Influence of weakly coordinated cations and basic sites upon the reaction of H2S and CO2 on zeolites

Batch formation of COS and H2O by heterogeneous reaction of H2S and CO2 on A- and X-type zeolites with various degrees of alkaline earth cation-exchange, on faujasite-type zeolites with various SiAl ratios, and on alkaline cation-exchanged X-type zeolites, has been studied. Results obtained at different reaction times illustrate the dual function of the zeolites as selective sorbents causing a shift in reaction equilibrium and as catalysts. Correlations between the catalytic activity and population of cation sites with low oxygen coordination have been found. Furthermore, the catalytic activity could be correlated with the efficiency of dissociative H2S adsorption (literature data) and the basicity of zeolites. These correlations are regarded as being in accordance with the concept of basic catalysis on zeolites.