CS2 and COS conversion under different combustion conditions

Abstract

Carbon disulfide (CS2) and carbonyl sulfide (COS) can be generated from sulfur-containing species in a combustion chamber, and thus may be present at the exhaust gas and even emitted to the atmosphere. Therefore, it is of great interest to study and understand the mechanism through which the conversion of CS2 and COS takes place under combustion conditions, both to develop strategies to control these emissions and, consequently, to preserve the environment.In this context, a combined experimental and modeling study addressing the conversion of CS2 and COS under different combustion conditions has been undertaken. The developed kinetic mechanism has been validated against experimental data obtained in the present work of the moist conversion of CS2 and COS in a laboratory quartz flow reactor. Experiments were performed at atmospheric pressure, in the 300–1400K temperature range, and under different combustion environments, ranging from fuel rich to fuel lean conditions, specifically air excess ratios of λ=0.2, 0.7, 1, 2 and 20. The experimental results have been analyzed and interpreted in terms of this detailed gas phase kinetic mechanism, and the elementary steps involving CS2 and COS conversion as a function of the different operating conditions have been identified.Results indicate that the oxidation of both, CS2 and COS, is produced by interaction with the radical pool, mainly with O radicals, and to a lesser extent with S radicals, being this last consumption step more relevant as the reaction environment becomes fuel richer. The CS2 conversion involves a more complex process compared to COS, since COS is an intermediate product during the oxidation of CS2 and thus its conversion process also involves the COS chemistry.