Sustainable recovery of nickel, molybdenum, and vanadium from spent hydroprocessing catalysts by an integrated selective route

• Published in: Journal of cleaner production 2020-04, Vol.252, p.119763, Article 119763
• Main Authors: Zhang, Di, Liu, Yunqing, Hu, Qizhao, Ke, Xinquan, Yuan, Shenghua, Liu, Shijun, Ji, Xiaobo, Hu, Jiugang
• Format: Article
• Language: English
• Subjects: Ammoniacal leaching; Flower-like V2O5; Selective recovery; Solvent extraction; Spent hydroprocessing catalysts
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2019.119763

In this work, nickel, molybdenum, and vanadium were selectively extracted from the spent hydroprocessing catalysts (Ni–Mo–V/Al2O3) by using an integrated ammoniacal leaching and selective separation process. After roasted at 400 °C, molybdenum and nickel were selectively extracted by ammoniacal liquors at pH 9 in the first step and the leaching efficiency of nickel and molybdenum was 88.74% and 97.92%, respectively. In the second leaching step, vanadium was selectively extracted from the residues by ammoniacal liquors containing 6% (v/v) H2O2 at pH 12 and the leaching efficiency of vanadium was above 97.13%. The selective separation of nickel in the leachate was achieved at pH of 6.86 by solvent extraction with 2 mol/L neo-decanoic acid (Versatic10) in sulfonated kerosene, where the extraction efficiency was about 96% and the complete stripping of Ni was achieved with 3 mol/L NaOH to directly obtain Ni(OH)2 precipitates. The molybdenum in extraction raffinate can be recovered by barium molybdate precipitate method. The vanadium-bearing leachate was further treated to obtain ammonium metavanadate precursor by adding HNO3 to adjust the solution pH to 7.5–9 and then flower-like V2O5 was obtained after calcination at 500 °C. Based on the above highly-selective treatment process, nickel, molybdenum, and vanadium in the spent hydroprocessing catalysts were recovered as the corresponding metal compounds, respectively. •Ni, Mo, and V were selectively extracted from the spent hydroprocessing catalysts.•An integrated ammoniacal leaching and selective separation process was proposed.•Vanadium leaching can be greatly improved by adding H2O2 at pH 9 and pH 12.•Ni(OH)2, BaMoO4, and V2O5 compounds can be obtained from the proposed recovery route.