SPECTROSCOPIC CHARACTERIZATION OF HYDROTREATING CATALYSTS CONTAINING COBALT, NICKEL, AND MOLYBDENUM

The interactions of Co, Ni, and Mo with a {dollar}gamma{dollar}-{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} support were studied as a function of metal loading, calcination temperature, and order of impregnation by employing electron spectroscopy for chemical analysis (ESCA), ion scattering spectroscopy (ISS), Raman spectroscopy (LRS), diffuse reflectance spectroscopy (DRS), and x-ray diffraction (XRD). Information concerning the speciation and dispersion of the supported metals was obtained by studying the catalysts in their oxidic, reduced, and sulfided states.; A method employing Raman spectroscopy is presented for quantitation of crystalline phases commonly found in commercial hydrodesulfurization catalysts. The method is based on the use of an internal standard and is accurate to within {dollar}pm{dollar}6% (relative) for {dollar}{lcub}rm MoOsb3{rcub}{dollar} and {dollar}{lcub}rm WOsb3{rcub}{dollar} concentrations greater than 0.1%.; A comparative study of the speciation and dispersion of Ni/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} and Co/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} catalysts has shown that Ni is better dispersed on the alumina support than Co above a metal loading of 3%. The relative proportions of an aluminate-like phase, an octahedrally coordinated surface phase, and a crystalline oxide phase in the Ni/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} and Co/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} catalysts vary with metal loading and calcination temperature. The octahedrally coordinated surface phase predominated at higher loadings in Ni/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} catalysts compared to pronounced formation of {dollar}{lcub}rm Cosb3 Osb4{rcub}{dollar} in Co/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} catalysts.; Addition of Mo to Ni/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} and Co/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} catalysts does little to alter the dispersion of the promoter phases. Significant changes in Ni and Co speciation on Mo addition include evidence for formation of a Ni (or Co)-Mo interaction species and a decrease in the amount of the aluminate-like phases.; A study of the speciation and disperson of Ni-Mo/{dollar}{lcub}rm Alsb2 Osb3{rcub}{dollar} catalysts has shown that the interaction between Ni and the support, and to a lesser extent between Mo and the support, is influenced by Ni loading, Mo loading, and the order of impregnation. Formation of a Ni-Mo interaction species is facilitated by impregnation of Mo-first and by increasing the Mo loading. Impregnation of Ni first results in greater formation of {dollar}{lcub}rm NiAlsb2 Osb4{rcub}{dollar}-like species. The speciation and dispersion of the molybdate phase was unaffected by Ni loading or impregnation order. Formation of polymolybdate octahdera increases with Mo loading.