Temperature dependent rate constant for the reaction of H-atoms with carbonyl sulfide

Abstract

The kinetics of the reaction of H-atom with carbonyl sulfide (OCS) has been investigated at nearly 2 Torr total pressure of helium over a wide temperature range, T = 255–960 K, using a low-pressure discharge flow reactor combined with an electron impact ionization quadrupole mass spectrometer. The rate constant of the reaction H + OCS → SH + CO (1) was determined under pseudo-first order conditions, monitoring the kinetics of H-atom consumption in excess of OCS, k₁ = 6.6 × 10⁻¹³ × (T/298)³ × exp(−1150/T) cm³ molecule⁻¹ s⁻¹ (with estimated total uncertainty on k₁ of 15% at all temperatures). Current measurements of k₁ at intermediate temperatures (520–960 K) appear to reconcile previous high and low temperature data and allow the above expression for k₁ to be recommended for use in the extended temperature range between 255 and 1830 K with a conservative uncertainty of 20%.