The thermal decomposition of hydrogen sulfide over vanadium and molybdenum sulfides and mixed sulfide catalysts in quartz and thermal diffusion column reactors

Abstract

The decomposition of hydrogen sulfide to hydrogen and sulfur on V2S3 has been studied in a quartz reactor using either flow or circulating systems and in thermal diffusion column reactors at 400-800°C. Hydrogen yields were measured as a function of temperature in order to determine the effectiveness of these sulfides in promoting the decomposition. The results were compared with those for MoS2, an established catalyst for this conversion. Vanadium sulfides were shown to be effective reagents for the conversion H2S→H2+ S° via a two-step process. Several mixed systems (V2S3/FeS, V2S3/Cu9S5 and V2S3/ZnS) were investigated in order to determine whether H2 yields could be improved by a cooperative effect. The mixture V2S3/Cu9S5 formed Cu3VS4 at elevated temperatures and exhibited higher catalytic activity than MoS2 in a closed circulating system using a quartz reactor. By contrast, MoS2 was found to be a better catalyst than either V2S3 or V2S3/Cu9S5 in a thermal diffusion column reactor, although better separation of product H2 from unreacted H2S was observed for the latter two systems. The use of thermal diffusion column reactors resulted in a much higher conversion of H2S into H2 than was attainable in the circulating system using a quartz reactor. © 1987.