Conversion diagram

Figure 3.37 Selectivity-conversion diagram of the oxidative dehydrogenation reaction [1].

Figure 16 Conversion diagram for (1 — 3)-p-D-glucans by a variety of physical treatments (based on Refs. 48 and 119).

PVDF is mainly obtained by radical polymerisation of 1,1-difluoroethylene head to tail is the preferred mode of linking between the monomer units, but according to the polymerisation conditions, head to head or tail to tail links may appear. The inversion percentage, which depends upon the polymerisation temperature (3.5% at 20°C, around 6% at 140°C), can be quantified by F or C NMR spectroscopy [30] or FTIR spectroscopy [31], and affects the crystallinity of the polymer and its physical properties. The latter have been extensively summarised by Lovinger [30]. Upon recrystallisation from the melted state, PVDF features a spherulitic structure with a crystalline phase representing 50% of the whole material [32]. Four different crystalline phases (a, jS, y, S) may be identified, but the a phase is the most common as it is the most stable from a thermodynamic point of view. Its helical structure is composed of two antiparallel chains. The other phases may be obtained, as shown by the conversion diagram (Fig. 7), by applying a mechanical or thermal stress or an electrical polarisation. The / phase owns ferroelectric, piezoelectric and pyroelectric properties. 

Fig. 2.4. The conversion diagram, stoichiometrically attainable region and reaction rate vector.

Fig. 2.6. Conversion diagram with two exemplary trajectories for identical temperature and cell voltage, but with different inlet conditions. Both end up in the same attractor, which is the intersecting point of the reforming and the oxidation equilibrium lines.

These considerations clearly show the advantage of the DIR concept. Independent of the pre-treatment of the feed gas, the application of DIR always leads to a high degree of fuel utilization. As shown here, the steady-state anode model and the representation of its solutions in the conversion diagram are useful tools for evaluation and comparison of different process configurations. 

Fig. 2.7. Conversion diagram with trajectories for different reforming configurations without DIR.

Fig. 2.8. Conversion diagram with trajectories for different reforming configurations based on DIR. High degrees of fuel utilization are attainable (cf. Fig. 2.7).

Fig.2.n. Conversion diagram with a trajectory for a single cell and a trajectory for a fuel cell cascade in electric parallel configuration. Cell voltages are optimized for maximum electric power output. For quantitative results, see Tab. 2.1. 

The interaction of these two processes can be described by a simple isothermal model, which is based on balances of mass and charge. The model describes the extent of the reforming and oxidation reactions along the anode channel. The essential simulation results can easily be displayed in a conversion diagram which is a phase diagram of the two dynamic state variables, namely the extents of two reactions. 

The basic scheme is hence very similar to those used to produce hydrogen and am mom a. The same applies to the conversioD of heavy products, for which partia] oxidation and gasiheation are generally more suitable. The presence of sulfur compounds in the raw materials used requires the consideration of two main variants, depending on the possibilities of the cat yst for CO shift conversion (diagrams a and b in Fig. 1.23). 

Which boxes of the conversion diagram (page 348) indicate the method of converting volumes of solutions to moles of reactants and/or products and vice versa ... 

Fig. 2. Time-conversion diagram for a double polymerisation of styrene in ethylene chloride at room temperature. A, reference experiment with IM)o = 0.35 M and IH2S04]q = 8 x 10" M. o, same as above, but CF3COOH (to give a concentration of 5.5 x 10 M) added at the time indicated by the arrow. (Taken from Ref. 293) ...

Fig. 24.3. Conversion diagram of (1 3)-/3-D-glucans by various physical treatments [17].

The discussions are mainly in terms of the conversion of the feed since this has a very important effect on the product distribution which can be obtained from yield versus conversion diagram directly. This is due to the fact that these data are nearly independent of temperature. 

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