Hydrotreating Catalyst Rejuvenation via MoO3-H3PO4 Impregnation

The patent applies preliminary action by conducting an oxidative treatment step before the main rejuvenation impregnation. The spent catalyst is first treated with an oxidative atmosphere (air or oxygen-containing gas) at elevated temperature (200-400°C) to remove carbon deposits and restore metal dispersion. This preliminary oxidation prevents metal agglomerate formation during subsequent impregnation with the rejuvenating solution containing molybdenum and phosphorus compounds, thereby maintaining high catalyst activity without requiring overly complex multi-step procedures.

The patent employs parameter changes by optimizing and controlling specific process variables: the oxidative treatment temperature (200-400°C), the composition of the rejuvenating solution (molybdenum compounds at 0.1-1.0 mmol/g catalyst, phosphorus compounds at 0.05-0.5 mmol/g catalyst), and the aging time (2-24 hours at room temperature). By precisely controlling these parameters, the patent achieves effective catalyst activity restoration through a relatively simple two-step process, avoiding the need for complex multi-parameter optimization while ensuring reliable rejuvenation results.

The patent converts the potential harm of metal agglomerate formation during regeneration into a benefit by using the oxidative treatment to deliberately remove carbon deposits that cause deactivation, while simultaneously adding molybdenum and phosphorus compounds that prevent agglomeration. The oxidative atmosphere, which could potentially over-oxidize and damage the catalyst, is controlled at moderate temperatures (200-400°C) to selectively remove carbon while preserving the metal sulfide structure. This approach transforms the regeneration process from a potentially damaging operation into a beneficial rejuvenation step that restores and even enhances catalyst activity.