An attempt to bridge the pressure and material gap with a disperse model catalyst for low-temperature alkane reforming

Pt black was exposed to n>-hexane/H₂ mixtures between 483 and 663 K followed by O₂ and H₂ treatments at 603 K. XP and UP spectra were measured without exposing the samples to air. 20–30% carbon accumulated after hydrocarbon exposures. O₂ removed most carbon. The surface C content increased after a subsequent contact with H₂, C 1s showing more atomic carbon as opposed to graphite after n-hexane exposure. Anisotropic recrystallization of Pt black favoring (220) and (311) lattice planes occurred under hydrogen-rich conditions. Both findings were attributed to a H₂-induced solid-state rearrangement; H atoms penetrating into the crystal lattice, force subsurface carbon and oxygen atoms to the surface and a concomitant restructuring would occur. Thus another hydrogen effect has been recognized, leading to structures favorable for skeletal reactions of alkanes.