Selectivity vs. conversion for

Figure 13. Selectivity vs. conversion for 850°F cut point (M), selectivity for Nir-W (0), selectivity for Nir-Mo.

In Figures 3 and 4 are reported respectively conversion vs. temperature and acrylonitrile selectivity vs. conversion for these four samples. It is possible to see, that even if the catalysts reach similar conversions, they have different activities, due to their different worldng temperature range. The acrylonitrile selectivity is very different sample 1 (EtOH) is the best... 

Figs. 5 and 6 show universal, time-independent plots for steady-state yield and selectivity vs. conversion for all residence times and HatButadiene ratios less than 6 (runs at the higher ratios were difficult to reproduce because of uncertainties in chemical analyses caused by the high dilution). It can be seen from these two plots that the optimum steady-state yield is 30% and the corresponding conversion and selectivity are 50% and 60% respectively. 

Figure 4. Isobutane initial conversion Figure 5. Isobutane conversion and vs temperature (O AlPON, isobutene selectivity vs time for...

The high pressure, liquid-phase hydrogenation of 3-methyl crotonaldehyde was carried out in a well-stirred batch autoclave under 4 MPa Ha (Air Liquide, 99.995% purity) pressure using 0.1 mol of 3-methyl crotonaldehyde (UAL) (Merck) and 0.6 g catalyst. Isopropanol (37.5 cc) was used as a solvent. The catalyst was activated by stirring under 4 MPa Ha pressure at 373K for two hours prior to introduction of the unsaturated aldehyde UAL reactant at the same temperature. The reaction products were monitored by repetitive sampling and gas chromatographic analysis. Since this was a batch reaction, data are reported as selectivity vs. conversion. Time of reaction to reach about 30% conversion was close to 60 minutes for Ru/NaY and 150 minutes for Ru/KY. 

Figure 2.19 Conversion and selectivity vs. pressure for partial oxidation of methane at 1200 °C reaction temperature and an O/C ratio of 1 half-filled symbols indicate calculated thermodynamic equilibrium values [44] (by courtesy of ACS).

Conversion of propane at time t was determined as Xr,t = (1 - Ir,t/Ir,o), where Ir,t is a sum of integral intensities of the resonances corresponding to propane in the NMR spectrum after heating for t min and Ir,o is the integral intensity of propane resonance in the initial NMR spectrum. Initial rate of propane conversion was taken as the initial slope of plots of Xr,t vs reaction time t. Initial rate of C scrambling in propane was determined from plots of conversion of propane l- C into propane 2- C vs reaction time t Selectivity to product p at time t was calculated as Sp,t = (Ip,t/SIp,t) l(X) (%), where Ip,t is the integral intensity of the resonance lines of product p in the NMR spectrum after heating for t min. Initial selectivities were obtained from plots of selectivity vs conversion by extrapolation to zero conversion. 

Figure 1. Olefin oligomerization by cationic nickel complexes. Yields of dimers vs. conversion for various types of reactors. AB hypothetical 100 % selective dimerization. AC hypothetical oligomerization without any consecutive reaction (BC percentage of trimers, tetramers). ADE the actual curve (DE zone of prevailing consecutive reaction).

The use of conversion instead of time as an independent variable can be very distinctive and informative for model verification. Also, as can be seen from Fig. 2, the yield (or selectivity) vs. conversion relationship can serve as a characteristic function describing the behavior of the system under various conditions. 

Availability of the data for different conversions varied over a maximum possible range to construct characteristic curves yield (or selectivity) vs. conversion ... 

Figure 4.16. Selectivity vs. conversion dependence for parallel reactions.

Figure 6. Selectivity for dihydroxyacetone vs. conversion of glycerol, on PtBi/C, for batch and continuous systems.

To impose the diffusion-controlled conversion of O to R as described earlier, the potential E impressed across the electrode-solution interface must be a value such that the ratio Cr/Cq is large. Table 3.1 shows the potentials that must be applied to the electrode to achieve various ratios of C /Cq for the case in which Eq R = 0. For practical purposes, C /C = 1000 is equivalent to reducing the concentration of O to zero at the electrode surface. According to Table 3.1, an applied potential of -177 mV (vs. E° ) for n = 1 (or -88.5 mV for n = 2) will achieve this ratio. Similar arguments apply to the selection of the final potential. On the reverse step, a small C /Cq is desired to cause diffusion-controlled oxidation of R. Impressed potentials of +177 mV beyond the E° for n = 1 (and +88.5 mV for n = 2) correspond to Cr/Cq = 10"3. These calculations are valid only for reversible systems. Larger potential excursions from E° are necessary for irreversible systems. Also, the effects of iR drop in both the electrode and solution must be considered and compensated for as described in Chapter 6. 

Figure 2.16 Methanol conversion as a function of temperature hydrogen selectivity vs. methanol conversion for autothermal methanol reforming [39] (by courtesy of ACS).

Figure 1. Olefins selectivity vs. LPG conversion plots for all the tested catalysts...

Equation (88) shows, for highly porous catalysts, how the conversion to B depends on the fraction of A reacted for various values of the intrinsic selectivity factor S = ki/ki. In Fig. 11, lower curve, we plot as vs. ttA for 5 = 4. Thus, Fig. 11 gives a direct comparison between the performance of porous and nonporous catalyst. For the porous catalyst (lower curve) the maximum conversion to B is only 33% (at about 75% conversion of. 4) with a yield of B of only 44%. This is to be compared with the 62% conversion to B with a yield of 78% obtained with nonporous catalyst of the same intrinsic selectivity. It thus appears that the pore structure can cut down on yields in Type III selectivity by a factor of about two. These conclusions apply for a selectivity factor of 4.0. Calculation with other values of the selectivity factor ranging from 1.0 to 10 show that in all cases the yield loss of B due to pore structure corresponds to a factor of about two. 

The second-generation Hoveyda catalyst 4 showed good solubility in RTILs with concomitant lower leaching. It was used to test the influence of the [bmim] counteranion and the alkyl group on the imidazolium cation. Contrary to the results reported by Tang on stilbene synthesis, the BFC anion provided here the best result in terms of activity, 92% conversion vs 80% for PFg, and 47% for NTf2 . In all three cases the selectivity toward 7-tetradecene was... 

Figure 28.6. Ethylene selectivity vs ethane conversion for Pt- and LaMn03 -based monoliths. Experiments with co-feed of H2 and CO. Data concerning the effect of H2 co-feed over Pt and Pt/Sn catalysts (taken from Schmidt and co-workers) are also reported in this figure. Reprinted with permission from Ref. 71. Copyright 2005 American Chemical Society.

Fig. 4.4 Selectivity to styrene and ethylbenzene vs. conversion of CH3OH for various zeolites in the alkylation of toluene with CHsOH.

The extent of branching, of whatever type, is dependent on the polymerization conditions and, in particular, on the solvent and temperature employed and the degree of conversion. Nozakura et at.1 1 found that, during bulk polymerization of VAc, the extent of transfer to polymer increased and the selectivity (for abstraction of a backbone vs an acetoxy hydrogen) decreases with increasing temperature. 

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