Catalytic combustion of Claus tail gas: Oxidation of sulfur species and CO using gold supported on lanthanide-modified TiO2

Abstract

Sulfur recovery processes aimed at the reduction of SO2 emissions can unintentionally contribute to increased greenhouse gas emission through the final incineration stage. In the past two decades, metal oxide supported gold nanoparticles have shown their catalytic activity for low-temperature CO oxidation, and they could be candidates for Claus plant tail gas incineration catalysts. This study was aimed at finding a durable catalyst and reasonable conditions for the Claus tail gas incineration process, which involves relatively high temperatures (573–623 K), up to 1% sulfur species, and a high concentration of water vapor (16.7%). Lanthanide oxides (i.e., La2O3, Eu2O3 or Er2O3) were deposited on the surface of titania xerogel, followed by impregnation with gold and calcination at 673 K. Results showed that the Eu2O3/TiO2 supported gold was the most active for CO oxidation, because the electron transfer from the bulk TiO2 to Au nanoparticles and higher sulfate tolerance.