Comparison with commercial catalysts

Another approach is the synthesis of Ru-covered Pt nanoparticles and their fixation to anionic phosphodecatungstate PW12O4Q [77]. By this layer-by-layer preparation method a network film can be realised. A carrier material was alternately immersed into the Pt/Ru solution and into phosphodecatungstate solution. First electrochemical measurements proved their activity in principle, but the noble metal loading was too low (typically 0.08 mg cm ) for direct comparison with commercial catalysts. 

Concerning the Fischer-Tropsch synthesis, carbon nanomaterials have already been successfully employed as catalyst support media on a laboratory scale. The main attention in literature has been paid so far to subjects such as the comparison of functionalization techniques,9-11 the influence of promoters on the catalytic performance,1 12 and the investigations of metal particle size effects7,8 as well as of metal-support interactions.14,15 However, research was focused on one nanomaterial type only in each of these studies. Yu et al.16 compared the performance of two different kinds of nanofibers (herringbones and platelets) in the Fischer-Tropsch synthesis. A direct comparison between nanotubes and nanofibers as catalyst support media has not yet been an issue of discussion in Fischer-Tropsch investigations. In addition, a comparison with commercially used FT catalysts has up to now not been published. 

Rate Comparisons With Other Catalysts. It is of interest to compare the space-time-yield for Rh-Mo/A1203 catalyst and industrial Cu/Zn0/A1203 catalysts. The space-time-yield STY, for Rh-7.5%Mo/Al203 at 250 at 36,000 GHSV in g/hr/ml catalyst corresponds to 1.0 for all products, 0.76 for oxygenates and hydrocaibons, or 0.4 for oxygenate liquids (0.51 ml /. Commercial catalysts are said to produce about 0.5 ml methanol/hr/gm cat. Tbus... 

The reactions were carried out in a 250 ml three-necked, roimd-bottomed flask equipped with a magnetic stirrer, a condenser with a calcium chloride guard tube and a gas-inlet tube. The catalyst (1 g), pre-activated at 450 °C, was suspended into a solution of allyl phenyl ether (15 mmol, Fluka) and tri-tert-butylbenzene (2 mmol, bulky internal standard, home-made) in benzene (100 ml. Baker Analyzed). The reaction mixture was heated to reflux temperature and stirred (1000 rpm) under nitrogen atmosphere. Aliquots were taken during the reaction and analysed by gas-liquid chromatography using a CP Sil 5 CB wide-hore column. Products were identified by GCMS and by comparison with commercially available and home-made reference compounds. 

The latest developments in catalysts for manufacturing acrylonitrile are those of the Japanese-firm Nitto Chemical, which commercialized a system in 1974 based on doped antimony and iron, called NS 733A or catalyst 13, offering higher productivity in comparison with Sohio catalyst 41. as well as lower production of acetonitrile and hydrogen cyanide by-products. 

The Microactivity Test (MAT) reactor is used primarily for cracking catalysts, such as those based on zeolites. In the MAT test, a given amount of feed is pumped within 1-75 s over a measured amount of catalyst in a fixed bed. Liquid and vapor products can be collected separately and analyzed. The MAT and TOS techniques are similar in principle, hence results for these two can be expected to be similar. Comparison with commercial reactors is carried out by empirically adjusting the test conditions. Conversion and simulated distillation results between MAT units can be compared by using standard catalysts and feeds using ASTM D-3907. 

The reaction progress is monitored ofF-Une by HPLC. Flow rates, residence times and initial concentrations of 4-chlorophenol are varied and kinetic parameters are calculated from the data obtained. It can be shown that the photocatalytic reaction is governed by Langmuir-Hinshelwood kinetics. The calculation of Damkohler numbers shows that no mass transfer limitation exists in the microreactor, hence the calculated kinetic data really represent the intrinsic kinetics of the reaction. Photonic efficiencies in the microreactor are still somewhat lower than in batch-type slurry reactors. This finding is indicative of the need to improve the catalytic activity of the deposited photocatalyst in comparison with commercially available catalysts such as Degussa P25 and Sachtleben Hombikat UV 100. The illuminated specific surface area in the microchannel reactor surpasses that of conventional photocatalytic reactors by a factor of 4-400 depending on the particular conventional reactor type. 

The presence of subtle differences in redox potentials and metal lattices of the different base metals in the ternary alloy allows better maneuvering of atoms in the nanoalloy formation and annealing processes than those in the binary counterparts. While this concept is under our investigation, we have demonstrated a number of ternary nanoalloys that outperform their binary counterparts. Examples are shown in Figure 11.15 for several ternary Pt-based nanocatalysts (e.g., PtNiCo/C, PtIrCo/C, PtVFe/C, and PtNiFe/C) [154,155,157,190] in comparison with commercial Pt catalysts for ORR in acidic electrolyte. 

