Evaluation of the sodium effect on the physicochemical properties of Mo/SnO2 catalysts

The effect of sodium addition on the physicochemical properties of Mo/SnO2 catalysts was studied. The catalysts were prepared by precipitation using aqueous solution of ammonium heptamolybdate in two Mo amounts (5.5 and 14.5% (wt)); afterwards they were impregnated with sodium ion (1% wt). The solids were characterized by nitrogen adsorption, X-ray diffraction, UV–vis diffuse reflectance spectroscopy, FTIR, and FTIR of adsorbed pyridine in order to evaluate changes on Mo species and textural and acidic properties. The results have shown that Mo/SnO2 samples present dispersed isolated tetrahedral Mo species. The addition of sodium ion to Mo/SnO2 catalysts promotes the transformation of dispersed isolated tetrahedral Mo species into dispersed two-dimensional polymolybdates and also causes changes in textural and acidic properties of these Mo/SnO2 catalysts.