Activity area-normalized

Sieve Plates. The conventional sieve or perforated plate is inexpensive and the simplest of the devices normally used. The contacting orifices in the conventional sieve plate are holes that measure 1 to 12 mm diameter and exhibit ratios of open area to active area ranging from 1 20 to 1 7. If the open area is too small, the pressure drop across the plate is excessive if the open area is too large, the Hquid weeps or dumps through the holes. 

High surface area for high activity which normally requires small particles... 

The performance of SOFCs with Cu—ceria—YSZ anodes has been tested with a wide variety of hydrocarbon fuels, and this has been documented elsewhere.With the exception of methane, which is known to be relatively unreactive in normal heterogeneous reactions as well, all of the hydrocarbons we examined appear to give similar performance characteristics. The fuels that were tested include /2-butane, /2-decane, toluene, and a synthetic diesel. The main difference observed between the various fuels is that some fuels tend to form tars more readily via gas-phase free-radical chemistry. Otherwise, with the exception of CH4, all hydrocarbons that were investigated showed similar power densities. This is shown in Figure 20, which displays the voltage and current densities for /2-decane, toluene, and synthetic diesel as a function of time. In this case, the hydrocarbon fuels were diluted in dry N2 to a concentration of 40 wt % hydrocarbon to prevent condensation of unreacted fuels that leave the cell. (In our studies, the active area for the fuel cell is typically 0.5 cm, and a current density of 1 A/cm would require a flow... 

The synthesis of [4.4.4.4]fenestrane or windowpane has become an active area of research due to the aesthetic appeal of the hydrocarbon and the nature of its central quaternary carbon atom which is expected to be distorted from normal tetrahedral geometry . Ongoing investigations have generated a number of ring-expanded triquinane and tetraquinane ([5.5.5.5]fenestrane) homologs. These molecules form the subject matter of the discussion which follows. 

Figure 6.33. Trends in Pt surface-area normalized electrochemical activity of various ternary alloy compositions with respect to the electrooxidation of methanol. Activity gains are seen in the order Pt, PtRu, PtRuNi, and PtRuCo (adapted from [69]).

The clear liquid back-up is obtained from a tray-pressure balance and is normally taken to be the sum of the tray-pressure-drop, the clear liquid height on the active area of the tray, and the pressure-drop of liquid flowing under the downcomer apron onto the active area. 

The structure and surface areas (after catalytic tests) of the different solids are given in Table 2. XRD and sulphur to metal ratios indicate that the techniques used for the low-temperature synthesis allow the preparation of the expected most stable binary sulphides. These solids are generally stable under the test conditions, but structural changes occur for some of them in an H2 atmosphere Ni, Co and Pd monosulphides are transformed into Ni3S2, CogS8 and Pd4S. In order to compare the catalytic properties of the different sulphides, the activity are normalized by unit area of the used samples. The proportionality between catalytic activities and surface areas was checked for several samples [7]. 

The pore/solid phase is further distinguished as transport and dead phase. The basic idea is that a pore phase unit cell surrounded by solid phase-only cells does not take part in species transport and hence in the electrochemical reaction and can, therefore, be treated as a dead pore and similarly for the electrolyte phase.25 The interface between the transport pore and the transport electrolyte phases is referred to as the electrochemically active area (ECA) and the ratio of ECA and the nominal CL cross-sectional area provides the ECA-ratio . It is be noted that in this chapter, ECA is normalized with the apparent electrode area and therefore differs from the definition in terms of the electrochemically active area per Pt loading reported elsewhere in the literature. 

Fig. 11.12 Electrochemical activity (area-specific activity) normalized by the surface area of Pt for the most active alloys. The Pt surface area was determined electrochemically using the hydrogen adsorption integral of each catalyst.

Fig. 11.17 Chronoamperometric screening results from the ternary catalyst library described in Figs. 11.15 and 11.16. Surface-area-normalized activity values of each individual composition are plotted as a function of composition. Color-coding indicates activity red = high, blue = low. The pt-Ru binary compositions are connected by a solid line to underscore the activity trends observed in this binary system. Conditions 1 M methanol, 0.5 M H2S04, 550 mV/RHE, 5 min.

Fig. 11.20 summarizes experimentally observed trends in the area-normalized activity (black bars) and the Pt weight-fraction-normalized activity (white bars) of some electrocatalysts in Fig. 11.17. It can be seen that a small difference in area-...

Fig. 11.20 Summary of relative area-normalized and Pt weight-fraction-normalized activities of pure Pt, Pt52Ru48, and two Pt-Ru-Co compositions at 550 mV/RHE in acidic solution. Hydrogen adsorption integrals were measured before electrochemical screening for methanol.

With the growth of the oil and gas industry in the USA, it was realised as early as 1934 that the blocking of gas pipelines at temperatures where normal water would not freeze was being caused by clathrate hydrate formation. The combination of water and hydrocarbons at low temperature, and often increased pressure, are ideal conditions for hydrate formation. Much understanding of this phenomenon has been gained since that time, but as drilling and transportation conditions become more extreme, clathrate hydrate formation continues to be a major problem and is still a very active area of research. 

Several equations are applied to calculate sieve tray hole area. Normally sieve tray hole individual diameters are Vie to % in. As for bubble caps, sieve tray hole pitch is the measure from center to center between sieve tray holes. The pitch may be square or triangular, each angle of the triangle being 60°. Section areas are the tray deck area of one pitch markoff area, noted as SECTAREA. For square pitch, one complete hole area is measured for triangular pitch, one-half hole area is measured, noted as SECTHA. The active area divided by SECTAREA equals the number of pitch sections on the tray deck, noted as SECTNO. Equations (3.98) through (3.103) will help clarify these statements. 

Absorption, 6, 8, 40 Accuracy, definition of, 99 Activity coefficient, 109-110 Adjusted retention volume, 10 Adsorption, 6, 8, 40 Affinity chromatography, 224-225 Area, measurement of, 102 Area normalization, 104 Asymmetry of peaks, 14, 43... 

Fig. 26. Activity versus surface area normalized time, for alumina-supported catalysts at 525 K, 1 atm (10 ppm H2S, H2/CO = 99) (Ref. 194).

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