A preliminary process design and economic assessment of a catalyst rejuvenation process for waste disposal of refinery spent catalysts

The importance of pre-treatment of spent hydrotreating catalysts on metals recovery

“…1,[3][4][5] This explains why discharged spent HDT catalysts are stored under inert atmosphere (N 2 ).…”

“…NiMo and CoMo/Al 2 O 3 are typical examples of spent catalysts coming from hydrotreating (HDT) units. [4][5][6] The lifetime of the catalysts tends to decrease due to the more severe operations required. 3,4,7 Catalyst deactivation is basically due to coke and metals deposition over its surface.…”

“…10 Spent HDT catalysts have been classified as dangerous wastes by the "United States Environmental Protection Agency" (USEPA). [1][2][3][4][5] They may release toxic gases, are subject to spontaneous ignition and present heavy metals and carcinogenic compounds. Even after calcination at high temperature metals such as nickel, vanadium, cobalt and molybdenum may be leached with water.…”

Sulfuric acid baking and leaching of spent Co-Mo/Al2O3 catalyst

“…When activities of these catalysts decline below certain level, they are usually re-generated and reused. However, re-generation and reuse of these catalysts are not feasible after certain cycles; thereafter these are discarded as waste materials from refinery plants [3][4][5]. Global generation of such spent hydroprocessing catalysts is estimated to be 150-170,000 tonnes per year [6].…”

Synthesis of NiMo/Al2O3 Nanocatalyst by one pot Co-impregnation Route

“…Many types of (HDS) are now used in the oil industry depending on feed properties and reaction conditions. The most important factor in hydrotreating is catalytic action and performance [6,7,8] .…”