Supercritical Carbon Dioxide Regeneration of Activated Carbon for Exhaust Processing

Supercritical carbon dioxide (ScCO2) is a promising solvent for regeneration because of its high diffusivity into the microstructure of activated carbon and its ability to operate at a moderate temperature. In this study, we investigated a ScCO2 cleaning method of the activated carbon used in the exhaust processor of a semiconductor manufacturing process. The ScCO2 cleaning was carried out at temperature of 80 degrees C, pressure of 20 MPa and regeneration time of 6.0h. The experimental results showed the activated carbon used in the exhaust processor for a long duration could not be regenerated. Thermogravimetric analysis (TGA) showed that ScCO2 could remove low boiling point adsorbates (100-400 degrees C) but not high boiling point adsorbates (400-900 degrees C). Analysis of the results of ScCO2 cleaning in terms of a high boiling point ratio, defined as the proportion of high boiling point adsorbates, showed that regeneration rates of 90% and 80% respectively were achieved at high boiling ratios of 2.0% and 4.0%, suggesting that the high boiling point ratio could serve as an indicator of potential regeneration rate.