In situ characterizations of Pd/Al2O3 and Pd/CeO2/Al2O3 catalysts for oxidative steam reforming of propane

Effect of interactions between Ni and Mo on catalytic properties of a bimetallic Ni-Mo/Al 2 O 3 propane reforming catalyst

“…This band overlaps bands 2940-2930 cm -1 which are assigned to asymmetric methyl (ν as CH 3 ) and methene (ν as CH 2 ) stretching, and bands around 2860 cm -1 assigned to symmetric methyl (ν s CH 3 ) and methene (ν s CH 2 ) stretching [15,53,54]. Bands at lower wavenumbers; 1473 and 1388 cm -1 could be attributed to asymmetric methyl (δ as CH 3 ) and symmetric methyl (δ s CH 3 ), respectively.…”

“…while bands at 1470-1530 cm -1 are assigned to asymmetric monodentate carbonates (ν as COO -) [53]. Asymmetric (δ as CH 3 ) and symmetric (δ s CH 3 ) methyl species can also co-exist in these two ranges.…”

“…As the conversion increased, with time Ni surface ensembles change to smaller islands with more active edge sites, enhancing the linear adsorption of CO. This change is based on the increase in the amount of linearly adsorbed CO and a decrease in bridging CO [53,55,56].…”

“…Figure 12 shows spectra of propane adsorption at the 15 th min for the two catalysts. The absorbance band at 2966 cm -1 is attributed to gaseous propane [53].…”

“…At all three times a distinguishable difference between the three catalysts was observed for the bands ranging from 1760 -2094 cm -1 , which are attributed to molecular CO adsorption. Bands in the 2100-2000 cm -1 region are assigned to linear CO adsorption, which is favored over isolated metal sites (corners and edges), while bands in the 1900-1800 cm -1 range are most likely a contribution of bridging CO, adsorbed on more flat and extensive metal sites [53,55,56]. For the 15Ni and the 0.1Mo catalysts, within the first 5 min of the reaction, CO was adsorbed more on the less reactive flat sites.…”