Influence of cobalt content on hydrotreatment catalytic activity for CoMo6/gamma-Al2O3 heteropolymetalate based catalyst

CABELLO, CARMEN I.; MUÑOZ, MERCEDES; PAYEN, EDMOND; THOMAS, HORACIO J.

CATALYSIS LETTERS

Springerlink

Año: 2004 vol. 92 p. 69 - 73

1011-372X

The influence of Co content in the catalytic activity in hydrotreatment reactions (hydrodesulfurization (HDS) of thiophene and hydrogenation (HYD) of cyclohexene) using CoMo6/g-Al2O3 type catalysts where the precursor is Co(III) heteropolymolybdate of (NH4)3[CoMo6O24H6].7H2O formula and Anderson type planar structure, (hereafter CoMo6) was investigated. The preparation of catalysts was carried out by co- impregnation of g-alumina with CoMo6 and (NH4)6[TeMo6O24].7H2O (TeMo6) in order to obtain catalysts with variable amounts of Co(III) keeping about the same Mo amount. That Anderson phase of Te(VI), (TeMo6), was chosen due to its good solubility and because no promoting effect of the Te was in hydrotreatment. Five catalysts were prepared by co-impregnation of g-Al2O3, by using aqueous solutions of both phases in different proportions. Catalysts with a ratio [Co]/([Co]+[Mo]) between 0 and ~0.14 and a Mo loading (wt % Mo) between 8 and 10 were obtained. The Raman and Diffuse Reflectance (DR) spectroscopies were used for characterization of bulk and  supported CoMo6 phase. By analyzing the respective adsorption isotherms and parameters and according to the catalytic tests it could be established that HDS as well as HYD activities of the catalysts increase as a function of the added Co.