Accelerated deactivation of hydrotreating catalysts: comparison to long-term deactivation in a commercial plant

Accelerated deactivation tests of a laboratory prepared Co–Mo/Al₂O₃ catalyst were performed using three kinds of petroleum feedstocks. A high reaction temperature employed in the accelerated aging resulted in large amounts of carbonaceous deposition with high aromaticity, which were found to be the major deactivation cause. However, the effect of carbonaceous deposition during accelerated deactivation tests might have been overestimated compared with that during practical hydrotreating. When the catalysts were aged in a H₂S/H₂ stream without petroleum under the same reaction conditions, the crystal growth of MoS₂ layered structures was significant, but this rather resulted in an increase of both k (HDS) and k (HY). It was also suggested that the crystal growth during a commercial hydrotreating run was unlikely to be the major cause of catalyst deactivation.