Ethylbenzene uptake curves

Fig. 6 Uptake curve of ethylbenzene diffusing at 415 K into an activated (at 675 K) H-ZSM-5 sample (wafer) upon a pressure jump from 0 to 1.15 mbar experimental data ...

Fig. 8 Effect of temperature on the amounts (a, upper part) adsorbed and (b, lower part) desorbed of ethylbenzene in ZSM-5 for different pressure jumps and three final partial pressures (115, 230, and 460 Pa) and effect on the (corrected) diffusivities (vide infra). The uptake curves 1, 2, 3, and 4 were determined at 355, 375, 395, and 415 K, respectively...

From sets of spectra such as those shown in Fig. 3 and uptake curves displayed by Fig. 8 not only isotherms and isosteres could be derived, using the respective plateaux for the temperatures and pressures indicated, but also from the ascending branches (measured via FTIR after an upward pressure jump) or the descending branches (determined after a downward pressure jump) the kinetics of adsorption and desorption into zeolitic pores could be derived. These processes were assumed to be diffusion controlled. Their evaluation required a fit of the appropriate solution of Tick s second law as provided by Crank [39] to the experimentally measured uptake (or removal) points, which are indicated in Fig. 6 by filled crosses for the case of ethylbenzene uptake. 

In Fig. 8, a set of uptake curves for ethylbenzene adsorbed and desorbed at various temperatures after various partial pressure changes has already been shown. The diffusivities of benzene and p-xylene derived from IR measurements in the same way as described for ethylbenzene are collected in Tables 3 and 4. Table 3 includes data for single-component diffusion as well as for co-and counter-diffusion (see Sect. 2.2.4.1)... 

Fig. 20 Uptake curves for ethylbenzene in freshly activated and coked H-ZSM-5 (sample No. 3). The curves obtained after 25.5 and 104 h of time on stream (see Table 6) are omitted for the sake of clarity...

All experiments in this study were carried out under conditions where C02 and styrene are miscible. The solubilities of C02 and ethylbenzene (a model for styrene) in HDPE were determined at 80 °C and 243 bar. The HDPE samples were immersed in either pure C02 or a 36 wt % ethylbenzene/C02 solution within pressure vessels under these conditions for various times. Figure 10.1 shows results of a typical desorption experiment to determine the mass uptake of ethylbenzene for a given soak time the equilibrium mass uptake was found to be 4% and this was reached after approximately 5 h. Figure 10.2 illustrates the mass uptakes as a function of soak time the diffusivity of ethylbenzene in C02-swollen HDPE under these conditions was calculated by curve fitting to be 9.23 x 10 7 cm2/s. Attempts to determine the equilibrium mass uptake of neat ethylbenzene in HDPE at 80 °C failed because ethylbenzene dissolves polyethylene under these conditions. 

The typical kinetic curves of the oxygen uptake in the initiated ethylbenzene oxidation in the absence and in the presence of TP-5 in dependence... 

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