Papers by Keyword: Catalysis

Abstract: Pt/Ni multilayer nanowire arrays were successfully fabricated inside the nanochannels of anodic aluminum oxide template by pulse electrodeposition method. The morphologies of the Pt/Ni nanowires were analyzed, which revealed that these nanowires had smooth surface and uniform diameter of about 70 nm. The ferromagnetic Ni layers were separated periodically by Pt layers along the axis of the nanowires. Magnetization measurements on the Pt/Ni nanowire arrays revealed a stronger magnetic anisotropy with the easy axis parallel to the nanowires. Following electrochemical performance tests indicated that the Pt/Ni multilayer nanowires comprising Pt and Ni layers showed enhanced electrocatalytic activity for methanol oxidation, as compared with pure Pt nanowires.

Abstract: This paper reports about the method of modified nanomaterials. The aluminum oxyhydroxide was modified by manganese ions (II) during the synthesis. It was shown that modified aluminum oxyhydroxide has new function properties such as catalytic properties. It was shown that the modified aluminum oxyhydroxide with the high concentration of manganese ions (II) could be used in the reaction of the oxidation of methane.

Abstract: Recently, numerous delafossite oxides in nanoscale have been reported for diverse applications. The present review summarized the recent overall views of delafossite nanoparticles in diverse applications such as energy, catalysis, photocatalysis, nanomedicine, sensors, electrochemical devices and environmental concerns. Delafossite nanoparticles possess unique features such as different and wide chemical composition, large surface area, small energy gap, ability for further functionalization, possess dual-active sites with different oxidation states (A⁺ and M³⁺), and eager for doping with various species with feasibility to undergo structure modification. Thus, they provided promising application such as solar cell, photocatalysis, hydrogen production, bioactive materials, separation purposes and others. Pros, cons, current and future status were also reviewed.

Abstract: A series of functional fibers have been prepared by modifying a commercially available polyacrylonitrilefiber (PANF) with polyamines such as ethylenediamine, tetraethylenepentamine and hyperbranched polyethylenimine (HPEI), and then used to coordinate with Fe³⁺, respectively, to produce Fe-modified PAN fiber complexes. The chemical structures of modified PANFs were verified by Fourier transform infrared spectroscopy (FT-IR). X-ray Diffraction (XRD) characterization showed that the inner crystal region of PANF was damaged during the introduction of amine groups.. Organic elemental analysis results to a certain extent demonstrate the success of modification. The coordination of Fe³⁺ was verified by Energy Dispersive Spectroscopy (EDS). The Fe-modified PAN fiber complexes were were used to eliminate the color from synthetic reactive dye wastewater (SRDW, including Reactive Red 195, RR 195) under normal conditions. This study presents a valuable route towards wastewater treatment in dyeing and finishing.

Abstract: This study investigated catalytic fast pyrolysis (CFP) of beech wood, low-density polyethylene (LDPE), and their mixture (mass ratio of 1) with a conventional microporous ZSM-5 and mesoporous bifunctional Zn/ZSM-5_meso zeolite prepared by desilication of the conventional ZSM-5 with NaOH solution and then impregnation with Zn.The generation of mesopores by desilication improved the diffusion property of the zeolite, which decreased the formation of undesired polyaromatic hydrocarbons from secondary polymerization reactions of monoaromatics in CFP. In addition, the impregnation of Zn increased the dehydrogenation activity of the zeolites, and thus enhanced the conversion of low-value alkanes to valuable olefins. As a result, Zn/ZSM-5_meso produced higher yields (56.0 C%) of valuable petrochemicals (monoaromatic hydrocarbons and olefins) and lower yields of undesired polyaromatics (1.70 C%) and alkanes (10.2 C%) in co-feed CFP of the beech wood and LDPE mixture than ZSM-5 (48.2 C%, 4.18 C%, and 18.7 C% for petrochemicals, polyaromatics, and alkanes, respectively).ZSM-5 desilication and impregnation with Zn thus have a beneficial effect on improve the product distribution in CFP of biomass and plastic mixtures. In addition, the results suggest that CFP may provide a promising technology for producing renewable petrochemicals from municipal and agricultural solid wastes, which usually contain high contents of biomass and waste plastics.

Abstract: Gold palladium (Au-Pd) bimetallic catalysts are very promising for various reactions including oxidative catalysis. Mesoporous silica supported Au-Pd catalysts have large surface area, controlled hydrophobi and file-cities and are thus highly efficient for the oxidation of alkyl benzene to selective products. Alkyl Benzene oxidation is important for the productions of drugs, perfumes, polymers, insecticides and pesticides. Unfortunately, the efficient oxidation of alkyl benzene has been remaining a challenging task due to lack of suitable catalysts. Functionalized mesoporous silica with ordered surface and uniform porosity is an exciting template for the synthesis of supported catalysts. Metal precursors could be co-impregnated on the highly ordered surface of ammine functionalized silica. This method facilitates great dispersion of the Au-Pd clusters with tiny and controlled particle size. Here, we described a two-step adsorption –reduction method along with various ratios of metal loadings for the synthesis of silica supported nanoporous Au-Pd catalyst for alkyl benzene oxidation.

Abstract: We report a facile synthesis of PtNi nanosheets on the flexible ITO/PET substrate by electrochemical deposition method. The morphology and composition of the PtNi nanosheets were characterized and it was revealed that the PtNi nanosheets were polycrystalline with a thickness of about 4 nm. The average Ni content in the nanosheets was about 10 at%. The results of the electrochemical measurements showed that the PtNi nanosheets have excellent catalytic activity and stability toward the electro-oxidation of methanol in alkaline medium, which making it more attractive for fuel cell applications.

Abstract: Four kinds of Brønsted-acidic ionic liquids were synthesized with netrogen-contained chemical groups and different anions,and were characterized by nuclear magnetic resonance (NMR) and infrared spectrum (IR). On this basic, when the mole ratio of catalyst quantity to oleic acid was 0.019, that of alcohol to acid was 2, the reaction temperature was 150°C and the reaction time was 5 hours,the esterification of oleic and methanol were studied and the catalytic activities of ionic liquids for the esterification were investigated. The results showed their catalytic activities were associated with the structures of nitrogen-contained chemical groups, anionic acid strength and acid volume. Under the coaction of anions and cations, ionic liquids ([MPy]HSO₄) had the best catalysis activity. Meanwhile the conversion rate of oleic acid could reach 88.21% .

Abstract: The microwave catalytic reduction of NO was studied in activated carbon bed. The conversion of NO to N₂ under microwave irradiation remarkably increased compared to conventional heating, which indicates that the microwave irradiation has microwave catalysis effect besides thermal effect. The effects of a series of reaction parameters on the productivity of N₂ with a new microwave catalytic reactor system were investigated. The results show that NO is converted predominantly to N₂ under all reaction conditions and the highest conversion of NO to N₂ is up to 99.8% under optimized conditions.

Abstract: In our investigation we focused on effects of the degradation of Pt-Rh gauzes from three different industrial catalytic systems. The aim of the study was to compare the degree and the mechanism of degradation under different conditions (pressure, temperature, gas flow direction). The investigation was performed on about 80μm diameter wires after long (6 months) exposition to chemically aggressive environment. Microscope observations and microtomography analysis showed that all wires surfaces were strongly developed by etching and deposition processes occurring under extreme conditions. Each wire differed in rate of degradation and morphology of the characteristic cauliflower-shape growths. Also differences in elements distribution on both, surface and cross sections, were observed. Obtained results can be basis of further investigation on improvement of endurance of PtRh alloys in high temperature chemical application.