Experimental, modelling and kinetic study for the recovery of molybdenum from spent (Ni-Mo/Al2O3) catalyst of hydrotreating process

Recovery of molybdenum from spent hydrodesulphurization (HDS) catalyst Ni, Mo/Al₂O₃ of light naphtha was studied using 1 L st.st autoclave reactor. Theoretical and experimental investigation were conducted to study the effect of process all variables. Auto clave reactor used in these experiments was designed and fabricated by researchers group of this work. Experiment design was used by using D-optimal method to reduce the number of the experiments. The optimum leaching conditions (P = 7 bar, T = 77-100 °C, C = 2.333M, P.S.R = 400 μm, MS = 600 rpm and t = 1 h), it is possible to extract 93% of molybdenum from the spent catalyst. Second order polynomial mathematical correlation was employed in the range of the experiments variable by using PLS method with correlation factor of 0.976. Diffusion Reaction Model (DRM) of non-catalytic liquid-solid reaction was discussed. The model equations have been solved by orthogonal collocation and Fifth Order Improved Runge-Kutta Schemes method. The parameters of the model have been estimated by the excess method of analysis. The calculated results based on this model are in good agreement with experimental data.