Catalytic activity of AlF3 nano-structure for hydrolysis of NF3

Abstract

This study examined the catalytic properties of AlF3 nanostructures for the hydrolysis of NF3 discharged from semiconductor processes. Alumina being used as a catalyst for the hydrolysis of NF3 was converted to AlF3 by fluorination in the presence of NF3 during a gas-solid chemical reaction. In general, AlF3 has low catalytic activity in the hydrolysis of fluorinated compounds, but its catalytic activity varies according to its crystal structure. Commercial AlF3 exhibited low catalytic activity in the hydrolysis of NF3, whereas AlF3 formed from the chemical reaction between NF3 and alumina exhibited very high catalytic activity. Although alumina has high catalytic activity in the hydrolysis of NF3, its activity decreases as it is converted to AlF3 during the process. On the other hand, the activity test and X-ray diffraction showed that its catalytic activity is recovered as the nanocrystals of AlF3 were grown. AlF3 nanocrystals grown by the gas-solid chemical reaction showed a similar distribution of acid sites as the alumina. These acid sites provided the catalytic activity of AlF3 in the hydrolysis of NF3.