Hydrocarbon-soluble, bimetallic catalyst precursors and methods for making same

A method for making a bimetallic catalyst precursor for hydroprocessing heavy oil, comprising:

• (i) providing a plurality of molybdenum atoms and a plurality of secondary transition metal atoms, wherein the secondary transition metal atoms comprise one or more transition metals other than molybdenum, wherein at least a portion of the secondary transition metal atoms form precipitated metal if heated together with an organic agent at or above a precipitation temperature for the secondary transition metal atoms;
• (ii) providing an organic agent comprising a plurality of organic molecules, each organic molecule having at least one functional group that is reactive to the molybdenum atoms and the secondary transition metal atoms;
• (iii) reacting the molybdenum atoms with a portion of the organic agent at a temperature range from about 100° C. to about 300° C. to yield a hydrocarbon-soluble molybdenum salt;
• and
• (iv) mixing the secondary transition metal atoms with the molybdenum salt and reacting the secondary transition metal atoms with a second portion of the organic agent to yield a hydrocarbon-soluble secondary transition metal salt mixed with the molybdenum salt and thereby form the bimetallic catalyst precursor, wherein the reaction temperature during step (iv) is less than the reaction temperature during step (iii) and also less than the precipitation temperature for the secondary transition metal atoms so that the secondary transition metal atoms preferentially react with the organic agent to form the hydrocarbon-soluble secondary transition metal salt rather than precipitated metal.