Chemisorption of sulfur dioxide on tungsten and platinum surfaces

The chemisorption of SO 2 on a W and a Pt surface has been investigated by flash desorption mass spectrometry (FDMS) and AES. AES data indicate that the chemisorbed sulfur dioxide molecules oxidized the W surface, and produced a stable tungsten oxide during the heating (up to 1400 K) process. FDMS data indicate that the decomposition of SO 2 yielded elemental and molecular sulfur during the desorption process. FDMS data show that SO 2 exists in four binding states (α 1 , α 2 , α 3 and α 4 ) on a clean Pt surface and in three binding states (α 5 , α 6 and α 7 ) on an oxidized Pt surface. In addition, the coadsorption of SO 2 and O 2 was carried out on a Pt surface. The coadsorption process can produce SO 3 which exists in two different binding states on a Pt surface. The data indicate that the oxidation of SO 2 to form SO 3 on a Pt surface occurs by means of a Langmuir–Hinshelwood mechanism.