Decomposition of CH2FCF3 (134a) over Metal Phosphate Catalysts

The decomposition of CH 2 FCF 3 over some phosphate catalysts was studied. CH 2 FCF 3 began to react at 250, 300, and 450 °C over Zr 3 (PO 4 ) 4, AlPO 4, and BPO 4, respectively, and the conversion reached 100% at 475, 500, and 700 °C, respectively. The primary reaction over Zr 3 (PO 4 ) 4 was estimated to be CH 2 FCF 3 + H 2 O + 1 / 2 O 2 → 2CO + 4HF, whereas the reactions over AlPO 4 and BPO 4 were CH 2 FCF 3 + H 2 O + O 2 → CO + CO 2 + 4HF and CO + 1 / 2 O 2 → CO 2 . Complete decomposition requires both hydrolysis and oxidation. The oxidation activities of these phosphate catalysts are not high enough to accomplish complete decomposition. However, AlPO 4 -based catalysts can be combined with each Co 3 O 4, Mn 2 O 3, CuO, and Cr 2 O 3 at a phosphate content of 1/10 by volume to make them sustainable at 550−550 °C. The addition of Ce to AlPO 4 brought about a promotion effect in CH 2 FCF 3 decomposition similar to that for CCl 2 F 2 decomposition. This might suggest a similarity in the reaction mechanism. The primary reaction in the absence of oxygen was estimated to be CH 2 FCF 3 + H 2 O → CO + C + 4HF.