Catalytic decomposition of perfluorocarbons - Part II. Decomposition of CF4 over AlPO4-rare earth phosphate catalysts

Catalytic activity of various metal phosphates were studied and it was foun d that Zr and Al phosphates are effective for CF4 decomposition in the pres ence of water vapor at above 600 degrees C and the specific surface areas o f these active catalysts were remarkably large after calcination at 1000 de grees C for 5 h. No CF4 decomposition took place up to 700 degrees C over t he Mg2P2O7, Ca2P2O7, BPO4, FePO4 or the BiPO4 catalysts. The catalysts prep ared from the solutions containing Al and rare earth (RE) nitrates and phos phoric acid are mixtures of the AlPO4 and RE phosphates. The mixtures of Al PO4 and phosphates of Y, La, Ce, Pr, Nd, and Gd increased in activity. Heav y rare earth elements (Er and Yb) showed little promotion effects. The cata lytic activity of the Ce10%-AlPO4 slightly declined within the initial 40 h and then reached a steady value. 4.2 mol% of water vapor in the feed is su fficient for CF4 decomposition over Ce10%-AlPO4.