Flow of sulphur dioxide over the surface of Spheron 6(2700) graphitized carbon black

Abstract

The flow of sulphur dioxide through a microporous plug formed from compressed Spheron 6(2700) powder has been examined. Particular emphasis was placed on performing as many complementary experiments as possible, so that the experimental data would permit a detailed examination of the processes involved. The major objective of this work was to determine whether the flux of adsorbed molecules could reasonably be described as a diffusion process, when the adsorbate concentration was high, and a concentration gradient existed across the barrier. This was achieved by comparing apparent surface diffusion coefficients obtained under these conditions, with the results of true diffusion experiments involving the use of radioactive sulphur dioxide as a tracer. At surface coverages greater than about 0.1–0.2 monolayer, diffusion was not an important mechanism for surface flow. The tracer experiments gave results which were consistent with the adsorbate behaving like a two-dimensional gas, at low surface coverages.