Co-Mo on alumina

Aj Hydrodesulfurization Removal of sulfur compounds from crude oil by reaction with hydrogen on CO - Mo on alumina. 

Hydrotreating of Tacoma filtrate was investigated over both an inert, low-surface-area alumina and a silica-promoted cobalt-molybdena (Co-Mo) on alumina catalyst. The filtrate feed used in this study was from a run made at Tacoma on June 21,1976 operating with Kentucky Colonial coal as feed at 843°F, 1500 psig at a solvent to coal ratio of 1.6 1. This... 

Physical Properties of Coked Catalysts. Surface areas for a series of Shell 244 (cobalt-molybdenum (Co-Mo) on alumina) catalysts varying from 0 to 22% coke were determined. The surface area is inversely proportional to coke deposition as shown in Figure 3. The catalysts with 10% coke deposit lose approximately 20% of their original surface areas. 

Figure 2. Coke vs. temperature and pressure. Catalyst used Shell 244 (Co-Mo on alumina).

Catalyst Screening Results. A comparison of the catalysts performance is given in Table VIII. Shell 214, (nickel-molybdenum (Ni-Mo)) on alumina, is the best among the five types of catalysts tested with Shell 244, Co-Mo on alumina being nearly as good. It achieved high removal of heteroatoms with the least hydrogen consumption. The... 

Figure 5. Trickle-bed hydrotreating results. Catalyst used Shell 244 catalyst (Co-Mo on alumina). Run condition 2500 psi, 400°C, and 1 WHSV. (D), Sulfur removal (O), nitrogen removal (A), oxygen removal (0), asphaltenes removal (Q), API gravity (X), atomic H/C ratio.

Catalysts with a high loading of impregnated metals, such as Ni-Mo and Co-Mo on alumina hydrotreatment catalysts, necessarily suffer from matrix modifications with variations in metal content. As wc are not limited in this instance by the need to analyse trace elements, the solid phase dilution method can be used to attenuate the matrix effects. 

Figure 9 shows rapid KDN deactivation of Co-Mo catalysts on both alumina and on carbon. The expectation that the carbon catalyst would deactivate quickly because it has a larger median pore diameter was observed. However, deactivation of the Co-Mo on alumina catalyst in Figure 9 was much faster than the Ni-Mo on alumina catalyst in Figure 8. An explanation for these differences may involve both the chemical coanposition of the catalyst surface as well as the diffusion path length. However, the deactivation of the 3.2 mm Co-Mo on alumina catalyst in Figure 9 was much faster than the 3.2 mm Ni-Mo on almnina catalyst in Figure 8. Since Ni-Mo is often considered to be a better hydrogenation catalyst more hydrogenation of adsorbed carbonaceous species, less coke formation, and less deactivation might be expected.

Figure 9. Nitrogen Conversion (wt %) Versus Time on Stream (hours) - open circles represent 3,2 mm extrudates of Co-Mo on alumina, solid squares represent Co-Mo supported on carbon.

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