Commercial catalyst comparison

For comparison, a 20wt% Pt/XC72 catalysts prepared commercially by E-TEK had an average diameter of 2.6 nm. The sputter deposited Pt had a standard deviation between 0.42 and 0.49 nm, whereas the commercial E-TEK catalyst has a standard deviation of 0.79 nm. Thus, the sputtering technique creates smaller and more uniformly dispersed Pt particles than those prepared chemically. It should be noted that the Pt/C samples having low loadings prepared via sputtering did not uniformly coat... 

Koebel, M. and Elsener, M. (1998) Selective Catalytic Reduction of NO over Commercial DeNOx-Catalysts Comparison of the Measured and Calculated Performance, Ind. Eng. Chem. Res., 37, 327. 

It is difficult to predict a priori which preparative method will produce the most active and selective catalyst or which preparative method will affect which, if any, of the previously mentioned properties. A great number of recipes have appeared in the patent literature, but any detailed description of the methods which yield the most active and selective catalyst, at least from a commercial viewpoint, remains proprietary. Of course, this makes it very difficult to make comparisons between experimental catalysts and commercial catalysts. Nevertheless, a number of general chemical variables have been identified as important in attempting to produce a specific catalyst. For example, for molybdate catalysts prepared by precipitation, these variables include the temperature of the precipitation, the concentration of the reagents, the aging of the precipitate, and the temperature of the calcination (6J). For supported catalysts, the nature of the support also becomes an important variable in determining the final catalytic activity and selectivity. 

The amount of wash coat which was deposited in the testing reactors was in the same range, between 14 and 17 mg, for the rhodium, platinum and palladium samples tested. The platinum sample was calcined after impregnation at a lower temperature of 450 °C, all other samples at 800 °C. The reason for this will be explained below. The content of the active noble metal was around 5 wt.%. All noble metal-containing samples were laboratory-made catalysts. A commercial a-alumina-based catalyst containing 14 wt.% Ni was added for comparison, as nickel catalysts are applied in industrial steam reforming [52],... 

Figure 24 describes schematically the three recent modes of preparation of membrane/electrode assemblies based on commercially available dispersed platinum catalysts. Comparison of catalyst utilization obtained with the different PEFC catalyzation techniques is given in Fig. 25. The advantage in catalyst utilization of the thin-layer approach is clearly seen, increasing at the higher cell currents (lower cell voltage) thanks to minimized mass-transport limitations in the thin catalyst layer.

A typical burning rate plot as obtained from a 107 mg. silica-alumina catalyst particle (commercial type catalyst, 349 m. /g. surface area, as used in Sec. IV.2.c) is shown in Figure 20, from which an oxygen diffusivity of. 0024 cm. Vsec. is obtained. In Table VII a direct comparison is made... 

Pt has the highest adsorption of methanol on its surface, but its catalytic properties are low due to the formation of poison species (most notably CO) that can be oxidized only after the Pt is covered with OH. Platinum-based bimetallic electrocatalysts, such as Pt-Ru alloys and Ru-decorated Pt materials, are the most active ones. The bi-functional mechanism is to a large extent operative in these catalysts. Most commercial Pt-Ru catalysts are based on 1 1 Pt-Ru alloy. While the alloys typically show enhanced activity in comparison with pure Pt, there is significant Pt loading in the bulk of the alloy in which catalysis does not proceed because the sites are inaccessible for methanol adsorption hence, the need for reducing the Pt content. 

Attention has also been focused on the oxidation of thiols in the presence of solid catalysts. One of the more comprehensive investigations into systems of this type has been made by Wallace et al. [133,145, 146] with a view to the possible use of phthalocyanine type complexes as commercial sweetening catalysts. Comparisons were drawn with metal pyrophosphates, phosphomolybdates, phosphotungstates, and phosphates. Pyrophosphates were found to be effective catalysts, possible due to the existence of six-membered rings involving the cobalt cation [147], which enhances the ability of the cation to donate an electron to oxygen and stabilises each oxidation state of the cation. For a series of pyrophosphates, the order of activity was Co > Cu > Ni > Fe, an activity pattern which was explained in terms of the stability of the 3d electron shells. 

IMPACT OF SULFUR ON THREE-WAY CATALYSTS COMPARISON OF COMMERCIALLY PRODUCED Pd AND... 

Beck, D. D. Sommers, J. W. Impact of sulfur on three-way catalysts Comparison of commercially produced Pd and Pt-Rh monohths in Catalysis and Automotive Pollution Control III, Proceedings of the Third International Symposium (CAPoCS), Frennet, A. Bastin, J.-M. (Eds.), Elsevier, Amsterdam (1995). 

The Knoevenagel condensation is illustrated in figure 5. For comparison, commercial MgO catalyst is also reported. This figure evidences that the conversion depends on the nitrogen content of the catalyst Comparable behavior has been observed in the malononitrile-benzaldehyde condensation (28). 

Comparison of Yield Structure for Fluid Catalytic Cracking of Waxy Gas Oil over Commercial Equilibrium Zeolite and Amorphous Catalysts... 

Fig. 1. Comparison between LP201 and the commercial catalysts in a slurry reactor 2.2 Circulating slurry bed reactor...

Table 41.3 shows a performance comparison of Pt/Pd TUD-1 with a commercial Pt/Pd catalyst (26). The feedstock is a typical straight run gasoil ( SRGO ), a distillate precursor to diesel fuel. Under identical test conditions, the TUD-1 catalyst achieved 75% aromatics saturation versus 50% for the same volume of commercial catalyst. This superior result is particularly interesting because the TUD-1 catalyst had a much lower density than the commercial material, so that less catalyst by weight was required in the reactor. 

Reagents were purchased from commercial sources and used without further purification. Product identities were confirmed by comparison of HPLC retention times with authentic samples. The Pd/C catalyst was purchased as a dry, edge-coated, unreduced catalyst with 5 wt% in Pd. HPLC analyses were performed on a HP 1090 (stationary phase C18, 25 cm x 0.46 cm mobile phase CH3CN/H20 1% H3P04, 90% H20 to 100% CH3CN gradient over 25 min, 1 ml/min flow, UV-Vis detection). For safety aspects of handling Pd/C, see ref. 7.7... 

Previous studies on the use of Anchored Homogeneous Catalysts (AHC s) have been concerned with studying the effect which different reaction variables had on the activity, selectivity and stability of these catalysts (1-9). These reactions were typically ran at relatively low substrate/catalyst ratios (turnover numbers-TON s), usually between 50 and 100. While these low TON reactions made it possible to obtain a great deal of information concerning the AHC s, in order to establish that these catalysts could be used in commercial applications it was necessary to apply them to reactions at much higher TON S and, also, to make direct comparisons with the corresponding homogeneous catalyst under the same reaction conditions. 

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