Abstract
A simple flow method has been developed for the determination of adsorption isotherms of high surface area solids with nitrogen. The gas flow is controlled by the pressure drop across a fine capillary in such a way that the flow rate is measurably independent of back pressure. Comparison of surface areas using reference silica-alumina samples shows excellent agreement; areas from pore size distributions agree well with those obtained by BET calculations. Approach to equilibrium is essential and has been shown to be very close by varying the sample size of a 700 m 2/g. silica gel sample. Results are shown with Types I, II, and IV isotherms using silica gel, finely divided silica, silica-alumina, and alumina samples.
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