Void ratio assumption

The deactivation of a catalyst by site coverage and pore blockage can be expressed in terms of relative activity, R, which is the ratio of the rate of the catalytic reaction at time t to the rate at time zero. Supposing the pore volume to be concentrated in voids (Fig. 2) and using assumptions 1-4, we have (cf. Section III,D)... 

The derivation of the separation conditions is based on the ideal or equilibrium model, i.e., on the assumption that axial dispersion and the mass transfer resistances are all negligible and that the column efficiency is practically infinite. In conventional studies of SMB, it is further assumed that the solid phase flow rate through each column and the void fraction of each column are the same. In the Hnear case, the ratio of the internal flow rate and the solid-phase flow rate can be combined with the slope of isotherm (a,) by using a safety margin, jSy [25,27] ... 

Note that the ratio of the permeability coefficient of H2 and CO by the poly-sulfone polymer matrix is 4.019 x 10 Vl0.047xlO = 40 therefore, the selectivity of the composite membrane is close to that of the polysulfone polymer matrix. It should be also noted that two important assumptions were made in the above calculation. They are (1) the permeability coefficient of the void space was assumed to be the same as that of silicone rubber, and (2) the effective thickness of the void space was assumed to be the same as that of the polymer network. This implies that the void space was completely filled with silicone rubber, and its effective thickness is the same as that of the polymer network. Furthermore, we can calculate the loss in permeability by coating. The resistance without coating is that of the porous substrate, and therefore, it is designated as / ub- With respect to hydrogen gas, it becomes... 

There is reason to believe that the system contained a large amount of dissolved gas in the water. Any gas in the water would affect the initial calibration if the gas came out of solution during the calibration run. Furthermore, the release of gases during boiling would indicate a larger void volume than would be expected for a gas =free system. The calculated slip ratios based on the assumption of no gas present could therefore be less than one. 

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