Catalysis Surveys from Asia最新文献

TiO₂ supported Ni₃Sn₂ intermetallic compound (IMC) catalysts were prepared by the coprecipitation method using resorcinol–formaldehyde resin (RF) and sodium dodecyl sulfate (SDS) as templates, and they were tested for in situ hydrodeoxygenation (HDO) of methyl palmitate using methanol as the hydrogen donor in the aqueous phase. It has been found that introducing SDS and RF enhances specific surface area, pore volume and pore diameter and reduces the Ni₃Sn₂ IMC particles and their electronic interaction with TiO₂. In in situ HDO of methyl palmitate, the catalysts prepared with co-introducing RF and SDS exhibit higher activity than that without templates and those separately introducing RF and SDS. The catalyst activity is mainly related to the Ni₃Sn₂ IMCs particles size and the degree of the electronic interaction between Ni₃Sn₂ and TiO₂. The catalyst with introducing a suitable amount of RF and SDS gives the n-pentadecane yield of 87.3% at 330 °C, and it is slightly deactivated after reaction for five times due to carbon deposition and the sintering of Ni₃Sn₂ IMC particles.

Hydrothermal sulfonation is a method that introduces sulfonic acid groups as active sites onto suitable support materials under autogenous pressure conditions. In this work, the effectiveness of hydrothermal sulfonation was studied on various lignin-carbons prepared at different thermal conditions of 400–600 °C for 1 and 2 h. The sulfonated lignin-carbon catalysts produced were characterized and evaluated for their catalytic performance in levulinic acid (LA) esterification under selected reaction conditions to synthesize ethyl levulinate (EL). The catalyst with the highest EL yield and LA conversion was selected for extended reaction time (1–6 h) to study the time-dependent performance in LA esterification. The influence of catalyst acidity and the surface area of the prepared catalysts on the reaction behavior was assessed and further analyzed through an extensive comparative study with related literature. The results indicated that all lignin-carbon catalysts exhibited enhanced porous structures and surface areas of 193–368 m²/g, along with amorphous characteristics. Additionally, a reduction in catalyst acidity was observed, decreasing from 1.3 to 0.5 mmol/g as the thermal conditions of lignin-carbon preparation increased. The catalytic activity was found to decrease for lignin-carbon prepared at higher thermal conditions. The catalyst performance achieved 75.9 mol% EL yield (TOF of 0.02 s⁻¹) with 76.5% LA conversion, and the EL yield increased to 81.1 mol% when the reaction time was extended to 5 h. The carbon catalyst can be reused over five reaction cycles with a decrease in EL yield from 81.1 mol% to 62.2 mol%. In comparative study, catalyst acidity plays an important role in catalyzing the esterification reaction of levulinic acid to ethyl levulinate, serving as a key design indicator for carbon-based catalysts. Catalyst acidity showed a positive correlation with reaction performance, and further increases in surface area (> 200 m²/ g) did not significantly enhance reaction performance. Besides, hydrothermal sulfonation demonstrated potential as a catalyst modification method and could be recommended for carbon-based catalyst preparation.

Ag-TiO₂/SiO₂ monolith photocatalyst was synthesized by a simple sol-gel and dip-coating method with AgNO₃ as Ag source, titanium n-butoxide and tetraethoxysilane as Si source. Photocatalytic activities of the synthesized Ag-TiO₂/SiO₂ monolith were evaluated through phenol degradation under UVA light irradiations. EDX-mapping verified that the Ag nanoparticles were successfully incorporated into the photocatalyst and evenly deposited on the surface of TiO₂/SiO₂. The surface and cross-sectional SEM images of the monolith material confirmed the successful coating of Ag(3%)-TiO₂/ SiO₂ catalyst on the monolith surface (Ag(3%)-TS05/S/M). The study showed that the peroxymonosulfate (PMS)/Ag-TiO₂/SiO₂ monolith with appropriate Ag doping exhibited excellent activity under UVA light irradiation, was easy to separate from contaminants, and had good reusability. After four rounds of recycling, about 92% of the phenol was removed within. 240 min by the PMS/Ag(3%)-TiO₂/SiO₂ monolith system with a sulfate radical as the main oxidation species. A new bond between SiO₂ and TiO₂ was formed to prevent TiO₂ removal during wastewater treatment. The performance of our Ag-TiO₂/SiO₂ monolith with the presence of PMS makes it highly suitable for practical application in treating wastewater contaminated with phenol pollutants.

