CO phase

For sodium palmitate, 5-phase is the thermodynamically preferred, or equiUbrium state, at room temperature and up to - 60° C P-phase contains a higher level of hydration and forms at higher temperatures and CO-phase is an anhydrous crystal that forms at temperatures comparable to P-phase. Most soap in the soHd state exists in one or a combination of these three phases. The phase diagram refers to equiUbrium states. In practice, the drying routes and other mechanical manipulation utilized in the formation of soHd soap can result in the formation of nonequilibrium phase stmcture. This point is important when dealing with the manufacturing of soap bars and their performance. 

Figure 12.19 Potential-dependent SFG spectra from atop CO on a Pt(lll)/Ru electrode in 0.1 M H2SO4 at 1 mV/s in 0.1 M H2SO4 (see Fig. 12.18). The scan potential for each spectrum is shown on the right. Spectra from Ru-Pt(lll)-CO and Pt(lll)/Ru-CO are shown, including the CO phase transition at > 0.17 V (vs. Ag/AgCl). The inset shows a blow-up of the SFG spectrum from Pt(lll)/Ru-CO at 0.17 V.

In most cases, there is a good agreement between the OSC measured upon the first pulse of CO (phase 1), and the OSC deduced from alternate pulses CO and 02 (phase 3), which tends to prove that the catalysts show stable redox properties all along the procedure of measurement [25],... 

For each wind speed value (v) from the cut-in (ci) to the cut-out (co) phase of the WTG, the product of its corresponding power output (Pv) multiplied by the time Hv (in hours) during which value v appears in a year is calculated. The sum of these products gives the annual energy production (WEY). Wind speed values are referred to the hub height of the turbine. The power output values, which compose the power curve of a WTG, are provided by the turbine manufacturer. Hv values are calculated from the annual distribution (or the histogram) of the wind speed values. 

During the CO/ phase, one obtains a long ranging low production of both CO2 and Hj in stoichiometric ration and at practically constant rate. This kind of responses suggest that the stimulated H 0 sorption capacitance is much larger than the CO capacitance ana that this part of 1 0 sorption must take place on surface sites different from the shift reaction sites, from where l O is probably transported by a slow mechanism to the shift reaction sites. The limiting step during this period is obviously the transfer of 1 0. 

On the other hand, the origin of the promoter metal and metal oxide effects is not always clear, despite the many detailed characterization studies. In what follows, we will give first a possible definition of the different promotion phenomena described in literature, as well as their mode of operation. The second part deals with an extensive literature overview of the effect of each promoter element on the F-T activity, selectivity and stability of the active Co phase. The different modes of operation will be evaluated for each element. Special attention will be paid to noble metal and transition metal oxide promotion effects. 

Zhang et al. studied the Mn promotion in C0/AI2O3 catalysts.It was found that the addition of Mn improves the catalytic activity, as well as the C5+ selectivity, while the formation of methane and C2 4 hydrocarbons is significantly suppressed. They observed that Mn improved the dispersion of the active Co phase and also favored the formation of bridged-bonded CO as probed with IR. A small amount of Mn was also able to increase the H2 uptake, although it was again decreased with an excess of Mn. 

In summary, no bulk Mo or Co phases are observed on catalysts having low to moderate Mo and Co concentrations (encompassing commercial compositions) in either oxidized or mildly sulfided forms. 

Co hardmetals, it is possible to improve both properties at the same time (Cherradi et al., 1994) (Fig. 22.13). This can be achieved by a gradation in the binder content from the centre to the surface of the tool. The improved mechanical properties of the FGM-cemented carbide are due to compressive stresses near the surface, which enable a reduction of the Co-phase content from 6 to 3 wt% without any loss in apparent fracture toughness. 

The transition temperatures Tco for the CO phase and Tc for the FM phase cross at the critical tolerance factor tc 0.975 where a unique FMM phase II appears. As can be seen in fig. 54, the room-temperature volume of phase II is larger than anticipated for a smooth evolution of unit-cell volume with increasing t at t = tc with Mn(IV)/Mn(III) = 1, A-cation... 

Figure 63 shows a(T) and both ZFC and FC M T) in 10 Oe for a t = 0.976 crystal lying in the two-phase region between phases II and III. This figure is to be compared with figs. 58 and 60. A 7c 230 K for the FMV matrix is only a little higher than the 7co of the minority phase below Tco, the volume fraction of the CO phase competes with that of the FM phase and appears to become dominant in the interval Tp < T < Too = T of that phase. 

To find out the phase composition of the intermetallic compound layers formed, X-ray patterns were taken immediately from the polished surfaces of the Ni-Zn and Co-Zn cross-sections. Annealing and subsequent cooling the specimens of the type shown in Fig. 3.12b in most cases resulted in their rupture along the interface between the zinc phase and the intermetallic layers, with the latter remaining strongly adherent to nickel or cobalt plates. Therefore, preparation of the cross-sections for X-ray analysis presented no difficulties. These could readily made by successive grinding and polishing the plate surface until the Ni or Co phase was reached. In total, four layer sections parallel to the initial interface were analysed for each cross-section. Simultaneously, layer composition on each section of the interaction zone was determined by electron probe microanalysis. 

As seen in Fig. 3.14a, two sublayers are visually distinguishable in the microstructure of the Co-bordering layer. The sublayer adjacent immediately to the Co phase was only 1 to 4 pm thick. Any relation between the sublayer thickness and the time of annealing could hardly be established. 

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