Sulfide characterization data

Complex manufacturing systems, such as an unbleached Kraft pulp plant (Fig. 9), are almost always characterized by some type of internal structure, composed of a number of interconnected subsystems with their own data collection and decisionmaking responsibilities. This raises a number of additional issues, not addressed in previous sections. For instance, if the learning methodology described in Section VI is applied to the digester module of a pulp plant (Fig. 9), it is possible for the final selected solution, to include ranges of desired values of sulfidity... 

The effects of tin/palladium ratio, temperatnre, pressnre, and recycling were studied and correlated with catalyst characterization. The catalysts were characterized by chemisorption titrations, in situ X-Ray Diffraction (XRD), and Electron Spectroscopy for Chemical Analysis (ESCA). Chemisorption studies with hydrogen sulfide show lack of adsorption at higher Sn/Pd ratios. Carbon monoxide chemisorption indicates an increase in adsorption with increasing palladium concentration. One form of palladium is transformed to a new phase at 140°C by measurement of in situ variable temperature XRD. ESCA studies of the catalysts show that the presence of tin concentration increases the surface palladium concentration. ESCA data also indicates that recycled catalysts show no palladium sulfide formation at the surface but palladium cyanide is present. 

Alunite forms under highly acidic oxidizing conditions and is characterized by the assemblage alunite + kaolinite + quartz pyrite. Stable isotope data of alunite in combination with associated sulfides and kaolinite permit recognition of environments and temperatures of formation (Rye et al. 1992). 

The goal of this contribution is to review the formation of at least some of these compounds in model systems (consisting of aldehydes, acetoin, and ammonium sulfide), their identification, and analytical characterization (mass spectra, Kov ts indices) accomplished by using the GC-MS-SPECMA data bank. 

This result is illustrated with STM line scans, as shown in Fig. 19, where data characterizing the edge of the freshly prepared, fully sulfided structures are compared with a similar line scan for an atomic hydrogen pre-treated cluster. The average height of the edge protrusions shifted down relative to the basal plane by approximately 0.2 A in the hydrogen-treated cluster. This downshift occurs as a... 

The TB ( + )-l adduct of methyltrioxorhenium [(+ )-Re03CH3], characterized by its crystal structural and spectroscopic data, was reported by Herrmann et al. The catalytic properties of this complex were tested in the epoxidation of olefins and the oxidation of sulfides. However, no enantioselective reactions of the pro-chiral olefins and sulfides were observed (97JOM(538)203). 

Similar to the W-edge data, the Ni K-edge data are characterized by the same types of plots. Figure 6 shows the magnitude of the FT of the y(fc),fc3 FT of the Ni EXAFS spectra collected during the sulfidation. The... 

The earliest isotopic record of sedimentary pyrite in the Archean lacks the large spread between coeval sulfate and sulfide sulfur that characterizes the Phanerozoic data. Sedimentary sulfides formed between 3.4 Ga and 2.7 Ga have isotopic compositions within 5%c of contemporaneous seawater SO . This change in isotopic pattern compared to Phanerozoic data is to be expected if atmospheric O2 was low, and consequently no widespread mechanism existed for oxidizing reduced sulfur to form 804 in seawater. Sulfate concentrations <200 p,M are required to suppress isotope fractionation by SRB (Habicht et al., 2002). Most researchers hold to a scenario that photosynthetic production of O2 began by 2.7 Ga, but that there was a lag of several hundred million years before atmospheric O2... 

The gas-phase pyrolysis of dimethyl disulfide in the range 316-373 °C is apparently homogeneous, first order, and characterized by a reproducible induction period . The overall rate coefiicient is fc = 2x 10 exp(—45,000/RT) sec". The main products found were H2S, CH3SH, CS2 and various sulfides which were not characterized. Using the toluene flow carrier technique only traces of dibenzyl were found, and in addition to H2S and CH3SH, CH4, H2, C2H4 and C2H6 were formed. The kinetic data are incomplete, but it is probable that dimethyl disulfide decomposes mainly by a molecular mechanism... 

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