The direct and sequential application of adsorption and catalytic wet air oxidation (CWAO) methods was evaluated for the removal of the veterinary antibiotic oxytetracycline hydrochloride (OTC-HCl) from wastewater. Cuttlefish bone (CFB), a natural marine material, was employed as both an adsorbent and a catalyst support to synthesize the composite CuFe₂O₄/CFB material. The optimal conditions for OTC-HCl adsorption were found to be 0.09 g/L CFB, pH 7.6, and 282 rpm, resulting in a 24% removal efficiency. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were evaluated, with the Temkin isotherm identified as the most suitable. The adsorption kinetics followed a second-order kinetic model. The Weber–Morris intraparticle diffusion model suggested that both liquid film and intraparticle diffusion processes govern the adsorption kinetics. In the catalytic wet air oxidation process, a 75% removal efficiency was achieved at 0.5 g/L CuFe₂O₄/CFB, pH 4, and 100 °C. The most suitable kinetic model for describing the CWAO of OTC-HCl was found to be a two-step first-order reaction rate model. In the hybrid treatment process, CWAO was applied following adsorption, and toxicity tests indicated that no toxic by-products were generated during the sequential treatment.

Design of efficient metal-acid bifunction catalysts is of significance for development of hydroisomerization of linear alkanes. In this study, the spatial configurational construction of Pt-ZSM-5 catalytic system was achieved by fabrication of acidic ZSM-5 zeolite and mesoporous silica core-shell composites equipped with controlled location of Pt sites, which aim to explore the effect of functional sites proximity on isomerization reactivity. A series of characterization techniques such as X-ray diffraction, transmission electronic microscopy, N₂ physical adsorption, NH₃ temperature programmed desorption, X-ray photoelectron spectroscopy and so on had confirmed that the synthesized core-shell bifunctional catalysts with different Pt location possessing similar textural, acid and metal properties. In the catalytic hydroisomerization of n-heptane, however, the catalyst with Pt sites locating at acid zeolite exhibits superior n-heptane conversion and isomerization selectivity, which indicates that proximity of active sites at atomic scale may be more conducive to their synergistic effect when the diffusional limitation from zeolitic channel is minimized. These results had presented new direction for the preparation of efficient bifunctional catalysts in hydroisomerization of linear alkanes.

This study reports a facile procedure for synthesizing and characterizing a novel catalyst based on thermo-responsive poly (N-isopropyl acrylamide-b-vinylimidazole)/Pd catalyst (PNIPAM-b-PVIm/Pd). A well-structured diblock copolymer was prepared using RAFT-controlled strategy. Initially, PNIPAM was fabricated with a lower critical solution temperature (LCST) at around 32 °C. Within another step, PNIPAM as a macro-RAFT agent and vinylimidazole as a monomer were utilized for synthesizing PNIPAM-b-PVIm. The reaction of PNIPAM-b-PVIm with Pd(OAc)₂ for one day, taken after applying NaBH₄ as a reducing agent, led to the synthesizing of PNIPAM-b-PVIm supported Pd. This new catalyst was characterized by different methods, i.e., ICP, FT-IR, NMR, UV–Vis spectrophotometer, TGA, DLS, SEM, EDX, and SEC. This catalytic system was utilized to deliver an assortment of substituted biaryl compounds in water with good to excellent yields through the Suzuki coupling reaction. The greatest advantage of this catalytic platform is related to the reusability of the catalyst up to 7 times and non-use of organic solvent in coupling reactions. Simple purification of the coupling products due to the effortless recyclability of the catalysts is another characteristic of the method. This important characteristic is achieved by just adding diethyl ether to the reaction mixture to extract the biphenyls. The catalyst remains intact in aqueous phase and reused in other reaction runs without considerable loss of efficiency.

Iron oxide-based superacid catalysts were successfully prepared using impregnation method. Graphene oxide was prepared from sugarcane bagasse, the biowaste of sugar factories, modified Hummer’s method. Fe₂O₃ prepared by precipitation method followed by impregnation with ammonium persulfate and doped with graphene oxide. These catalysts were applied to the esterification of oleic acid with methanol at various conditions such as temperature, reaction time, and catalyst dosage. The highest yield of 96% was achieved using 0.2 g of S₂/Fe₂O₃ at 100 °C for 3 h, indicating a high density of Brønsted and Lewis acid sites on its surface. Catalyst characterization (XRD, SEM, FTIR, N₂ adsorption-desorption analysis, and TGA) confirmed good nanoparticle crystallinity, effective intercalation of metal oxides with persulfate and graphene oxide, and a predominantly mesoporous structure. Sulfation with ammonium persulfate significantly enhanced the acidity of iron oxide, while the addition of graphene oxide provided a moderate acidity increase. This increase in acidity positively impacted the conversion rate of oleic acid with methanol. All three catalysts (GF, SF, GSF) demonstrated strong reusability for oleic acid esterification, maintaining conversion efficiency above 50% after six cycles, indicating economic feasibility with minimal efficiency loss. Overall, this solid superacid catalyst presents a promising green pathway for ester synthesis and biodiesel production.

