Research on Leaching of V and Ni in Spent FCC Catalyst Using Oxalic Acid/H2O2 under Microwave-Assisted Conditions

In this work, we propose a rapid and facile method (oxalic acid leaching under microwave-assisted conditions) to study the simultaneous recovery of vanadium (V) and nickel (Ni) from spent fluid catalytic cracking (SFCC) catalysts. The central issue in all of these studies is to test the modeling and experimental results of excellent fitting effects of leaching parameters. In order to maximize the recovery of V and Ni, leaching parameters were investigated. Furthermore, response surface methodology (RSM) was applied to optimize the leaching parameters. The optimum conditions obtained were as follows: oxalic acid concentration of 1.8 mol/L; leaching time of 91 min; microwave-assisted power of 500 W; H2O2 concentration of 1.1 mol/L. The maximum leaching rates of V and Ni reached the values of 91.36% and 46.35%, respectively. The results showed that microwave energy was very helpful in improving the efficiency of the leaching process and shortening the leaching time by 75%. According to the shrinking core model, test results showed that a surface chemical reaction was the controlling step of the overall reaction kinetics. The activation energy of V and Ni during the leaching reaction was calculated to be 3.28 and 34.41 kJ/mol, respectively.