Kinetics of interaction of sulphur dioxide with clean and oxidized metal films of iron, nickel and lead

Abstract

The interaction of SO₂with evaporated films of iron, nickel and lead has been investigated in the temperature range from –80 to about 300°C. Rapid and irreversible chemisorption occurred on both of iron and nickel films at –80°C, and above 100°C extensive incorporation of the gas took place at a rate which was faster, for a given temperature and pressure, on iron than on nickel films. The incorporation occurred with a constant activation energy which was independent of the thickness of the “product layer”, and the kinetics conformed to a first-order quation; the slow step is probably the dissociative adsorption of an adsorbed SO₂ layer undergoing free translation. Presorbed oxygen on nickel and iron films reduced the total amount of adsorption at –80 °C, and at the same time lowered the rate of incorporation above 100°C to a great extent.

A multilayer adsorption was observed on lead films at –80°C; a substantial fraction of the adsorption was reversible. No clear evidence was obtained for the incorporation of SO₂ in lead films below 300°C. Presorbed oxygen on lead films considerably restricted the mobility of the activated complexes of the reaction.