Advancing total management of oily spent hydroprocessing catalyst: From hazardous waste to circular and...

Hydroprocessing technology is essential for refining crude oil, playing a critical role in improving oil quality. This process consumes large quantities of catalysts, which become spent hydroprocessing catalysts because of deactivation. These spent catalysts, containing substantial amounts of residual oil, coke, and heavy metals, are recognized as challenging hazardous solid waste. However, they also contain critical rare metals and crude oil, making them an important and valuable secondary resource. Managing these ever-growing volumes of spent catalysts to ensure safe disposal of hazardous waste while maximizing circular and eco-sustainable utilization has become a pressing global challenge and key research focus. Therefore, this paper provides a comprehensive review of popular technologies and recent advancements in managing oily spent hydroprocessing catalysts, aiming to achieve the dual goals of environmental protection and maximizing resource utilization. This review first introduces the types and functions of hydroprocessing technology and catalysts and explores the causes and hazards associated with deactivating hydroprocessing catalysts. It thoroughly discusses popular and innovative emerging technologies in deoiling, regeneration, high-value reuse, and recovery metals from spent catalysts, highlighting the strengths and challenges of each method. The review concludes with outlook on future directions, proposing directions and considerations for advancing total management of oily spent hydroprocessing catalyst.