摘要
A nanocatalyst composed of 10wt% Pd supported on TiO2 was synthesized using one-step flame spray pyrolysis with a highly-quenched premixed stagnation flame.The as-prepared nanoparticles,having a mean diameter of approximately 10nm,were then subjected to isothermal oxidation and reduction in a fixed bed reactor.The potential roles of Pd and PdO as well as possible synergistic effects between these two active species were explored during methane conversion.The lowest light-off temperature T20 was obtained at a Pd ratio of 53% and this result can be reasonably explained based on a surface Pd-PdO site pair mechanism.Additionally,differences in the hysteresis behavior during methane oxidation were noted throughout a heating-cooling cycle over the temperature range of 200-600℃,such that the degree of hysteresis was strongly correlated with the Pd ratio.
