study aimed to establish a method for immobilized α-glucosidase using artificial antibody-antigen interaction. The proposed method consists of three main parts: synthesis of artificial antibodies, synthesis of artificial antigens, and assembly of the artificial antibody-antigen complex. The critical step in this method involves selecting a pair of structurally similar compounds: catechol as a template for preparing artificial antibodies and protocatechualdehyde for modifying the enzyme to create the artificial antigens. By utilizing the same functional groups in these compounds, specific recognition of the antigen by the artificial antibody can be achieved, thereby immobilizing the enzymes. The results demonstrated that the immobilization amount, specific activity, and enzyme activity of the immobilized α-glucosidase were 25.09 ± 0.10 mg/g, 5.71 ± 0.17 U/mgprotein and 143.25 ± 1.71 U/gcarrier, respectively. The immobilized α-glucosidase not only exhibited excellent reusability but also demonstrated remarkable performance in catalyzing the hydrolysis of 4-methylumbelliferyl-α-D-glucopyranoside.

Construction of coal pitch-based HA-K grafted poly condensates and their excellent anti-temperature and viscosity-reducing properties

Humic acids (HAs) are widely used as filtrate and viscosity reducers in drilling fluids. However, their practical utility is limited due to poor stability in salt resistance and high-temperature resistance. High-temperature coal pitch (CP) is a by-product from coal pyrolysis above 650 °C. The substance's molecular structure is characterized by a dense arrangement of aromatic hydrocarbon and alkyl substituents. This unique structure gives it unique chemical properties and excellent drilling performance, surpassing traditional humic acids in drilling operations. Potassium humate is prepared from CP (CP-HA-K) by thermal catalysis. A new type of high-quality humic acid temperature-resistant viscosity-reducer (Graft CP-HA-K polymer) is synthesized with CP-HA-K, hydrolyzed polyacrylonitrile sodium salt (Na-HPAN), urea, formaldehyde, phenol and acrylamide (AAM) as raw materials. The experimental results demonstrate that the most favorable conditions for the catalytic preparation of CP-HA-K are 1 wt% catalyst dosage, 30 wt% KOH dosage, a reaction temperature of 250 °C, and a reaction time of 2 h, resulting in a maximum yield of CP-HA-K of 39.58%. The temperature resistance of the Graft CP-HA-K polymer is measured to be 177.39 °C, which is 55.39 °C higher than that of commercial HA-K. This is due to the abundant presence of amide, hydroxyl, and amine functional groups in the Graft CP-HA-K polymer, which increase the length of the carbon chains, enhance the electrostatic repulsion on the surface of solid particles. After being aged to 120 °C for a specified duration, the Graft CP-HA-K polymer demonstrates significantly higher viscosity reduction (42.12%) compared to commercial HA-K (C-HA-K). Furthermore, the Graft CP-HA-K polymer can tolerate a high salt concentration of 8000 mg·L−1, measured after the addition of optimum amount of 3 wt% Graft CP-HA-K polymer. The action mechanism of Graft CP-HA-K polymer on high-temperature drilling fluid is that the Graft CP-HA-K polymer can increase the repulsive force between solid particles and disrupt bentonite's reticulation structure. Overall, this research provides novelty insights into the synthesis of artificial humic acid materials and the development of temperature-resistant viscosity reducers, offering a new avenue for the utilization of CP resources.

Cost-Effective Single-Step Synthesis of Metal Oxide-Supported Ni Catalyst for H2-Production Through Dry Reforming of Methane

AbstractPreparing catalysts from cheap metal precursors in a single pot are an appealing method for reducing catalytic preparation costs, minimizing chemical waste, and saving time. With regards to the catalytic conversion of dry reforming of methane, it offers the prospect of significantly reducing the cost of H2 production. Herein, NiO-stabilized metal oxides like Ni/TiO2, Ni/MgO, Ni/ZrO2, and Ni/Al2O3 are prepared at two different calcination temperatures (600 °C and 800 °C). Catalysts are characterized by X-ray diffraction, Raman spectroscopy, surface area-porosity analysis, Temperature program experiments, infrared spectroscopy, and thermogravimetry analysis. The MgO-supported Ni catalyst (Ni/MgO-600), ZrO2-supported Ni catalyst (Ni/ZrO2-600), and Al2O3-supported Ni (Ni/Al2O3-600) catalyst calcined at 600 °C show initial equal H2 yields (~ 55%). The population of CH4 decomposition sites over ZrO2-supported Ni catalyst remains highest, but H2-yield drops to 45% against high coke deposition. The catalytic activity remains constant over the Ni/MgO-600 catalyst due to the enrichment of “surface interacted CO2-species”. MgO-supported Ni catalyst calcined at 800 °C undergoes weak interactions of NiO-M′ (M′ = support), serious loss of CH4 decomposition sites and potential consumption of H2 by reverse water gas shift reaction, resulting in inferior H2 yield. H2-yield remains unaffected over an Al2O3-supported Ni catalyst even against the highest coke deposition due to the formation of stable Ni (which exsolves from NiAl2O4) and proper matching between carbon formation and rate of carbon diffusion.

