The chemisorption of carbon monoxide on tantalum monocarbide

Abstract

The chemisorption of carbon monoxide on a tantalum monocarbide filament was investigated at gas pressures between 5 × 10 −8 and 5 × 10 −7 Torr and at filament temperatures between 295 and 1120° K. When the filament was flashed to 1730° K after adsorbing carbon monoxide, the gas was desorbed in two separate pressure bursts at about 600 and 1350° K. The more strongly bonded, β, gas was adsorbed with first order kinetics, the less strongly bonded, α, gas with zero order kinetics. The sticking probability versus uptake curve for the β-carbon monoxide is strongly curved towards the uptake axis. It is concluded from this that unlike its behaviour on many transition metals carbon monoxide does not form a mobile precursor to chemisorption on tantalum monocarbide.