Decomposition of CCl4, CCl2F2, CClF3, and CF4 was studied in the presence of water vapor over AlPO4. They began to decompose at about 300, 330, 450, and 550°C, respectively. A good linear relationship between the reactivity of CFCs and the bond dissociation energy of the C-Cl bond suggests that the C-Cl bond cleavage is the rate-determining step. The lattice structure of AlPO4 before reaction was slightly distorted but the environment of Al and P ions became uniform after the reaction, consistent with a slight progress of crystallization of AlPO4. Supporting AlPO4 onto active charcoal is not preferable to the support because of its reactivity to water vapor. ALPO-5 was less active than that AlPO4 because the inside of the pores of ALPO-5 is hydrophobic and not effective for the CCl2F2 decomposition. Meso-porous AlPO4 showed almost the same activity with AlPO4, but the destruction of the meso-porous structure brought about a loss of activity at 400°C.
All Science Journal Classification (ASJC) codes
- Process Chemistry and Technology