One‐Pot Catalytic Synthesis of Optically Active Drug (S)‐Clopidogrel

AbstractA first catalytic preparation of the popular antiplatelet drug (S)‐clopidogrel, known with the tradename of Plavix, has been developed in a one‐pot and innovative approach. The synthesis can be performed using commercially available ortho‐chlorobenzaldehyde, 1‐naphthylsulfonyl acetonitrile, tert‐butyl hydroperoxide (TBHP), 4,5,6,7‐tetrahydrothieno[3,2‐c]pyridine and 20 mol % of a quinidine derived organocatalyst in a single solvent. A Knoevenagel/asymmetric epoxidation/domino ring‐opening esterification (DROE) sequence enabled to obtain (S)‐clopidogrel in 61 % overall yield and 62 % ee. Fine optimization of the reaction conditions proved to be crucial to set up a selective and efficient process.

Magnetic carbon nanotubes mesoporous silica nanocomposite functionalized with copper: Synthesis, characterization, and application for the efficient catalytic preparation of dihydrano-choromenes

Nanoparticles of Fe3O4 were prepared and immobilized onto the surface of carbon nanotube (CNTs), followed by copper immobilization on the nanoparticles. The resulting MWCNT@Fe3O4@SiO2@CPTMO@DEA/Cu(II) nanocatalysts were characterized using Fourier transform infrared spectroscopy, X-ray diffraction patterns, scanning electron microscopy, energy dispersive X-ray spectroscopy, vibrating sample magnetometer, and thermal gravimetric analysis. The catalyst was then employed for the benign synthesis of 3,4-dihydropyrano[3,2-c]chromene derivatives. The main advantages of this work are high efficiency, short reaction time, simple operation and easy separation of the catalyst from the reaction mixture using an external magnet. The catalyst was magnetically retrieved and reused for six sequential cycles without significant loss of activity or re-selection. Furthermore, this method exhibits superior characteristics, including high efficiency, short reaction time and simple separation operation, compared to traditional dihydropyran-chromene reactions and other methods.

Integrated “adsorption-catalysis-adsorption” green strategy for efficient adsorption for the removal of methylene blue and catalytic preparation of hydrocarbon-rich, low N/O bio-oil

This study proposes an “adsorption-catalysis-adsorption” strategy to improve the recycling capacity of bio-char, which has implications for improving bio-char utilization and reducing greenhouse gas emissions. A porous bio-char (EPAC) was prepared and used for effective methylene blue (MB) adsorption. The adsorbent after MB adsorption was used to fabricate a new carbon catalyst (EPMCC), which exhibited an excellent catalytic capacity for low N/O bio-oil. The nitrogen content of the bio-oil catalyzed by EPMCC decreased from 34.46 wt% to 17.04 wt%, and the hydrocarbon content increased from 15.52 wt% to 29.09 wt% compared to the pyrolysis of Enteromorpha clathrate alone. The used EPMCC was then regenerated to obtain a new EPMNC adsorbent with a high specific surface area (1097.99 m2·g−1). The maximum adsorption capacity of EPMNC was 554.38 mg·g−1, and the adsorption mechanisms involved electrostatic interactions, π-π interactions, and hydrogen bonding. This study promotes the cycling of carbon and nitrogen in organic wastewater systems containing nitrogen.

Potassium-assisted activation strategy regulating metal-support interaction to promote hydrothermal hydrogenation/deoxygenation of palmitic acid

The catalytic preparation of renewable fuels from biomass using palmitic acid as a model compound of bio-oil has been a research focus in the field of renewable energy in recent years. However, the development of highly active, low-priced, and hydrothermal stable catalysts remains a challenging task. Here, a trace potassium-assisted activation method is proposed to improve the hydrothermal hydrogenation/deoxygenation activity of palmitic acid in this work. The conversion was successfully increased from 71.7% to 96.2%, and the total yield of alkanes was increased from 38.0% to 82.5% at 260 °C for 180 min. The research results indicate that additional defect sites and a small amount of P doping in coconut shell carbon are generated with K3PO4-assisted activation, enhancing the stronger metal-support interaction, and improving the hydrothermal stability and catalytic activity of the catalyst. XPS and H2-TPR jointly illustrate that K3PO4-assisted activation makes nickel species on the surface of the catalyst more easily reduced, resulting in a significant increase in the Ni0/Ni2+ ratio and oxygen vacancies during the carbothermal reduction process. This work provides a new strategy to further improve catalytic activity of bio-oil deoxygenation.

