The kinetics of the CO2+CS2=2COS reaction over new and used alumina catalysts was studied at 523-623 K. The adsorption of the reaction components was measured at the temperature of the catalytic tests by volumetric and thermogravimetric methods. The number and energetics of the acidic and basic sites were investigated with a combined volumetric-microcalorimetric method using NH3 and CO2 as probe molecules. The equilibrium constants of the main reaction and several assumed side reactions have also been calculated. Closely zero order and first order behaviour were observed for CO2 and CS2, respectively. The loss of catalytic activity upon long term loading was roughly proportional to the loss of the surface basic sites whereas the number of the acidic centers moderately increased. On all catalysts, very likely by the removal of basic OH and 02-sites, carbon tetrachloride immediately caused an ultimate cession of the catalytic activity. As CS2 also reacts with the surface OH groups, leading to H2S and side products, under steady state conditions the rate-determining step is considered to be the reaction of strongly adsorbed CO2 (presumably in a bidentate or a bridging carbonate form) with physisorbed or gas-phase CS2. Efforts to regenerate the aged catalysts by treatments with oxygen at 573 K or by leaching with liquid phase CS2 have failed.
|Titolo:||KINETIC-STUDY OF THE CARBONYL SULFIDE SYNTHESIS FROM CARBON-DIOXIDE AND CARBON-DISULFIDE ON ALUMINA CATALYSTS|
|Settore Scientifico Disciplinare:||Settore CHIM/02 - Chimica Fisica|
|Data di pubblicazione:||1990|
|Digital Object Identifier (DOI):||10.1016/S0166-9834(00)81558-4|
|Appare nelle tipologie:||01 - Articolo su periodico|