نتایج جستجو برای: natural catalysts
تعداد نتایج: 513446 فیلتر نتایج به سال:
A novel, solvent-deficient precipitation (SDP) method for catalyst preparation in general and for preparation of iron FT catalysts in particular is reported. Eight catalysts using a 23 factorial design of experiments to identify the key preparation variables were prepared. The catalysts were characterized by electron microprobe, N2 adsorption, TEM, XRD, and ICP. Results show that the morphology...
the mono-metallic and bi-metallic catalysts have been prepared by impregnating with solutions containing a compound of h2ptcl6,wo3 and 1ml hcl (0.1 mol). it should be noted that the catalysts’ activity and selectivity have been determined under these conditions : 450-5000c ,and 15-25atm by h2. for converting n-heptane , the molar ratio h2/c7h16 is 5 , and lhsv is 1.5ml/h. it has been proved tha...
Magnetically recyclable catalysts with magnetic nanoparticles (MNPs) are becoming a major trend towards sustainable catalysts. In this area, recyclable supported ruthenium complexes and ruthenium nanoparticles occupy a key place and present great advantages compared to classic catalysts. In this micro-review, attention is focused on the fabrication of MNP-supported ruthenium catalysts and their...
In this study, the nanoporous γ-alumina catalysts were prepared by the sol-gel method using hydrolysis of aluminum isopropoxide in the presence of TX-100 or gelatin/TX-100 mixture. Catalysts were characterized by XRD, FT-IR, TEM, BET-BJH and N2 adsorption-desorption isotherms. To investigate reactivity and selectivity of the synthesized catalysts, dehydration reaction of 2-octanol was carried o...
abstract the influence of cation?? and anion?? interactions on the strength and nature of n…h hydrogen bond has been investigated by quantum chemical calculations in s-triazine…3hf complex. ab initio calculations were performed at mp2/6-311++g(d,p) level of theory. the natural bond orbital (nbo) analysis and the bader’s quantum theory of atoms in molecules (aim) were also used to elucidate t...
Received: 15 December 2004; Revised: 26 January 2005 Abstract Copper zinc oxide catalysts prepared similar to industrially used catalysts were studied by high-resolution electron microscopy. The microstructure of the Cu/ZnO catalysts deviates considerably from that of bulk copper metal and idealized copper model systems. In order to reveal reliable structure-activity relationships for copper ca...
Copper-manganese oxide catalysts are prepared with an atomic ratio of Cu/Mn=2/1 using a coprecipitation procedure under air atmosphere. The time of aging, i.e., the time that precipitate remains in contact with the precipitating medium, has been varied from 0 (for unaged precursor) to 300 minutes and the effect of precipitate aging time in each atmosphere upon the structure and morphology of di...
Using MeN=CMe(2) as an imine model, computational chemistry has been applied to design metal-free hydrogenation catalysts. The implementation includes designing proper electronic structures to split H(2) and building appropriate chemical scaffolds to prevent possible side reactions which may deactivate the catalysts. Interestingly, the designed catalysts bear resemblances to the well-known meta...
Atomically dispersed catalysts refer to substrate-supported heterogeneous catalysts featuring one or a few active metal atoms that are separated from one another. They represent an important class of materials ranging from single-atom catalysts (SACs) and nanoparticles (NPs). While SACs and NPs have been extensively reported, catalysts featuring a few atoms with well-defined structures are poor...
In contrast to solid acid catalysts, much fewer efforts have been made to study solid base catalysts. In this thesis, preparation, characterization and application of oxides and modified oxide as solid base catalysts were studied. The catalysts include MgO prepared by different methods, potassium-modified ZrO2, calcined Mg-Al hydrotalcites, and a novel catalyst system Mg(O,F), which was prepare...
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