In situ XPS and MS study of methanol decomposition and oxidation on Pd(111) under millibar pressure range

► We study the methanol decomposition and oxidation on Pd(111) in situ using ambient-pressure XPS and mass-spectrometry in the temperature range of 300-600 K. ► We found that even in the oxygen presence the methanol decomposition on palladium proceeds through two competitive routes: full dehydrogenation to CO and H2, and decomposition of methanol via the C-O bond scission. ► The rate of the second route is significant even in the mbar pressure range, which leads to a blocking of the palladium surface by carbon and to a prevention of the further methanol conversion.