Pore formation in carbon-coated ceramic fiber filter media

Abstract

Resin-coated ceramic fiber filter media were prepared from chopped ceramic fibers and phenolic resin. The coated resin was converted to activated carbon by pyrolysis in N 2 followed by activation in a mixture of steam (75%)–N 2 flow at 750–900 °C. The BET area and pore structure of the ceramic fiber-supported activated carbon (FAC) were studied as a function of burn-off and compared with published data of activated carbon fiber (ACF) derived from phenolic fabrics. The observed BET area curve of FAC has a similar trend to that of ACF, i.e., increase of BET area occurs parabolically with increasing burn-off, with the difference that the BET area of the FAC is about 20% lower than that of the ACF at the same burn-off. It is also found that FAC has a relatively wide pore size distribution than ACF. These discrepancies are presumed because of the difference in the steam concentration of the activating agent. The breakthrough experiments on toluene were performed to compare the absorption efficiency of FAC and ACF filters prepared in this study. Assuming that the shape of the breakthrough curves for toluene achieved by the FAC and ACF filters does not change and breakthrough time is simply proportional to the activated carbon content of each filter, both FAC and ACF filters containing 1 g of activated carbon show similar estimated breakthrough time.