Composite catalytic materials for steam reforming of methane and oxygenates: Combinatorial synthesis, characterization and performance

Nanocomposite Catalysts for Steam Reforming of Methane and Biofuels: Design and Performance

“…After testing in the reaction of CH 4 steam reforming in stoichiometric feeds, NiO is completely reduced to metallic Ni. For composite II without supported Pt group metals, a weak broad reflection at 2θ ~ 27 o corresponding to graphitized carbon was observed agreeing with TEM data (Sadykov et al, 2008b(Sadykov et al, , 2009b. More subtle details were revealed in diffraction patterns of composite III and composites with a low content of NiO and YSZ.…”

“…Indeed, similar position of reduction peak was earlier observed for NiO supported on Ce-Zr-O 2 (Romero-Sarria et al, 2008). For unpromoted NiO + YSZ composite III, reduction starts at ~330 o C and is characterized by three overlapping peaks with T max situated at ~ 350, 400 and 450 o C (Sadykov et al, 2009b). In addition, the high-temperature (up to 700ºC) tail of hydrogen consumption was observed for both undoped and doped samples of composite III.…”

“…More subtle details were revealed in diffraction patterns of composite III and composites with a low content of NiO and YSZ. Thus, for composite III both before and after supporting doped ceria-zirconia oxide, along with reflections corresponding to cubic/tetragonal YSZ phase (highly dispersed c-or t-ZrO 2 phases are not discerned easily by routine XRD analysis (Sadykov et al, 2009b), reflections corresponding to monoclinic zirconia phase [JCPDS 78-1807] were observed as well (Fig. 8).…”

“…For composites I and II with a high content of NiO and doped zirconia, strong reflections of these phases and weak broad reflections corresponding to dispersed complex oxide promoters were observed (Sadykov et al, 2008b(Sadykov et al, , 2009b. After testing in the reaction of CH 4 steam reforming in stoichiometric feeds, NiO is completely reduced to metallic Ni.…”

“…As judged by the ratio of reflections intensity, promotion of NiO + YSZ composite by Pr-La-doped ceriazirconia oxide increases further the content of monoclinic zirconia. This implies that preparation procedure of composite III, namely, successive impregnation of YSZ powder with the excess of acidic nitrate solutions followed by evaporation to dryness and calcination (Sadykov et al, 2009b) favors leaching of Y from doped zirconia. This results in destabilization and disordering of the cubic zirconia structure, while at least the surface layers of perovskite-like yttrium nickelates can be formed.…”