EFFECT OF HIGH-TEMPERATURE COKE DEPOSITION METHANE UPON THE STRUCTUREOF MANGANESE-YTTRIUM OXIDES

Interaction of manganese-yttrium oxides with methane at 970 K can be v iewed as proceeding in two consecutive steps: initial reduction of the system followed by formation of carbonaceous deposits due to CH4 deco mposition. It was shown by SEM that methane degradation on Mn/Y2O3 sys tems resulted in vermicular and funnel-shaped carbonaceous deposits, a s well as layered carbon. Upon carbonization, a substantial modificati on of oxide surface was observed by XRD and TEM; this included phase s egregation and surface destruction with oxide species being torn off b y growing carbonaceous deposits. (C) 1997 Elsevier Science Ltd.