SELECTIVE DISSOLUTION OF CRITICAL METALS FROM DIESEL AND NAPTHA SPENTHYDRODESULFURIZATION CATALYSTS

The petroleum refining industry makes extensive use of catalysts, cont aining critical metals, such as, Mo, Co and Ni, for the desulphurizati on of various oil fractions. The selective recovery of these metals fr om two uncrushed and at low temperature calcined industrial hydrodesul phurization (Mo-Co/Al2O3 and Mo-Ni/Al2O3-SiO2) catalysts was studied, applying a two-step alkali-acid procedure. Fundamental kinetic aspects of the process, such as, reaction time, leaching reagents concentrati on and reaction temperature, were studied. Recoveries up to 97% for Mo and up to 92% for Co or Ni in separate solutions were achieved, using low cost and easily available reagents, such as sodium hydroxide and sulphuric acid.