Process for recovering boehmite and y-AI2O3 from spent hydroprocessing catalysts

A method for recovering boehmite and/or γ-alumina from alumina-supported spent catalysts, said method consisting of the following steps:

• a.) providing a mass of alumina-supported spent catalysts containing from 1-10 wt. % molybdenum, 1-6 wt. % nickel, 1-20 wt. % vanadium and 1-30 wt. % carbonaceous deposits containing carbon, sulfur and oil residue;
• b.) removing oil residue from said spent catalysts by washing with naphtha;
• c.) drying the spent catalysts after removal of the oil residue;
• d.) grinding the dried spent catalysts after removal of the oil residue to produce a particle size of less than 500 microns;
• e.) removing carbonaceous deposits by decoking under a temperature range of 370-500° C. to produce a residue;
• f.) roasting the residue from step (e.) with soda ash at a temperature of 750° C.;
• g.) filtering the roasted residue for removal of extracted vanadium and molybdenum in which hot water has been added leaving a NiO/Al2O3 residue;
• h.) digestion of the NiO/Al2O3 residue in NaOH;
• i.) filtering the digested NiO/Al2O3 to obtain nickel oxide as a solid residue and alumina as sodium aluminate in the filtrate;
• j.) precipitating pseudoboehmite by adding CO2;
• k.) hydrothermal treatment of the pseudoboehmite to obtain well crystallized boehmite from step j;
• and
• l.) filtering, drying and subsequently calcining the filtered and dried well crystallized boehmite from step k at 500° C. for 4 hours to produce γ-alumina with surface area greater than 240 m2/g, a pore volume of greater than 0.75 ml/g and a mean pore diameter in the range of 100-110 Å.