Selectivity vs. time

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

Figure 15.3. Direct synthesis of H2O2 from hydrogen and oxygen (Polimeri Europa DISY process). A typical pilot run hydrogen peroxide concentration and hydrogen-based selectivity vs time on stream (T.O.S.). All values, including those measured during change in reaction parameters and plant stop-and-go procedures, are shown (smoothed by amoving average line on 10 periods).

The selectivity for 5-HT4 vs. other 5-HT receptor subtypes was examined in a set of radioligand binding assays available at the time (5-HT1A, 5-HT1D, 5-HT2A., 5-HT2c and 5-HT3) for some of the new compounds. While most derivatives exhibited a high selectivity for 5-HT4 vs. 5-HT3 receptors, structural adjustments of 5 led to profound effects on selectivity vs. other 5-HT receptors. 

A test sample of a resin containing a selected experimental agent was weighed in a DSC pan to 0.0.00001 g. The uncured sample was placed on a sample cell and a precured sample of the same weight was placed in the same type of DSC pan on the reference cell set and maintained at 37°C while being irradiated for 1 hour. From the resulting heat flow (watts/g vs. time curve), the time of maximum reaction rate (peak maximum time), onset of reaction (induction time), and enthalpy of reaction were recorded. These testing results are provided in Table 1. 

Figure 37A (symbols) displays selected step-response TRM experiments performed with 2% 02 at different temperatures, namely at 200, 225, 250 and 275 °C, in terms of NH3, NO and N2 outlet concentrations vs. time. In the run performed at T — 250°C (squares), upon NH3 step feed at t — 0 s the NH3 outlet concentration trace exhibited a dead time ( 250 s) and then slowly grew with time on stream, eventually approaching a steady-state value of about 200 ppm, that is much lower than the ammonia feed concentration level (1,000 ppm). In correspondence to the NH3 admittance to the reactor, a sudden drop of the NO outlet concentration was observed together with a mirror-like increment of the N2 concentration, associated with the start-up of the SCR reaction. The levels of NH3, NO and N2 at steady state were in fact consistent... 

Examples of u vs time curves for TNT and Tetryl, obtained by Jacobs Edwards (Ref 4) are diown in Figs 4—6. As expressed by these authors The determination of a CJ particle velocity and a reaction zone time by the EMV gage has required judgment to select the point on the curves which one would associate with the termination of the reaction. This is not always a simple matter. In our pressed TNT records there was little choice but to take the time at which the u—t curve levels off as the CJ... 

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. 

Use the Rates of Reaction simulation (eChapter 12.2) to determine the value of the rate constant for the process at 0°C. Calculate the half-life for the process from the value of k. Select a value for initial concentration and run the reaction. Determine the half-life using the [A] vs Time graph. How does doubling the initial concentration affect the half-life ... 

The cure cycle is the temperature vs time schedule used to polymerize the thermoset precursors. The selection of an adequate cure cycle has several purposes. What is desired is to obtain the final part without strains exceeding design tolerances, with a uniform conversion (usually close to the maximum possible conversion), without degradation produced by the high temperatures attained during the cure, with convenient morphologies (in the case of heterogeneous materials), and all this, must be achieved in the minimum possible time for economic reasons. 

Figure 2 shows propane conversion vs. time-on-stream (TOS) for reaction-regeneration cycles 1 to 5. Propane conversion at various TOS and product selectivities at TOS = 100 min vs. number of reaction-regeneration cycles are represented in Figs. 2 and 3, respectively. 

Figure L Uptake of oxygen by selected coals vs. time no heat or pumping (%) heated at 65° C under vacuum ( ).

Select FILE, NEW SETUP from the top of the window. Press the arrow next to TECHNIQUE and select ECORR VS. TIME. Set TIME STEP 1 to 300 seconds and TIME/PT. to 1 second. Your setup window should look like the... 

Fig. 9 Molecular selection in coupled equilibria through the self-replication of a specific mesos-tructure. (a) Concentration of imines 1A and 7A vs time starting from an equimolar mixture of 1, 7, and A (c = 50 mM each) in CD3CN and, after reaching the thermodynamic equilibrium, by changing the solvent to pure D20. (b) Concentration of imines 1A and 7A vs time starting from an equimolar mixture of 1, 7, and A in D20 (c = 50 mM each). (Reproduced from [46])...

Figure 5. Selectivity vs. space time. Benzene/propylene (mole) = 10 parameter --reactor inlet temperature (tJ), °F (°C).

Data for the time to the onset of diffusion control, as determined by infrared spectroscopy, are also included in Fig. 15. The time to dififiision control was selected as the point at which the extent of conversion vs. time data, plotted for first order kinetics, deviated from linearity. The onset of diffusion control corresponds with vitrification, as determined by TBA, for the system of Fig. 15... 

However, for planarization, polish rate is not the only criterion. Indeed, the most important performance indicator is planarization ability. Figure 5.13 shows the polish rate of the high areas and the low areas vs. time for both ceria and silica abrasives. For both slurries, the polish rates of the high areas and the low areas converge, with polish time decreasing the planarization selectivity (selectivity is the polish rate in the high areas divided by the polish rate in the low areas). This is to be expected, however as the surface planarizes, the difference in height between the low areas... 

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. 

Conditions 60 mg of catalysts 0.70 % Ti, all derived from the same lots of titanium alkyl and hydride surface complexes 150 mol TBHP/mol Ti 20 mol 1-octene/mol TBHR 80 °C. Initial activity was defined as the tangent of the TOF vs. time curve at the origin. Selectivities are mol epoxide/mol TBHR consumed. Yield = conversion X selectivity. 

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