Catalytic tests

Heterogeneisation of such dithiourea catalysts was achieved by the synthesis of a series of chiral polythioureas from the corresponding chiral diamine and diisothiocyanate [81]. Results of the catalytic tests have shown that it is important to preserve the C2-symmetry inside the polymeric material [82]... 

Cobalt-supported-on-MgO catalysts were prepared by impregnating MgO (JRC-MGO-4 lOOOA, 14-16 m g ) with aqueous solutions of Co(N03)2-6H20 (Kanto Co.), followed by drying. The material was then calcined in air for 8 h at 873 K or 1173 K. Before catalytic tests, catalysts were reduced at 1173 K in H2/Ar (50/50 vol.%). 

The results of the catalytic tests were expressed as DPM total conversion. These experimental results were compared to theoretical values (Cj), calculated considering, as an approximation, a zero-order reaction and the absence of interactions of any kind between both phases, according to the following expression ... 

This interpretation of the experimental data is supported by the differences observed in the deactivation patterns and carbon contents after test, since one notorious effect of Hjp is the capacity to diminish the deactivation caused by coke deposition on the active sites [21,22]. This is supposed to be due to a reaction with the coke precursors, very likely a hydrogenolysis. In pure silica-aluminas, where no source of spillover is present, no special protection against deactivation should be observed. Indeed, the silica-aluminas lose most of their activity (about 80%) before reaching the steady-state and present the highest carbon contents after catalytic test. On the other hand, in the case of the mechanical mixtures, where spillover hydrogen is continuously produced by the CoMo/Si02 phase and can migrate to the silica-alumina surface, the predicted protection effect is noticed. The relative losses of activity are much lower... 

Transport properties have been studied before and after Si deposition using a rig similar to the one for catalytic testings (Figure 2). Pure gas permeabilities (H2, He, N2, normal and isobutane) were studied by measuring the flux passing though the membrane as a function of temperature and pressure for a constant transmembrane differential pressure (no sweep gas). 

Catalytic testings have been performed using the same rig and a conventional fixed-bed placed in the inner volume of the tubular membrane. The catalyst for isobutane dehydrogenation [9] was a Pt-based solid and sweep gas was used as indicated in Fig. 2. For propane oxidative dehydrogenation a V-Mg-0 mixed oxide [10] was used and the membrane separates oxygen and propane (the hydrocarbon being introduced in the inner part of the reactor). 

In this paper we attempt a preliminary investigation on the feasibility of catalytic combustion of CO/ H2 mixtures over mixed oxide catalysts and a comparison in this respect of perovskite and hexaaluminate type catalysts The catalysts have been characterized and tested in the combustion of CO, H2 and CH4 (as reference fuel). The catalytic tests have been carried out on powder materials and the results have been scaled up by means of a mathematical model of the catalyst section of the Hybrid Combustor. 

In the absence of O2, NO reduction continued, however at a rate about ten times lower than that in the presence of O2. During 20 h experiments NO conversion remained constant. On O2 addition, the catalytic activity increased with O2 content in the mixture up to about 1000 ppm, and changed little thereafter. We noticed that increasing the O2 concentration caused NO conversion to become lower than that of NH3, probably due to changes in the stoichiometry of the overall reaction (the NO/NH3 ratio passed from 1.5 to 1). Catalytic tests of NH3 oxidation with O2 yielded high selectivity to N2 (66-90%), which decreased with the higher loading catalysts. 

In contrast, substituting the ort/to-methyl groups of SIMes with ortho-fluoride atoms profoundly alters the catalytic metathesis performance. In 2006, Grubbs and co-workers reported the synthesis of the fluorinated NHC-Ru catalysts 25 and 26 [41] (Fig. 3.8). Catalytic tests in the RCM of 1 to form 2 showed that the phosphine-free catalyst 26 was slower than the standard catalyst 16, which was consistent with theoretical investigations suggesting the electron-withdrawing fluoride atoms would lead to a decrease in catalyst activity [42]. However, in contrast to the computational... 

Figure 8. Relative size distribution for the MPIF Na /Pd catalyst particles before (left, 35 particles) and after catalytic tests (right, 75 particles, magnetic stirring). Arithmetic average diameters 319 and 276mm were determined for particles before and after catalytic tests, respectively. Image Pro Plus program. (Reprinted from Ref [29], 2003, with permission from Elsevier.)...

The catalytic tests show that, over the Pt(l 0 0)/Al2O3 catalyst, the formation of CO and NH3 is largely prevented, whereas the yield of N2O increases compared with the Pt(polycrystalline)/Al203 catalyst. These main differences observed should be ascribed to the morphological differences between two catalysts, i.e., the dominant orientation of the crystallographic facets and the average size... 

Catalytic Reactions. The copper catalysts were pre-reduced at 270°C with H2 before the catalytic test. Citral (0.1 g) was dissolved in toluene or heptane dehydrated over zeolites (8 ml) or not and the solution transferred under N2 into a glass reaction... 

The catalytic tests [temperature = 543-703 K liquid hourly space velocity (LHSV) = 2,0 h gas hotuly space velocity (GHSV) (if not differently reported) = 510 h PYC/formaldehyde acetal =1 1 moEmol were carried out in... 

Catalytic tests were performed in a gas-phase continuous-flow reactor. The outlet flow of the reactor was either sampled for the analysis of the gaseous components, or condensed in a dry frozen trap, for the analysis of the solid and liquid products. Two liquid layers formed an organic layer containing the unconverted n-hexane, and an aqueous layer, some products dissolved preferentially in the organic layer, others in the aqueous one. Both layers were analyzed by gas chromatography. 

Figure 40.1 reports the flammabihty diagrams for the ternary mixtures ammonia/oxygen/inert and n-hexane/oxygen/inert. The boundary conditions for the catalytic tests were the following ... 

Figure 40.1. Flammability areas for NH3/02/inert and -hexane/02/inert mixtures. Experimental feed composition used for catalytic tests.

The synthesis of Ti-Si-TUD-1 is analogous to the silica version a portion of the reactant is a titanium alkoxide, such as titanium (IV) n-butoxide. One of the early comparative catalytic tests of TUD-1 versus MCM-41 was for cyclohexene epoxidation. 

Richter, A., Langpape, M., Kolf, S. et al. (2002) Combinatorial preparation and high-throughput catalytic tests of multi-component deNO(x) catalysts. Appl. Catal. B Environ., 36, 261. 

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