Process optimization and modeling of recycling Mo (VI) from spent Mo-Fe2O3/Al2O3 catalyst by roasting with sodium carbonate using response surface methodology (RSM)

Abstract The oil-containing spent Mo-Fe2O3/Al2O3 catalyst can be deemed as an environmental threat and an attractive source of minerals that can reduce the consumption of natural resources. Herein, recovery of Mo from spent Mo-Fe2O3/Al2O3 catalyst was conducted by the Na2CO3 roast-leach process, response surface methodology (RSM) coupled with central composite design (CCD) was employed to optimize the roasting process and a polynomial equation was derived to predict the response. The three roasting independent variables the roasting temperature, the Na2CO3/sample weight ratio, and the roasting duration were investigated in the Na2CO3 roasting process while water-leaching parameters were identical. The predictions of model showed that the roasting temperature had a major effect on the response with respect to other parameters. According to analysis of variance (ANOVA), the proprosed model equation had shown satisfactory agreement with the experimental data with a correlation coefficient (R2) of 0.9811. The optimum conditions for Mo recovery were predicted to be as the roasting temperature of 771.2 °C, the Na2CO3/sample weight ratio of 2.09 and the roasting duration of 93.56 min. Under the optimum conditions, maximal value of Mo recovery rate was reached as 92.58%.