Low-cost PFC recycling by continuous gas chromatography

Futatsuki, Takashi*; Tajima, Yoshinori*; Abe, Tetsuya ; Tanzawa, Sadamitsu

We propose a new system to reduce emissions of Perfluorocompounds (PFCs) from semiconductor industries by the continuous gas chromatography technology. The conventional recycling technology, for example the cryogenic distillation, has some problems in its repurification step. It needs a huge distillation tower and much power for refrigeration. The continuous gas chromatography technology is a compact alternative to the conventional technology. This system is composed of the series of separation columns, vacuum pumps and automatic valves. The mixed PFCs are separated by the difference of the affinity for the filling material in the column. Only the perfectly separated PFCs are output and the others are injected to the next column. By recycling the PFC mixture, which was not separated by the single column, the continuous gas chromatography outputs the pure PFCs continuously. Accumulation and consideration of experimental data, we realized in the continuous efficient separation of CF/CF with the Large-scale pilot plant of the continuous gas chromatography. In this method high recovery rate of more than 99% was obtained and residual CF in recovered CF and residual CF in recovered CF were less than 0.01%. This recycling system is compact and it can operate with low energy consumption.