No abstract

No abstract

The problem of spent fluid catalytic cracking (SFCC) catalyst resource utilization, draws more and more attention to system analysis. SFCC was leached in an oxalic solution for comprehensive utilization. The results showed that for a D50 ≤ 17.34 μm, the catalyst leached for 240 min at 95 °C in the presence of a 2 mol/L oxalic acid solution, and the extent of leaching of V, Ni, Fe, and Al was 73.4%, 32.4%, 48.2%, and 36.8%, respectively. Studies on the occurrence state of the main ions (V, Ni, Fe, and Al) in the leaching solution were presented. Additionally, the separation of the main ions from such a solution by the “solvent extraction-stripping-hydrothermal precipitation-comprehensive recovery of valuable metal” process was studied. The immobilization rates of vanadium and nickel in geopolymers can be obtained using the toxicity characteristic leaching procedure (TCLP) test, and the geopolymers prepared by SFCC leaching residues can be considered a non-hazardous material. A process diagram of the comprehensive utilization of SFCC catalysts is presented.

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.

No abstract