This study investigates the fabrication, characterization, and catalytic performance of innovative biochars derived from sunflower stalk cellulose, emphasizing their potential as sustainable catalysts in green chemistry applications. Biochars were produced via pyrolysis at 450, 550, and 650 °C, yielding samples labeled SSB1, SSB2, and SSB3, respectively. The production of glycerol carbonate through the transesterification of glycerol and dimethyl carbonate (DMC) was selected as a model reaction to evaluate the catalytic efficacy of these biochars. This approach aligns with the principles of green chemistry, addressing the effective utilization of biomass waste and excess glycerol while contributing to a circular economy. Characterization using FTIR, XRD, TGA, N₂ adsorption, and SEM-EDX analyses revealed significant effects of pyrolysis temperature on the physicochemical properties of the biochars, including yield, pH, surface area, and mineral content. Higher pyrolysis temperatures led to increased porosity, surface area, and mineral content, which enhanced catalytic performance. Under optimized conditions, the catalytic activity of SSB1, SSB2, and SSB3 was evaluated at a reaction temperature of 110 °C, a catalyst loading of 5 wt%, a reaction period of 20 min, and a DMC-to-glycerol molar ratio of 5:1. Among the biochars, SSB3 demonstrated the highest catalytic activity, achieving a glycerol conversion rate of 65.3% and glycerol carbonate selectivity of 53.4%. By linking the structure-performance relationship, this paper highlights the innovation and logic of utilizing biochars as effective catalysts in heterogeneous processes. The findings demonstrate the potential of biochars derived from sunflower stalk residues as sustainable alternatives to conventional catalysts, offering valuable insights into the development of functional materials for environmentally friendly chemical processes.

The investigation of the process of converting levulinic acid (LA) into ethyl levulinate (EL) using tungstic acid (TA)-functionalized activated natural zeolite (AZ) was systematically conducted. The aims of this work were to synthesize and characterize the activated zeolite modified by tungstic acid (TA-AZ) and also evaluate its performance in LA esterification. We employed the wet impregnation approach and ultrasonication-assisted method to produce TA-AZ catalyst with different concentrations of TA (15, 20, and 25 wt%). Fourier transform infrared (FTIR), ammonia-temperature programmed desorption (NH₃-TPD), X-ray diffraction (XRD), scanning electron microscope with an energy dispersive X-ray spectrometer (SEM-EDX), transmission electron microscope (TEM), and surface area analyzer (SAA) were among the analytical methods used to investigate the chemical and physical characteristics of AZ and TA-AZ catalysts. The liquid yields from LA esterification were analyzed by GC-FID. The findings indicated that the 25TA-AZ catalyst exhibited the highest acidity, reaching 3.65 mmol/g. The presence of TA in AZ resulted in an enhancement of LA conversion and an increase in EL yield. The LA esterification process, employing a 25TA-AZ catalyst with a reaction temperature of 150 °C and a weight% of 0.5 wt%, produced 91.72% for LA conversion and 82.65% for EL yield.

This study explores the use of graphene oxide (GO) modified with PyrCO-cyclo@Fe as an efficient and selective catalyst. The modification of GO with PyrCO-cyclo@Fe provides a robust platform for the synthesis of (S)-2-phenylpropanoic acid derivatives 4(a–l), facilitated by the presence of choline chloride ethylene glycol (ChCl/EGC) as the electrolyte in good to excellent yields (89–97%). The experimental results demonstrate that this catalytic system not only enhances the enantioselectivity of the carboxylation process but also improves the overall yield and efficiency. This method presents a promising approach for the production of valuable enantioenriched carboxylic acids, contributing to the development of green and sustainable catalytic processes in organic synthesis. The synthesized GO-PyrCO-cyclo@Fe electrode was examined utilizing various analytical methods, including FT-IR, CV, SEM, EDS, BET, TGA, and XPS The synthesized (S)-2-phenylpropanoic acid derivatives 4(a–l) were identified and characterized through melting point determination, FT-IR, ¹HNMR, and CHN analyses.

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