Recovery of Mo and V from the Spent Catalyst Using Organophosphorus Extractants

The extraction and separation of Mo and V from sulphate media were investigated with phosphorus-based extractants such as D2EHPA, PC88A and Cyanex 272. The extraction was maximum within pH 1–3 and decreased after that pH. After pH 6.0, there was no extraction of Mo and V with the above extractants. The FTIR spectra indicated the bonding of hydroxyl group attached to phosphorus atom in each case which is due to the reaction of the cationic form of Mo (H3MoO4+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{H}}_{3} {\text{MoO}}_{4}^{ + }$$\end{document}) and V (VO2+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{VO}}_{2}^{ + }$$\end{document}) with the extractants. The highest separation factor was obtained with PC 88A. Hence, PC 88A was used for the separation of Mo and V from sulphate leach liquor of hydrodesulphurization spent catalyst. The McCabe–Thiele plot with 0.5 M PC 88A indicated three stages at A/O ratio of 2:1. Vanadium was selectively stripped with 0.5% H2SO4 followed by Mo stripping with NH4OH + (NH4)2CO3.