(134b) CH4 Dry Reforming with CO2: Characterization of Surface Carbon Species Formed On CeOx-ZrOy Based Ni, Ni-Co and Ni-Rh Catalysts

Methane dry reforming with CO2 is greatly affected by the presence of various form of surface carbon (carbide, graphites carbon nanotubes (CNT), etc). To characterize them two methods have been chosen: (i) temperature programmed oxidation (TPO) and (ii) by TEM. The samples prepared by sol/gel technique catalyzed the CH4 + CO2 reaction and the surface carbon was generally characterized by Tmax in TPO. On sol/gel Ce0.6Zr2,97Ni0,43 and impregnated 5% Ni/Ce2Zr2O8 catalysts the Tmax appeared at 400oC and at 600oC, respectively. Simultaneously, TEM image pointed to the extensive CNT formation on the impregnated Ni catalyst along with an increase in Ni particle size. On the sol/gel sample the Ni nanoparticles are stabilized ib form of Ni nanoparticles and the character of the carbon was found to be also different. On bimetallic Ce2Zr1,5Ni0,3Co0,2 and Ce2Zr1,5Ni0,47Rh0,03 samples two kinds of surface carbon species coexist. The species characterized by Tmax at 360oC was slowly transformed to the high temperature peak at 600oC. The amount of carbon is considerably higher on the Co containing sample. We can speculate that on Co/Ni containing sample the carbidic (CoCx or NiCx) species forms predominantly and after the stracture of catalyst being cahnged, the CNT and graphitc species becomes prevailing.