Hydroprocessing catalysts regeneration and recycling

The three typical causes of deactivation of hydroprocessing catalysts are coke, sintering and contamination. The two first can be eliminated by regeneration, the ex situ method being the rule nowadays for a better performance recovery. Regeneration consists in a controlled oxidation which eliminates coke and converts sulfides back to oxides. The main limits to catalyst reuse are the decrease of activity and mechanical properties. Non-contaminated regenerated catalysts can recover activities rather similar to fresh ones, as assessed by a statistical study performed at Eurecat on CoMo catalysts. Nevertheless some new generation catalysts require additional treatments to recover full activity. The handling and transport of spent catalysts to an off-site regeneration facility is currently performed, but requires some precaution as the material is classified as self-heating. At the end of the cycle, spent non-reusable catalysts have to be recycled for metals reclamation. This can be performed either by hydrometallurgical or pyrometallurgical routes.