Catalyst supports, supported catalysts, and a method of preparing and using the catalysts for the demetallation of metal-containing heavy oil feedstocks are disclosed. The catalyst supports comprise precipitated alumina prepared by a low temperature pH swing process. A large portion of the pore volume of the catalyst supports has pores with a diameter in the range of about 200 Å to about 500 Å. Catalysts prepared from the supports of the invention exhibit improved catalytic activity and stability to remove metals from heavy hydrocarbon feedstocks during a hydroconversion process. The catalysts also exhibit increased sulfur and MCR conversion during the hydroconversion process.