Dispersion catalyst

In the presence of a potassium catalyst dispersed on calcium oxide, toluene reacts with 1,3-butadiene to yield 5-phenyl-2-pentane (22). 

The precious metal or metal oxide imparts high intrinsic activity, the carrier provides a stable, high surface area for catalyst dispersion, and the mechanical support gives a high geometric surface area for physical support and engineering design features (20). Only the correct combination of these... 

S. Wodiunig, F. Bokeloh, J. Nicole, and C. Comninellis, Electrochemical Promotion of R11O2 Catalyst Dispersed on an Yttria-Stabilized Zirconia Monolith, Electrochemical and Solid State Letters 2(6), 281-283 (1999). 

Since the catalytically active phase is frequently quite expensive (e.g. noble metals) it is clear that it is in principle advantageous to prepare catalysts with high, approaching 100%, catalyst dispersion Dc. This can be usually accomplished without much difficulty by impregnating the porous carrier with an aqueous solution of a soluble compound (acid or salt) of the active metal followed by drying, calcination and reduction.1... 

In this section, we demonstrate the real ORR activities (apparent rate constant per real active surface area, fe pp) and P(H202) at bulk Pt and nanosized Pt catalysts dispersed on carbon black (Pt/CB) with dp,= 1.6 + 0.4, 2.6 + 0.7, and 4.8 1.0 nm in the practical temperature range 30-110 °C [Yano et al., 2006b]. The use of a channel flow double-electrode (CFDE) cell allowed us to evaluate fe pp and P(H202) precisely. 

Baranton S, Coutanceau C, Gamier E, Leger JM. 2006. How does a-FePc catalysts dispersed onto high specific surface carbon support work towards oxygen reduction reaction (orr) J Electroanal Chem 590 100-110. 

The high sensitivity of the reaction to particle size of Rh is confirmed at 230°C, in a mixture of 0.5% NO+1% CO, the turnover frequency increases from 0.017 s-1 for a highly dispersed catalyst to 0.74 s 1 for a catalyst dispersed at 1.7%, the activity per metal site on unsupported Rh catalysts being still much higher. 

Catalyst Dispersion (%) Metal crystallite size (run) Metal Surface Area (mV) Pore diameter (mil) PSD (50) (microns)... 

Catalyst Dispersion (%) (CO Chemisorptio n) Amount of Catalyst Charged (mg) Pd Concentrat ion ( xmol/g cat.) Initial Activity (nmol/g cat. sec) Initial TOF (sec-1)... 

The PDMS-membrane-occluded FePcY was the first room temperature catalytic membrane and the first solid catalyst dispersed in dense organic polymer.169 The catalytic system mimics the cytochrome P-450 enzyme and can oxidize alkanes at room temperature with rates comparable to those of the... 

A heterogeneous Pd catalyst dispersed on supports such as o-A1203, C, MgO and CaC03 was found to be an recyclable and selective catalyst for heterogeneous Heck arylation (an important method of C-C bond formation - Chapt. 11) of several olefins (styrene, a-methylstyrene, 1-decene, acrylonitrile, etc.) with iodobenzene [45], Scheme 10.5. 

Colloidal catalysts in alkyne hydrogenation are widely used in conventional solvents, but their reactivity and high efficiency were very attractive for application in scC02. This method, which is based on colloidal catalyst dispersed in scC02, yields products of high purity at very high reactions rates. Bimetallic Pd/Au nanoparticles (Pd exclusively at the surface, while Au forms the cores) embedded in block copolymer micelles of polystyrene-block-poly-4-vinylpyridine... 

Catalyst % Dispersion of Ir CO conversion Activation energy (kJ/mol) for COz formation Activation energy (kJ/mol) for H2 formation... 

Y. Yoo, M. Tuck, R. Kondakindi, C.-Y. Seo, Z. Dehouche, K. Belkacemi, Enhanced hydrogen reaction kinetics of nanostructured Mg-based composites with nanoparticle metal catalysts dispersed on supports , J. Alloys and Compounds, 446-447 (2007) 84-89. 

The solubility of a reactant in an ionic liquid affects the performance of the ionic liquid as a catalyst and that of a catalyst dispersed in an ionic liquid. However, there are only a few reports about the solubilities of species in ionic liquid media. The solubility values of typical molecules of interest, as described below, are based on a limited number of reports. 

Pt/Ru electrocatalysts are currently used in DMFC stacks of a few watts to a few kilowatts. The atomic ratio between Pt and Ru, the particle si2 e and the metal loading of carbon-supported anodes play a key role in their electrocatalytic behavior. Commercial electrocatalysts (e.g. from E-Tek) consist of 1 1 Pt/Ru catalysts dispersed on an electron-conducting substrate, for example carbon powder such as Vulcan XC72 (specific surface area of 200-250 m g ). However, fundamental studies carried out in our laboratory [13] showed that a 4 1 Pt/Ru ratio gives higher current and power densities (Figure 1.6). 

It is clear that ruthenium-cobalt-iodide catalyst dispersed in low-melting tetrabutylphosphonium bromide provides a unique means of selectively converting synthesis gas in one step to acetic acid. Modest changes in catalyst formulation can, however, have profound effects upon liquid product composition. 

Metal catalysed skeletal reactions of hydrocarbons on metal catalysts. Dispersed metal catalysts. 

Analysis and characterization of catalyst dispersion and surface areas... 

Table 4. Rest potential and current/voltage values for the cathodic reduction of oxygen on pigment-catalyst dispersions at 25 °C in 4.5 N H2SO4 °C 38>...

Since 1981, three-way catalytic systems have been standard in new cars sold in North America.6,280 These systems consist of platinum, palladium, and rhodium catalysts dispersed on an activated alumina layer ( wash-coat ) on a ceramic honeycomb monolith the Pt and Pd serve primarily to catalyze oxidation of the CO and hydrocarbons, and the Rh to catalyze reduction of the NO. These converters operate with a near-stoichiometric air-fuel mix at 400-600 °C higher temperatures may cause the Rh to react with the washcoat. In some designs, the catalyst bed is electrically heated at start-up to avoid the problem of temporarily excessive CO emissions from a cold catalyst. Zeolite-type catalysts containing bound metal atoms or ions (e.g., Cu/ZSM-5) have been proposed as alternatives to systems based on precious metals. 

Polymers using the ring opening metathesis polymerization (ROMP) technique were first obtained at 1960 by Eleuterio (1,2). The patents deal with the polymerization of bicyclo[2.2.1]heptene-2, i.e., nor-bomene using a molybdenum catalyst dispersed on alumina. 

Gas-phase epoxidation of propylene with 02/H2 mixtures was accomplished over Ag1267 or Au1268 catalysts dispersed on TS-1 or other Ti-containing supports and Ti-modified high-silica zeolites.1269 Sodium ions were shown to be beneficial on the selectivity of propylene epoxidation with H202 over titanium silicalite.1270 A chromia-silica catalyst is active in the visible light-induced photoepoxidation of propylene by molecular oxygen.1271... 

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