Rate hydrogen flux

The exact composition of the liquid with respect to hydrogen cannot be guessed. Consequently, we can only estimate either transfer or reaction maximum rates and fluxes. From Eq. (12), the maximum mass transfer rate YI 1X (mol s ) is obtained when the reaction is so fast that the bulk concentration of dissolved hydrogen is zero (Ch,l= 0), as given in Eq. (18). 

Figure 2. Molecular hydrogen flux of single crystal ZnO as a function of temperature. The sample was heated with a heating rate of 20 K/min.

Experiments were carried out with Ionac MC 3470 to determine the self-diffusion coefficient values for H+ and Al + in the coupled transport. Data points were used from the experiment involving 2N acid sweep solution in Figure 34.24b, presented later. These values formed the basis for aluminum transport rate or flux (7ai) calculation at different time intervals. The equilibrium data generated in Figure 34.20b were used in conjunction with Equation 34.25 to determine the interdiffusion coefficient values. Local equilibrium was assumed at the membrane-water interface. Eigure 34.24a shows computed Dai,h values for this membrane. When compared with Dai,h values for Nafion 117, it was noticed that the drop in interdiffusion coefficient values was not so steep, indicative of slow kinetics. The model discussed earlier was applied to determine the self-diffusion coefficient values of aluminum and hydrogen ions in Ionac MC 3470 membrane. A notable point was that the osmosis effect was not taken into account in this case, as no significant osmosis was observed in a separate experiment. 

This new technique has been developed at Lure by A. Fontaine and E. Dartyge Figure 8 a shows the evolution of the Pt L3 edge of a dried catalyst which has been reduced, the rate of increase of temperature under a hydrogen flux being 6°/min the decrease of the amplitude of the white line is complete after one hour. Figure 8 b shows the variation of the area of this white line, normalised to that of the elemental metal. Two points are worth mentioning here ... 

The solid diamonds in Fig. 9.3 represent data collected for the first membrane tested with a feed stream composed of hydrogen, nitrogen, and helium. Hydrogen flux increased as the pressure on the feed side of the membrane was increased. At 250 psig (18.3 bar) feed pressure, the hydrogen flux rate was 85 mL min cm. ... 

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