Recycling of Mo and V from Spent Hydrogenation Catalysts via a One-Step Soda-Roasting Process

Spent hydrogenation catalysts (SHC) are solid wastes from petroleum refining but contain high levels of MoS₂ and V₂S₃, offering a valuable source for recycling Mo, V, and S. This study presented a one-step soda-roasting process designed to achieve simultaneous desulfurization and sodium conversion of SHC. During roasting, MoS₂ and V₂S₃ were oxidized and reacted with Na₂CO₃ to form water-soluble Na₂MoO₄ and NaVO₃, thereby enhancing the leaching efficiency of Mo and V. Increasing temperature favored spontaneous desulfurization and prevents its fixation in the calcine. Ni was immobilized as stable NiAl₂O₄, while alumina transformed into α-Al₂O₃, thereby suppressing the leaching of Ni and Al. Response surface methodology was employed to optimize soda-roasting parameters. About 99.55% of S was removed, and 98.26% of V and 99.68% of Mo were leached out, after roasting at 1150 °C for 60 min with Na₂CO₃ dosage molar ratio of 1.21. Compared with conventional multistep roasting, the one-step process generates a net incremental benefit of USD 3.405 million/a at 15 000 t/a, with the extra investment recovered in only 0.12 years. This process provides a direct soda-roasting approach for recovery of Mo, V and removal of S from SHC.