Rapid Production of Hydrogen and Carbon Monoxide via the Heterogeneous Oxidation of Zn(g) Available to Purchase

The heterogeneous oxidation of Zn(g) is considered as an improved approach to the production of H₂ and CO in the two-step Zn/ZnO solar thermochemical cycle. The rate of Zn(g) oxidation by H₂O and CO₂ is measured gravimetrically in a quartz tubular flow reactor for temperatures between 800 and 1150 K, Zn(g) concentrations up to 36 mol%, and H₂O/CO₂ concentrations up to 45 mol%. The rate of the heterogeneous oxidation of Zn(g) by both H₂O and CO₂ is on the order of 10⁻⁸–10⁻⁵ mol cm⁻² s⁻¹. For similar oxidizing conditions, H₂O oxidizes Zn(g) three times as fast as CO₂, indicative of a lower heterogeneous oxidation activation energy in the H₂O system. Less than one second is required to convert more than 85% of Zn to ZnO for all temperatures in both the H₂O and CO₂ reacting systems.