Metal-Free Catalytic Preparation of Graphene Films on a Silicon Surface Using CO as a Carbon Source in Chemical Vapor Deposition

The metal-free synthesis of graphene films on Si substrates, the most common commercial semiconductors, is of paramount significance for graphene application on semiconductors and in the field of electronics. However, since current research mainly uses C-H gas as the carbon source in chemical vapor deposition (CVD), and Si does not have a catalytic effect on the decomposition and adsorption of C-H gas, it is challenging to prepare high-quality graphene on the Si surface directly. In this work, we report the growth of graphene directly on Si without metal catalysis by CVD using CO was selected as the carbon source. By controlling the growth temperature (1000–1150 °C), a process of 2–5 layers of graphene growth on silicon was developed. The electrical performance results showed that the graphene film had a sheet resistance of 79 Ω/sq, a resistivity of 7.06 × 10−7 Ω·m, and a carrier migration rate of up to 1473.1 cm2 V−1·S−1. This work would be a significant step toward the growth of graphene on silicon substrates with CO as the carbon source.

Molten Salt-Assisted Catalytic Preparation of MoS2/α-MoO3/Graphene as High-Performance Anode of Li-Ion Battery

We report on the facile and scalable catalytic conversion of natural graphite and MoS2 minerals into α-MoO3 nanoribbons incorporated into hexagonal MoS2 and graphene nanosheets, and evaluate the structural, morphological and electrochemical performances of the hybrid nanostructured material obtained. Mechanochemical treatment of raw materials, followed by catalytic molten salt treatment leads to the formation of nanostructures with promising electrochemical performances. We examined the effect of processing temperature on the electrochemical performance of the products. At 1100 °C, an excellent Li-ion storage capacity of 773.5 mAh g−1 is obtained after 180 cycles, considerably greater than that of MoS2 (176.8 mAh g−1). The enhanced capacity and the rate performance of this electrode are attributed to the well-integrated components, characterized by the formation of interfacial molybdenum oxycarbide layer during the synthesis process, contributing to the reduced electrical/electrochemical resistance of the sample. This unique morphology promotes the charge and ions transfer through the reduction of the Li-ion diffusion coefficient (1.2 × 10−18 cm2 s−1), enhancing the pseudocapacitive performance of the electrode; 59.3% at the scan rate of 0.5 mV s−1. This article provides a green and low-cost route to convert highly available natural graphite and MoS2 minerals into nanostructured hybrid materials with promising Li-ion storage performance.

Conversion of biomass-derived monosaccharide into furfural over Cr–Mg-LDO@bagasse catalysts

5-hydroxymethylfurfural (HMF) and furfural, sourced from biomass-derived sugars, are promising platform molecules that can be further transformed into fuel intermediates and hydrocarbon fuels. Therefore, it is of great significance to study their catalytic preparation processes, especially the development of efficient catalysts. The degradation of biomass derived aldose (glucose and xylose) into furan compounds (HMF and furfural) involves the isomerization of aldose to ketose and then further dehydration and cyclization of ketose to produce corresponding furan compounds. Herein we reported a Cr-containing layered hydrotalcite structure composite with biochar material, which can be used for efficiently dehydration of glucose and xylose to produce HMF and furfural. The alkali metal hydroxide structure in the hydrotalcite structure provides the basic environment required for the isomerization reaction, while Cr3+ will provide the Lewis acid environment for the dehydration of ketoses. The optimum Cr3+/Mg2+ mass ratio for the preparation process were 13:15. The highest 5-HMF and furfural yields of the dehydration process were 90.2% and 95.4%, respectively. The specific surface area of the optimum Cr–Mg-LDO@bagasse catalyst was around 127.5 m2/g. The catalytic activity recovery was good even after five batch reactions. This study is helpful to establish an efficient catalytic reaction system for conversion of biomass-derived monosaccharides into corresponding furan compounds, so as to realize the high-efficiency and high-value conversion of biomass-derived sugars.

