EFFECT OF CALCINATION CONDITIONS OF THE OXIDIZED PRECURSOR ON THE STRUCTURE OF A SULFIDED K-MO GAMMA-AL2O3 CATALYST FOR MIXED ALCOHOL SYNTHESIS/

The effect of the calcination temperature and time of the oxidized pre cursor on the structure of a sulfided K-Mo/gamma-Al2O3 catalyst was in vestigated by surface area analysis, X-ray diffraction, X-ray photoele ctron spectroscopy, transmission electron microscopy and energy disper sive spectroscopy. The experimental results show that calcination of t he oxidized precursor at high temperature leads to a surface sintering , whereby the surface areas of the samples decrease sharply. Because o f the strong K-Mo interaction, various K-Mo-O phases are formed. These K-Mo-O phases are transformed to K-Mo-O-S and K-Mo-S phases during su lfidation. The K-Mo interaction species retard, to some extent, the su lfidation and reduction of molybdenum and result in an increase in Mo- VI content in the samples. The surface K+ ions are enriched and surfac e Cl- ions are partially lost after calcination. Three kinds of surfac e sulfur species are formed on the sulfided samples. Some sulfur speci es might be unstable and might be lost in the reactant stream. The syn thesis of mixed alcohols was measured in a micro-reactor. It was found that calcination at 700 degrees C-800 degrees C of the oxidized precu rsor is more beneficial for alcohol formation. The correlation between the activity, selectivity of mixed alcohols and the structures of the samples are discussed.