Method of preparing high activity hydrotreating catalysts

A method for preparing a catalyst precursor composition suitable for hydrotreating hydrocarbon feedstocks, the method comprising:

• (a) impregnating an inorganic catalyst support, the support comprising a porous inorganic refractory selected from the group consisting of silica, alumina, alumina-silica, and crystalline silica-alumina with an aqueous solution containing (i) a salt of a Group VIB metal selected from Mo and W, (ii) a salt of a Group VIII metal selected from Co and Ni, and (iii) an organic acid wherein the organic acid is a hydroxycarboxylic acid selected from the group consisting of glycolic acid, lactic acid, glyceric acid, gluconic acid, malic acid, tartaric acid, mucic acid, and citric acid;
• (b) drying the impregnated catalyst support, thereby resulting in a metal-organic component on a dried catalyst precursor;
• (c) calcining the dried catalyst precursor in an oxygen-containing atmosphere for a time and temperature sufficient to oxidize some but not all of the organic portion of the metal-organic component, thereby resulting in a partially oxidized catalyst precursor having:
• (i) a loss-on-ignition of greater than 1 wt. % and up to 10 wt %;
• and
• (ii) a carbon-as-carboxy to total residual carbon ratio (Ccarboxy/Ctotal) of from 0.10 to 0.19 and determined by X-ray photoelectron spectroscopy;
• and
• wherein:
• (1) loss-on-ignition is determined using a test conducted by heating a sample of the partially oxidized catalyst precursor in an oxygen-containing atmosphere for 1 hour @ 1020° F. (549° C.) and measuring weight loss alter such heating;
• and (2) calcining is carried out for a time of from 1 minute to 1 hour at a temperature of 350° C. to 500° C.