The dead volumes of the equipment w

The dead volumes of the equipment were highly minimized and the adsorption rate was not extremely fast, so the adsorption step previous to desorption was also measured. As an example, in Fig. 9 we present the adsorption/ desorption steps at 343 K, both in normal scale (Fig. 9a) as well as in semi-logarithmic scale using the transformation of 12C/C for the adsorption curve (Fig. 9b). The error in the adsorption curve in the final tail of the curve is higher than in the desorption step due to the lower sensitivity of the FID detector at higher concentrations. The equilibrium and kinetic parameters for the fitting of both curves were the same. As both curves are symmetrical, we can conclude that we are working in the linear zone of the isotherm. At the three temperatures the amounts adsorbed in adsorption and desorption steps (obtained by integration of the curve) was the same although only poor agreement is obtained with the manometric data. These large differences are due to an incomplete integration (the area below C/C that is not accounted for in some cases should even be higher than the integrated area). In all the cases the differences are higher at lower temperatures.