Preparation of high-surface-area catalysts supports coated with SiC by CVI

Abstract

In this research, permeating dichlorodimethylsilane (DDS) and depositing a Sic layer on surfaces of spherical activated carbons by CVI was studied in a continuous flow reactor. Related mathematical modeling was also undertaken. The results were compared with those obtained in a fluidized bed reactor [1,2]. It is desirable to coat pore walls uniformly with their pore entrances open. The conditions for obtaining these desirable results were a low pressure and a low DDS concentration, such as 10 torr and 3%, respectively. When the deposition rate constant was 10 cm/min, the modeling and experimental results fit well with one another. At a high total pressure and a high partial pressure of DDS, the initial deposition rate was large, but Sic particles deposited at a low pressure were relatively small and uniform. Less uniform deposition was obtained relative to the deposition obtained in a fluidized bed reactor. The dependence of the morphologies of the deposited Sic on both the pressure and concentration were similar to those obtained in a fluidized bed reactor.