Relationship between oxygen species and activity/stability in heteroatom (Zr, Y)-doped cerium-based catalysts for catalytic decomposition of CH3SH

Abstract

CeO 2 , Ce 1– x Zr x O 2 , and Ce 1– x Y x O 2– δ ( x = 0.25, 0.50, 0.75, and 1.00) have been rapidly synthesized to estimate their catalytic behavior in decomposing CH 3 SH. The role of oxygen vacancies, and the relationship between the oxygen species and catalytic properties of CeO 2 and Zr-doped and Y-doped ceria-based materials are investigated in detail. Combining the observed catalytic performance with the characterization results, it can be deemed that surface lattice oxygen plays a critical role in methanethiol catalytic conversion over cerium oxides. Ce 0.75 Zr 0.25 O 2 shows higher catalytic activity for CH 3 SH decomposition due to the large amount of surface lattice oxygen, readily available oxygen species, and excellent redox properties. Ce 0.75 Y 0.25 O 2– δ displays better catalytic stability owing to the greater number of oxygen vacancies that would promote bulk lattice oxygen migration to the surface of the catalyst in order to replenish surface lattice oxygen. In addition, the results show that the difference in chemical valence between Ce and the heteroatoms would strongly influence the amount of surface lattice oxygen as well as the mobility of bulk-phase oxygen in these catalysts, thus affecting their activity and stability. Surface lattice oxygen plays a key role in decomposing CH 3 SH. Oxygen vacancies promote bulk lattice oxygen migration. The valence difference between the doped ions affects the catalytic behavior.