The surface chemistry of a PEMFC commercial catalyst from BASF (Pt(20wt.%)/Vulcan XC72) has been analyzed and taken as a reference for comparison with other catalysts. By comparing the properties of this catalyst (denoted as PtXC-R in the following) with those... 

The band at 1280 cm is the characteristic absorption of vc o in acetic acid. More CO2 and less acetic acid are formed on HIF-Pt/C catalysts during ethanol oxidation in comparison with commercial Pt/C catalysts. The ratio of band intensities of CO2 to acetic acid on HIF-Pt/C is twice that of the commercial Pt/C. The in situ FTIRS results therefore reveal that the HIF-Pt/C catalysts have enhanced activity for breaking the C-C bond in ethanol. 

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. 

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. 

In. he industrial processes for the production of polybutadiene with Ti, Co, or Ni catalysts it can be controlled to only a very small extent. In comparison with the commercially available polybutadienes, SE-BR (SE stands for Seltene Erden, which means rare earths) has a broader molecular- weight distribution, which can be altered, however, by varying the ratio of Lewis acid to neodymium. Table II shows that an increase of this ratio from 0.8 to 2.0 increases the molecular weight distribution from 7 (which is close to that of Ni-BR) to 27. 

Clearly, the acid leached catalysts (Table 57) displayed much lower BET surface areas and lower activities in comparison with the caustic extracted samples, the commercial catalyst, and the precipitated experimental catalyst (Table 55). The authors suggest that use of a weaker acid solution strength (perhaps <5%) for... 

Militz (1993) treated European beech with DMDHEU and evaluated the effectiveness of a variety of commercial catalysts. It was found that temperatures of 100 °C were necessary for effective curing of the resin. The ASE was calculated from the dimensions at 100 % RH in comparison to the sample dimensions at 30 % RH, rather than in a water-soak test, so that any possible effect of leaching was not determined. The highest ASE measured in this way was 75 %. The EMC of the treated samples was also determined and found to be higher than unmodified samples in all cases. 

A commercial iron-promoted catalyst (Sn/Sb/Fe = 1/4/0.25) was studied by Germain et al. [92,93,135,137]. Iron is reported to improve the ammoxidation qualities of the catalyst although it has no effect on the oxidation [93], The kinetics, determined in a flow reactor at 445°C and with a feed ratio C3H6/NH3/air = 1/1.2/10, are essentially similar for this catalyst and bismuth molybdate. The initial selectivity is 80% and the maximum yield is 65% (at 445°C). The initial selectivity markedly depends on the temperature (e.g. 91% at 415°C and 72% at 507°C). The effect of water is hardly significant for this catalyst the acrylonitrile formation is slightly inhibited, while some more acrolein is formed. Presumably, water and ammonia compete in the interaction with the catalyst, which is much less reactive with respect to ammonia than bismuth molybdate. The acrolein ammoxidation is very rapid (about six times the propene ammoxidation rate) and selective (86%). A comparison of the Sn—Sb—Fe—O catalyst with bismuth molybdate is presented in Table 14. 

Tests on the activity of LP-produced Fe-based nanopowders for liquefaction of a sub-bituminous coal under high (688 K, 1 h of reaction) and low (658 K, 0.25 h of reaction) severity conditions have been reported.38 The catalysts tested were Fe7C3 (92 m2 g 1 (BET), particle size = 17 nm (XRD))and Fe XS (42 m2 g 1 (BET), particle size = 14 nm (XRD).38 For comparison, a commercial superfine iron oxide catalyst (SFIO, supplied by Mach I, Inc.) whose major phase has been identified in one study as y-Fe20339 (surface area = 195 m2 g 1 (BET), particle diameter = 3 nm (XRD)) and in other study as the ferrihydrite40 was also evaluated under similar conditions. The coal liquefaction experiments were carried out in 50 cm3 horizontal microautoclave reactors loaded with 3 g of sub bituminous Black Thunder coal and 5 g of tetralin used as hydrogen donor. Catalyst loadings of 0.7% and 1.4% of as-received coal... 

In each run, one channel was loaded with graphite or quartz and used as bypass reference, and one channel was loaded with reference catalyst (commercial or proprietary) for comparison. The temperature was varied from 100 to 250 °C, with a 5 min isotherm every 20 °C. Reaction products were monitored by fast gas chromatography (micro-GC) and on-line mass spectrometry (MS). The carbon mass-balance was calculated by monitoring the effluents from the bypass reactor and kept between 98 and 102%. 

A Comparison of the Hydrodesulfurization and Hydrodenitrogenation Activities of Monolith Alumina Impregnated with Cobalt and Molybdenum and a Commercial Catalyst... 

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