نتایج جستجو برای: heterogeneous catalyst
تعداد نتایج: 166602 فیلتر نتایج به سال:
A novel magnetite nanoparticle-based heterogeneous acidic catalyst [Fe3O4@SiO2@Am-PPC-SO3H] [HSO4] was successfully prepared and characterized by SEM, EDX, TGA, VSM and FT-IR techniques. The magnetically retrievable and sustainable catalyst was investigated in the reaction of aldehyde and o-aminophenol for the synthesis of benzoxazoles. The...
An environmentally benign procedure for the synthesis of vicinal nitrohydrins via the regioselective ring opening reaction of epoxides with nitrite anion using silica-bound 3-{2-[poly(ethylene glycol)]ethyl}-substituted 1-methyl-1H-imidazol-3-ium bromide as an effective heterogeneous phase transfer catalyst was described. Short reaction time, high yield of products, simple work-up proc...
5-Substituted-1H-tetrazoles were synthesized by the [3 + 2] cycloaddition of sodium azide with various nitriles in the presence of nickel zirconium phosphate (NiZrP) as an effective heterogeneous catalyst in dimethylsulfoxide at 120 °C. This method has the advantages of good to high yields, simple methodology and easy work-up. The catalyst can be recovered by centrifuging and reused with good y...
Cross-linked sulfonated polyacrylamide (Cross-PAA-SO3H) attached to nano-Fe3O4 as an efficientheterogeneous solid acid catalyst has been used for the preparation of spiro[pyrazoloquinoline-oxindoles]and spiro[chromenopyrazolo-oxindoles] through a four-component reactions of phenylhydrazineor hydrazine hydrate, isatins, ketoesters and naphthylamine or 2-naphthol under reflux co...
The palladium nanoparticles were immobilized on DNA-modified multi walled carbon nanotubes as stable and powerful heterogeneous catalyst. The catalyst was characterized by FT-IR spectroscopy, UV-Vis spectroscopy, field emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, inductively coupled plasma and elemental analysis. DNA as a well-defined structure and...
The new heterogeneous catalyst based on MoO2(acac)2 immobilized on superparamagnetic nanoparticle functionalized with dendrimer was synthesized. The dendrimer with amine and sulfur functional groups offer proper positions for a strong connection between MoO2(acac)2 and support. The synthesized catalyst was characterized by FT-IR spectroscopy, ICP, TGA, SEM, TEM, and XRD. This catalyst showed hi...
A simple procedure afforded novel spiroacenaphthylene derivatives in high yields at room temperature from acenaphthenequinone, malononitrile, and phenol derivatives using amino-functionalized silica (SBA-Pr-NH2) as a heterogeneous efficient solid base catalyst. Using SBA-Pr-NH2 in the current procedure presents several advantages, such as a simpler procedure, shorter reaction times, facile synt...
Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical) and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing). The key...
In the present study, a heterogeneous and homogeneous gas flow dispersion model for simulation and optimization of a large-scale catalytic slurry reactor for the direct synthesis of dimethyl ether (DME) from synthesis gas (syngas) and CO2, using a churn-turbulent regime was developed. In the heterogeneous flow model, the gas phase was distributed into two bubble phases including small and large...
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