Sustainable tailor-made and bio-based high-performance lubricants that combine biorenewability, biodegradability and economic efficiency

A new generation of bio-based lubricants is presented, which fulfil the criteria of (1) a biorenewable raw material basis, (2) biodegradability, (3) suitability for fine-tuning of performance properties, and (4) an efficient catalytic preparation.

In-Situ Catalytic Preparation of Two-Dimensional BCN/Graphene Composite for Anti-Corrosion Application

In-situ catalytic growth of two-dimensional materials shows great potential for metal surface protection because of the impermeability and strong interaction of the materials with metal surfaces. Two-dimensional hexagonal boron-carbon nitrogen (h-BCN) is composed of alternating boron, carbon, and nitrogen atoms in a two-dimensional honeycomb lattice, which is similar to graphene. The corrosion caused by defects such as grain boundary of two-dimensional materials can be weakened by dislocation overlap via the transfer method. However, two-dimensional composite films prepared using the transfer method have problems, such as the introduction of impurities and poor adhesion, which limit their corrosion resistance. In this study, a layer of BCN/Gr two-dimensional composite was directly grown on the surface of copper foil using the CVD in-situ catalysis method, and its anti-corrosion performance was characterized by electrochemical and salt spray experiments. The results showed that the directly grown two-dimensional composite had better adhesion to the substrate and the advantage of grain boundary dislocation, thus showing a better anti-corrosion capability.

CATALYSIS OF TRIVALENT PHOSPHORUS COMPOUNDS OF THE REACTIONS OF SUBSTITUTED BENZOIC ACIDS WITH ANILINE

The catalytic preparation of substituted benzanilides by the reaction of substituted benzoic acids with aniline is an important model process that has been intensively deve­lo­ped recently, in the field of the «green chemistry» concept, direct catalytic amidation, and its study is an urgent scientific and practical task.
 Within the framework of solving this problem, the catalysis of the acylation of aniline by substituted benzoic acids with trivalent phosphorus compounds P(III) was studied. It was established that P(III) in the amount of only 2% mol. from substituted benzoic acid effectively catalyze this reaction, which proceeds in boiling low-polar solvents with intensive water distillation in an air atmosphere, which leads to obtaining anilides of substituted benzoic acids with a yield close to quantitative. The new catalysts, phosphorus trichloride and tribromide, phosphorous acid, successfully complement the catalytic system tetrabutoxytitanate/polybutoxytitanate, previously used for these purposes, allowing to obtain anilides of amino­benzoic acids with greater selectivity, as well as anilides of oxybenzoic acids.
 The study of the kinetic regularities of the reaction catalyzed by phosphorus trichloride showed a weak effect of substituents: |ρ| ≤ 0.61. Hammett dependences are represented by curves with a maximum, straight line segments are characteristic only for certain groups of substituents, both for meta- and para-substituted and for orthosubstituted benzoic acids.
 One of the possible mechanisms of acylation is the formation in situ in the first mi­nutes of the reaction of aniline phosphite, which can act as an oxygen-nucleophilic catalyst, and, upon interaction with substituted benzoic acid, forms the corresponding benzoyl phosphite, which is then attacked by a free aniline molecule to obtain substituted benzanilide.
 The ortho effect for P(III) catalysis is absent or very weak, in the case of aminobenzoic acids. At the same time, anthranilic acid can form a phosphite with phosphorous acid, which directly participates in catalysis.

Perovskite oxide catalyst having improved oxygen catalytic activity and preparation method thereof

Perovskite oxide catalyst having improved oxygen catalytic activity and preparation method thereof

Catalytic preparation of carbon nanotube/SiC whisker bonded low carbon MgO–C refractories and their high-temperature mechanical properties

The effects of Co, Fe and Ni catalysts generated from their nitrate precursors on the formation of carbon nanotubes (CNTs) from pyrolysis of phenolic resin were investigated, and the former two performed the best at 873 K, and 1073–1273 K, respectively. Density functional theory calculations indicate that a Co nanocluster requires the lowest energy for forming the five-membered carbon ring (the controlling step in the CNT generation), making Co the best catalyst for the formation of CNTs at relatively low temperatures. On the other hand, molecular dynamics calculations show that an Fe nanocluster has the highest melting point among the three nanoclusters and can retain its integrity at 1280 K, making Fe the best catalyst for the formation of CNTs at relatively high temperatures. Hot modulus of rupture of the CNT (along with additionally formed SiC whisker) reinforced low-carbon MgO–C refractory sample containing 0.25 wt% Fe catalyst was about 20% higher than that of its catalyst-free counterpart.