Catalytic decomposition of CFC-12 on transition metal chloride promoted γ-alumina

Ching Fai Ng*, Shaochun Shan, Suk Yin LAI

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

The activity of γ-alumina and γ-alumina promoted with transition metal chlorides for the hydrolytic decomposition of dichlorodifluoromethane was investigated in the temperature range 250-400°C. It was found that the hydrolysis of dichlorodifluoromethane occurs on the acid sites of the γ-alumina. Carbon dioxide was the main product formed. γ-alumina was deactivated by reaction with hydrogen fluoride formed by the hydrolysis reaction. The fresh catalysts and catalysts after the reaction were characterized by X-ray photoelectron spectroscopy and X-ray diffraction. Surface chloride was found to be replaced by fluoride during catalytic reaction. After prolonged reaction, rhombohedral aluminum fluoride was detected in the aged catalysts. The deactivated catalyst also catalyzed the formation of chlorotrifluoromethane. Transition metal chlorides were dispersed on the surface of γ-alumina and reduced the hydrolytic activity of the fresh catalyst. Transition metal fluoride phase formed by reaction of the chlorides with HF during reaction, especially that formed from CrCl3, reduced the rate of fluorination of γ-alumina and thus its deactivation.

Original languageEnglish
Pages (from-to)209-217
Number of pages9
JournalApplied Catalysis B: Environmental
Volume16
Issue number3
DOIs
Publication statusPublished - 20 May 1998

Scopus Subject Areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

User-Defined Keywords

  • γ-Alumina
  • Acid catalyst
  • Chlorofluorocarbon
  • Dichlorodifluoromethane
  • Freon decomposition

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