Catalysts, specific names

Support name Catalyst Specific area (SBEr)(mVg) Pore volume (mL/g) COD removal (%)... 

The active carbon-supported cobalt catalyst was prepared by impregnation of cobalt nitrate aqueous solution onto active carbon (Kanto Chemical Co., specific surface 1071.7 mVg, pore volume 0.43 mVg, pellet size 20-40 mesh). The noble metal promoted Co/A.C. catalysts were prepared by co-impregnation of cobalt nitrate and aqueous solution of noble metal coordinated compounds with different noble metal loading. The cobalt loading of all of catalysts was 10 wt%. The noble metal promoted catalysts were named as lOCo+XM, where X was noble metal loading and M was symbol of noble metal. The details of catalyst preparation were described elsewhere [7]. 

Recent developments on acidity characterization of solid acid catalysts, specifically those invoking P solid-state nuclear magnetic resonance (SSNMR) spectroscopy using phosphorus-containing molecules as probes, have been summarized. In particular, various P SSNMR approaches using trimethylphosphine, diphosphines, and trialkylphosphine oxides (R3PO) will be Introduced, and their practical applications for the characterization of important qualitative and quantitative features, namely, type, distribution, accessibility (location/proximity), concentration (amount), and strength of acid sites in various solid acids, will be illustrated. 

Figure Bl.22.1. Reflection-absorption IR spectra (RAIRS) from palladium flat surfaces in the presence of a 1 X 10 Torr 1 1 NO CO mixture at 200 K. Data are shown here for tluee different surfaces, namely, for Pd (100) (bottom) and Pd(l 11) (middle) single crystals and for palladium particles (about 500 A m diameter) deposited on a 100 A diick Si02 film grown on top of a Mo(l 10) single crystal. These experiments illustrate how RAIRS titration experiments can be used for the identification of specific surface sites in supported catalysts. On Pd(lOO) CO and NO each adsorbs on twofold sites, as indicated by their stretching bands at about 1970 and 1670 cm, respectively. On Pd(l 11), on the other hand, the main IR peaks are seen around 1745 for NO (on-top adsorption) and about 1915 for CO (tlueefold coordination). Using those two spectra as references, the data from the supported Pd system can be analysed to obtain estimates of the relative fractions of (100) and (111) planes exposed in the metal particles [26].

Both of these structures are open-chained compounds corresponding to crown ethers in function if not exactly in structure (see Chap. 7). They have repeating ethyleneoxy side-chains generally terminated in a methyl group. Montanari and co-workers introduced the polypodes 22 as phase transfer catalysts . These compounds were based on the triazine nucleus as illustrated below. The first octopus molecule (23) was prepared by Vogtle and Weber and is shown below. The implication of the name is that the compound is multiarmed and not specifically that it has eight such side-chains. Related molecules have recently been prepared by Hyatt and the name octopus adopted. For further information on this group of compounds and for examples of structures, refer to the discussion and tables in Chap. 7. 

The monomers, catalysts or hardeners, or plasticizers can include chemicals with the potential to irritate the skin, mucous membranes or respiratory tract. Some can promote skin or respiratory sensitization. The range of chemicals in use is extremely wide, so that reference should be made to the Materials Safety Data Sheet for each specific formulation or variation of it identifiable by reference to the supplier s proprietary name and code number. Some common resin types are summarized in Table 5.55. 

Applications X-ray fluorescence is widely used for direct examination of polymeric materials (analysis of additives, catalyst residues, etc.) from research to recycling, through production and quality control, to troubleshooting. Many problems meet the concentration range in which conventional XRF is strong, namely from ppm upwards. Table 8.42 is merely indicative of the presence of certain additive classes corresponding to elemental analysis element combinations are obviously more specific for a given additive. It should be considered that some 60 atomic elements may be found in polymeric formulations. The XRF technique does not provide any structural information about the analytes detected the technique also has limited utility when... 

Unlike in the previous example, here the catalysts are not reported specifically to deactivate one another. Rather, the immobilization of the lipase in these silica elastomer spheres allows access to reaction conditions that are otherwise unavailable, namely higher temperatures, as the lipase is no longer deactivated and is able to undergo multiple reaction cycles, resulting in a much higher enzyme productivity, in terms of mass of product per unit mass of protein. The activity of the lipase is also observed to have increased, possibly not only from its ability to access higher temperatures when immobilized, but also due to the increased stability of the active... 

Although the exact nature of the active center in polymerizations of butadiene with these Ba-Mg-Al catalysts is not known, we believe that the preference for trans-1,4 addition is a direct consequence of two aspects of this polymerization system, namely (1) the formation of a specific organobarium structure in a highly complexed state with Mg and A1 species, and (2) the association of the polybutadiene chain end with a dipositive barium counterion which is highly electropositive. 

The nomenclature for the catalysts is as follows XAGaZB, where letter X refers to the treatments to which the sample was submitted, letter T referring specifically to the case where the sample was submitted to the two reduction-oxidation cycles described above letter A refers to the wt. % impregnated gallium amount letter B indicates the SAR of the zeolite. In this way, for example, the catalyst named T3GaZ38 is a ZSM-5 zeolite with SAR 38 impregnated with 3 wt. % gallium submitted to two reduction-oxidation cycles. 

The comparison of catalytic properties was made under identical reaction conditions, among three important candidate catalysts, namely, the Pt/y-Al203, Au/a-Fe203, and Cu Ce, x02 y systems [50], The catalytic tests were performed in the reactant feed containing CO, H2, C02, and HzO — the so-called reformate fuel. The effects of the presence of both C02 and H20 in the reactant feed on the catalytic performance (activity and selectivity) of these catalysts as well as their stability with time under reaction conditions have been studied. The composition of the prepared samples and their BET specific surface areas are presented in Table 7.6. The results obtained with the three catalysts in the presence of 15 vol% COz and of both 15 vol% COz and 10 vol% H20 in the reactant feed (with contact time wcat/v = 0.144 g sec/cm3 and X = 2.5) are shown in Figure 7.12. For comparison, the corresponding curves obtained under the same conditions but without water vapor in the feed are also shown in Figure 7.12. 

These reactions exemplify the two major types of catalytic processes, namely, those where the specific activity is sensitive to changes in the catalyst particle morphology (structure sensitive), and those where the specific activity is independent of the catalyst morphology (structure insensitive). Generally, reactions (1) and (2) are structure insensitive whereas reactions of type (3) are structure sensitive. 

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