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.