Hydrogen production via the direct cracking of methane over Ni/SiO2: catalyst deactivation and regeneration

The catalytic cracking of methane over supported nickel catalysts is a pote ntial route to the production of GO-free hydrogen and filamentous carbon. E ventually, however, the catalyst deactivates due to the spatial limitations imposed on the filamentous carbon growth by the reactor. In this study we show that a 15 wt.% Ni/SiO2 catalyst can be fully regenerated at 923 K with steam for up to 10 successive cracking/regeneration cycles without any sig nificant loss of catalytic activity. XRD analyses indicate no increase in t he amount of carbon remaining on the catalyst after successive regeneration s and no structural changes in the nickel particles as the catalyst is cycl ed between cracking and steam regeneration. SEM micrographs are in agreemen t with the XRD results and show that most of the filamentous carbon is remo ved during steam regeneration, leaving only small pockets of this material which resist this treatment. (C) 2000 Elsevier Science B.V. All rights rese rved.