Figure 3
Analysis of the catalyst surface state. (a,b) Histogram of particle size obtained (a) without and (b) with catalyst pretreatment measured by TEM. (c,d) (c) XPS and (d) EDX spectra of Co film (black), oxidized-Co film (blue), oxidized-Co film obtained after pretreatment (red). (e,f) FT-EXAFS spectra of zeolite supported Co (e) without and (f) with pretreatment. Control spectra obtained from reference samples are shown in (e) CoO and Co2O3 and (f) Co. (g) XAFS spectra of zeolite-supported Co with pretreatment (red) and the fitted curve for (i) Co component (black dash), (ii) CoOx component (blue dash), sum of (i + ii) (green dash), and reproduction of the experimental data (red). The curve of CoOx component is same as that of non-treated zeolite supported Co. (h) Concentration of Co and CoOx in zeolite supported Co without and with pretreatment as estimated by fitting the XAFS curve (g).
