Studies of Molybdena‐Alumina Catalysts XIII no Adsorption and Sh Content of Sulfided Catalysts

A series of Mo/Al2O3 catalysts were prepared containing various levels of Mo, several different Al2O3 supports, and by different solution pH's. Sulfided catalysts were characterized by NO chemisorption, SH content and thiophene HDS activity. Uptake of NO depended on the temperature of adsorption employed, and consequently an absolute number of adsorption sites could not be determined. Also, correction for NO adsorption on the support was needed to obtain values representative of the MoS2 species present. Assuming NO adsorbs at edge sites of the MoS2 slabs, it was found that the size of the MoS2 slabs was affected by the nature of the Al2O3 support but only slightly by the pH of the impregnating solution. Residual SH content roughly correlated with net NO adsorption. HDS activity was roughly proportional to net NO adsorption and to residual SH content. Significant deviations, however, were observed, indicating that catalytic activity is not precisely related to either.