Effect of calcination conditions of the oxidized precursor on the structure of a sulfided K-Mo/γ-Al2O3 catalyst for mixed alcohol synthesis Original Research Article

The effect of the calcination temperature and time of the oxidized precursor on the structure of a sulfided K-Mo/γ-Al2O3 catalyst was investigated by surface area analysis, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive spectroscopy. The experimental results show that calcination of the oxidized precursor at high temperature leads to a surface sintering, whereby the surface areas of the samples decrease sharply. Because of the strong Ksingle bondMo interaction, various Ksingle bondMosingle bondO phases are formed. These Ksingle bondMosingle bondO phases are transformed to Ksingle bondMosingle bondOsingle bondS and Ksingle bondMosingle bondS phases during sulfidation. The Ksingle bondMo interaction species retard, to some extent, the sulfidation and reduction of molybdenum and result in an increase in MoVI content in the samples. The surface K+ ions are enriched and surface Cl− ions are partially lost after calcination. Three kinds of surface sulfur species are formed on the sulfided samples. Some sulfur species might be unstable and might be lost in the reactant stream. The synthesis of mixed alcohols was measured in a micro-reactor. It was found that calcination at 700°C–800°C of the oxidized precursor is more beneficial for alcohol formation. The correlation between the activity, selectivity of mixed alcohols and the structures of the samples are discussed.