Effect of structural defects in alumina supports on the formation and catalytic properties of the active component of reforming catalysts

The pair distribution function (PDF method) was used to investigate the phase composition and local structure of supports and the model reforming catalysts Pt/gamma-Al2O3. The structural modification of support during acidic peptization of aluminum hydroxide with the pseudoboehmite structure was suggested as a possible approach to obtaining highly defective alumina. This modification of gamma-Al2O3 results in the formation of a greater number of cation vacancies in the octahedral positions of the spinel-like alumina structure. The effect of structural defects in the support on the oxidation state of the active component and catalytic properties of the catalysts was demonstrated. It was found that platinum ions are located in the vacant octahedral positions (defects) of the spinel-like structure of the support. These ionic platinum centers on alumina with higher defect density demonstrated a higher selectivity in the model reaction of n-heptane aromatization as compared to metallic centers which prevail in traditional Pt/gamma-Al2O3 catalyst.