Hydrotreating catalyst activation

CA provides simultaneous sulfidation of Co and Mo favoring to the selective formation of the hydrotreating catalysts active sites. 

D.6. Metallic Brim States as Active Sites in Hydrotreating Catalysts... 

The natural material catalysts exhibit similar metal removal selectivity patterns as conventional hydrotreating catalysts. Vanadium removal activity is higher than that of nickel and overall activity increases with hydrogen pressure. Thus little change in intrinsic demetallation pathways is indicated with these materials. However, in contrast to CoMo/A1203, the nodule catalysts are only moderately active for HDS and essentially inactive for HDN. 

Formation of Coke on Hydrotreating Catalysts and its Effect on Activity... 

To this end initial adsorption experiments were performed in order to study coke in the very first period of the catalyst life, Also aged hydrotreating catalysts were characterized. These studies combined with model compound coking and activity studies were used to obtain more insight into the properties of the deposits on the working catalyst. 

Model compound testing was used to study the role of coke in the deactivation of hydrotreating catalysts. The approach used was to pick one of the compounds used in the initial adsorption experiments that gave a measurable increase in coke over a period of a few days and to study whether the rate of coking was affected by the presence of a sulfur or nitrogen compound that could be used to measure activity (HDS and HDNt respectively). If the rate of coking was unaffected, the activity was measured as a function of time, It would then be possible to relate activity to coke content. 

An industrially spent hydrotreating catalyst from naphtha service was extracted with tetrahydrofuran, carbon dioxide, pyridine and sulfur dioxide under subcritical and supercritical conditions. After extraction, the catalyst activity, coke content, and pore characteristics were measured. Tetrahydrofuran was not effective in the removal of coke from catalyst, but the other three solvents could remove from 18% to 54% of the coke from catalyst. 

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