No abstract

The first step in the two-step CO-catalyzed conversion of H2S to H2 and sulfur, reactions 1 and 2, has been studied in order to establish the optimal experimental conditions for the reaction. Without a catalyst, H2S conversions of the order of only 1−2% could be achieved. NiS on alumina proved to be an efficient catalyst, and at 267 °C, H2S conversions reached 52% or 100% of the thermodynamic limit. Small amounts of CO2 and CS2 have also been detected among the products. In comparative experiments using CoS on alumina as the catalyst, up to 67% conversion, representing 100% of the thermodynamic equilibrium H2 yield, could be achieved at a substantially lower temperature, 177 °C. Furthermore, formation of CO2 and CS2 was found to be negligible (<1%) at this low temperature, eliminating the need for the suppression of the COS disproportionation reaction.

In this journal, research articles which reflect the survey with the results and translations that can be considered as a high scientific quality, scientific observation and review articles are published. Teachers, students and scientists who conduct research to the field (e.g. articles on pure sciences or social sciences, mathematics and technology) and in relevant sections of field education (e.g. articles on science education, social science education, mathematics education and technology education) in the education faculties are target group. In this journal, the target group can benefit from qualified scientific studies are published. The publication languages are English and Turkish.

Research and Technology Branch, Alberta Energy, Edmonton, AB T5K 2G6, CanadaThe pyrolysis of COS has been studied over the temperature range 300 to 750°C using a variety of catalysts. The observed product distribution confirmed that two parallel reaction paths: 2 COS -+ 2 CO + S, (2) and 2 COS -+ CO, + CS, (4) are involved in the decomposition. The decomposition yield increased with rising temperature, accompanied with a shift in selectivity. At temperatures lower than -700°C the disproportionation reaction 4 was predominant, whereas at temperatures higher than 70O0C, reaction 2 was favoured. In the high-temperature region (700 to 750°C) it was possible to achieve full suppression of reaction 4 with added CS,. The pyrolysis of COS was also studied in a reactor packed with quartz chips without catalysts at high temperatures. Between 800 and 9OO"C, up to 99% conversion (with respect to the thermodynamic limit) could be achieved, with the almost complete absence of the disproportionation reaction 4. The results point to the commercial potential in the two-step reaction sequence: 2 H,S + 2 CO t) 2 COS + 2 H, 2 H,S t) 2 H, + S, 2 cos tf 2 co + s, for the economic conversion of hydrogen sulfide to hydrogen and sulfur.On a etudie la pyrolyse du COS dans une gamme de temperatures de 200 a 750°C a I'aide de divers catalyseurs. La distribution de produits observee confirme que deux chemins de reaction parallbles interviennent dans la decomposition, soit 2 COS + 2 CO + S, (2) et 2 COS + CO, + CS, (4). Le rendement de decomposition augmente avec la hausse de la temperature et est accompagne d'un changement de selectivite. A des temperatures inferieures a -700"C, la reaction de dismutation 4 I'emporte, tandis qu'a des temperatures superieures a 700"C, la reaction 2 est favorisee. Dans la region des temperatures superieures a 700"C, la reaction 2 est favorisee. Dans la region des temperatures elevees (700 a 750"C), il a ete possible d'eliminer totalement la reaction 4 par ajout de CS,. La pyrolyse de COS a egalement ete etudiee dans un reacteur garni d'eclats de quartz sans catalyseur a des temperatures elevees. Entre 800 et 900"C, jusqu'a 99% de la conversion (en tenant compte de la limite thennodynamique) a pu itre realisee, avec I'absence presque complete de la reaction de dismutation 4. Les resultats montrent le potentiel economique de la sequence de reaction a deux etapes : 2 H,S + 2 CO c+ 2 COS + 2 H, 2 cos t) 2 co + s, 2 H,S t) 2 H, + s, he hydrogen content of hydrogen sulfide is close to 6% T and if hydrogen sulfide could be converted directly to its elements, sulfur and hydrogen, the hydrogen thereby produced would be industrially significant. In the current, universallyapplied Claus process, only the sulfur is recovered while the hydrogen in the hydrogen sulfide is burnt to water, and essentially wasted. Extensive research has been directed in the recent past to develop alternative technologies for the economic conversion hydrogen sulfide to sulfur and hydrogen. One of such alternative technologies, would be the two-...

No abstract