Amphiboles. Part V. The catalysis of the disproportionation of carbon monoxide by crocidolite

Abstract

Crocidolite is shown to effect the disproportionation of carbon monoxide after an induction period of several hours during which only reduction of iron(III) to iron(II) and some chemisorption of carbon monoxide occur. Disproportionation does not take place in contact with crocidolite which has been previously oxidised or is in the anhydride form, but proceeds without any induction period if the amphibole has been prereduced with hydrogen. It is postulated that reaction occurs only on the surface of the crocidolite, and that the disproportionation is catalysed by atoms of iron(0). It is suggested further that the presence of hydroxyl ions is necessary for the formation of iron(0) in the reaction between carbon monoxide and fresh crocidolite, and that their absence accounts for the lack of catalytic activity of the oxidised and anhydride forms.