Acta Phys. -Chim. Sin. ›› 2008, Vol. 24 ›› Issue (07): 1271-1276.doi: 10.3866/PKU.WHXB20080725

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Decomposition of CF4 over Al2O3-Based Metal Oxides

FAN Jie; XU Xiu-Feng; NIU Xian-Jun   

  1. Institute of Applied Catalysis, Yantai University, Yantai 264005, Shandong Province, P. R. China
  • Received:2007-12-03 Revised:2008-03-09 Published:2008-07-04
  • Contact: XU Xiu-Feng

Abstract: The decomposition of CF4 in the absence of water on γ-Al2O3-based metal oxides was carried out to destruct the disposal perfluoro-carbons (PFCs) from industrial processes. In the present work, the conversion of CF4 was tested over bare γ-Al2O3 at different temperatures of 825, 850 and 900 ℃. It was found that the initial activity of Al2O3 increased in the order of 825 ℃<850 ℃<900 ℃CO2 yield declined quickly with time on stream because the un-reacted γ-Al2O3 was transformed into inactive α-Al2O3 phase that resulted from the highly exothermic effect of Al2O3-fluorination reaction. As for the CF4 decomposition on MgO-Al2O3, fluorination of Mg species and the highly exothermic effect produced led to the collapse of MgAl2O4 structure, in which the magnesium element was fluorinated into MgF2. Al2O3 modified with P or Ni could inhibit the transformation of un-reacted γ-Al2O3 into α-Al2O3 during CF4 decomposition, and consequently CF4 conversion reached a stable level with time on stream.

Key words: CF4 decomposition, Al2O3, Transformation of γ-Al2O3 into α-Al2O3, Modified Al2O3


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