The reactivity and composition of strongly adsorbed carbonaceous deposits on platinum. Model of the working hydrocarbon conversion catalyst

摘要: The role of strongly adsorbed hydrocarbon deposits in reforming catalysis on a series flat, stepped, and kinked platinum single-crystal surfaces at atmospheric pressures temperatures between 300 700 K has been established model developed for the working structure composition active catalyst surface. Restart reaction studies rate using precovered with carbonaceous overlayers containing carbon-14 were used to investigate catalytic activity selectivity carbon-covered hydrogenation, dehydrogenation, skeletal rearrangement. Quantitative hydrogen thermal desorption carried out as function surface temperature determine (1) composition, (2) energetics sequential dehydrogenation derived from variety hydrocarbons including isobutane, neopentane, n-hexane, cyclohexene. Carbon monoxide adsorption methods titrate uncovered sites before after studies. uncovered-site concentrations correlated total carbon coverage determined by Auger electron spectroscopy platinum. These experiments together results related sensitivity, desorption, deuterium exchange, radiotracer revealed that primary disordered deposit is nonselective poison which blocks incident reactant molecules. most important chemical properties are its abilities store exchange reacting species provide product growth mechanism this sensitive hydrocarbon, morphology appears vary continuously two dimensional low (<550 K) three higher than about 600 K.