نتایج جستجو برای: wetness impregnation
تعداد نتایج: 4803 فیلتر نتایج به سال:
Pd nanoparticles (PdNPs) stabilized by methyl cellulose (MC) were synthesized in an aqueous solution, which are monodispersed nanoparticles. PdNPs/α-Al2O3 catalyst was prepared with monodispersed PdNPs and showed better catalytic performance than Pd/α-Al2O3 catalyst prepared by the incipient wetness impregnation method using Pd(NO3)2 as a precursor. The catalysts were characterized by transmiss...
Fe-MCM-41 materials were prepared by different methods. The Fe was both incorporated into the structure and formed crystallites attached to the silica. High Fe content MCM-41 (~16 wt%) with retention of mesoporosity and long-range order was achieved by a range of new synthetic methodologies: (i) by delaying the addition of Fe(aq) to the stirred synthesis gel by 2 h, (ii) by addition of Fe precu...
The effects of palladium addition and the reduction methods on Au/TiO2 were investigated. Pd was loaded on TiO2 firstly by incipient-wetness impregnation, Au was then loaded by deposition-precipitation method. The nominal loadings of Au and Pd were 1 wt% and 0.01 wt%. The bimetallic catalysts were reduced by heating at 453 K, by flowing H2 at 423 K, or by NaBH4 at 298 K. The catalysts were char...
We report on the excellent stereo and chemoselectivity of nanosized silver and gold catalysts in the three-phase hydrogenation of acetylenic compounds under flow chemistry conditions. The materials featuring metal nanoparticles in the range of 2-21 nm were prepared by spray deposition or incipient wetness impregnation of silver nitrate and sol immobilisation of gold chloride on different carrie...
Hyperpolarization of substrates for magnetic resonance spectroscopy (MRS) and imaging (MRI) by dissolution dynamic nuclear polarization (D-DNP) usually involves saturating the ESR transitions of polarizing agents (PAs; e.g., persistent radicals embedded in frozen glassy matrices). This approach has shown enormous potential to achieve greatly enhanced nuclear spin polarization, but the presence ...
Supported WOx/SiO2 catalysts were investigated for propylene metathesis as a function of tungsten oxide loading and temperature. The catalysts were synthesized by incipient-wetness impregnation of an aqueous ammonium metatungstate solution onto the silica support and calcined at elevated temperatures to form the supported tungsten oxide phase. In situ Raman spectroscopy under dehydrated conditi...
Present process of transesterification faces various challenges. The most challenging is to obtain high conversion rate when using high free fatty acid (FFA) feedstock. The aim of this study is to investigate transesterification process of rubber seed oil (RSO) through direct-ultrasonic irradiation (UI) with addition of waste material based heterogeneous catalyst. The waste material based heter...
In the present study, ability for novel carbon microspheres (CMs) derived from date palm (Phoenix dactylifera) biomass using a hydrothermal carbonization (HTC) process and activated phosphoric acid to remove methylene blue dye was investigated. Three types of palm-based wastes (seeds, leaflet, inedible crystallized molasses) were used converted CMs via HTC process. The prepared samples then inc...
The catalytic wet air oxidation (CWAO) of phenol has been studied in trickled bed reactor using 2 wt.% platinum supported on carbon nanofibers (Pt/CNF) as catalyst. The catalyst was prepared by incipient wetness impregnation, and characterized by N2 adsorption, XRD and TEM. The operational variables studied and their range were: total air pressure, temperature, catalyst load, air and liquid flo...
The direct synthesis of hydrogen peroxide using supported gold palladium catalysts prepared by incipient wetness impregnation is described and discussed. The effect of an acid pre-treatment step on the activated carbon support prior to the deposition of the metals, together with the effect of the calcination temperature, has been investigated. The acid pre-treated samples all show superior acti...
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