Methods of sulfurizing metal containing particles in the absence of hydrogen are described. One method includes contacting a bed of metal containing particles with a gaseous stream comprising hydrogen sulfide and inert gas under reaction conditions sufficient to produce sulfided metal containing particles. The gaseous stream is introduced into a vertical reactor at an inlet positioned at the bottom portion of the reactor and any unreacted hydrogen sulfide and inert gas is removed at an outlet positioned above the inlet. The sulfided metal containing particles can be removed from the reactor and stored.