Reaction temperature, conversion curve

Homogeneous oxidation of n-pentane presented as conversion vs. reaction temperature under various n-pentane/oxygen ratios displayed tjrpical bell-shape curves over the temperature region of 300 - 500 °C [3], as illustrated in Fig. 2. The n-pentane conversion is near to zero at 5 % of oxygen and increases with oxygen content. 

In Fig. 1 the CO conversion curves versus temperature over both samples, mono 1 and 2 are displayed. With the aim to check ageing effects, four runs were iterated over the same substrate, by cooling the sample to room temperature in the reaction mixture at the end of each test. In Table 2 the CO... 

The plot of the integrand e /[ko(l-X)] versus X is shown in Figure 4.10.22. By graphical integration, that is, by evaluation of the area underneath the curve from 0 to Xa, we find the time needed to reach a certain conversion - for example, 1.2 min for 30% conversion. The reaction temperature and the temperature difference compared to the initial value To is then easily determined as we know that AT= T— To = XATad (Figure 4.10.22b). 

Fig. 15. Temperature vs heat generation or removal in estabHshing stationary states. The heavy line (—) shows the effect of reaction temperature on heat-generation rates for an exothermic first-order reaction. Curve A represents a high rate of heat removal resulting in the reactor operating at a low temperature with low conversion, ie, stationary state at a B represents a low rate of heat removal and consequently both a high temperature and high conversion at its stationary state, b and at intermediate heat removal rates, ie, C, multiple stationary states are attainable, c and The stationary state at c ...

Peaking and Non-isothermal Polymerizations. Biesenberger a (3) have studied the theory of "thermal ignition" applied to chain addition polymerization and worked out computational and experimental cases for batch styrene polymerization with various catalysts. They define thermal ignition as the condition where the reaction temperature increases rapidly with time and the rate of increase in temperature also increases with time (concave upward curve). Their theory, computations, and experiments were for well stirred batch reactors with constant heat transfer coefficients. Their work is of interest for understanding the boundaries of stability for abnormal situations like catalyst mischarge or control malfunctions. In practice, however, the criterion for stability in low conversion... 

Figure 4. Conversion-time curves on a regenerated 2NiSZ(s) sample obtained at intermitent reaction periods after which the flow of n-butane was stopped, leaving the catalyst at the reaction temperature under a 100 cm/min flow of He for a few minutes, and then resuming the flow of n-butane. The arrows indicate 15 (tl injections of 1-butene.

The desired product is P, while S is an unwanted by-product. The reaction is carried out in a solution for which the physical properties are independent of temperature and composition. Both reactions are of first-order kinetics with the parameters given in Table 5.3-2 the specific heat of the reaction mixture, c, is 4 kJ kg K , and the density, p, is 1000 kg m . The initial concentration of /I is cao = 1 mol litre and the initial temperature is To = 295 K. The coolant temperature is 345 K for the first period of 1 h, and then it is decreased to 295 K for the subsequent period of 0.5 h. Figs. 5.3-13 and 5.3-14 show temperature and conversion curves for the 63 and 6,300 litres batch reactors, which are typical sizes of pilot and full-scale plants. The overall heat-transfer coefficient was assumed to be 500 W m K. The two reactors behaved very different. The yield of P in a large-scale reactor is significantly lower than that in a pilot scale 1.2 mol % and 38.5 mol %, respectively. Because conversions were commensurate in both reactors, the selectivity of the process in the large reactor was also much lower. 

The FTS was conducted at varying temperatures (from 483 to 513 K) over approximately 50 h of reaction time in order to investigate the reaction kinetics achieved with the respective catalysts. A typical conversion curve using the Co/ HB catalyst as an example is shown in Figure 2.3. After a short settling phase (caused by the pore filling of liquid Fischer-Tropsch products) of only about 4 h, steady-state conditions were reached. In the observed synthesis period of 50 h no deactivation of the catalysts was detected. However, industrially relevant experiments over several weeks are still outstanding. 

Although there are some important differences between what we describe as 3-connected aluminium sites in our bb-matrices and what the active sites are thought to be in zeolites, we have begun a preliminary study of the activities of the Al, Ti and V-containing bb-catalysts as solid acid catalysts in the dehydration of alcohols. For this type of bench marking reaction, there are two parameters that can be used as preliminary indicators of catalytic activity lightoff temperatures and product selectivity. A plot of conversion versus temperature produces what is known as a lightoff curve. The temperature at which 50% of the maximum... 

These data are plotted in Figure 5-1 1. Thus we have a very serious problem if this reaction is reversible because the adiabatic reactor trajectory intersects the equilibrium curve at a low conversion. For these kinetics, equilibrium limits the process to a very low conversion at high temperatures. 

Figure 6-13 Plots of X(T) for tiie exotiiermic irre-versible (dashed curve) and reversible (solid curve) reactions. If the reaction is reversible, the conversion falls at high temperature, but multiple steady states are still possible.

A high reaction temperature should accelerate the successive reaction. The mole ratio of CO/MeOH also exhibited marked effects on the rate and the selectivity. With an increase in the CO/MeOH ratio, the methanol conversion and the acetic acid selectivity increased while the selectivities to DME and methane decreased. In Figure 5 are shown selectivity-conversion curves for methyl acetate, acetic acid and DME. The figures indicate clearly that methyl acetate and DME are the primary products and that acetic acid is produced successively from them. 

Figure 8. Temperature (curves 1-5) and conversion (curves 1 -5 ) profiles in the reactor with periodic flow reversal. Example of exothermic reversible reaction.

For a given dose rate the break in the conversion curves occurs at approximately the same conversion regardless of reaction temperature. 

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