Home – Home – Jornals – Chemistry for Sustainable Development 2012 number 2

Regularities were studied concerning dimethyl disulphide transformation in an atmosphere of helium in the presence of solid catalysts those differ from each other in the acid-base properties. The catalysts containing mainly BrØnsted acidic centres or strong basic centres on the surface exhibit a low activity level. Under the action of weak Lewis acidic centres, the dimethyl sulphide is formed at a low rate, however with increasing the strength of these centres the rate of dimethyl sulphide formation increases. For a catalyst to exhibit a high activity level in the formation of dimethyl sulphide, it is required for the presence of strong Lewis and BrØnsted centers, as well as basic centres with a moderate strength on the surface. The results of kinetic studies indicate that before 200 °C there is a parallel reaction scheme realized, whereas at a higher temperature the reaction scheme is consecutive. The reaction kinetic type varies from the first-order kinetics to zero-order one depending on the concentration of the substrate. The rate of dimethyl sulphide formation increases with increasing the temperature, the apparent activation energy amounts to (55±1) kJ/mol. The selectivity level of dimethyl sulphide formation in the case of complete conversion level of the substrate reaches 50–60 %.