Catalytic oxidation of hydrogen sulfide: influence of pore structure and chemical composition of various porous substances

The catalytic oxidation of H₂S with O₂ at 200 °C on various porous materials was investigated. The influence of the pore structure and the chemical composition of the materials on the activity and the selectivity toward the product (sulfur) was studied. It was found that in materials with an average pore diameter between 5 and 10 Å the sulfur adsorption is strong. The catalytic activity per square meter of total surface area is approximately proportional to the amount of adsorbed sulfur. In this case the selectivity toward sulfur is high. In materials with larger
pores sulfur adsorption is enhanced by the presence of Lewis acid sites and by a hydrophobic surface. For these materials the presence of water in the feed has an activity lowering effect. If iron oxide is present, at 200 °C, SO₂ is the main product. This is the case when other group 6-8 metal ions are present. For practical use in an H₂S removal process the industrial active charcoals, zeolite NaX, Ti0₂, and ZrO₂ are most suitable.