Catalyst deactivation pattern along a residue hydrotreating bench-scale reactor

• The profile of metals and coke through the catalytic bed was determined.
• Metals are stored in midsized pores while coke seems to fill big pores.
• The deactivation extent is closely related to the loss of textural properties.
• Activity of spent catalysts matches the values in the remaining of pore volume.
• An enhancement of HDC activity by regeneration of spent catalysts was found.

An atmospheric residue (312 °C+) was hydrotreated in a bench-scale reactor. After shutdown, spent catalysts of the first bed of the hydrotreating reactor were sampled. A portion of the samples was regenerated. Both spent and regenerated catalysts were characterized by nitrogen physisorption and SEM-EDX. The type of coke deposited on spent catalysts was analyzed by DRIFT. The remaining catalytic activity was evaluated by thiophene HDS and cumene HDC. The profile of metals and coke depositions through the catalytic bed in fresh-basis was determined. The results showed that vanadium and nickel depositions decrease and carbon increases from top to bottom of the bed. It was found that both hard and soft coke amounts increases towards the bed outlet. A tendency of metals to deposit in pores of midsize and coke to fill big pores was observed. Around 25% of the fresh catalyst activity in thiophene HDS and cumene HDC remains in spent catalysts. These results match the values in the remaining of pore volume. Additionally, an enhancement of cumene HDC activity through the regeneration of spent catalysts was noticed.