Selective monochlorination of methane over solid acid and zeolite catalysts

Imre Bucsi, George A. Olah

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Abstract

Chlorination of methane was studied over amorphous silica-alumina, silicalite as well as H-mordenite, X, Y, NaL and H-ZSM-5 zeolite catalysts. The heterogeneous transformations were carried out in a continuous flow reactor in the 200-425 °C temperature range, under atmospheric pressure (methane to chlorine ratio 4:1, GHSV 600 ml/ g h). Chlorination of methane over zeolites in the 200-300 °C temperature range proceeds without selectivity indicating a radical mechanism. Above 300-350 °C, depending on the nature of zeolite, selective monochlorination takes place indicating the dominance of an ionic mechanism. H-mordenite was found to give the best monochlorination at the lowest temperature (99.2% CH3Cl at 350 °C). The observed selectivity of the investigated zeolites is strongly time limited. All investigated catalysts lose their selectivity after five hours on-stream due to extraction of aluminum from the framework of zeolites by hydrogen chloride. Amorphous silica-alumina above 350 °C also catalyzes ionic chlorination. The chlorination of methane over silicalite proceeds via the nonselective radical pathway at the investigated temperatures.

Original languageEnglish
Pages (from-to)27-38
Number of pages12
JournalCatalysis Letters
Volume16
Issue number1-2
DOIs
Publication statusPublished - Mar 1 1992

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Keywords

  • Methane
  • chlorination
  • solid acid
  • zeolites

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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