نتایج جستجو برای: nano metal oxides
تعداد نتایج: 259901 فیلتر نتایج به سال:
The catalysis science of mixed metal oxides (supported metal oxides, molecular sieves and bulk mixed metal oxides) has undergone dramatic paradigm changes over the past 25 years as new characterization techniques became available (X-ray absorption spectroscopy (EXAFS/XANES/soft XANES), Raman, solid-state NMR, HR-TEM, UV–vis DRS and LEISS) to catalysis researchers. The major advantages offered b...
Introduction Catalytic oxidations with O2 are one of the most important and widely studied reaction classes in heterogeneous catalysis. Metal oxides are of particular interest as catalysts because of the potential to replace expensive precious metals such as Pt and Pd. Despite the promising catalytic oxidation activities metal oxides have shown, practical applications are limited by surface poi...
Oxygen vacancies in metal oxides are known to determine their chemistry and physics. The properties of neutral oxygen vacancies in metal oxides of increasing complexity (MgO, CaO, alpha-Al2O3, and ZnO) have been studied using density functional theory. Vacancy formation energies, vacancy-vacancy interaction, and the barriers for vacancy migration are determined and rationalized in terms of the ...
The paper contrasts the main drawbacks of silica based packings such as their relative thermal and chemical instability with excellent stability of metal oxides. The paper concerns mainly ZrO2, TiO2 and Al2O3. Surface chemistry of the oxides is however very different from that of silica. Ability of the oxides to ionand ligand-exchange is discussed from a chromatographic point of view.
Aspects of the chemistry of selected metal fluorides, which are pertinent to their real or potential use as Lewis acidic, heterogeneous catalysts, are reviewed. Particular attention is paid to β-aluminum trifluoride, aluminum chlorofluoride and aluminas γ and η, whose surfaces become partially fluorinated or chlorinated, through pre-treatment with halogenating reagents or during a catalytic rea...
a simple method has been developed for the preconcentration of copper(ii) based on the adsorption of its modified nano polyacrylonitrile fiber. modified nano polyacrylonitrile fiber (panf) was prepared by adding of acrylic fibers to msethanolamine (mma) with different concentration solutions. the stability of a chemically modified nano polyacrylonitrile fiber especially in concentrated hydrochl...
in the current study, synthesis and characterization of a new nano-structured zirconium(iv)-minoxidil complex (1), where minoxidil, (c9h15n5o; 6-(1-piperidinyl)-2,4-pyrimidinediamine 3-oxide), have been investigated in two different solvents. the compound 1 has been synthesized by sonochemical method in the presence of methanol and monoethylene glycol (meg) as solvents and characterized by scan...
The performance of metal oxides as redox materials is limited by their oxygen conductivity and thermochemical stability. Predicting these properties from the electronic structure can support the screening of advanced metal oxides and accelerate their development for clean energy applications. Specifically, reducible metal oxide catalysts and potential redox materials for the solar-thermochemica...
We used halloysite, a nano-sized natural mineral, and high surface area montmorillonite as supports for nano-sized Mn oxides to synthesize efficient water-oxidising catalysts. The composites were synthesized by an easy and simple procedure, and characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrosco...
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